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Journal of Chemical Technology and Biotechnology

Wiley Online Library : Journal of Chemical Technology and Biotechnology

Published: 2017-10-01T00:00:00-05:00


Cork processing wastewaters components fractioned by ultrafiltration membranes-Studies of antioxidant and antitumoral activity


BACKGROUND Cork processing wastewater is an environmental problem due to high content in organic matter, such as sugars and non-biodegradable compounds like polyphenols (PPs), namely tannins. Membrane technology aimed valorisation of the wastewaters components, concentrate stream, and simultaneously offer a pre-treatment of the wastewater, permeate stream. In this work, it was also envisaged the identification of bioactive PPs. Several fractions of cork processing wastewaters were generated using two cellulose acetate ultrafiltration membranes of 3 kDa and 74 kDa for PPs isolation according to nature and molecular weights. The membranes were prepared by the phase inversion method and fractionation was made in concentration and diafiltration modes. The wastewater and the fractions were analyzed in terms of Total Organic Carbon, Total Phenols, Tannins and Total Polysaccharides content and the compounds present were identified by FTIR, LC-MS and quantified by HPLC-DAD. RESULTS Compounds such as quinic, gallic, protocatechuic, brevifolin carboxylic and ellagic acids were identified as the major compounds in cork wastewater. The wastewater and the fractions were tested for antioxidant activity and for capacity to inhibit the proliferation of the growth of human breast carcinoma cell lines, MCF-7. The fractions revealed high antioxidant activity with EC50 values ranging from 1.174 ± 0.069 to 1.943 ± 0.179 mg/mgDPPH. The fractions demonstrated to be efficient as cell proliferation inhibitors, with values of IC50 ranging from 0.20 ± 0.003 to 0.46 ± 0.02 mg/mL. CONCLUSION The process reported demonstrates that PPs compounds can be recovered from cork effluent and further reused as high-value bioactive compounds.

Enhanced succinic acid production from polyacrylamide-pretreated cane molasses in microbial electrolysis cells


BACKGROUND Microbial electrolysis cells (MECs) are bioelectrochemical reactors in which chemical energy stored in organic compounds is converted to hydrogen through biocatalytic oxidation by microorganisms. This study is the first to report on the practical application of an electric MEC bioreactor to succinic acid anaerobic fed-batch fermentation from polyacrylamide-pretreated cane molasses by Actinobacillus succinogenes (130Z). RESULTS When molasses was used as the carbon source with an initial sugar concentration of 15 g/L, the succinic acid concentration was 22.4% higher in electric MECs than in non-electric MECs. However, the high molasses concentration inhibited the function of MECs. Nevertheless, anionic polyacrylamide (APAM) pretreatment of molasses was noted to be effective for succinic acid production in MECs even at an initial sugar concentration of 75 g/L. Therefore, fed-batch fermentation of APAM-pretreated cane molasses with electric MECs at −1.0 V was performed, and a succinic acid concentration of 83.67 g/L and productivity of 1.743 g/L · h were obtained, which were 20.7% and 505% higher than those achieved in non-electric MECs and without pretreated molasses in MECs, respectively. CONCLUSION The succinic acid concentration is significant increased in electric MECs. Polyacrylamide treatment strategy can resolve the inhibition of high molasses concentration to succinic acid production in MECs and might be an effective method for improvement of chemical production from high hydrolysate content using MECs. Fed-batch fermentation with polyacrylamide-pretreated cane molasses in electric MECs is noted to be ideal to achieve further increase in succinic acid concentration and yield.

The effect of furfural and 5-hydroxymethyl furfural on butyric acid fermentation by Clostridium tyrobutyricum


BACKGROUND Potential inhibitory effects of byproducts from lignocellulosic hydrolysis process, including furfural and 5-hydroxymethyl furfural (HMF) on butyric acid fermentation by Clostridium tyrobutyricum were studied by adding furfural (0, 0.3, 0.6, 0.9 and 1.2 g L−1) and HMF (0, 0.6, 1.2, 1.8 and 2.4 g L−1) separately into the xylose medium. RESULTS Increases in furfural or HMF concentration led to reduced butyric acid productivity. Delays on cell growth and xylose consumption were also noticed with increasing concentrations of furfural and HMF. Complete inhibition on C. tyrobutyricum fermentation was observed at 1.2 g L−1 of furfural, while HMF showed less severe effects that C. tyrobutyricum could tolerate up to 2.4 g L−1 of HMF. Both furfural and HMF could be metabolized by C. tyrobutyricum. CONCLUSION Furfural with concentrations higher than 0.3 g L−1 and HMF with concentrations higher than 0.6 g L−1 can significantly inhibit the butyric acid fermentation of C. tyrobutyricum and furfural had more severe effects in terms of cell growth and metabolisms.

Kinetic characterization of Scenedesmus quadricauda under low irradiation conditions


BACKGROUND The kinetic parameters of a model culture of S. quadricauda were assessed under low light irradiation conditions. A simple and reliable method was developed for the kinetic characterization, which avoided CO2 mass transfer limitations and allowed for retrieving accurate kinetic data. Biomass and oxygen yields were also assessed. RESULTS A maximum specific CO2 uptake rate of 0.015 ± 0.002 gCO2 gVS−1 h−1 and half-saturation constant of 91 ± 13 gCO2 mLiq−3 were determined for S. quadricauda at a light intensity of 30 µmol m−2 s−1 at 25 °C. The biomass and oxygen yields ranged from 0.045–0.137 gVS gCO2−1 and 0.211–0.505 gO2 gCO2−1, respectively, both parameters being dependent on the initial CO2 concentration used. CONCLUSION A simple and reliable methodology for the kinetic characterization of microalgal cultures was developed and tested. We herein demonstrated that the maximum specific CO2 uptake rate of S. quadricauda at 30 µmol m−2 s−1 was higher than previous values reported for Scenedesmus cultures exposed to light intensities up to 4.5 times higher but limited by CO2 mass transfer. The methodology and results here obtained are useful towards determining whether is recommendable to implement a given microalgal-based process under low irradiance conditions or not.

Enhanced heterologous expression of Trichoderma reesei Cel5A / Cel6A in Pichia pastoris with extracellular co-expression of Vitreoscilla hemoglobin


BACKGROUND The deficiency of family 5 endoglucanase (Cel5A) and family 6 cellobiohydrolase (Cel6A) has become a key limiting factor on cellulase enzymatic hydrolysis in bioprocessing of cellulosic biomass. To improve the production of Trichoderma reesei Cel5A / Cel6A, a Vitreoscilla hemoglobin (VHb) gene was tried to co-express extracellularly for the first time with Cel5A / Cel6A in P. pastoris GS115. RESULTS Newly constructed recombinant of co-expressing Cel5A / Cel6A extracellularly with VHb was consistent with the single expression at some key variables of culture condition, i.e., inoculum size, initial pH, culture temperature and methanol concentration. Comparing their single expression, the CMCase activity of co-expressed Cel5A and Cel6A enzymes enhanced by 40% and 30%, respectively. With high-cell-density fed-batch (HCDFB) fermentation, the co-expressed Cel5A enzyme activity was 366.8 U mL−1 with 4.3 g L−1 protein content and the Cel6A enzyme activity reached 1.3 U mL−1 with 2.23 g L−1 protein content. The two co-expressed enzyme activities were enhanced by 35% and 20%, respectively, as compared to the single expression. CONCLUSION VHb protein capable of binding oxygen can be successfully co-expressed extracellularly with other target proteins. The co-expression of VHb with recombinant Cel5A / Cel6A is efficient at improving oxygen-limited condition and thus enzyme production in both shake-flask and HCDFB fermentation.

Screening of glycoside hydrolases and ionic liquids for fibre modification


BACKGROUND This study elaborates the possibility to apply combined ionic liquid and enzyme treatments for pulp fibre modification. The approach involves swelling of fibre surfaces with ionic liquid (IL) followed by enzymatic modification of the disrupted fibre surface using carbohydrate active enzymes. RESULTS The capacity of seven cellulose-dissolving or cellulose-swelling ionic liquids to swell pulp fibres was compared. In addition, thirteen cellulases and five xylanases were screened for their IL tolerance, which determines their applicability in combined or sequential IL-enzyme treatments of fibres. Among the studied ionic liquids, 1-ethyl-3-methylimidazolium dimethylphopshate ([EMIM]DMP) and 1,3-dimethylimidazolium dimethylphosphate ([DMIM]DMP) had the strongest effect on fibre swelling. These solvents were also found to be the least inactivating for the studied enzymes. CONCLUSION Enzyme compatibility and cellulose-dissolving capability are not two conflicting properties of an ionic liquid.

Catalytic distillation for esterification of acetic acid with ethanol: Promising SS-fiber@HZSM-5 catalytic packings and experimental optimization via response surface methodology


BACKGROUND Catalytic distillation (CD) has been received as an inviting green chemical process for numerous catalytic esterification reactions. Rendering novel structured CD packings is particularly desirable but remains challenging. RESULTS We present a microfibrous-structured HZSM-5 solid acid catalyst as CD packings and demonstrate its separation and esterification reaction efficiency for producing ethyl acetate from acetic acid and ethanol. The factorial design based on response surface methodology is employed for fast determination of optimum reaction conditions, which is working effectively and efficiently. Such structured catalyst packings are obtained by direct growth of zeolite onto the θ-ring analogues shaped from a microfibrous-structure consisting of 15 vol% 20 µm stainless-steel-fiber (SS-fiber) and 85 vol% voidage. CONCLUSION The SS-fiber@HZSM-5 packings provide a unique combination of instantaneous distillation and desired catalytic properties with respect to stability, adequate acidic sites and high mass/heat transfer, and therefore work efficiently and effectively. High total (95.9%) and actual (90.9%) yields of ethyl acetate with 89.8% purity are achievable while the high CD efficiency was well-preserved after at least 240 h over 30 consecutive batch runs.

Novel Aspects and Future Trends in The Use of Aqueous Two-Phase System as a Bioengineering Tool


Traditionally, ATPS have been used as a liquid-liquid extraction technique for the primary recovery and purification of biological samples. The enormous potential of their usage comes with great economical and technical advantages mainly due to the mild physicochemical environment. Nowadays, the use of ATPS as a bioengineering technique is approaching an era where new possibilities are being explored to maximize their use and implementation in the development of novel practical applications and tools. In this context, “intelligent” polymers are being used as phase forming chemicals in ATPS in route to process integration. Extractive fermentation in ATPS is being re-evaluated with the aim of effectively growing microorganisms while recovering their fermentation products in different phases. ATPS are also being used as a tool for refolding of proteins. There are also several innovative efforts being made towards implementing this bioengineering tool as a continuous process moving away from traditional batch operations. In general, the possibilities of implementing ATPS in different bioprocessing aspects are growing considerably and gain importance. This review aims to present the novel trends in the use and development of ATPS strategies as complete bioengineering tools and to provide a full perspective of their possibilities in the near future.

Effects of metabolic engineering on downstream processing operational cost and energy consumption: the case of Escherichia coli's glycerol conversion to succinic acid


BACKGROUND Succinic acid production has been studied from a metabolic engineering or a downstream processing perspective, separately. The concentration of succinic acid and other by-products obtained after the strain design influences the production cost during the recovery and purification stage. A metabolic engineering-downstream coupling evaluation is important when selecting the metabolic targets for the strain design. In this in silico study, the metabolic engineering of an Escherichia coli strain to produce succinic acid using glycerol as a carbon source in the downstream process was evaluated in terms of operational cost and energy consumption. RESULTS Three strain scenarios were selected using a bi-level linear optimization problem solved by Mixed Integer Linear Programing, and simulated in a transient fashion with dynamic flux balance analysis considering both biomass growth rate (0.3068, 0.0576, 0.1089 1/hr) and succinate productivity (2.7534, 6.0772, 5.5661 mmol/gDW hr), respectively. The results showed that the succinic acid productivity constituted a central parameter when selecting the appropriate gene targets for deletion, despite the presence of organic acids in the downstream process and the biomass growth rate. CONCLUSION A metabolism-downstream coupled model shows that the bioproduct productivity and fermentation time are key points when considering the operational cost and energy consumption involved in the engineering of strains for industrial-scale production.

Hybrid natural systems for treatment of olive mill wastewater


BACKGROUND This study examines the efficiency of various natural systems in treating untreated OMW before it is discharged to the environment. The experimental set-up consisted of two hybrid pilot-scale natural systems. The first hybrid system (HS-A) comprised two open tanks (OTs), one vertical flow (VF) CW and one free water surface flow (FWS) CW and the second one (HS-B) comprised two OTs and one FWS CW. RESULTS Regarding the HS-A system, TSS, COD, TKN and phenols (PHE) removals in the two OTs were 83.0%, 21.6%, 62.3% and 12.9%, and cumulative removals in the VF and FWS CW systems were 52.0%, 54.1%, 44.4% and 60.1%, respectively. Regarding the HS-B system, TSS, COD, TKN and PHE mean removals in the two OTs were 80.7%, 32.2%, 64.1% and 24.7%, and in the FWS CW were 72.0%, 49.4%, 26.9% and 51.1%, respectively. The final pollutant effluent concentrations remained high for disposal in water bodies or reuse for irrigation; further reduction could be achieved by adding additional FWS CWs in series. CONCLUSION Hybrid natural systems can be used in efficiently and economically treating OMW. Such hybrid systems could be applied to small family-owned olive oil producing enterprises for economically treating OMW.

CFD studies on hydrodynamic characteristics of shaking bioreactors with wide conical bottom


BACKGROUND The disposable bioreactors based on orbital shaking technology have been extensively employed for mammalian cell culture, which proved to be more inexpensive and flexible compared to mechanical stirred-tank bioreactors. It is of great difficulty to evaluate flow parameters quantitatively since the flow field in bioreactors is complicated. RESULTS The flow characteristics of shaking bioreactors with wide conical bottom under different shaking frequency and filling volume were simulated by CFD method. Validity of simulation model was conducted by comparing simulated free-surface shapes and liquid levels with experimental results, and the CFD simulation results are in good agreement with experiment data. CONCLUSION The results show that: turbulence parameters (k and ε) increase with shaking frequency, while they decrease with filling volume proportionally; shaking frequency has no significant effect on specific gas–liquid interface area (a) but positive effect on mass transfer coefficient (kL); the volumetric mass transfer coefficient (kLa) decreases with filling volume because of combined effect of a and kL; the average shear strain rate (SSR) increases with frequency significantly, while it decreases with filling volume. Results also show that SSR of shaking bioreactors is mainly distributed in low range which is acceptable for cell cultivation.

The Biomaker: An entry-level bioprinting device for biotechnological applications


BACKGROUND 3D printing and bioprinting in particular are emerging technologies in the field of biotechnology. The developments of bioprinters and applications lie mostly in the highly observed working fields of tissue engineering and regenerative medicine. Until now only little attention has been paid to the application of 3D bioprinting for the investigation of hydrogel - liquid phase interactions in biotechnological applications. This can mostly be attributed to the need for complex and expensive equipment. RESULTS In this work, an entry-level bioprinter on the base of a commercially available Fused-Filament-Fabrication 3D printer and an easy to handle user interface was designed. This newly developed bioprinter allowed the structuring of bioinks and hydrogels in microwell plates and even complex models were printed. The applicability of the presented printer setup in the field of biotechnology was shown by the encapsulation of β-galactosidase (EC in poly(ethylene glycol) diacrylate based hydrogels. Subsequently, an automated screening of the biocatalytic conversion of the substrate ONPG by the encapsulated enzyme was executed on a liquid handling station. Under varied pH conditions in the surrounding liquid phase highest substrate turnover rates were detected at pH 3 and pH 5 which is in good accordance with previously reported pH optima of β-galactosidase. CONCLUSION This approach shows an easy access to 3D bioprinting in the field of biotechnology and the implementation of 3D printed hydrogels in high-throughput experimentation.

