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Preview: Journal of Chemical Technology & Biotechnology

Journal of Chemical Technology and Biotechnology

Wiley Online Library : Journal of Chemical Technology and Biotechnology

Published: 2017-12-01T00:00:00-05:00


Increasing mass transfer of volatile organic compounds in air scrubbers: a fundamental study for different gas-liquid systems


Abstract BACKGROUND Air scrubbers are commonly used as treatment techniques for industrial waste gases containing volatile organic compounds (VOCs). Mass transfer of hydrophobic compounds to liquid can be increased using water soluble additives in the scrubbing liquid or applying water-miscible or immiscible solvents. The design of air scrubbers requires reliable partition data, which are limited in literature. This manuscript provides partitioning data of new scrubber liquids and subsequent research will link the partitioning data with mass transfer characteristics in a pilot-scale scrubber. RESULTS The DynAb method was applied for the first time to a broad set gas-liquid systems to study the partitioning behaviour of volatile organic sulphides and aldehydes. Cyclodextrins (CD) were chosen as water soluble additives. Silicone oil (SO) and isopropylmyristate (IPM) were used as water immiscible solvents, whereas dipropylene glycol methyl ether was applied as a water-miscible solvent. The inclusion of VOCs into the CD structure is very compound specific. Binding constants were calculated to quantify the CD-VOC affinity and the partitioning behaviour of the VOCs with oils and solvents were quantified. The air-to-water partition coefficient of hexanal could be reduced more than 50 times with a concentration of 72 g L-1 α-CD. IPM (100% v/v) could reduce the air-to-IPM partitioning coefficient with factor 120 for dimethyl disulphide. CONCLUSION The determined partition coefficients can be used for suitability evaluation for the design and modelling of air treatment systems. A broad range of evaluated gas-liquid systems provides quantitative knowledge about VOC behaviour.

Co-production of 2,3-BDO and succinic acid using xylose by Enterobacter cloacae


BACKGROUND 2,3-Butanediol and succinic acid are staple chemicals that are widely used in the chemical industry. In this study, a new strategy for the simultaneous fermentation of 2,3-butanediol and succinic acid by Enterobacter cloacae using xylose was developed. The mechanism by which the succinic acid pathway was enhanced during 2,3-butanediol fermentation in E. cloacae was studied. In addition, the sodium bicarbonate feeding mode and time, pH, and aeration rate were optimized. Fed-batch fermentation was performed under the optimal conditions using industrial xylose as a raw material. RESULTS The succinic acid pathway was enhanced by the addition of sodium bicarbonate during 2,3-butanediol fermentation. Interestingly, a simple increase of the initial pH had no effect on the production of succinic acid. The sodium bicarbonate feeding mode and time, pH and aeration rate were optimized. Under the optimum conditions, including a sodium bicarbonate feeding mode of 2 and time of 12 h, a pH of 6.5 and an aeration rate of 0.4 vvm, a maximum of 40.67 g/L of 2,3-butanediol and 21.79 g/L of succinic acid were obtained after a 72 h fed-batch fermentation when xylose was used as raw material, with a total 2,3-butanediol + succinic acid yield of 0.69 mol/mol xylose. CONCLUSION 2,3-Butanediol and succinic acid were produced in a single fermentation step using E. cloacae. The production of 2,3-butanediol and succinic acid was enhanced by controlling the sodium bicarbonate feeding mode and time, pH, and aeration rate. This type of fermentation provides a promising means of lowering the cost of production of these chemicals by reducing the fermentation operating time and fermentation equipment maintenance.

Effective bioremediation of Cu(II) contaminated waters with immobilized sulfate-reducing bacteria-microalgae beads in a continuous treatment system and mechanism analysis


BACKGROUND Microalgae which have greater biodegradable fractions than other organics were chosen as a carbon source for sulfate-reducing bacteria (SRB). Immobilized SRB–microalgae beads were then prepared and used for bioremediation of synthetic copper mine wastewater. RESULTS We observed hydrolysis fermentation of the microalgae and noted that the microalgae were first degraded to volatile fatty acids by co-existing fermentative bacteria; they then served as a carbon source for SRB. Freshly prepared immobilized SRB beads not only possessed high mechanical strength and mass transfer ability, but also showed better sulfate reduction than that of suspended SRB. Moreover, immobilized SRB-Scenedesmus obliquus beads packed in the upflow bioreactor were satisfactory for the treatment of copper mine wastewater, as shown by the high removal efficiency of their sulfate (182.17 mg SO42-·g-1 microalgae·day-1) and copper ions (45.28 mg Cu2+·g-1 microalgae·day-1), and low discharge of chemical oxygen demand. After the reaction, metal sulfides were not produced on the bead surfaces, but likely within them. CONCLUSIONS The anaerobic bioreactor, filled with immobilized SRB-Scenedesmus obliquus beads, demonstrated excellent removal efficiency and low discharge of chemical oxygen demand, which may provide a promising strategy for dealing with heavy metal pollution in water.

Effects of influent loads on performance and microbial community dynamics of aerobic granular sludge treating piggery wastewater


BACKGROUND Understanding how influent loads affect microbial community may promote applications of aerobic granular sludge (AGS). Herein, performance and microbial community dynamics of the AGS were assessed with stepwise increasing influent loads. RESULTS AGS exhibited good structure stability and effective removal efficiency, when the influent load increased from 6.5 kg COD·m-3·d-1 (0.255 NH4+-N·m-3·d-1) to 10.1 kg COD·m-3·d-1 (0.455 kg NH4+-N·m-3·d-1). COD and NH4+-N removal efficiencies reached 97.1 - 97.9% and 84.5 - 98.0%, respectively. As indicated from the PCR-DGGE results, the microbial community and dominant species in the AGS also gradually evolved along with the increase of influent loads. A coincidence was observed, namely, three main distinct clusters of the phylogenetic tree appeared respectively in the three stages of influent loads. The microbial diversity attained its maximum in the medium loads stage. Besides, the identified bacteria mainly belonged to Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes. The dominant species were responsible for the AGS stability and pollutant removal. CONCLUSION Variation in the influent load strongly affected the microbial community dynamics, and hence the AGS performance. These results and understanding could lead to potential improvements in guiding AGS wastewater treatment.

Electrochemical treatment of copper complexed by chelating agent and chelating surfactant in alkaline solution using a membrane cell


Abstract BACKGROUND The electrochemical recovery of copper from DTPA and C12-DTPA (a surface-active derivative of DTPA) complex solutions was investigated in a membrane flow cell. Electrolysis time, solution flow rate, applied current density, and solution pH were evaluated. RESULTS The chelating surfactant C12-DTPA can promote the kinetics of copper electrodeposition more than DTPA depending on the experimental conditions. At a current density of 30 A m–2, a solution flow rate of 0.6 L min–1, and pH 10 after 180 min treatment, the copper recovery and current efficiency were 50% and 43.3%, respectively, in the Cu(II)-DTPA system and about 65% and 53.6%, respectively, in the Cu(II)-C12-DTPA system. The differences in the amount of recovery could be explained in terms of differences in the diffusion of copper complexes with DTPA and C12-DTPA to the cathode, as well as their solution behavior and pH-dependent conditional stability constants (log10 K’CuDTPA3-). CONCLUSION Electrochemical methods could be effectively combined with foam flotation for the chelating surfactant C12-DTPA, to recover copper and C12-DTPA. This makes the overall treatment more sustainable, and can be helpful in complying with the increasingly stringent environmental regulations.

Sulfonated poly(arylene ether nitrile)/polypyrrole core/shell nanofibrous mat: an efficient absorbent for the removal of hexavalent chromium from aqueous solution


BACKGROUND Sulfonated poly(arylene ether nitrile)/polypyrrole core/shell nanofibrous mats were prepared by electrospinning technique, followed by in situ polymerization of pyrrole monomer. Their removal behaviour of hexavalent chromium (Cr (VI)) from aqueous solution was systematically investigated. The structure and composition of core/shell PEN/PPy nanofibrous mats were examined and confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). RESULTS The adsorption results revealed that the adsorption capacity of core/shell PEN/PPy nanofibrous mats increased with the decrease of initial solution pH and adsorption process can be described by using the pseudo-second order model. These core/shell PEN/PPy nanofibrous mats showed a high Cr (VI) adsorption capacity up to 165.3 mg/g at room temperature, which can be largely maintained after four adsorption/desorption cycles. Furthermore, the adsorption isotherms of PEN/PPy nanofibrous mats for Cr(VI) removal fitted the Langmuir isotherm model. The adsorption mechanism of electrostatic attraction between PEN/PPy nanofibrous mats was also presented. CONCLUSION The core/shell PEN/PPy nanofibrous mats in the form of flexible membrane allowed easy handling during application, which can be considered as a stable and effective adsorbent for removal of heavy metals and other anionic contaminants from wastewater.

Design of a heterogeneous enzymatic catalyst on chitosan: investigation on the role of conjugation chemistry in the catalytic activity of a Laccase from Trametes versicolor


BACKGROUND Three protocols are presented in order to immobilise a laccase (EC from Trametes versicolor on chitosan. In particular, chitosan is functionalized with glutaraldehyde and epichlorohydrin to explore to what extent the conjugation of the enzyme is affected by a carbonyl- or epoxy-modified surface, respectively. In addition, an oxidation procedure is tested to modify, for the first time, the carbohydrate moiety of the enzyme and exploit it for the linking with amine group of chitosan. RESULTS The system in which laccase is directly conjugated to chitosan seems to be the most performant since it is able to maintain 100% of initial activity over a 30-days period and at least 50% of the starting activity after 3 catalytic cycles. CONCLUSION The methods show the capability to develop three biocatalysts suitable for the immobilization of laccase. All of them provide covalent bonds that don't inactivate the enzyme through any conformational change and any distortion of the active pocket. Specifically, the oxidation procedure proves to be feasible for the preparation of stabilized glycoproteins without the introduction of foreign molecules, suggesting that the carbohydrate moiety of laccase does not appear to be closely related to the catalytic site of the protein.