A novel photocatalytic membrane decorated with RGO-Ag-TiO2 for dye degradation and oil-water emulsion separation


BACKGROUD Membrane separation is a most promising process for treatment of dye and oily wastewater if the antifouling capacity and recyclability can be improved. In recent years, the development of photocatalytic materials has provided new methods for the research of membrane technology. RESULTS In this study, a novel photocatalytic membrane decorated with RGO-Ag-TiO2 nanomaterial was fabricated by simple vacuum filtration for degradation of dye and separation of oil-water. Firstly, TiO2 nanowires were prepared for more effective photocatalysis, reduced graphene oxide (RGO)-Ag-TiO2 was fabricated by a facile hydrothermal reaction, then it was directly decorated on cellulose acetate (CA) membrane using polyethylene glycol and glutaraldehyde. CONCLUSION The as-prepared photocatalytic membrane can simultaneously degrade dye and separate oil-water emulsions under visible-light irradiation in a short time. Besides, the membrane has extremely high water flux (191 L·m-2·h-1) and rejection rates (almost 100 %) of dye-oil-water emulsion. More importantly, the photocatalytic membrane shows excellent antifouling capacity and recyclability, and keeps relatively stable dye-oil-water permeation flux (about 27.5 L·m-2·h-1) and high rejection rates (up to 99 %) after 6 cyclic experiments under visible-light irradiation. Overall, the photocatalytic membrane opens new avenue for treatment of wastewater.

Titanium dioxide-coated biochar composites as adsorptive and photocatalytic degradation materials for the removal of aqueous organic pollutants


BACKGROUND In this article, we report the synthesis and characterization of titanium dioxide-coated biochar composites (TBCs) by pyrolysing titanium dioxide-treated biomass prepared by a modified sol-gel method. Their adsorptive and photocatalytic activities were evaluated based on the removal of safranine T (ST) from an aqueous solution with/without UV-light irradiation. RESULTS Characterisation studies suggested that TiO2 was successfully loaded on the biochar substrate. The biochar and TiO2 contents of the composite significantly affected its performance. The ST removal capabilities of the TBCs with 1, 1.5, 2, and 2.5 g of the biomass are 1.7, 2.3, 7.2, and 2.3 times better than that of the raw biochar, respectively. Thus, the optimum amount of the biomass in TBC-x was determined to be 2 g, with the corresponding sample exhibiting excellent stability, effectiveness over a wide pH range, and a maximum ST removal capacity of 226.7 mg/g. CONCLUSION The loading of TiO2 significantly enhanced the adsorption performance of biochar and the high specific surface area of the biochar synergistically promoted the photocatalytic activity of TiO2. Both adsorption and photocatalytic degradation were confirmed to contribute to the decolourisation of the aqueous solution because of the removal of ST, with the effect of adsorption being slightly higher than that of photocatalysis. The synthesised composite is a promising alternative material for removing chemical contaminants.

Enhanced adsorption behavior of 17β-estradiol by anaerobic granular sludge combined with zero-valent iron


BACKGROUND The natural estrogen 17 β-estradiol (E2) is of great environmental concern. Batch experiments were conducted to study the adsorption of E2 by anaerobic granular sludge (AnGS) combined with zero-valent iron (ZVI). The enhancement mechanism of ZVI on E2 adsorption by AnGS was also analyzed. RESULTS E2 adsorption efficiency with ZVI was 48% higher than that without ZVI. The optimal condition for high E2 adsorption efficiency (92.21%) and high equilibrium adsorption capacity (4.92 μg·gVSS-1) was rZVI/AnGS 1.33, pH 6, and temperature 25°C. E2 adsorption by ZVI/AnGS was a spontaneous and exothermic process. The process was well described by the Freundlich isotherm. CONCLUSION The addition of suitable amount of ZVI enhanced E2 adsorption by AnGS.

Optimization of Sulfide-Based Autotrophic Denitrification Process in an Anaerobic Baffled Reactor


BACKGROUND High SO42-, COD, and nitrogen containing wastewater treatment requires different bacterial groups and environmental conditions, which can be achieved by sequential separate processes. This study examined the simultaneous removal of SO42-, COD and nitrogen in a four-compartment ABR, which allowed enrichment of different group of bacteria in each compartment. Feed COD and SO42- concentrations were kept constant at 1200 and 1500 mg/L, corresponding to COD/SO4-2 ratio of 0.8. Initially, ABR was tested at varying influent ammonium concentrations (25-1500 mg NH4+-N/L). Further, the third compartment of ABR was supplemented with nitrate under varying loading rates (60-300 mgNO3--N/L.d) for autotrophic denitrification with the sulfide produced in the previous compartments. This kind of application mimicked the internal recirculation of nitrate, which can be generated via nitrification of ABR effluent. RESULTS High sulfate reduction efficiencies (over 86%) were observed up to 1000 mg/L NH4+-N, however, 1500mg/L NH4+-N caused decrease in reduction efficiency. Optimum nitrate loading rate was determined as 146 mgNO3--N/L.d at molar N/S ratio of 0.42, corresponding to 100% nitrate, 83% sulfate, and 79% COD removals. Nitrate removal decreased at higher nitrate loadings and high sulfate generation arising from sulfide oxidation was observed. CONCLUSION Sulfate and COD removals together with efficient sulfide-based autotrophic denitrification were succeeded in a single reactor configuration at S/N ratio of 0.42. The developed process has the potential to be used in filed scale applications.

Oxalate degradation by alkaliphilic biofilms acclimatised to nitrogen-supplemented and nitrogen-deficient conditions


BACKGROUND Sodium oxalate is a key organic contaminant in many industrial wastewater such as alumina industry, which diminish the process yields and product quality. Given that Bayer process liquor is typically deficient in nitrogen (N), there is external supplementation of N in current full-scale biological treatment processes. This study, for the first time examines oxalate degradation under N deficient conditions in a comparative study using two parallel biofilm-reactors, one N-supplemented and the other under N-deficient conditions. Oxalate degradation rates and oxygen uptake rates (OUR) were determined at different bulk water dissolve oxygen (DO) set-points. RESULTS The results revealed that oxalate removal rates (33 – 111 mg/h.g biomass) linearly correlate with OUR (0 – 70 mg O2/h.g biomass) in the N-supplemented reactor. However, in the N-deficient reactor, a linear increase of oxalate removal was recorded only with DO upto ≤ 3 mg/L. Surprisingly, anaerobic oxalate removal was evident even in the presence of DO (up to 8 mg/L) in both reactors. Further elucidation revealed formate, acetate and methane by-products during anaerobic oxalate removal in both reactors. CONCLUSION This study revealed the feasibility of aerobic oxalate oxidation and fermentation under alkaline and N-deficient conditions. Further, this study confirms the critical role of DO in aerobic oxalate biodegradation.

Novel Microbial and Root Mediated Green Synthesis of TiO2 nanoparticles and its Application in Wastewater Remediation


BACKGROUND Rhizosphere is a natural phenomenon which has been identified as plant assisted bioremediation and comprises of bacteria, fungi and actinomycetes along the root zone. Rhizosphere can be enhanced by providing the nutrients and favourable environmental condition and is considered as an ecological remediation unit. In the present study, mycorrhizal sorghum roots and bacterial strains present therein have been used as a natural source for the synthesis of photocatalytic TiO2 nanoparticles. RESULTS The microorganisms from the root zone of the rhizosphere were isolated and identified by 16srDNA. The microorganisms Micrococcus lylae (MF1), Micrococcus aloeverae (MF2), Cellulosimicrobium sp. (MF3), their consortium and the root extracts were found to be effective for synthesis of TiO2 nanoparticles. The synthesized TiO2 nanoparticles were characterized by XRD, TEM and FTIR. These synthesized nanoparticles were used for photodegradation of methyl orange dye under the influence of UV light in a reactor. CONCLUSION The rhizospheric microorganisms and roots have been established as novel natural source for synthesis of TiO2 nanoparticles and were found to be effective for degradation of toxic methyl orange dye. This green synthesis of TiO2 nanoparticles is beneficial for hazardous wastewater remediation to clean up the environment.

Struvite precipitation and COD reduction in a 2-Step Treatment of Olive Mill Wastewater


Background In the present work, a combination of several physicochemical methods has been applied aiming at recovering phosphorus from OMW in the form of struvite (NH4MgPO4·6H2O, MAP) and at the same time achieving reduction of the Chemical Oxygen Demand (COD) of the wastes. Phosphorus is a valuable raw material used for the production of fertilizers and numerous other products. Results The experiments were conducted in a two-stage process, over a pH range between 5 and 10. The first step consisted of a batch process, in which MgCl2 or MgSO4 were used as coagulants of suspended particles of the OMW. During the second step, the nitrogen source (NH4OH(aq)) was added to the supernatant and solid precipitation took place without delay. The measured COD values of the fluid phase of the OMW was reduced up to 73% of the initial value, while the final crystalline product consisted of a mixture of struvite and dittmarite (NH4MgPO4·H2O). Conclusion Over 90% dissolved phosphorus recovery from OMW samples in the form of struvite was achieved through the application of a 2-step process together with a significant reduction of the COD of initial raw wastewaters.

Study on the Properties of Adsorption of SO2- Thermal Regeneration Cycle of Activated Coke Modified by Oxidization


BACKGROUND In order to clarify the effect of thermal regeneration on the desulfurization performance of activated coke, consecutive adsorption of SO2- thermal regeneration cycle experiments were carried out under different thermal conditions in this study. RESULTS Results showed that the decrease of the breakthrough sulfur capacity was not very significant for the cokes except for the first regeneration cycles. From 400°C-600°C, the higher the regeneration temperature was, the better of desulfurization activity of the cokes after regeneration was. Various means (FT-IR, BET, XPS, TGA, SEM and in situ DRIFTS) were used to characterize samples. The results indicated that the desulfurization products were divided into physisorbed SO2, H2SO4 and sulfate. The phenolic hydroxyl and carboxyl groups on the surface of activated cokes could promote the removal of SO2. CONCLUSION The deposition of sulfate resulted in a significant decrease in the sulfur capacity of activated coke after first regeneration. However, the residual amount of sulfate on the activated coke after regeneration would decline with the regeneration temperature increasing. Moreover, the phenolic hydroxyl and carboxyl groups did not disappear after regenerated, resulting in the fact that the desulfurization activity of cokes could maintain relatively stable during the subsequent desulfurization cycle.

Automation and control system for fluid dynamic stability in hollow-fiber membrane bioreactor for cell culture


BACKGROUND In recent years, biochemical and biotechnological engineering has been applied to the culture of human and animal tissue cells, which requires the design, operation and control of complex bioreactors. Hollow fibre membrane bioreactors provide favourable conditions for cellular function and metabolism. To develop bioartificial systems ensuring stable and long-term operation, fluid dynamics and transport phenomena require careful automation strategies. RESULTS Starting from a crossed hollow-fiber membrane bioreactor for the culture of complex cell systems configured to operate manually, a 2x2 liquid level/flow-rate control system is experimentally developed and thoroughly tested for its robustness against liquid level or flow-rate set-point changes and disturbances arising from loop interaction. The automation system is shown to be fast for flow-rate and sufficiently reliable for liquid level (response times of minutes). Limitations are mostly due to flow-rate difference constraints and level sensor noise, both originating from cell culture requirements. Prolonged operation (27 days) of the bioreactor in maintaining human hepatocytes in a three-cell co-culture system is presented and discussed. CONCLUSION The results shown in the present work allow improving the understanding of the dynamic behaviour of a membrane bioreactor for biomedical application and examining the possibility to run the bioreactor under fully automated pre-set conditions smoothly and for extended periods of time.

Synthesis of graphene oxide/ metal-organic frameworks hybrid materials for enhanced removal of Methylenen blue in acidic and alkaline solutions


Background Nowadays, dye wastewater has caused a seriously problem to the environment and human healthy. Considerable amount of colored wastewater has been generated from many industries. Moreover, many dyes in the wastewater are believed to be toxic and even carcinogenic. Therefore, the removal of dyes from wastewater is necessary and urgent. Results Adsorption kinetics, isotherms and intra-particle diffusion model were determined from the experimental data, and the results indicated that pseudo-second-order kinetic model and Langmuir adsorption isotherm matched well for the adsorption of MB onto GO/MOFs. Thermodynamic parameters revealed that the adsorption of MB over GO/MOFs was spontaneous and exothermic. The adsorption capacity could be greatly improved in acidic or alkaline aqueous solution. And the maximum adsorption capacity of GO/MOFs reached 274 mg/g, higher than most of the previously reported adsorbents. Besides, the adsorbent could be used at least five times after washing with ethanol. Conclusion In this paper, our research group successfully utilized microwave-assisted ball milling method to synthesize Ni-MOFs and GO/MOFs. The maximum adsorption amount of GO/MOFs reached 274 mg/g, higher than most of the previously reported adsorbents. Because of electrostatic interaction and acid-base interaction, both acidic and alkaline aqueous solutions were found to be more favorable for adsorption of MB over GO/MOFs, different from the previous reports. Besides, GO/MOFs also showed acceptable reusability after regenerated by ethanol. All these results suggest that the MOFs prepared by microwave-assisted ball milling have a great prospect in the removal of MB from aqueous solution.

Suitability of Pyrolusite as Additive to Activated Coke for Low-Temperature NO Removal


BACKGROUND The pyrolusite was used as addictive to prepare coal-based activated coke for low-temperature NO removal. The pyrolusite modified AC was prepared by blending method, and their denitrification performance were evaluated in lab-scale simulated fix-bed reactor. RESULTS The blending of pyrolusite promoted the SSA and pore structure of AC, even though the MnO2 and Fe2O3 showed inhibitory effects when they blended separately. Both the basic and acid sites of AC-Mn(x) increased due to the participation of the blended MnO2 during the activation, while the blending of Fe2O3 showed inhibited effect. AC-P10 showed the highest NO removal efficiency at 74.2%, which was 32.8%, 27.0% and 24.2% higher than that of AC, AC-Mn4 and AC-Fe6. The operation temperature adaptability and stability of catalysis activity of AC-P10 are prominent. Manganese is the main catalyst of AC-P(x), and Fe is an accelerant to stimulate the catalytic activity of Mn. The extremely high NO removal activity of AC-P(x) was due to the synergistic effect of surface functional groups and metals, but the catalysis of metals played a more important role. CONCLUSION The pyrolusite is suitable to prepare the AC-based denitrification catalyst (AC-P(x)) for SCR NO removal because the Mn and Fe containing in pyrolusite showed synergistic effect.

Enantioseparation with liquid membranes


Background Chiral resolution of racemic products is a challenging and important task in the pharmaceutical, agrochemical, flavor, polymer and fragrances industries. One of the options for these challenging separations is to use liquid membranes. Although liquid membranes are known since almost four decades and have been used for optical resolutions, no comprehensive review has been published about the use of this technology for enantioseparations. Results In this review, the various liquid membrane-related technologies are described and compared, including bulk liquid membranes, emulsion liquid membranes, micelle-extraction and micellar enhanced ultrafiltration, as well as supported liquid membranes. Next to technological advances, an overview of recent developments in chiral recognition chemistry in liquid-liquid equilibria is presented. The following extractant classes have recently been reported in conjunction with chiral separation: cyclodextrines, BINOL's, calixarenes, crown ethers, BINAP's, tartaric acids and ionic liquids. Conclusions The use of two supported (non-liquid) membranes with an inner loop of extract phase appears to be the most stable liquid membrane configuration, allowing for large degree of freedom in operational conditions such as solvent to feed ratio. The library of solvents still needs broadening to make the technology more versatile and based on the variety of successes with catalytically active organometallic complexes, development of new chiral selector systems based on asymmetric catalysis literature is suggested for future selector screening studies.

Inteins as Tools for Tagless and Traceless Protein Purification


The purification of recombinant proteins is a complicated process that requires a thorough understanding of the physical and chemical properties of each protein of interest. The unique characteristics of each protein require the development of a complicated, multi-step process consisting of several orthogonal chromatographic techniques. Although affinity tag methods have been useful in simplifying this process, these approaches have significant drawbacks when tagless proteins are required. Therefore, the development of a flexible, economical, and efficient purification platform for traceless and tagless target proteins would represent a significant advance in bioprocess development. Self-cleaving tags have enabled purification of a broad range of target proteins using simple affinity approaches, but with the ability to ultimately deliver a tagless target protein. Thus these tags potentially offer a purification platform analogous to Protein A, but without the limitation to antibody targets. In this review, we summarize the advances in developing various intein-based self-cleaving tag technologies, their preferred cleavage conditions (reducing agents, pH, temp etc.) and the effect of different target proteins on intein catalytic activity. We also discuss engineered inteins whose activity (protein splicing or cleavage) is stringently controlled/triggered by small molecules, light, or environmental condition such as salt concentration.