Promising abilities of mercapto-degrading Staphylococcus capitis strain SH6 in both crude oil and waste motor oil as sole carbon and energy sources: its biosurfactant production and preliminary characterization


BACKGROUND We showed previously that a Staphylococcus capitis strain SH6 was found to be able to degrade several malodorous mercaptans and simultaneously reduce the surface tension. RESULTS Herein, we revealed the capacity of strain SH6 to grow on various hydrocarbons, used as the only carbon and energy sources. Based on GC-MS analyses, the substantial ability to degrade up to 45% and 64% of aliphatic hydrocarbons (n-alkanes) of crude oil and waste motor oil, respectively, after 30 days of incubation at 37 °C and 180 rpm, was shown. Moreover, the properties of biosurfactant produced by strain SH6 grown on different oil substrates; diesel oil and waste motor oil, were studied. Biosurfactants exhibited enhanced emulsification capacities and significant stabilities over a wide range of salinity (20-150 g/l), temperature (-20-100 °C), pH (2-12) and also a promising abilities in crude oil removal from contaminated soils. Their CMC were of 800 mg/l. FTIR analyses suggested the lipopetide nature of biosurfactants. CONCLUSION Overall, the stabilities of biosurfactants under a wide pH range, high temperatures and variable concentrations of salt, as well as its emulsifying properties, suggest potential applications in bioremediation processes.

Quorum quenching activity of indigenous quorum quenching bacteria and its potential application in mitigation of membrane biofouling


BACKGROUND Quorum sensing (QS) could regulate gene expression so as to mediate some bacterial behaviors such as the production of extracellular polymeric substances (EPS) and biofilm formation. In this study, a quorum quenching (QQ) bacterium, was isolated from an indigenous lab-scale MBR and encapsulated in a dumpling-shaped microbial bag for biofouling control. RESULTS This QQ bacteria has a higher genetic homology with Acinetobacter bereziniae strain. The effect of time and temperature on the QQ activity of microbial bag was tested by degrading N-acyl homoserine lactone (AHL). The results showed the degradation of C8-HSL (N-Octanoyl-DL-homoserine lactone) and C6-HSL (N-Hexanoyl-L-homoserine lactone) could reach equilibrium within 2 h. In addition, the relatively suitable temperature for AHL degradation was 20°C, at which degradation rate of C6-HSL and C8-HSL by microbial bag was 88% and 69%, respectively. The antifouling efficiency of microbial bag was investigated by a constant pressure filtration system. With the microbial bag added, the decrease of permeability was obviously improved. After 14 d, the permeability with QQ decreased to 18% while the control experiment exhibited almost no permeability. CONCLUSION The excellent AHL degradation rate and the filtration test showed that this QQ bacteria has an excellent antifouling potential in membrane filtration systems.

Factors affecting the separation performance of graphene oxide membranes: mechanical support, properties of graphene oxide, and exotic species


BACKGROUND Graphene oxide (GO) membrane with 2-dimentional nanocapillaries has gained worldwide attention. To manipulate the membrane separation performance, most existing studies focused on sandwiching appropriate species between GO layers. This study aimed to provide multiple strategies to manipulate the GO membrane separation performance, including the mechanical support, properties of GO nanosheets, and exotic species (i.e. cross-linkers and residual water molecules). RESULTS Used as the support material, compared to the nitrocellulose membrane, the polyvinylidene fluoride membrane offered stronger mechanical strength to ensure a stable flux. Additional mechanical support could be provided by the non-woven cloth underneath the GO membrane. The usage of GO nanosheets with smaller sizes obtained by centrifugation of the GO suspension increased the water flux and NaCl rejection. Cross-linking GO layers by Ca2+ resulted in a decreased water flux but increased salt rejection. The same phenomena was observed for the GO membranes post-treated by vacuum drying, which, compared to air drying, evaporated more residual water molecules from the nanocapillaries. CONCLUSION Results suggested that the mechanical support, properties of GO nanosheets, cross-linkers, and residual water molecules greatly affected the membrane water flux and rejections, which could be utilized as the strategies to manipulate the GO membrane separation performance.