Polypyrrole vapor phase polymerization on PVDF membrane surface for conductive membrane preparation and fouling mitigation


Abstract BACKGROUND The conductive membrane, such as carbon material modified membrane and nickel metal film could be used for membrane fouling mitigation and energy generation during filtration. But it is necessary to simplify the preparing process and reduce the cost for practical application. So the conducting polymer polypyrrole was polymerized on PVDF membrane surface for conductive membrane preparation via vapor phase polymerization in this study. RESULTS After modification, the pure water flux was reduced from 3393.26 ± 222.99 L/m2/h to 569.48 ± 150.82 L/m2/h. The contact angle was 58.63° for blank membrane after 8 s of delay, which was reduced to 27.53° for modified membrane. During the short term filtration, the modified membrane maintained the higher stable flux and lower effluent turbidity. The fouling of conductive membrane could be mitigated by the 1 V/cm of electric filed during long term filtration. The better effluent properties were obtained from modified membrane, which were improved further when electric field was applied. CONCLUSION It is concluded that the conductive membrane has smoother and more hydrophilic surface, resulting the better anti-fouling and effluent property with the assistance of electric field.

Bioelectrochemical enhancement of organic matter mineralization and sulfate reduction during acidogenesis


BACKGROUND Microbial electrolysis cell (MEC) has been widely reported as an efficient strategy to enhance anaerobic digestion. However, the role of MEC during acidogenesis for treatment of sulfate-containing wastes remains unclear as so far. In this study a pair of electrodes was placed into an acidogennic reactor to form a MEC-based acidogenesis to investigate its performance in sulfate-containing wastewater treatment. RESULTS MEC obviously improved anaerobic acidogenesis to treat sulfate-containing wastewater. Higher COD removal and sulfate reduction were obtained in the MEC-based acidogenesis even under high sulfate loading conditions. MEC accelerated the conversion of substrate to acetate, indicationg the acidogenesis was enhanced. From Fluorescence in situ hybridization (FISH) analysis, exoelectrogenic bacteria were enriched in anodic biofilm. CONCLUSION The syntrophic metabolism between anodic exoelectrogenic bacteria and anaerobic fermentative bacteria enriched might accelerate the anodic decomposition of complex substrates as well as cathodic sulfate reduction, then providing a positive environment for sulfate reduction during acidogenesis.

Effect of the organic loading rate over the performance and microbial populations during the anaerobic treatment of tequila vinasses in a pilot-scale packed bed reactor


BACKGROUND Pilot-scale studies focused on evaluating the robustness of biofilm-based anaerobic digestion processes for further application at full-scale are scarce. Therefore, the aim of this work was to evaluate the performance of a 445 L packed bed reactor (PBR) operated at different organic loading rates (OLRs between 4–12.5 g COD/L*d) for the treatment of tequila vinasses. The reactor performance was correlated with the microbial dynamics to elucidate the specific role of the microbial communities into the degradation pathways that governs the process. RESULTS The PBR was operated during 231 days under different OLRs showing a stable performance. The COD removal and methane yield were maintained throughout the reactor operation at 86-89% and 0.24-0.28 L CH4/g CODadded, respectively. Meanwhile, the highest volumetric methane production rate of 3.03 L CH4/d*L was reached at the highest OLR, 12.5 g COD/L*d. Regarding microbial dynamics, the Bacteria and Archaea populations were able to adapt to the OLR disturbances, favoring the interactions between syntrophic Bacteria and Methanosaeta at high OLRs. CONCLUSION This work contributes to the scarce information regarding anaerobic treatment of tequila vinasses at pilot-scale and demonstrates that PBR is a promising and robust configuration that allows treating higher OLRs than current reported technologies.

Protein Adsorption in Anion Exchange Resins – Effects of Polymer Grafting, Support Structure Porosity, and Protein Size


BACKGROUND Anion exchange resins are used extensively for the purification of acidic proteins. Grafting charged polymers to a rigid porous structure has been shown to improve performance under varying conditions. Understanding the underlying mechanisms is important for the optimum design and selection of material properties and operating conditions. RESULTS Positively charged grafted polymers incorporated into a rigid, porous polymeric backbone structure are found to significantly enhance adsorption capacity and kinetics of the proteins bovine serum albumin (BSA, Mr~65 kDa) and thyroglobulin (Tg, Mr~660 kDa) but under different conditions. For the smaller BSA, binding increases with grafted polymer length and content and decreases with salt concentration. For the much larger Tg, binding increases with the addition of some salt for the polymer-grafted resins but can be lower than that observed for ungrafted resins without added salt. This behavior is caused by diffusional hindrance due to the bound protein. Increasing the length of the grafted polymer or the pore size of the backbone improve the Tg adsorption kinetics. CONCLUSION Protein adsorption is controlled by different mechanisms dependent on polymer grafting, backbone structure, and size of the adsorbed protein. Optimum selection of resin properties and conditions is needed to maximize adsorption capacity and mass transfer kinetics.

Gas Diffusion Electrodes improve hydrogen gas mass transfer for a hydrogen oxidizing bioanode


Background Bioelectrochemical Systems (BESs) are capable of recovery of metals at a cathode through oxidation of organic substrate at an anode. Recently, also hydrogen gas was used as an electron donor for recovery of copper in BESs. Oxidation of hydrogen gas produced a current density of 0.8 A/m2 and combined with Cu2+ reduction at the cathode, produced 0.25 W/m2. The main factor limiting current production was the mass transfer of hydrogen to the biofilm due to the low solubility of hydrogen in the anolyte. Here, we improved the mass transfer of hydrogen gas to the bioanode by use of a gas diffusion electrode (GDE). Results With the GDE, hydrogen was oxidized to produce a current density of 2.9 A/m2 at an anode potential of -0.2 V. Addition of bicarbonate to the influent led to production of acetate, in addition to current. At a bicarbonate concentration of 50 mM, current density increased to 10.7 A/m2 at an anode potential of -0.2 V. This increase in current density could be due to oxidation of formed acetate in addition to oxidation of hydrogen, or enhanced growth of hydrogen oxidizing bacteria due to availability of acetate as carbon source. The effect of mass transfer was further assessed through enhanced mixing and in combination with addition of bicarbonate (50 mM) current density increased further to 17.1 A/m2. Conclusion Hydrogen gas may offer opportunities as electron donor for bioanodes, with acetate as potential intermediate, at locations where excess hydrogen and no organics are available.

Effects of Bed Compression on Protein Separation on Gel Filtration Chromatography at Bench and Pilot Scale


BACKGROUND Poorly packed chromatography columns are known to reduce drastically the column efficiency and produce broader peaks. Controlled bed compression has been suggested to be a useful approach for solving this problem. Here the relationship between column efficiency and resolution of protein separation are examined when preparative chromatography media were compressed using mechanical and hydrodynamic methods. Sepharose CL-6B, an agarose based size exclusion media was examined at bench and pilot scale. The asymmetry and height equivalent of a theoretical plate (HETP) was determined by using 2% v/v acetone, whereas the void volume and intraparticle porosity (εp) were estimated by using blue dextran. A protein mixture of ovalbumin (chicken), bovine serum albumin (BSA) and ɣ′- globulin (bovine) with molecular weights of 44, 67 and 158 kDa, respectively, were used as a “model” separation challenge. RESULTS Mechanical compression achieved a reduction in plate height for the column with a concomitant improvement in asymmetry. Furthermore, the theoretical plate height decreased significantly with mechanical compression resulting in a 40% improvement in purity compared to uncompressed columns at the most extreme conditions of compression used. CONCLUSION The results suggest that the mechanical bed compression of Sepharose CL-6B can be used to improve the resolution of protein separation.

Harnessing soybean hulls for improved polygalacturonase production by Aspergillus sojae through fine-tuning of ambient pH


BACKGROUND Soybean hulls result from the processing of the bean for producing oil and protein products. This by-product generated massively in America has virtually no commercial value, so substantial effort is being paid into its exploitation for generating value-added goods. This work evaluates soybean hulls as inducer of the production of pectinolytic enzymes, through optimization studies regarding polygalacturonase production by Aspergillus sojae in submerged cultures. RESULTS A 2-fold improvement in polygalacturonase yield was found by varying the initial pH of the culture in a very narrow acid pH range (2.40-2.80). The optimized fermentation process was successfully transferred to stirred-tank bioreactors in terms of volumetric productivity, and final polygalacturonase yields were 42 U/ml and 1.39 U/g soybean hulls, which are among the highest reported with this by-product. Morphological characterization of A. sojae during cultivation showed that the fungus mainly developed in dispersed mycelia at initial pH of 2.40-2.80 whilst, conversely, fungal pellets predominated in cultures performed at initial pH of 5.40. CONCLUSION High enzyme titers are possibly connected to the formation of dispersed mycelia, as well as to acid-induced expression of the respective gene/s. We foresee this data will be helpful regarding the production of fungal pectinases or other acid-induced enzymes.

Using a Combined Oxygen-Supply and Substrate-Feeding Strategy to Improve 2,3-Butanediol Production by Metabolically Engineered Klebsiella oxytoca KMS005


BACKGROUND There is much demand for and extensive application for 2,3-Butanediol (2,3-BD) in various fields, and micro-aerobic and substrate-feeding conditions greatly affect on microbial growth and production. The theoretical maximum of 2,3-BD fermentative yield has rarely been reported. Therefore, our study aimed to develop an efficient combined oxygen-supply and substrate-feeding strategy to improve 2,3-BD production yield in metabolically engineered Klebsiella oxytoca KMS005. RESULTS The optimized oxygen consumption for 2,3-BD production by strain KMS005 was demonstrated at 9.2 g for 1 l working volume corresponding to kLa of 25.2 h-1. During fed-batch, a glucose feeding rate of 2 g h-1 starting at the end of the growth phase during 48 h followed by a final batch phase of 40 h was found likely to be satisfactory for 2,3-BD production by the strain KMS005. A final 2,3-BD concentration was obtained at 74.7 g L-1 with few by-products formation. A theoretical maximum of 2,3-BD production yield of 0.5 g g-1 substrate used was also approached. CONCLUSION Our oxygen-supply strategy with the specific feeding pattern developed in this study allowed the highest fermentative production yield of 2,3-BD ever reported. The KMS005 strain may be used as a biocatalyst for cost-effective 2,3-BD production from renewable substrates. In addition, the outcome might bring a message for further developments of simple fed-batch fermentation under micro-aeration conditions into larger scales for 2,3-BD production by K. oxytoca KMS005 or even other microorganisms.

Integrated process development - quality by design compliant evaluation of upstream variations at the microscale level


BACKGROUND Evaluation of optimized upstream conditions is often solely based on titers that do not reflect the downstream process and, consequently, the final purity and yield. This is especially critical for proteins expressed as inclusion bodies (IBs) because the subsequent downstream process is more complex than for soluble proteins. A miniaturized process development platform representing the entire downstream process at a microscale level combined with a multi-fermenter system for bioprocess screening enables fast investigation, using quality by design (QbD) measures, of the quality of feedstock compositions that are altered by upstream conditions. RESULTS We integrated high-throughput methods for an entire process chain, including upstream and downstream processing, for production of a recombinant protein as IBs. The miniaturized process chain consisted of cell disruption, IB harvesting, solubilization, refolding, and chromatographic purification. This enables processing and evaluation of 16 different fermentation conditions within 7 days. Only 2 g of initial biomass was required for evaluation of an individual fermentation. This resulted in a 15-fold reduction of time and a 100-fold reduction of material compared with common bench scale experiments. CONCLUSION This microscale process chain mimics the bench process and is able to differentiate purity variations as low as 2%.

Effect of fed-batch and semicontinuous regimen on Nannochloropsis oculata grown in different culture media to high-value products


BACKGROUND The high cell density in culture of microalgae is a key factor to recover biomass and extract metabolites of interest. Fed Batch Tubular Reactor (FBTR) and Semi Continuous Reactor (SCR) with f/2 Guillard Medium (f/2GM) and Algal Medium (AM) were evaluated. Both modes were operated under completely defined conditions to assess their effect on cell density, lipid, protein and carbohydrate productivity of the microalgae Nannochloropsis oculata. RESULTS Results show, that FBTR promotes highest cell density for both culture media, achieving 525±1.84x106 cell mL-1. With AM in SCR, specific growth rate, productivities of biomass and lipids were the highest, as well as, content of protein (48%), lipid (52.1%) and carbohydrates (17%). No significant differences were found in saturated fatty acids composition, whereas unsaturated fatty acids composition was affected by the operation regimen, this being higher in FBTR. CONCLUSION The use of AM in both operation mode, FBTR and SCR, increased the cell density and improved the lipid content of N. oculata. A good option would be to combine both modes of cultures; first, use the FBTR to obtain high cell densities and then apply the SCR mode to increase lipid productivity; finally, an important quantity of high value products could be recovered.

Accelerated start-up and microbial community structures of simultaneous nitrification and denitrification by using novel suspended carriers


BACKGROUND Integrated free-floating biofilm and activated sludge (IFFAS) process is an ideal candidate for simultaneous nitrification and denitrification (SND) process. However, traditional carriers have their inherent drawbacks like the weak hydrophilicity and negative charges on the surface. In this study, novel carriers with favorable hydrophilicity and electrophilicity were prepared and implemented in an IFFAS-based SND reactor. RESULTS Compared with traditional carriers, the water contact angle of novel carriers dropped to 60.2° and the positive charges on the surface (+11.7 mV, pH 7.0) were acquired. Through accurate control of dissolved oxygen (DO), it took only 30 days to start up SND with total nitrogen (TN) removal efficiency of 80.2%. On the contrary, the start-up period was 42 days with weaker TN removal capacity in the control reactor filled with traditional carriers. Novel carriers provided favorable niche for more types of bacteria to survive, of which Nitrosomonadales and Nitrospirale were identified as nitrifiers while anoxic denitrifiers, aerobic denitrifiers and anammox bacteria also co-existed in the system contributing to TN removal. CONCLUSION Novel carriers with favorable hydrophilicity and electrophilicity were successfully prepared through a relatively facile approach, and novel carriers-based SND process released shorter start-up period, higher biomass and better TN removal efficiency.

Evaluation of two start-up strategies to obtain nitrogen removal via nitrite and examination of the nitrous oxide emissions for different nitritation levels during the treatment of slaughterhouse wastewater


BACKGROUND This study investigated the use of a novel start-up strategy to obtain nitrogen removal via nitrite using real-time aeration control, in a sequencing batch reactor (SBR1), for the treatment of slaughterhouse wastewater. In addition, another SBR (SBR2) was operated with the same objective, but with a start-up from seed sludge. Furthermore, analysis of the nitrous oxide (N2O) production and emission was conducted for different levels of nitritation degree (ND). RESULTS Through the absence of inoculum in SBR1, the nitrifying population could be regulated from the beginning and prevented nitrite oxidising bacteria to occur. This was proved by the ND, which was already above 80% from day 28. Although, it lasted 59 days to achieve a sufficient nitrogen removal efficiency (> 80%). In contrast for SBR2, it took 90-110 days to achieve full nitritation, however the nitrogen removal efficiency was above 90% at all time. The maximum N2O emission resulted in 0.12% of the nitrogen load. CONCLUSION This study suggested the importance of the seeding sludge for the achievement of full nitritation. Moreover, a strong positive relationship between the ND and N2O emission was observed.

Integration of microbial and chemical processing for a sustainable metallurgy


Bioprocessing for metal's recovery from divergent resources using the microbial strategy has emerged as a green technology in metallurgical operations. The limitations to maintain the ideal condition for bacterial growth with slow kinetics however have been considered as major obstacles of bioprocessing to be implemented widely. It can be overcome by integrating the microbes with chemical processing route. The available reports on recent developments in hybrid bio-chemical processing of both primary and secondary resources have presented promising results, exhibiting potential to be implanted in large scale of metallurgy. In this context, reviewing the factors of hybrid process would benefit from knowledge acquired in fundamental studies. The present review focuses on the bio-chemical process integration using eco-friendly design tools for treating the difficult to extract resources and complex spent materials as well. Furthermore, the potential of hybrid technology has evaluated by establishing economic model as a case study which encompasses features of economic development, environmental consideration and societal matters for achieving the process sustainability.

Iron(III)-modified tungstophosphoric acid supported on silica-pillared montmorillonite as catalysts for fructose conversion to methyl levulinate


BACKGROUND Under the decline of conventional source of energy and increasing pollution, the fossil fuel based energy structure is being replaced by renewable energy based structure such as biomass energy. Among current biodiesel sources, methyl levulinate (ML) obtained from catalytic conversion of renewable carbohydrate with methanol has received a great deal of attention. Silica-pillared montmorillonites (MMTSi) functionalized by iron-modified tungstophosphoric acid (HPWFe) were prepared, their physicochemical properties and catalytic effects on ML production were studied. RESULTS The catalysts characterization demonstrated the high dispersion and Keggin structure of HPWFe in the framework of MMTSi. Effects of various reaction parameters and catalyst recycle towards the reaction performance were studied to optimize fructose conversion. With 4-HPWFe-MMTSi as the catalyst, an optimized ML yield of around 74 mol% was obtained at 180 °C for 1 h, and the recovered catalyst after calcination was found to remain high activity after being reused five times. CONCLUSION The prepared HPWFe-MMTSi catalysts showed porous advantage, perfect Brǿnsted-Lewis acidity and high thermal stability, which made their catalytic activity for fructose conversion and catalyst reusability values higher compared with others reported in the literature.

Capillary membrane bioreactor for abatement of low soluble compounds in waste gas


BACKGROUND The removal of problematic volatile organic compounds (VOCs) from polluted gas (toluene, iso-octane and hexane) has been investigated in a membrane bioreactor (MBR) by adapting a commercial capillary microporous polypropylene membrane. The MBR performance was carried out under several operational conditions. The influence of the empty bed residence times (EBRT), the liquid velocity and the inlet concentration was evaluated. RESULTS For toluene, it was possible to treat higher loading rates than 1600 g · m−3 · h−1 with a maximum elimination capacity (EC) of 1309 g · m−3 · h−1, removal efficiencies (RE) of ~80%. However, iso-octane was poorly degraded as a single pollutant. Hexane presented lower EC values (400 g · m−3 · h−1) than toluene. The synergistic effect of hexane degradation in two different mixtures was also considered. CONCLUSION Our results demonstrate that a commercial membrane for wastewater treatment can be adapted for biological gas treatment, becoming a potential alternative to conventional biological treatment technologies, especially for pollutants with low solubility.

Effect of acyl-acceptor stepwise addition strategy using alperujo oil as a substrate in enzymatic biodiesel synthesis.


BACKGROUND Using renewable feedstock sources for biodiesel production seem to be a promising strategy and even more when enzymatic catalysis with lipases is used. However, it is well known that these enzymes could be inactivated due to reaction conditions such as temperature or alcohol concentration. In this work, the effect of temperature and initial water activity (aw) value on immobilised recombinant Rhizopus oryzae lipase (rROL) were studied. Methanolysis and ethanolysis reactions using alperujo oil with three different stepwise addition strategies were employed. RESULTS recombinant 1,3-positional selective rROL covalently immobilised on polymethacrylate amino-epoxy activated support showed maximum initial reaction rate at low aw value (0,093). It was found that 30 °C was the optimal temperature in terms of biocatalyst's stability during transesterification reactions. Adding alcohol at once, ethanol was clearly better acyl-acceptor in terms of stability than methanol. Productivity was found to be 2-fold higher when five pulses of ethanol were used instead of methanol. CONCLUSIONS alperujo oil has a great potential as a low cost feedstock for biodiesel production through enzymatic catalysis using a nearly semi-continuous alcohol addition strategy.

Immobilization of Fluoride in Cement Clinkers using Hydroxyl-Alumina Modified Paddy Husk Ash based Adsorbent


Background Paddy Husk Ash (PHA) is a commonly available bio waste rich in silica which when coated with oligomeric Aluminium hydroxyl species becomes a good adsorbent for treatment of Fluoride bearing water. This is due to high affinity to Al3+ ions towards F− ion and good coating of cationic oligomers over silica surface. To control the serious environmental problem of post adsorption disposal of the sludge produced in defluoridation process, it was studied whether they can be further used as a raw material or additive for cement preparation. Results The surface modified PHA when found as a good adsorbent for fluoride the resulting sludge was used as a cement clinker additive. The clinker formed was found to have the required cementitious phases. Also, on addition of the sludge the clinker formation temperature was lowered from conventional 1450 to 1350 °C, as presence of Al-F like coating over PHA worked as mineraliser. It was observed that the Fluoride ion was immobilized in the cement matrix in a form which was difficult to be leached out. Conclusion Oligomeric aluminium activated PHA act as good defluoridising adsorbent which when used for cement clinker formation immobilises the Fluoride ion and reduces the clinkerization temperature.

Selective biostimulation of cold- and salt-tolerant hydrocarbon-degrading Dietzia maris in petroleum-contaminated sub-Arctic soils with high salinity


Abstract BACKGROUND The dual tolerance of hydrocarbon-degrading bacteria to low temperatures and salinity has not been extensively reported. This study identifies cold- and salt-tolerant hydrocarbon degraders obtained from petroleum-contaminated sub-Arctic soils, with the objective of stimulating target populations and assessing hydrocarbon biodegradation in soils abruptly impacted by salinity. RESULTS Halotolerant Dietzia and Arthrobacter bacteria were isolated from the soils. Dietzia maris strain NWWC4 can grow in the absence and presence of NaCl (≤12.5% w/v), adheres to hydrocarbons, and produces biosurfactant. The nutrient conditions preferred by strain NWWC4 were characterized to stimulate halotolerant hydrocarbon degraders related to strain NWWC4. In soil-slurry microcosms with the selected nutrient, Terminal Restriction Fragment Length Polymorphism indicated the dominance of alkB-gene-harboring NWWC4 relatives. Radiolabeled 14C-hexadecane mineralization in high-salinity soil-slurry microcosms (29±0.33% 14CO2 production) was strikingly comparable to that in non-saline conditions (35±0.84% 14CO2 production). In nutrient-amended, Arctic-diesel-spiked soil microcosms subjected to dual stresses (10 °C and 5% NaCl, w/v), hydrocarbon removal in the diesel range (C10-C21) was 21±8% after 18 days and was comparable with the removal achieved under non-saline conditions (37±6% removal). CONCLUSION This study reports the unique versatility of cold-adapted and salt-tolerant Dietzia maris capable of degrading hydrocarbons in highly saline and non-saline conditions.

Nonlinear Robust Adaptive Control Strategies for a Lactic Fermentation Process


BACKGROUND This work addresses the design of robust adaptive control strategies for a lactic fermentation process carried out inside a Continuous Stirred Tank Reactor (CSTR). This bioprocess is widely used in bioindustry for lactic acid production, and it is characterized by strong nonlinearities and uncertainties. Under the realistic assumption that the reaction kinetics and the influent flow rates are unknown and time-varying, but lower and upper bounds of the uncertainties are known, two innovative robust adaptive control structures are proposed. RESULTS The control strategies are designed by combining a linearizing control law with two novel parameter estimators able to estimate the unknown reaction rates. The first strategy uses a modified observer based estimator and the second one utilizes an interval parameter estimator. The control objective is to adjust the plant load so as to convert the glucose into lactic acid via fermentation, which is directly correlated to the economic aspects of lactic acid production. Numerical simulations are performed in order to validate the proposed solution. CONCLUSION By using the proposed control strategies the process is maintained at certain operating points that correspond to a maximal lactic production rate and a minimal residual glucose concentration. The simulations performed by considering various uncertainties and noisy measurement data show that the proposed novel robust adaptive controllers are suitable to control this kind of fermentation processes.

Efficient Solvent Extraction of Phosphoric Acid with Dibutyl Sulfoxide


BACKGROUND In china, the grade of phosphate ores has decreased fiercely in recent years. Existing solvents are low-efficient for the extraction of wet-process phosphoric acid produced by low-grade phosphate ores. Organic solvent dibutyl sulfoxide was developed to improve the extraction capacity of wet-process phosphoric acid, especially for the low-acid concentration. RESULTS The effects of extraction time, temperature, phosphoric acid concentration and impurities concentration on the extraction were investigated. The extraction process is exothermic and the enthalpy change is −5.86 kJ/mol. Dibutyl sulfoxide is relatively selective for Mg2+ and Al3+ while the selectivities of Fe3+, F− and SO42− are moderate. The liquid-liquid equilibrium of water-dibutyl sulfoxide-phosphoric acid system was determined at 298.15 K. The stability of dibutyl sulfoxide and the process flows of extraction, scrubbing and stripping were investigated. The extraction mechanism of dibutyl sulfoxide for phosphoric acid was proposed and the extracted complex H3PO4·0.3DBSO was obtained. CONCLUSION Dibutyl sulfoxide is demonstrated as powerful solvent for the extraction of wet-process phosphoric acid even at low-concentration. Dibutyl sulfoxide can be potential supplemental organic solvent for the extraction of wet-process phosphoric acid produced by low-grade phosphate ores.

Demonstration of complete bacterial-killing in water at a very high flow-rate: use of a surface-enhanced copper nanoparticle with activated carbon as a hybrid


BACKGROUND To address the objective of disinfecting water, copper nanoparticles (Cu-NPs) have been synthesized and impregnated on activated carbon (AC). This material when packed in a continuous column can potentially satisfy the need of a household-scale water disinfection unit. RESULTS Accordingly, Cu-NPs of 6.11 nm mean diameter were deposited in the form of discrete NPs, on plasma treated AC, with a Cu loading of 2.1 wt%, in Cu-AC. Selective impregnation of Cu-NPs was achieved on the external surface of plasma treated AC, as plasma treatment generates surface function groups on the AC surface. The superior qualities of the hybrid achieved complete killing of 104 CFU mL-1 of E. coli cells in only 10 min contact, on using 8 mg mL-1 of Cu-AC in batch mode. A flow-column (8 cm diameter and 25 cm height) designed on the basis of this batch contact time achieved disinfected water at a high flow rate of 4.13 L h-1, even when operated non-stop, over 7 days. Simultaneously, it maintained a very low steady state Cu concentration (83.7 μg L-1) in the disinfected water, much below the permissible limit of 1000 μg L-1 for drinking water. CONCLUSION This study achieved: (i) selective impregnation of Cu-NPs on AC with controlled degree of oxidation; (ii) maximum flow rate of E. coli-free drinking water in a continuously operating column, packed with Cu-AC granules; and (iii) complete E. coli cell-killing and Cu concentration within the permissible limit for drinking water over a very long duration. © 2017 Society of Chemical Industry

Model validation for enzymatic reactive distillation to produce chiral compounds


BACKGROUND Enzymatic reactive distillation (ERD) is a biocatalyzed process, in which enzymes are immobilized in catalytic packing. The combination of enzymatic reaction and thermal separation helps to overcome chemical reaction and phase equilibrium limitations. Processing of chiral molecules, in particular, can benefit from ERD application, which might lead to more eco-efficient processing of these valuable chemicals. Therefore an integrated approach to evaluate this technology is followed. RESULTS To evaluate ERD the transesterification of racemic (R/S)-1-phenylethanol (RPE/SPE) to (R)-phenylethyl acetate (PEA) catalyzed by Candida antarctica lipase B (EC: is investigated with regard to kinetics and physical property data, which provide a basis for the modeling of an ERD process. Furthermore, ERD experiments show a selective conversion of RPE to PEA, which is predicted by the established ERD model with high accuracy. CONCLUSION The ERD experiments demonstrate the feasibility of chiral processing for the transesterification by means of ERD and a validated ERD model is developed, allowing for a conceptual evaluation of ERD. This provides the basis for a future comparison of ERD with benchmark processes that will reveal the economic potential of ERD processes. © 2017 Society of Chemical Industry

Differences in growth physiology and aggregation of Pichia pastoris cells between solid-state and submerged fermentations under aerobic conditions


BACKGROUND Morphology and size of biofilms of Pichia pastoris under different culture conditions are key to understanding growth physiology in solid-state fermentation (SSF) and differences relative to submerged fermentation (SmF). Two microscopic techniques were used to contrast these phenomena, comparing SSF on polyurethane foam and SmF, with three concentrations of glycerol as carbon source. Growth parameters such as specific growth rate, maintenance energy, and substrate consumption were also evaluated. RESULTS Higher specific growth rate and maximum growth were obtained in SSF at every glycerol concentration compared with that obtained in SmF. Maintenance energy was higher (33%) in SmF and was related to lower biomass production (66%) than that obtained in SSF. Besides, in SmF, as substrate concentration increased, oxygen availability decreased; such differences in oxygenation could explain differences in biofilm formation. Scanning electron microscopy revealed that P. pastoris produced a compact multilayered biofilm embedded in SSF when compared with SmF, where smaller aggregates were scarcely observed by confocal microscopy. CONCLUSION This is the first work where growth parameters of P. pastoris in SSF and SmF are related to biofilm observations, which will help to improve SSF systems for P. pastoris production and its industrial application. © 2017 Society of Chemical Industry

A robust and stable nano-biocatalyst by co-immobilization of chloroperoxidase and horseradish peroxidase for the decolorization of azo dyes


BACKGROUND Immobilization of more than one peroxidase on the same support is an ideal technology for application because such a multi-enzyme catalytic system may show high activity over a very wide optimal range of pH, temperature and H2O2 concentration. In this work, chloroperoxidase (CPO) and horseradish peroxidase (HRP) were co-immobilized on ZnO nanowires/macroporous SiO2 composite support through an in situ cross-linking method. An anionic bi-epoxy cross-linker was used by adsorption on the surface of ZnO nanowires before cross-linking. RESULTS The cross-linking was carried out under suitable conditions: pH 6.5, reaction temperature 15°C and reaction time 15 h. Using a 1/1 mixture of CPO and HRP resulted in a co-immobilized enzyme with loading 79.6 mgCPO g-1support and 52.8 mgHRP g-1support, and total specific activity up to 15.7 U per mgsupport. The co-immobilized enzyme also showed good stability after 60 days of storage, and excellent reusability over 20 repeat uses. CONCLUSIONS For the decolorization of azo dyes the co-immobilized CPO (60%)/HRP (40%) exhibited high catalytic activity over very wide ranges of pH, temperature and H2O2 concentration. Using this robust biocatalyst, complete decolorizations of azo dyes have been realized within 3 h of reaction. © 2017 Society of Chemical Industry

High efficiency microbial electrosynthesis of acetate from carbon dioxide using a novel graphene–nickel foam as cathode


BACKGROUND Microbial electrosynthesis (MES) is a biocathode-driven process, producing high-value chemicals, from CO2. However, the low efficiency of the biocathode hinders the MES process efficiency significantly. RESULTS A novel 3D graphene–nickel foam (G-NF) cathode has been fabricated, by hydrothermal approach for the improvement of microbially-catalyzed reduction at the MES cathode. An increase of 1.8 times in the volumetric acetate production rate was obtained, compared with the untreated nickel foam. In MES with G-NF, a volumetric acetate production rate of 3.11 mmol L-1 day-1 has been achieved; 70% of the electrons consumed were recovered and the final acetate concentration reached 5.46 g L-1 within 28 days. CONCLUSION The hierarchical porous G-NF cathode improved bacterial colonization and the efficiency of mass, nutrients and protons transfer due to its 3D composition; the graphene coating considerably increased the effective surface area for microbial adhesion, as well as the electron transfer rate of biofilm in the MES. This study attempted to improve the efficiency of the biocathode, and provides a promising large electrode for large-scale MES devices. © 2017 Society of Chemical Industry

A smart engineering material with UV-induced switchable wettability for controllable oil/water separation


BACKGROUND Recently, some smart superwetting materials with switchable wettability have attracted great interest due to their ability to controllably separate oil/water mixtures. However, the fabrication of most smart materials requires complex procedures and precious chemical reagents for surface modification, limiting large-scale engineering applications of the fabricated smart surface. RESULTS In this study, a silver surface was prepared by extremely simple displacement deposition on copper mesh. The silver-coated mesh exhibits superhydrophobicity and superoleophilicity after heating treatment, which allows oil to permeate while blocking water. Interestingly, the heated silver-coated mesh gains superhydrophilic and underwater superoleophobic properties after UV irradiation, which allows water to permeate but prevents oil. As a consequence, the as-fabricated mesh is capable of achieving two completely different oil/water separation processes. In addition, the silver-coated mesh shows excellent environmental stability under a series of harsh conditions. CONCLUSION A novel smart engineering material with UV-induced switchable wettability was successfully fabricated. In view of the rapid and simple fabrication approach, it is envisaged that this work will provide a promising prospect of large-scale production in smart oil/water separation materials. © 2017 Society of Chemical Industry

Valorisation of the liquid fraction from hydrothermal carbonisation of sewage sludge by anaerobic digestion


BACKGROUND The mesophilic anaerobic digestion of the liquid fraction from hydrothermal carbonisation (208°C, 1 h) of dehydrated sewage sludge has been studied. Two initial inoculum concentrations (IC) (10 and 25 g COD L-1) and four inoculum to substrate ratios (ISR) (2, 1, 0.5 and 0.4 on a COD basis) have been selected to analyse their influence on the evolution of the anaerobic digestion process. RESULTS The substrate is characterised by a high COD (95.5 g L-1) and TKN (8.7 g N L-1) values. High inoculum concentration (25 g COD L-1) and/or low ISR (≤ 0.5) inhibited methanogenesis due to the high ammonia nitrogen (1.4 g TAN L-1) and VFA (>4 g COD L-1) released. For the inhibited samples final COD removals lower than 15% and IA/TA ratios higher than 0.3 were found. The greatest methane yield (177±5 mL CH4 STP g-1 CODadded) was achieved at 25 g COD L-1 of IC and at an ISR of 2. CONCLUSION During anaerobic digestion of the liquid fraction from the hydrothermal carbonisation of sewage sludge, the IC and ISR must be adequately selected for proper operation of the process and successful valorisation. According to the results, working at an ISR ≥ 1 is recommended. © 2017 Society of Chemical Industry

Influence of imidazolium-based ionic liquids on steroid biotransformation by Arthrobacter simplex


BACKGROUND Ionic liquids (ILs) have become increasingly attractive as alternatives for organic solvents. In this study, the influences of ILs on the cellular growth rate, cellular activity, cortisone acetate (CA) conversion, CA solubility, and cell membrane permeability of Arthrobacter simplex CPCC 140451 (ASP) were examined. RESULTS Results showed that ILs with ≥3 carbon atoms in their side chains increased CA conversion, CA solubility, and cell membrane permeability of ASP and universally inhibited the cellular growth rate and activity, with ILs with [PF6]-anion exhibiting the most severe inhibition activity. Inhibition was also more serious using ILs with longer alkyl side chains and at higher concentrations. CA conversion, CA solubility, and leakage of cell inclusions showed higher increase under ILs with [PF6]-anion than those of ILs with [BF4]-anion and lower increase for ILs with longer side chains. CONCLUSION This study improved the understanding of the influence and primary selection of imidazolium-based ILs when applied in steroid biotransformation with Arthrobacter simplex whole cells. The data provided a foundation for the selection of suitable ILs for various applications. © 2017 Society of Chemical Industry

Denitrification of metallurgic wastewater: mechanisms of inhibition by Fe, Cr and Ni


BACKGROUND Metallurgic wastewaters are acidic effluents containing large amounts of nitrate and heavy metals. Citric acid is one of the acids used by this industry and forms stable complexes with metal ions. The aim of this study was to elucidate the chemical aspects driving inhibitory or stimulatory effects of heavy metals on denitrifying processes, based on speciation analysis and monitoring key denitrification intermediates (nitrite and N2O). RESULTS Denitrifying sludge incubations were conducted with iron, chromium and nickel, in single and multi-metal assays, using citrate and ethanol as electron donors. Ferric-citrate complex, [Fe-cit](aq), was readily consumed, while complexes of divalent metals, [Fe-cit]- and [Ni-cit2]4-, remained very stable affecting denitrification. Nitrate reduction was affected by Ni2+, while nitrite and N2O accumulation was observed with NiCO3 and Ni(OH)2 oversaturation. [Cr-cit2]4- resulted in overall denitrification inhibition, while species of [Cr-cit]2- caused denitrification stimulation. CONCLUSION Fe and Cr inhibited the overall denitrification process, while Ni caused accumulation of intermediates. Synergistic inhibition imposed by multi-metal systems revealed lower inhibitory effects compared with those observed by the sum of individual effects of metals. This study elucidates chemical aspects determining the effects of heavy metals on denitrification, which is relevant to develop efficient biological processes for metallurgic effluents. © 2017 Society of Chemical Industry

Surface hydrophobicity and acidity effect on alumina catalyst in catalytic methanol dehydration reaction


BACKGROUND Methanol to dimethyl ether (MTD) is considered one of the main routes for the production of clean bio-fuel. The effect of copper loading on the catalytic performance of different phases of alumina that formed by calcination at two different temperatures was examined for the dehydration of methanol to dimethyl ether (DME). RESULTS A range of Cu loadings of (1, 2, 4, 6, 10 and 15% Cu wt/wt) on Al2O3 calcined at 350 and 550 °C were prepared and characterized by TGA, XRD, BET, NH3-TPD, TEM, H2-TPR, SEM, EDX, XPS and DRIFT-Pyridine techniques. The prepared catalysts were used in a fixed bed reactor under reaction conditions in which the temperature ranged from 180–300 °C with weight hourly space velocity (WHSV) = 12.1 h-1. It was observed that all catalysts calcined at 550 °C (γ-Al2O3 support phase) exhibited higher activity than those calcined at 350 °C (γ-AlOOH), and this is due to the phase support change. Furthermore, the optimum Cu loading was found to be 6% Cu/γ-Al2O3 with this catalyst also showing a high degree of stability under steady state conditions and this is attributed to the enhancement in surface acidity and hydrophobicity. CONCLUSION The addition of copper to the support improved the catalyst properties and activity. For all the copper modified catalysts, the optimum catalyst with high degree of activity and stability was 6% copper loaded on gamma alumina. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Optimization of synthesis condition for carboxymethyl cellulose-based hydrogel from rice straw by microwave-assisted method and its application in heavy metal ions removal


BACKGROUND An alternative carboxymethyl cellulose-based biosorbent hydrogel was synthesized by grafting 2-acrylamido-2-methylpropanesulfonic acid (AMPS) onto the prepared carboxymethyl cellulose backbone via microwave heating. Response surface methodology was employed to optimize the hydrogel synthesis condition for maximum gel content with respect to AMPS dose, N,N′-methylene-bis-acrylamide dose, and microwave exposure time. The prepared gels were then characterized and evaluated in terms of their heavy metal ions adsorption performance and reusability. RESULTS The optimum synthesis condition yielded the maximum gel content and maximum equilibrium swelling of 96.33% and 2819 ± 15%, respectively. The Langmuir model fitted the experimental isotherm data well, with maximum adsorption capacity of 86.21, 102.04 and 33.56 mg g-1 for Cu2+, Pb2+ and Fe3+, respectively. Microwave heating was clearly noted to result in hydrogel of higher porosity and could shorten the synthesis time by 88.33%; the gel content was 7.46% higher compared with that obtained via conventional heating. CONCLUSION Microwave-assisted heating is a feasible alternative and an efficient technique for CMC-g-AMPS hydrogel synthesis. The optimized CMC-g-AMPS hydrogel exhibited good performance for Cu2+, Pb2+ and Fe3+ ions removal and was satisfactorily reused, thus contributing to the alleviation of environmental problems caused by discarded rice straw and water contaminated with heavy metal ions. © 2017 Society of Chemical Industry

Behavior of activated sludge systems with an active heterotrophic biomass inflow – a novel perspective for sludge minimization


BACKGROUND This study evaluated the microbial behavior of activated sludge systems operated with an active heterotrophic biomass inflow. The evaluation focused on the possibility of sludge minimization. Thus, related process stoichiometry was derived on the basis of mass balance for essential parameters. RESULTS Stoichiometric relationships showed that the reactor holds a larger amount of biomass without the controlling impact of the sludge age, which decreases the magnitude of microbial growth compared with endogenous decay. Consequently, the observed yield, YOBS becomes much lower than what may be observed in conventional activated sludge systems. This stoichiometry exactly defines the microbial basis of the OSA (oxic/settling/anaerobic) system and identifies the interchange stream connecting the anaerobic reactor to the aerobic main reactor as the source of the active biomass inflow. Therefore, biomass inflow, largely overlooked in related studies, offers a novel microbial perspective for the merit of the OSA process in minimizing sludge generation. CONCLUSION The impact of lower YOBS, while explaining lower active biomass production, cannot be extrapolated to cover inert particulate COD fractions, namely a similar reduction in the initial inert COD and the residual particulate microbial products. Future studies should be directed to explore the fate of residual particulate compounds. © 2017 Society of Chemical Industry

Hydrodynamic characteristics of an aerated coaxial mixing vessel equipped with a pitched blade turbine and an anchor


Background In this work, computational fluid dynamics (CFD) simulation of an aerated coaxial mixing vessel composed of a centered impeller and a wall scraping anchor was conducted to investigate the effects of speed ratio, rotation modes (co-rotating and counter-rotating), and fluid viscosity on the local and global gas holdup values, flow pattern within the vessel, and turbulent kinetic energy. To validate the developed model, simulated gas holdup and gassed power uptake were compared with the measured experimental values. To gather experimental gas holdup values, an electrical resistance tomography technique was utilized. Results The results demonstrated that the co-rotating coaxial mixer with a speed ratio higher than 10 provided a higher gas volume fraction within the vessel. It was also shown that the turbulent kinetic energy attained in the counter-rotating mode was lower than those for the co-rotating coaxial mixer in most regions within the mixing tank, especially near the vessel walls. The size and the number of circulation loops developed within the coaxial mixer were affected by the speed ratio. Conclusion It was demonstrated that speed ratio and rotation mode of the impellers affected the hydrodynamics developed within the aerated coaxial mixer. © 2017 Society of Chemical Industry

Adsorptive filtration of low-concentration lead with wet-laid filter media made from nano-TiO2 decorated cellulose fibers


Background TiO2-cellulose composite fibers are a new type of bio-sorbent combining natural polymers and nanoparticles. However, their batch adsorption capacity is limited. Here mesoporous TiO2-cellulose composite fibers were synthesized and a filter medium was subsequently made from them to remove lead continuously by dynamic adsorption. Results TiO2-cellulose composite fibers with rough hierarchical surface structure were fabricated by in situ growing mesoporous TiO2 on cellulose fibers via microwave-facilitated hydrolysis. The composite fibers were then wet-laid into a filter medium to remove low-concentration Pb2+ in water through adsorptive filtration. The breakthrough curves were found to be better predicted by the dose–response model originally established for a fixed column bed. With a volume of merely 2.07 cm3, the medium can treat 150.0 L of water containing 50 ppb lead to the drinking water standard. The filter performance was improved by incorporation of small non-functional glass fibers to minimize the pore size and its distribution. The medium was also Pb2+ selective over co-existing cations, and could be easily regenerated and reused without reduction in performance. Conclusion The filter medium fabricated by nano-TiO2 decorated cellulose fibers showed enhanced adsorption capacity for lead through adsorptive filtration. Such filter beds have high potential for toxic micro-pollutant removal from drinking water. © 2017 Society of Chemical Industry

Screening of sorbents for recovery of succinic and itaconic acid from fermentation broths


BACKGROUND The di-carboxylic acids succinic acid and itaconic acid are promising building block chemicals that can be produced through fermentation, but the processes would benefit from enhancements in product recovery. While sorption has already been studied to some extent for succinate/succinic acid removal, literature on the potential of sorption for itaconic acid recovery is scarce. This work aimed to screen a range of sorbents and/or resins for their capacity to separate both acids from fermentation broths, envisaging both ex situ and in situ product recovery applications. RESULTS Static batch screening led to a shortlist of four promising products. These were further characterized in terms of dynamic sorption capacity, regenerability, acid recovery, ability to concentrate the product and stability during sorption–desorption cycles. Final tests with real fermentation broth gave unsatisfactory results for succinic acid recovery. For itaconic acid, promising results were obtained both on synthetic solutions and on a real fermentation broth. CONCLUSION While it is doubtful that adsorption will be the process of choice for in situ or ex situ succinic acid recovery, well performing sorbents could be identified for itaconic acid recovery from fermentation broths, offering perspectives for in situ product recovery applications. © 2017 Society of Chemical Industry

A short review on the research progress in alfalfa leaf protein separation technology


Alfalfa leaf protein constitutes an important food ingredient and is widely used in food technology. Due to high nutritive value and high proteins content, alfalfa is widely used in animal and human food. Conventionally, industrial leaf protein production from alfalfa requires complex processing and high separation temperature (90 °C), which causes high energy cost, release of sensitive elements and protein denaturation. To overcome these issues, developing novel separation technologies with low energy consumption and high yield and purity is of paramount importance to meet the requirements of green separation. In this review, some separation methods including acid heating method, pH method, salting method, organic solvent method, fermentation method and membrane separation are described. Among them, membrane separation has the best performance. The feasibility of adopting conventional and new promising technology (membrane) to recover leaf protein from plant food materials is discussed from an environmental and economical point of view. © 2017 Society of Chemical Industry

Synthesis and optimization of a novel poly-silicic metal coagulant from coal gangue for tertiary-treatment of coking wastewater


BACKGROUND Bio-treated coking wastewater is difficult to treat further, mainly due to the bio-refractory organic content. Coal gangue is the largest solid waste in China and it contains large amounts of aluminum, iron and silicon. This study attempts to recover the waste in coal gangue as a novel poly-silicic metal coagulant for bio-treated coking wastewater treatment. RESULTS The poly-silicic metal coagulant was synthesized from coal gangue under different conditions. Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy confirmed that both amorphous and crystalline phases were present in the samples and new chemical bonds such as Si–O–Al and Si–O–Fe were formed. The results show that the composite coagulant was effective for organic removal from the bio-treated coking wastewater and the optimal Al/Fe/Si molar ratios were Al/Fe = 3 and (Al + Fe)/Si = 13. The removal of organics exhibits a parabolic curve as the coagulant dosage increases. However, the optimal dosage (125 mg L-1) for organic removal was not equal to the isoelectric point (100 mg L-1). Furthermore, SEM images showed that the flocs start to disintegrate at a dosage of 150 mg L-1, leading to deteriorating sludge settling. CONCLUSIONS It is feasible to fabricate poly-silicic metal coagulants for coking wastewater treatment by using coal gangue as the raw material. The removal of the bio-refractory organics by the composite coagulant was attributed to the combined effects of charge neutralization, bridge adsorption and the net capturing. © 2017 Society of Chemical Industry

D-psicose 3-epimerase secretory overexpression, immobilization, and d-psicose biotransformation, separation and crystallization


BACKGROUND D-psicose is a rare sugar and exists in extremely small quantities in nature. It has important physiological functions and is allowed to be used as an ingredient in foods and dietary supplements. The aim of this study is to develop the biotransformation, separation and purification methods for highly efficient mass production of d-psicose. RESULTS First, the gene of d-psicose 3-epimerase (DPE) from Ruminococcus sp. was cloned and overexpressed in the food-grade microorganism Bacillus pumilus, and the recombinant protein was soluble, bioactive, and secretory overexpressed at a high level. The substrate specificity and metal ion effects of DPE were investigated. The recombinant DPE was immobilized onto anion exchange resin matrix, and the enzymatic properties and rounds of reuses of the immobilized DPE were investigated. Then, d-psicose was produced using the immobilized enzyme, separated by simulated moving bed chromatography (SMB), and finally purified by crystallization. The purity of the d-psicose crystal reached 99.1%. CONCLUSION Food grade high purity d-psicose can be efficiently produced and purified using the methods developed in this research, which can be easily scaled up for industrial-scale mass production. © 2017 Society of Chemical Industry

Phosphate recovery from treated municipal wastewater using hybrid anion exchangers containing hydrated ferric oxide nanoparticles


BACKDROUND This study presents the evaluation of two ion exchangers (granular and fibrous) impregnated with nanoparticles of hydrated ferric oxide (HFO) as selective sorbents for phosphate recovery from aqueous solutions. The hybrid impregnated anion exchangers combine the durability and mechanical strength of a polymeric weak base anion exchange resin with the high sorption affinity of HFO towards phosphate species. Dynamic experiments were carried out and data obtained were fitted to a well-known fixed-bed sorption model. RESULTS The theoretical sorption capacities reported by the Thomas model were in good agreement with the breakthrough experimental capacities determined from the sorption data. The sorption capacity decreased when using wastewater treatment plant secondary effluents in comparison with synthetic water mainly owing to the presence of organic matter and suspended solids. The phosphate sorbed on the impregnated ion exchangers was efficiently desorbed by using a 0.5 mol L-1 sodium hydroxide solution, reporting up to 90% of recovery. CONCLUSION The reusability of sorbents was evaluated through five sorption–desorption working cycles. Fiban-As was able to operate up to three consecutive cycles with good sorption performance while a significant decrease of sorption capacity after the first cycle was observed for FO36 resin. © 2017 Society of Chemical Industry

Algal biomass as fuel for stacked-MFCs for profitable, sustainable and carbon neutral bioenergy generation


BACKGROUND This work compares the performance of three stacked microbial fuel cells constructed with different number of single-MFC (MFC1 with two stacked-MFCs, MFC2 with ten stacked-MFCs and MFC3 with twenty stacked-MFCs), and operated under the same conditions for one month. RESULTS According to results, algae suspensions can be used as fuel for MFC-stacks, although current efficiencies obtained are low. In comparing the effect of number of cells stacked on the performance of the stacks, it was found that the higher the number of cells stacked, the higher the energy harvested from algae. However, because of the very efficient consumption of COD in the first MFC of the stacks (not only by electrogenic but also by non-electrogenic microorganisms) and the sequential circulation of the fuel through the different cells of the stack, in all cases the systems ran out of fuel and this was reflected in lower production of electricity, compared with that expected taking into account the number of cells stacked. Results obtained from the polarization curves and the cathodic oxygen consumption also support this explanation. CONCLUSIONS Results demonstrate that algal biomass is a suitable fuel for energy generation using MFC technology and provides microorganisms not only of a carbon source but also with the required nutrients. However, the low coulombic efficiencies obtained in the three stacks indicate that feeding algae to MFC also promotes the formation of an important amount of non-electrogenic microorganisms that compete successfully with bioelectrogenic microorganisms for the substrate provided. © 2017 Society of Chemical Industry

Recovery and primary purification of bacteriophage M13 using aqueous two-phase systems


BACKGROUND Bacteriophage M13 is an Escherichia coli-specific non-lytic filamentous virus commonly used in applications ranging from antibody screening and nanomaterial construction to drug delivery, among others. In this tenor, alternative methods for the fractionation, recovery and partial purification of phage particles are desired. In this work, the use of aqueous two-phase systems (ATPS) was evaluated as an alternative method for the recovery of phage particles. RESULTS The partition behavior of M13 in PEG–salt and ionic liquid (IL)–salt ATPS was characterized using a pre-purified feedstock. In PEG-salt ATPS, M13 was preferentially partitioned to the interface. In IL ATPS, however, M13 showed a high-top phase preference with recovery yields above 65%. Selected systems were tested for the extraction of M13 from a crude fermentation broth. From crude broth, a PEG 400-potassium phosphate system with volume ratio (VR) of 1 and 25% w/w tie line length (TLL) gave the best M13 top phase recovery (83%) and purification fold (18.2) in terms of total protein concentration. CONCLUSIONS The results presented here demonstrate the practical application of ATPS as an efficient process for the primary recovery and partial purification of M13 and represent the first study of the extraction of viral particles directly from a crude broth as well as the use of IL-Salt ATPS. © 2017 Society of Chemical Industry

Salting-out extraction of bio-based isobutanol from an aqueous solution


BACKGROUND More efficient downstream separation technologies need to be explored due to the low concentration of bio-based isobutanol in the fermentation broth. The salting-out extraction of isobutanol from its aqueous solution by employing nine salts (K4P2O7·3H2O, K2HPO4·3H2O, K3PO4·3H2O, K2CO3, K2SO4, KCl, Na2CO3, Na2SO4, NaCl) as salting-out agents and three organic solvents (2-ethyl-1-hexanol, cyclopentanol, 2-methyl-2-butanol) as extractants were investigated at 298.15 K. RESULTS The recovery was greatly influenced by the salt concentration and types of salts and organic solvents. When the initial molar K4P2O7 concentration was equal to or higher than 1.01 mol kg-1 and the mass ratio of aqueous isobutanol solution to 2-ethyl-1-hexanol was 1:1, the recovery of isobutanol reached 100%, and more than 91.62% of water was removed from the organic phase. CONCLUSION The salting-out effects of different anions in nine salts were ordered in the sequence: Cl- < SO42- < HPO42- < CO32- < PO43- < P2O74- at the same initial molar salt concentration and using the same organic solvent. 2-Ethyl-1-hexanol was verified to be the most suitable extractant. The distribution behavior and salting-out extraction effects can be evaluated by tie-line correlations and solubility correlation. © 2017 Society of Chemical Industry

Winery wastewater treatment by integrating Fenton's process with biofiltration by Corbicula fluminea


BACKGROUND Corbicula fluminea is an invasive freshwater clam with strong environmental and economic impact. Management of this pest should include its application, thus biofiltration by C. fluminea was successfully tested for the treatment of winery wastewater. Fenton's process was used in order to reduce the initial effluent toxicity. RESULTS Clam mortality was observed to significantly decrease when exposed to Fenton-treated samples compared with untreated wastewater. Although COD depletion by oxidation was strongly affected by the reactant concentration applied, the toxicity of the output effluent did not change markedly even when higher iron and hydrogen peroxide loads were used. Biofiltration led to COD abatements near 100% both when applied to raw and Fenton-treated effluents. However, for the raw effluent significant COD removal occurred only after an initial period where the organic load remained unchanged. CONCLUSION It seems advisable to integrate biofiltration with Fenton's peroxidation as a pre-treatment. The results discussed here support the integration of C. fluminea in wastewater treatment as a potential contribution to pest management. © 2017 Society of Chemical Industry

Analysis of gas holdup and bubble behavior in a biopolymer solution inside a bioreactor using tomography and dynamic gas disengagement techniques


BACKGROUND The interfacial mass transfer rate in an aerated system vessel in which the liquid phase is in contact with the gas phase is closely related to the interfacial area between two phases. The gas–liquid interfacial area strongly depends on the bubble size, bubble size distribution, and the gas holdup. For the first time, in this study the performance of the ASI impeller was assessed by determining the bubble classes, bubble size distribution, local gas holdup, and global gas holdup in an aerated mixing system containing a highly viscous and non-Newtonian biopolymer solution. The effects of the volumetric gas flow, impeller speed, and fluid rheology on the gas dispersion attained by the ASI impeller were investigated. RESULTS Electrical resistance tomography (ERT) was coupled with the dynamic gas disengagement (DGD) technique to determine the bubble classes, to measure the gas holdup, and to calculate the Sauter mean bubble diameter. The performance of the ASI impeller was compared with those of the pitched blade turbine and the Rushton impeller in terms of the bubble size distribution and gas holdup. The experimental data revealed that three classes of bubbles were formed within the aerated system. An empirical correlation for the gas holdup as a function of the gas flow number and apparent viscosity of fluid was developed for the aerated mixing tank equipped with the ASI impeller. CONCLUSION The ASI impeller effectively enhanced the breakage of the bubbles and gas holdup at the higher gas flow rates in a yield-pseudoplastic fluid. © 2017 Society of Chemical Industry

Implementation of a fluorescence based PAT control for fouling of protein A chromatography resin


BACKGROUND Protein A chromatography fouling is accompanied by two major events, one is the loss of protein A ligands and other is fouling due to non-specific, irreversible interactions of foulants with resin particles. This paper presents implementation of process analytical technology based control for fouling of protein A chromatography resin using a novel, fluorescence based approach. This approach enables direct, in situ measurement of protein A ligand density as well as monitoring of resin fouling during resin reuse. RESULTS A novel, fluorescence based process analytical technology (PAT) tool has been designed and used for screening a variety of cleaning protocols. A two-step cleaning protocol was created using this methodology. The above mentioned fluorescence based approach was successfully used to monitor fouling and to take a decision on when to initiate cleaning. This resulted in effective maintenance of dynamic binding capacity and step yield at 50 cycles (DBC: 97% of the original value vs 65% with conventional protocols and yield: 93% of the original value vs 73% with conventional protocols) and at 200 cycles (> 90% of the original value). CONCLUSIONS The proposed fluorescence based approach has been effectively used for monitoring and control of resin fouling upon reuse, thereby resulting in a substantial increase in resin lifetime. © 2017 Society of Chemical Industry

Role of ion-exchange resins as catalyst in the reaction-network of transformation of biomass into biofuels


The use of acidic ion exchange resins in the transformation of biomass into biofuels is revised and their potential application is presented. Relationships between morphology and structure of resins and their catalytic activity for some existing reactions of the transformation network from sugars to biofuels are observed. In the synthesis of 5-hydroxymethyfurfural and levulinic acid, catalytic activity of resins increases when the crosslinking content is decreased for both macroreticular and gel-type resins. Gel-type resins with low crosslinking were found to be the most suitable resins for direct esterification of levulinic acid with linear alcohols. However, for the alcoholysis of furfuryl alcohol, macroreticular resins are better than gel-type ones. Deactivation probably due to humins formation is the main drawback for industrial application. © 2017 Society of Chemical Industry

Physicochemical properties of some hydrophobic room-temperature ionic liquids applied to volatile organic compounds biodegradation processes


BACKGROUND Ionic liquids (IL) are an interesting solvent choice for specific industrial applications since physicochemical properties can be fine-tuned by modifying the substituent groups or the cation/anion pair. Hydrophobic ILs are considered green solvents and known to be good absorbents for hydrophobic organic compounds. Given their physicochemical properties an industrial application of such compounds is conceivable. Classical physicochemical properties such as density, viscosity and surface tension have a strong influence on the fluid dynamics; they were therefore measured and determined. RESULTS The density, viscosity and surface tension of 23 hydrophobic ILs were measured at room temperature. These compounds are potential candidates for the absorption and biodegradation of volatile organic compounds (VOCs) in a two-phase partitioning bioreactor. The thermal expansion coefficient, molecular volume, standard molar entropy and lattice energy were determined for each IL using empirical and semi-empirical equations based on the density values. Viscosity values were correlated by the Arrhenius equation. Then, the surface excess enthalpy and surface excess entropy were determined from the surface tension values. CONCLUSION The influence of the presence of different functional moieties (unsaturated bonding, oxygenated and cyanide) and the side chain length in the physicochemical properties of these hydrophobic ILs was discussed, since their presence affected directly the density, viscosity and surface tension. © 2017 Society of Chemical Industry

Silver nanoparticle impregnated rechargeable polyethersulfone (PES) membrane for biofouling prevention and water disinfection


BACKGROUND Biofouling severely limits membrane life and performance. To address the twin challenges of biofouling prevention and water disinfection, silver nanoparticle (Ag-NP) impregnated, sulfonated polyethersulfone (SPES) membrane was chosen. RESULTS By tuning the degree of sulfonation, Ag-SPES-1, Ag-SPES-2 and Ag-SPES-3 membranes were synthesized, having increasing Ag content of 4.1, 8.8 and 15.1 wt%, respectively. Time-dependent confocal microscopy images of E. coli cells (after the passage of 104 CFU mL-1) show that all attached E. coli cells were killed in 5, 2 and 2 min for Ag-SPES-1, Ag-SPES-2 and Ag-SPES-3 membranes, respectively. However, Ag-SPES-2 shows maximum permeability coefficient (452 L m-2 h-1 bar-1) of decontaminated water in a cross-flow module. This is because, Ag-SPES-1 takes a longer time for E. coli cell-death due to its lowest Ag loading, whereas Ag-SPES-3 – due to excess Ag loading – results in the formation of an undesirable Ag-NP layer on the membrane surface, leading to 16.7% decrease in its porosity. The latter translates into lower permeability. Fresh membranes showed the same permeability over six runs. However, to simulate the eventual depletion of Ag in the very long run, the membranes were recharged with Ag, upon which it showed similar permeability to a fresh membrane. CONCLUSION Therefore, the study achieved: (i) optimization of Ag content for highest permeability; (ii) recharging of membrane for prevention of biofouling-initiation with both fresh and recharged Ag-SPES membrane, leading to membrane reuse; and (iii) E. coli free disinfected water with Ag concentration (39 μg L-1), well-within the permissible limit for drinking-water (100 μg L-1). © 2017 Society of Chemical Industry

Refining of wine lees and cheese whey for the production of microbial oil, polyphenol-rich extracts and value-added co-products


BACKGROUND Refining of renewable resources for the production of various end-products should be applied in order to develop sustainable processes and ensure the transition to the bio-economy era. With this principle in mind, a novel integrated biorefinery has been developed based on cheese whey and wine lees valorization. RESULTS Polyphenols, tartrate salts and ethanol were extracted from wine lees, while the remaining solids enriched in yeast cells were converted into nutrient-rich fermentation supplements. The composition of phenolics varied between solid and liquid fractions of wine lees. Protein concentrate was separated from cheese whey via ultrafiltration, while the concentrated lactose-rich permeate stream was supplemented with wine lees derived hydrolysates to form fermentation media for microbial oil production by Cryptococcus curvatus and Mortierella ramanniana. Functional oil containing 4.5% (w/w) of the omega-6 fatty acid γ-linolenic acid was produced in shake flask cultures by Mortierella ramanniana with total dry weight of 25.8 g L−1 and 30.6% (w/w) lipid content. Fed-batch bioreactor cultures with Cryptococcus curvatus using only crude resources led to one of the highest lipid concentrations (33.1 g L−1) reported in literature-cited publications using cheese whey. CONCLUSION This is the first study proposing the integrated refining of cheese whey and wine lees for the production of both commodity and speciality products, namely whey protein concentrate, antioxidants, ethanol, tartrate salts and microbial oil. © 2017 Society of Chemical Industry

Photocatalytic degradation of saccharin under UV-LED and blacklight irradiation


BACKGROUND The photocatalytic treatment of the artificial sweetener saccharin (SAC), an emerging environmental contaminant, was investigated. UVA irradiation was provided by an environmentally friendly light-emitting diode (UV-LED), whose efficiency was compared with a conventional blacklight fluorescent lamp (UV-BL). RESULTS The effect of the initial SAC concentration (2.5–10 mg L-1), TiO2 concentration (0–500 mg L-1), water matrix (absence/presence of humic acids), and treatment time on process efficiency was evaluated. Under the best conditions assayed ([SAC]0 = 2.5 mg L-1, [TiO2] = 250 mg L-1), SAC was degraded within 20 and 90 min under UV-LED and UV-BL irradiation, respectively. Liquid chromatography-high resolution mass spectrometry (LC-HR/MS) revealed that SAC degradation proceeds via hydroxylation of the phenyl ring, cleavage of C–N bond and further oxidation reactions. Finally, UV-LED was found to be up to 16 times more energy efficient than UV-BL. CONCLUSIONS In all cases, UV-LED achieved higher photocatalytic efficiency, in terms of organic degradation, and was found to be significantly more energy and cost efficient than conventional UV-BL irradiation source, thus rendering LED-photocatalysis a sustainable technology for the treatment of persistent contaminants. © 2017 Society of Chemical Industry

Succinic acid production from cheese whey by biofilms of Actinobacillus succinogenes: packed bed bioreactor tests


BACKGROUND Succinic acid (SA) biotechnological production represents a promising alternative to the fossil-fuel based chemical production route. The goal of this study was to develop a SA production process conducted with biofilms of Actinobacillus succinogenes and fed with cheese whey, a lactose-rich by-product of the cheese-making processes. RESULTS The screening between five commercial biofilm carriers, based on a statistical analysis of the process rates and yields, led to the selection of Glaxstone®, a sintered glass porous material. The attached-cell performances obtained when SA production was fed with cheese whey or with pure lactose were equivalent. The feasibility of a repeated batch process of SA production by biofilms of A. succinogenes was demonstrated in a Glaxstone®-filled 1 L packed bed bioreactor, and an effective sequence of biofilm growth and SA production phases was identified. A SA productivity of 0.72 gSA L-1packed bed h-1, a SA specific production rate of 0.18 gSA gprotein-1 h-1 and a biofilm concentration of about 4 g L-1packed bed were obtained. CONCLUSIONS SA bioproduction under biofilm conditions from organic by-products such as cheese whey is a feasible and promising process. This work represents the first attempt to develop a biofilm-based process of SA bioproduction from cheese whey. © 2017 Society of Chemical Industry

Sonochemical oxidation of piroxicam drug: effect of key operating parameters and degradation pathways


BACKGROUND Piroxicam (PRX) is a non-steroidal anti-inflammatory drug (NSAID) commonly used to relieve pain and swelling of conditions like arthritis. PRX has been extensively detected in seawater, surface, and sewage waters worldwide and therefore its efficient treatment is an issue of emerging concern. In this work, the sonochemical degradation of PRX was investigated. RESULTS All experiments were conducted at constant ultrasound frequency of 20 kHz while the following range of experimental conditions was investigated: initial PRX concentration 320–960 µg L-1, ultrasound power density 20–60 W L-1, temperature 20–60 °C, reaction time up to 60 min. The effect of different water matrices, namely surface water (SW), bottled water (BW), ultrapure water (UPW) and humic acid (HA) aqueous solution on process efficiency was also explored. It was found that PRX degradation reached 96% after only 10 min of treatment under the best conditions (i.e. [PRX]0 = 320 mg L-1, 20 °C, 36 W L-1) assayed. Power density could positively affect PRX degradation. Nevertheless, PRX degradation decreased when its initial concentration and the temperature of the bulk liquid was increased. PRX degradation was found to decrease, in different water matrices, in the order: UPW > 5 mg L-1 HA > BW > 10 mg L-1 HA > SW. High resolution mass spectrometry analysis revealed that 14 transformation by-products (TBPs) were formed and subsequently degraded during treatment while the PRX degradation pathways were also elucidated. CONCLUSION At the optimal operating conditions assayed, PRX was efficiently degraded after about 10 min of sonochemical oxidation, thus rendering it a promising technology for the treatment of xenobiotics. © 2017 Society of Chemical Industry

Prototype of a scaled-up microbial fuel cell for copper recovery


Background Bioelectrochemical systems (BESs) enable recovery of electrical energy through oxidation of a wide range of substrates at an anode and simultaneous recovery of metals at a cathode. Scale-up of BESs from the laboratory to pilot scale is a challenging step in the development of the process, and there are only a few successful experiences to build on. This paper presents a prototype BES for the recovery of copper. Results The cell design presented here had removable electrodes, similar to those in electroplating baths. The anode and cathode in this design could be replaced independently. The prototype bioelectrochemical cell consisted of an 835 cm2 bioanode fed with acetate, and a 700 cm2 cathode fed with copper. A current density of 1.2 A/−2 was achieved with 48 mW m−2 of power production. The contribution of each component (anode, electrolytes, cathode and membrane) was evaluated through the analysis of the internal resistance distribution. This revealed that major losses occurred at the anode, and that the design with removable electrodes results in higher internal resistance compared with other systems. To further assess the practical applicability of BES for copper recovery, an economic evaluation was performed. Conclusion Analysis shows that the internal resistance of several lab-scale BESs is already sufficiently low to make the system economic, while the internal resistance for scaled-up systems still needs to be improved considerably to become economically applicable.© 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

High purity fructose from inulin with heterogeneous catalysis – kinetics and modelling


BACKGROUND Inulin can be extracted from the non-edible chicory root and high purity fructose can be obtained from hydrolysis of inulin and used as a valuable platform molecule for further valorization. Heterogeneous catalysts are sought as alternatives to mineral acids because of costly separation and severe corrosion problems. In this work, hydrolysis of inulin was performed in a batch reactor with an advanced sulfonic resin (Smopex-101) employing HCl as a reference catalyst, at 75–95 °C and pH ranging from 1 to 2. RESULTS The reaction was shown to proceed predominantly via an end-biting mechanism. The activity of the heterogeneous catalyst was on par with the reference catalyst, with the special advantage that Smopex-101 was more selective towards monomer formation at milder reaction conditions. Mathematical modelling of the kinetics was successfully performed with a recently developed model incorporating a reaction mechanism based on an autocatalytic effect. CONCLUSIONS The current work demonstrates that high purity fructose can be obtained by hydrolysis of inulin employing a heterogeneous catalyst at ambient pressure. The results can be utilized directly for optimization and design purposes and they open up novel possibilities in production and process design, i.e. batch or possibly continuous operation without the need for costly separation and corrosion problems commonly encountered with homogeneous catalysts. © 2017 Society of Chemical Industry

Performance of thermophilic anaerobic digesters using inoculum mixes with enhanced methanogenic diversity


BACKGROUND Various mixes of seeds have been quasi-randomly selected to startup anaerobic digesters. In contrast, this study examines the impact of inoculating thermophilic anaerobic digesters with a designed mix of non-acclimated seeds based on their methanogen composition, using quantitative polymerase chain reaction (QPCR) of 16S rRNA gene, to achieve high abundance and diversity of methanogens. RESULTS Based on QPCR results, two seed mixes were selected to inoculate two anaerobic digesters: digester (A) was inoculated with a control seed consisting of digestate, manure, and activated sludge; and digester (B) was inoculated with a further methanogen-enriched seed consisting of the control seed with added compost and leachate. Both seed combinations yielded a balanced microflora that is able to achieve a successful startup. However, upon reaching steady state, digester B exhibited lower propionate levels, resulting in lower volatile fatty acids (VFAs) concentration and increased buffering capacity, indicating greater stability. Acetotrophs and hydrogenotrophs were dominated by Methanosarcinaceae and Methanobacteriales, respectively, in both digesters, exhibiting an average ratio of 66-to-34% in A and 76-to-24% in B during steady-state. CONCLUSION The inoculation strategy in digester B resulted in improved stability, lower propionate concentration and 10% higher relative abundance of acetotrophs. © 2017 Society of Chemical Industry

Hybrid chloroperoxidase-magnetic nanoparticle clusters: effect of functionalization on biocatalyst performance


BACKGROUND Hybrid enzyme–nanoparticle complexes, obtained by enzyme immobilization onto superparamagnetic particles, display unique properties for use as biocatalysts. A novel methodology for the immobilization of chloroperoxidase (CPO) onto magnetic nanoparticle clusters (mNC) is presented. Chloroperoxidase catalyzes alcohol oxidations using peroxides, and it has recently been shown to recognize β-amino alcohols as substrates, although high required peroxide concentration led to poor CPO stability. RESULTS mNC retains the superparamagnetic properties of the single nanoparticle plus an increased magnetic moment, necessary for effective magnetic recovery. Different functional groups have been introduced on the silica layer that covers mNC. The linkage enzyme–support has been intended through different reactive groups on the CPO surface. The selected biocatalyst (95% yield, 63% retained activity), obtained by prior enzyme oxidation followed by coupling to the amino groups on the mNC surface, has been compared with soluble CPO in the model reaction (N-Cbz-3-aminopropanol oxidation) with significantly higher substrate conversion due to 4-fold increased enzyme stability. CONCLUSIONS Functionalized mNC has demonstrated to be efficient for the preparation of hybrid enzyme-mNC biocatalysts. The systematic study of chloroperoxidase immobilization onto mNC led to several useful biocatalysts. The described methodology could easily be extended to many other enzymes in the preparation of efficient and reusable biocatalysts. © 2017 Society of Chemical Industry

Aerobic co-metabolism of 1,1,2,2-tetrachloroethane by Rhodococcus aetherivorans TPA grown on propane: kinetic study and bioreactor configuration analysis


BACKGROUND 1,1,2,2-tetrachloroethane (TeCA) has been generally considered as non-biodegradable under aerobic conditions, while its complete biodegradation was reported with microbial consortia growing anaerobically. This study describes TeCA aerobic co-metabolic degradation by the propanotroph Rhodococcus aetherivorans strain TPA isolated from a TeCA-degrading consortium. RESULTS R. aetherivorans TPA was able to grow on aliphatic hydrocarbons from propane to pentane and on gaseous n-alkane metabolic intermediates. The Michaelis–Menten model allowed a satisfactory fit of the TPA propane utilization rates under resting cell conditions, while the TeCA degradation rates were successfully interpolated with Andrew's inhibition model. A significant propane–TeCA mutual inhibition was observed, although the results did not allow distinguishing between competitive and non-competitive inhibition. Among different bioreactor options for the on-site bioremediation of TeCA-contaminated groundwater, a single suspended-cell continuous stirred-tank reactor (CSTR) appeared to be the optimal one. CONCLUSIONS This study provides for the first time the kinetic and microbiological characterization of a bacterial strain capable of degrading TeCA under aerobic conditions. © 2017 Society of Chemical Industry

Spray congealing as innovative technique for enzyme encapsulation


BACKGROUND Spray congealing is investigated as a new innovative immobilization technique for biocatalysts. The immobilization is realized by atomization of a mixture of a melted carrier and the enzyme, which is re-solidifyed due to temperature decrease. This method needs neither organic solvents, nor difficult downstream processing after preparation. For the encapsulation of different matrices, long chain alcohols and glyceryl derivatives, with melting points below 86 °C and environmentally friendly properties, are chosen and tested for their suitability for enzyme encapsulation. RESULTS The immobilization of a laccase (EC, Novozym 51003, from Myceliophthora thermophila) was investigated and the produced microparticles were characterized. The obtained particles showed a mean particle size around 40 μm and a spherical surface with different structures depending on the used matrix. Spray congealing with the laccase reached yields of 80% and residual activities up to 56%. Furthermore, four consecutive reactions were realized with cetyl alcohol as carrier and an activity of 20% was retained. CONCLUSION Cetyl alcohol was found to be the most appropriate carrier for the immobilization of the investigated laccase, due to easy handling and high yields. In comparison with the other tested carriers, the best retained activities were obtained and recycling of the biocatalyst was realized. © 2017 Society of Chemical Industry

Production of gamma-aminobutyric acid by Escherichia coli using glycerol as a sole carbon source


BACKGROUND In the biodiesel industry, crude glycerol is produced in huge quantities as a by-product, and therefore, the economic conversion of crude glycerol into a value-added product is a priority. One possible way of achieving such a conversion is to feed glycerol to Escherichia coli cells so that they can grow and produce valuable products such as gamma-aminobutyric acid (GABA) at the same time. RESULTS Four E. coli strains were compared for their growth rates and GABA production using glycerol as sole carbon source. GABA production was associated with cell growth by constitutively expressed mutant glutamate decarboxylase that exhibited activity at neutral pH. Simple treatment of crude glycerol with phosphoric acid resulted in a fermentable grade of glycerol, and the superb strain, W, converted 2.0 g L−1 of crude glycerol into 0.15 g L−1 of GABA in 12 h in a batch culture. In a fed-batch type culture with pH titration, the strain W converted overall 15 g L−1 of crude glycerol into 0.98 g L−1 of GABA in 36 h. CONCLUSION It is possible to convert crude glycerol into GABA in a growth-associated manner using E. coli W, and the strain will serve as a base strain for future metabolic engineering approaches. © 2017 Society of Chemical Industry

Characterization and ammonia adsorption of biochar prepared from distillers' grains anaerobic digestion residue with different pyrolysis temperatures


BACKGROUND Increasing attention is being paid to find an alternative way to handle biogas residue from biogas production which is important for sustainable development of biogas project. In this study, biochars from distillers' grains anaerobic digestion residue (BRC) in the pyrolysis temperature range of 300 to 800°C were prepared. Subsequently, elemental analysis, thermal stability, specific surface area (SSA), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and the performance of ammonia (NH4+) adsorption were studied. RESULTS BRC produced at 700°C exhibited the highest SSA (251.47 m2 g−1). Generally, the pH (6.2–8.4), ash (17.58–36.93%), carbon (48.09–56.18%) and the NH4+ adsorption capacity (1.95–5.86 mg N g−1) of BRC increased with increasing pyrolysis temperature (300–700°C). However, for pyrolysis yield (76.39–40.44%), volatile matter (48.72–4.69%), phenolic (0.85–0.01 mmol g−1), total acidity (1.39–0.21 mmol g−1) and the contribution of H (4.92–1.13%), O (29.41–5.76%), O/C (0.61–0.10), H/C (0.10–0.02), (O+N)/C (0.65–0.13), an opposite trend was found. CONCLUSIONS Pyrolysis temperature has a significant effect on the physicochemical properties of BRC and thus on the quantity of NH4+ adsorbed. The BRC produced at 700°C could serve as a highly efficient material for NH4+ removal, therefore presenting a high value-added application for biogas residues. © 2017 Society of Chemical Industry

Cost effective recovery of lithium from lithium ion battery by reverse osmosis and precipitation: a perspective


Production of lithium from primary resources is lagging behind demand (12% versus 16% in 2016), cost of lithium is increasing (between 40 and 60% in 2016), battery energy density rapidly increasing versus declining cost, and estimated lithium ion battery (LIB) markets size ($77.42 billion by 2024) driven by projected demands for plug-in electric vehicles (PEVs) clearly justifies recycling. PEV technology and projected demand raise several challenges, including lithium demand/scarcity and future technology to recover lithium from LIB waste. To address the circular economy, steady supply chain security, self-reliance, environment safety, environment directive, energy security, resources conservation, futuristic carbon footprint, WEEE directives and waste crime, recycling of LIB is an absolute essential. During the last decade, LIB recycling research and industrial recycling of LIB have attracted the interest of researchers, industrialists, and environmentalists. All have reported progress in the recovery of valuable metals like Co, but have rarely focused on lithium recovery. Hence, this paper addresses logical hypothesis and application of available technology in a fashion where lithium recycling from LIB can be addressed. © 2017 Society of Chemical Industry

Synthesis of zeolite A using raw kaolin from Ethiopia and its application in removal of Cr(III) from tannery wastewater


BACKGROUND The commercial production of zeolite A mainly involves costly synthetic chemicals. However, cheaper raw materials such as clay minerals, coal ashes, natural zeolites, solid wastes and industrial sludge have been tested. Based on this, the objective of the present study is synthesis of zeolite A from two sources of raw kaolins (Ansho and Bombowha) from Ethiopia and evaluation of its application in tannery wastewater treatment. RESULTS The synthesis result indicated high crystallinity (>90%) of zeolite A using Ansho kaolin. Lower grade Bombowha kaolin yielded zeolite A with crystallinity of 80%. In the tannery wastewater treatment study, a real sample having chromium concentration of 2036 mg L−1 was treated, obtaining 99.8% removal and about 200 mg g−1 adsorption capacity of Cr(III) using 100 g L−1 and 5 g L−1 adsorbent dose, respectively. This indicated that the synthesized zeolite A has great potential for Cr(III) removal from tannery wastewater. CONCLUSION In this study, zeolite A has been synthesized from two sources of kaolin from Ethiopia and has been evaluated in tannery wastewater treatment. The synthesis result indicated the formation of crystals of zeolite A with optimum crystallinity of 91% and the material exhibited chromium removal efficiency of 99.8%. © 2017 Society of Chemical Industry

Removal of arsenic (III) and arsenic (V) from aqueous solutions through adsorption by Fe/Cu nanoparticles


BACKGROUND While various iron-based nanomaterials have been studied for the removal of arsenic from groundwater or its immobilization in soils, this study focuses on the applicability of iron/copper bimetallic nanoparticles for removal of arsenic from synthetic contaminated waters. In order to determine the effectiveness of these nanoparticles for arsenic removal, after synthesis, various sorption tests were performed with aqueous arsenic solutions. RESULTS Detailed physicochemical characterization of synthesized nanoparticles confirmed the successful formation of Fe/Cu nanoparticles with a mean diameter of 13.17 nm. These nanoparticles were found to be effective for removing arsenic from aqueous solutions. The maximum sorption capacities for As(III) and As(V) were 19.68 mg g−1 and 21.32 mg g−1, respectively, at a pH of 7.0. Adsorption isotherms fit well into the Langmuir equation, and sorption follows pseudo-second-order kinetics. Coexisting carbonate, sulfate, and phosphate ions had no significant effect on the removal efficiency of arsenic at the concentrations studied. Arsenic removal efficiency by Fe/Cu nanoparticles is enhanced in acidic environments and in basic conditions, desorption of arsenic is possible. CONCLUSION The Fe/Cu nanoparticle powder was found to be effective for removal of arsenic from water and has potential to be used for arsenic remediation from the aquatic environment or in situ immobilization of arsenic. © 2017 Society of Chemical Industry

New efficient laccase immobilization strategy using ionic liquids for biocatalysis and microbial fuel cells applications


BACKGROUND Laccases belong to the family of blue multicopper oxidases, these enzymes are efficient in many applications, including in biofuel cells to produce electricity through chemical reactions. Several laccase immobilization methods have been elucidated, such as covalent link and entrapment. RESULTS The present work describes how, for the first time, laccase was successfully immobilized by entrapment into polymer inclusion ionic liquid membranes (PILMs) based on ionic liquids and polyvinylchloride. The immobilization rate was very high in all cases (99.2 ± 0.6%), so that the enzyme entrapment strategy described can be considered as successful and one of the best methods for laccases immobilization that have been reported to date. The assayed membranes were evaluated as performing carrier for laccase by means of the ABTS oxidation. Four screened ionic liquids were used for the first time for this purpose: [OMIM][NTf2], [EMIM][NTf2], [Epy][NTf2] and [Chol][NTf2]. This work demonstrated the efficiency in terms of the activity rate and stability of the enzyme versus IL concentrations. The most suitable IL as regards activity [Chol][NTf2]. However, the reuse assays showed that the most stable PILM was the one constituted by 50% [Epy][NTf2]. For physical resistance and water insolubility, the [OMIM][NTf2] based PILM was selected for microbial fuel cell (MFC) application. CONCLUSION This is the first report describing this original entrapment strategy for laccase immobilization into PILM. The application of this laccase-membrane in MFC showed high stability during almost one week of use and good efficiency in producing bio-energy and removing COD from industria[...]

Treatment of 1,2-dichloroethane and n-hexane in a combined system of non-thermal plasma catalysis reactor coupled with a biotrickling filter


BACKGROUND A combined system with non-thermal plasma catalysis, CuO/MnO2 as the catalyst, and biotrickling filter (BTF) unit for the treatment of gases containing 1,2-dichloroethane and n-hexane was investigated. RESULTS The degradation of single 1,2-dichloroethane in the combined system was superior to that of the single BTF system. The combined system exhibited better adaptability when facing sudden changes in inlet concentrations and empty bed residence time. The presence of catalysts in the dielectric barrier discharge (DBD) reactor helped to reduce ozone generation and increase CO2 production and selectivity. Water solubility and degradability of the byproducts were also enhanced by the catalysts in the DBD reactor. Further studies showed that the degradation of 1,2-dichloroethane and n-hexane mixed exhaust gases and the re-acclimation performance after starvation in the combined system were better than those in the single BTF. Analysis of microbial communities showed higher biological diversity and abundance of microbial communities in the single-BTF system compared with the combined system. CONCLUSION The combined system with plasma-catalysis as pretreatment for the BTF can be used effectively to remove slowly biodegradable pollutants and has better stability and adaptability to changes in experimental conditions. © 2017 Society of Chemical Industry

Aldol condensation of benzaldehyde and heptanal: a comparative study of laboratory and industrially prepared Mg–Al mixed oxides


BACKGROUND Several layered double hydroxides (with Mg:Al ratio varying from 2:1 to 4:1) were prepared by a co-precipitation method at constant pH value. The activity of laboratory prepared samples was compared with that of industrially prepared layered double hydroxides with the same Mg/Al ratio in aldol condensation of benzaldehyde with heptanal. RESULTS Characterization of all solid catalysts was performed using different techniques (ICP-MS, thermogravimetry, X-ray diffraction, DRIFT spectroscopy, nitrogen physisorption method, scanning electron microscopy). Acido-basic properties of prepared materials were investigated using ammonia (carbon dioxide, respectively) temperature programmed desorption. Heptanal conversion and selectivity to two main products, i.e. 2-pentylcinnamylaldehyde (jasmine aldehyde) and 2-pentylnon-2-enal, were monitored. All catalysts resulted in heptanal conversions higher than 95%. CONCLUSION The highest selectivity to jasmine aldehyde (66% at 70% heptanal conversion, 46% theoretical yield) was obtained using ESM 3:1 catalyst (100°C, heptanal:benzaldehyde = 1:2 molar, solvent-free synthesis). © 2017 Society of Chemical Industry

Immobilization of lipase B from Candida antarctica on epoxy-functionalized silica: characterization and improving biocatalytic parameters


BACKGROUND In this work, lipase B from Candida antarctica (CaLB) was immobilized on Purolite® ECR8205F, Purolite® ECR8214F and Immobead® IB150 P epoxy resins with no modification to their surfaces. Biocatalysts were evaluated for thermal stability and applied in reactions of hydrolysis, esterification and the synthesis of glyceryl carbonate by transesterification with dimethyl-carbonate both with glycerol and Macauba oil as well as dynamic kinetic resolution of α-methylbenzylamine, all of them compared with commercial Novozyme 435®. RESULTS Protein desorption of the biocatalysts with Triton X-100 showed that lipase was immobilized by covalent single-bond type binding. The immobilization efficiencies were 55.1% for the biocatalyst 8205, 57.1% for 8214, and 14.9 for the 150P, demonstrating the intense effect of surface and material composition on lipase immobilization. The biocatalysts also showed higher initial velocities of esterification and hydrolysis reactions as well as higher thermal stability than Novozyme 435®. On glycerol carbonate synthesis, conversion of 97% and selectivity higher than 99% was demonstrated by enzyme 8214, similar to Novozyme 435®. On kinetic dynamic resolution, conversions higher than 94% and and enantiomeric excesses greater than 90% were also depicted. CONCLUSION Compared with commercial preparation Novozyme 435®, the novel biocatalysts obtained by immobilization on new epoxy resins demonstrated protein loads about 10-fold lower and higher specific activity. In all reactions performed, competitive performances were found, demonstrating high po[...]

Improving catalytic activity of laccase immobilized on the branched polymer chains of magnetic nanoparticles under alternating magnetic field


BACKGROUND Immobilization of laccase may cause more or less mass transfer limitation in practical applications. In order to enhance the reaction rate, there is great interest in developing an effective way to increase the rate of diffusion in reactions catalyzed by immobilized laccase. RESULTS The laccase from Trametes versicolor (p-diphenol: dioxygen oxidoreductases, EC immobilized on different molecular weight polyethylenimine (PEI) modified amine-functionalized Fe3O4 nanoparticles [Fe3O4–NH2–PEI (1200/10 000/60 000)–laccase] was separately fabricated. The oxidation reaction rate of catechol catalyzed by Fe3O4–NH2–PEI (1200)–laccase under an alternating magnetic field (600 Hz, 10 Gs) was separately 2.10 times and 1.16 times higher than the control without any external force and with mechanical stirring at 150 rpm. This was a larger increase than for Fe3O4–NH2–PEI (10 000/60 000)–laccase. In addition, the reaction rate catalyzed by Fe3O4–NH2–PEI (1200)–laccase was enhanced as the magnetic field frequency, strength and Fe3O4–NH2–PEI (1200)–laccase or catechol concentration was increased. The immobilized laccase retained 85% of its initial activity after six consecutive operations. CONCLUSION Using an alternating magnetic field was a powerful way to intensify the reaction rate catalyzed by laccase immobilized on branched polymer chains of magnetic nanoparticles and showed potential for large-scale catalytic reaction. © 2017 Society of Chemical Industry

Factors controlling adsorption of recalcitrant organic contaminant from bio-treated coking wastewater using lignite activated coke and coal tar-derived activated carbon


BACKGROUND Low-cost coal-based carbonaceous material has attracted special attention for removal of organics from industrial wastewaters. In this study, coal tar-derived activated carbon (AC1) and lignite activated coke (AC2) were employed to identify the fundamental factors that facilitate the selection of suitable adsorbents for removing recalcitrant organic contaminant (ROC) from bio-treated coking wastewater (BTCW). RESULTS Results show that AC2 exhibited superior ROC adsorption efficiency (57.9%), which was apparently higher than that of AC1 (45.2%), in spite of its lower specific surface area (238.05 m2 g−1) and pore volume (0.21 cm3 g−1). FTIR and XPS characterization indicated that AC2 possessed a distinctive configuration of functional groups, of which the basic oxygenic groups (60%) provided more hydrophobic adsorption sites for ROC. 3D-EEM spectra suggested more aromatics and fluorescent materials were removed by AC2 compared with AC1. GC-MS further confirmed that AC2 had stronger affinity with the ROC in BTCW, especially for PAHs and heterocyclic compounds. CONCLUSION Surface chemistry is vital to the adsorption of ROC from coking wastewater, of which basic oxygenic functional groups have specific interactions with PAHs and heterocyclic compounds. The mechanism that best explains ROC adsorption is π–π dispersion between carbon materials and the pollutants, as well as the hydrogen-bonding interactions. This study provides an encouraging and practical guide to ROC adsorption from BTCW in future operations. [...]

Alkaline fermentation and elutriation of waste activated sludge for short chain fatty acids abstraction


BACKGROUND Alkaline fermentation of waste activated sludge (WAS) is feasible to recover carbon for biological nutrients removal. However, it is difficult to abstract the soluble organics from the fermented mixture since sludge dewaterability is deteriorated after fermentation. In this study, a novel system consisting of complete mixing fermentation, water elutriation and settling reactor was developed to produce and abstract short chain fatty acids (SCFAs) from waste activated sludge through an alkaline fermentation process. RESULTS For the novel system, 57% of sludge solubilization and 327 mg COD g−1 VS of SCFAs production were achieved in the fermentation zone, resulting in a sludge reduction of 54%. In the elutriation zone, nearly 70% of soluble organics was recovered when the water exchange ratio was 33.3%. Moreover, mass balance of the system was calculated and the results showed that C, N, and P element were converted into the liquors phase in the fermentation process with proportions of 54%, 30%, and 16%, respectively. CONCLUSION This work successfully developed a novel process for wasted sludge fermentation and soluble organic carbon separation. Effective results were obtained in the system, indicating it is favorable for pilot and full scale application. © 2017 Society of Chemical Industry

Effect of the height-to-diameter ratio on the mass transfer and mixing performance of a biotrickling filter


BACKGROUND Biotrickling filters (BTFs) are among the most widely used biological technologies for air pollution control. The pollutant removal rate in BTFs relies to a large extent on its gas–liquid mass transfer performance. Therefore, knowledge of the design parameters affecting the mass transfer and mixing performance of full-scale BTFs is of paramount importance. RESULTS This work showed that the height-to-diameter (H/D) ratio is an important parameter in the design of BTFs devoted to air pollution control. The H/D ratio significantly affected the mass transfer and mixing performance of the BTF with and without additional stirring in the holding tank. It was observed that under the same liquid velocity, the mass transfer coefficient (kLa) and the mixing time (tmix) can be optimized only by selecting an adequate H/D ratio. Additional stirring in the holding tank also affected kLa and tmix, this effect being different for each H/D ratio tested. CONCLUSIONS The H/D ratio should be considered in the design of full-scale BTFs since this parameter will significantly affect the mass transfer and mixing performance, regardless of the agitation conditions prevailing in the holding tank. As far as the authors know this is first report addressing the combined effect of the H/D ratio, liquid velocity and holding tank stirring on kLa and tmix in BTFs devoted to air pollution control. © 2017 Society of Chemical Industry

A comparative study of the influence of salt concentration on the performance of an osmotic membrane bioreactor and a sequencing batch reactor


BACKGROUND An osmotic membrane bioreactor (OMBR) is a wastewater treatment technique that presents low energy requirements, low membrane fouling and high removal of nutrients and organic matter. However, reverse salt flux is the main disadvantage because it causes conductivity increase in the bioreactor. This study compares the performance of a sequencing batch reactor (SBR) and an OMBR in terms of chemical oxygen demand (COD) removal, soluble microbial products (SMP) and extracellular polymeric substances (EPS) production. For that, the influent conductivity in the SBR was increased as this increases conductivity in the osmotic membrane bioreactor. RESULTS Comparing the results obtained at two mixed liquor suspended solids (MLSS) concentrations in terms of membrane fouling, a concentration of 5 g L−1 of MLSS was chosen for the comparison with the SBR. The SBR achieved slightly higher COD removal efficiencies than the OMBR is spite of the accumulation of cellular debris in the membrane bioreactor. The accumulation of SMP and EPS in the OMBR was also higher than in the SBR due to the cellular debris and organic matter accumulation. In both reactors the microbial activity measured in terms of standard oxygen uptake rate decreased due to the increase of salt concentration in the bioreactor. CONCLUSIONS As a conclusion, OMBR will be especially feasible when the draw solution is a residual stream of the same industry, like tannery wastewater or tab[...]

Fabrication of Ni-Fe LDH/GF anode for enhanced Fe(III) regeneration in fuel cell-assisted chelated-iron dehydrosulfurization process


BACKGROUND The incorporation of an air-cathode fuel cell into the chelated iron dehydrosulfurization process realizes simultaneous recovery of electricity and elemental sulfur from H2S. However, the slow oxidation kinetics of chelated Fe(II) in the fuel cell limits the efficiency of such a process. RESULTS A novel Ni–Fe layered double hydroxides/graphite felt (Ni-Fe LDH/GF) anode is fabricated to speed up the electro-oxidation of chelated Fe(II). The prepared Ni-Fe LDH gives a formula of Ni0.68Fe0.32(OH)2(CO3)0.16·yH2O and covers the GF as nano-scaled hexagonal plate. The Ni-Fe LDH demonstrates stable catalytic activity towards the electro-oxidation of Fe(II)-EDTA, evidenced by the enhanced reaction rate and decreased reaction resistance at LDH modified GF. As a result, the total time for Fe(II)-EDTA oxidation in the fuel cell reduces significantly from 90 to 50 h when Ni-Fe LDH/GF composite is used instead of GF, and the coulombic efficiency (CE) of circuit is increased by 53% concomitantly. The catalysis activity of Ni-Fe LDH is proposed to be due to its anion-exchange ability for Fe(EDTA)2− and Fe(OH)(EDTA)3−, which benefits the diffusion of the two dominant Fe(II) species onto the electrode surface to perform electro-oxidation. CONCLUSION In summary, the fabricated Ni-Fe LDH/GF anode material is suitable for enhancing the Fe(III) regeneration in an air-cathode fuel cell, and can further improve the efficienc[...]

Biosynthesis of 4-isopropylbenzoic acid from α-pinene by using a mutant strain originated from the α-pinene degrader Pseudomonas veronii ZW


BACKGROUND Anthropogenic activities, in particular industrial processes, increase the emissions of volatile organic compounds to the atmosphere. Using special microorganisms to achieve resource recovery is a challenge for pollutant purification. RESULTS The α-pinene-degrading bacterium, Pseudomonas veronii ZW completely mineralized α-pinene to CO2 and H2O. One important intermediate metabolite, 4-isopropylbenzoic acid, was chosen as the target accumulated compound. Through mutagenesis technology, the mutant, P. veronii ZW-A (CCTCC M2015788), was obtained from the wild strain, and its metabolic pathway for α-pinene was verified to block in the step of 4-isopropylbenzoic acid. A 663-bp DNA fragment flanking the transposon insertion site was obtained through self-formed adaptor PCR, and was designated as gene orfA, displaying 96% deduced amino acid sequence – similar to rulAB-like protein. Since this protein contained the mono-aromatic and polyaromatic compounds homologue degradation gene, the mutant ZW-A might be an orfA-disrupted strain, incapable of degrading 4-isopropylbenzoic acid. Through the optimization of cultural medium, the accumulation rate increased from 19% to 30.4%. CONCLUSION This research identified the gene which was related to the degradation of 4-isopropylbenzoic acid. Such results provided a further understanding of microbial metabolism of α-pinene by Pseudomonas sp[...]

Lipase B of Candida antarctica co-adsorbed with polyols onto TiO2 nanoparticles for improved biocatalytic performance


BACKGROUND The immobilization of the lipase B of Candida antarctica CALB over TiO2 nanoparticles was thoroughly investigated with the isotherms of adsorption at various temperatures with and without the addition of sorbitol and glycerol. The surface composition, secondary structure and the effect of the addition of the polyols was addressed. RESULTS The maximum dispersion limit of protein on TiO2 nanoparticles (NPs) is 0.073 ± 0.007 µmol m−2. Glycerol and sorbitol co-adsorb on the TiO2 NPs reaching 45% of the surface composition of the biocatalyst. The optimized material was able to catalyze the esterification of 52% of R/S-ibuprofen with ethanol (0.31 ± 0.01 µmol min−1 mg−1) with 41% of enantiomeric excess towards S(+)-ibuprofen in 24 h reaction. Under similar reaction conditions, the commercial counterpart Novozym® 435 showed 34% conversion (0.091 ± 0.003 µmol min−1 mg−1) and 16% of enantiomeric excess. CONCLUSIONS The molecular association between the protein and the polyols exerts a positive cooperativism which prevents aggregation of the protein and protects its active conformation. The residual esterase activity of the immobilized CALB compared with the free lipase depends directly on the amount of co-adsorbed polyols. Moreover, polyols boost the catalytic performance in the kinetic resolution of racemic ibuprofen showing an optimum at the ma[...]