In situ extractive ethanol fermentation in a drop column bioreactor


BACKGROUND In conventional ethanol fermentation processes, the low ethanol content in the wine is due to inhibition of its production by the yeast cells. Extractive fermentation is an alternative process that can be used to overcome product inhibition by removing the ethanol from the fermentation broth. The present study describes the modeling and experimental validation of ethanol production in extractive batch fermentation, with in situ ethanol extraction by oleic acid, in a non-conventional drop column bioreactor (DCB) operated under industrial conditions. RESULTS A model was developed using the hybrid Andrews-Levenspiel equation and the ethanol distribution coefficient (KDE), which provided an excellent description of the extractive fermentation process with oleic acid. Furthermore, higher ethanol productivities were obtained in the extractive fermentations, with ethanol productivity of 11.27-12.98 kg⋅m-3⋅h-1, 12.7-29.8% higher when compared to the conventional process without ethanol removal. This was especially evident for the best extractive fermentation, which finished around 2 h earlier than the conventional fermentation. CONCLUSION The DCB showed good performance for use in extractive fermentation with liquid-liquid extraction of the ethanol and this technique presented higher ethanol productivity compared to the conventional process.

Removal of heavy metals by Klebsiella sp. 3S1. Kinetics, equilibrium and interaction mechanisms of Zn(II) biosorption


BACKGROUND In this work, the ability of biosorption and bioaccumulation of Zn (II) ions by Klebsiella sp. 3S1 has been investigated. This bacterium had already demonstrated its ability to remove Pb and Ag ions by different mechanisms. The mechanisms involved in the process have been studied using four techniques: FTIR, SEM-EDX, TEM-EDX and Confocal Microscopy. Kinetic and equilibrium studies have also been performed. RESULTS The main operating variables were optimized by a Rotatable Central Composite Design (RCCD) that yielded the following values: 0.36 g/L biomass, pH 5.20 and 34 °C temperature, although the equilibrium data were obtained at a temperature of 25 °C, more in line with the environmental conditions. The model that best fitted the experimental kinetic data turned out to be the pseudo-first order one. Maximum capacity of biosorption under Langmuir model was 48.4 mg/g. Finally, the presence of two general mechanisms in the biosorption process was confirmed: cytoplasmic bioaccumulation and complex surface adsorption. CONCLUSIONS Klebsiella sp. 3S1 can be an effective and inexpensive microorganism to remove heavy metals from contaminated effluents, which along with its ubiquity and great ability to form biofilms, make it a promising biosorbent for use in biofilters.

Factors affecting the selection of PHB accumulating methanotrophs from waste activated sludge while utilizing ammonium as their nitrogen source


BACKGROUND Methanotrophs can offer a long-term reliable solution for two of the major problems causing environmental pollution. These microorganisms can convert methane i.e. second major GHG into biodegradable polymers as polyhydroxybutyrate (PHB). In this research, waste activated sludge was used as a seed for cultivating enrichments utilizing methane and ammonium as their sole carbon and nitrogen sources respectively with high PHB accumulation capacity. Moreover, to test the effect of different parameters as the initial ratio between the ammonium and the microorganisms (N/M), food to microorganisms ratio (F/M), the solids retention time (SRT), copper elimination and nitrate on the selection of PHB accumulating i.e. Type II methanotrophs. RESULTS After establishing a mixed culture dominated by Type II methanotrophs, the enriched culture was kept at the exponential phase of growth and had a stable performance for almost 30 consecutive cycles with a specific growth rate of 0.077±0.005hr-1 and biomass yield of 0.81±0.06 mg-VSS/mg-CH4. The PHB accumulation capacity of the enrichment reached 52.9±4% with a yield of 0.54±0.12 mg-PHB/mg-CH4. CONCLUSIONS Increasing the N/M ratio can be successfully employed to ensure the dominance of Type II methanotrophs in mixed cultures having high PHB accumulation capacity while maintaining a high F/M ratio released any inhibition resulting from ammonium co-metabolism. Despite the dominance of Type II, switching the nitrogen source to nitrate caused an invasion for Type I methanotrophs and a deterioration in the PHB accumulation of the enriched culture.

Improvement of enzyme stability for alkyl esters synthesis in miniemulsion systems by using media engineering


BACKGROUND Oil-in-water miniemulsions have been suggested to display potential for application as a “green” system for enzymatic alkyl ester synthesis. Still, a realistic assessment of the feasibility of this approach for practical applications requires further insight, namely the relation between enzyme stability and reaction operational conditions. The objective of this work is within such scope. Accordingly, it extends previous research on esterification catalyzed by Fusarium solani pisi cutinase, by addressing medium-chain length substrates, and aims to contribute to the optimization of reaction conditions and towards the design of an efficient set-up. RESULTS The esterification yield was significantly enhanced (e.g. 50% increase for octyl octanoate system) through the correction of the initial pH of the reaction medium to pH 6. Under such environment, conformational changes of the enzyme were negligible after 24 h, resulting in improved enzyme stability for all systems under study. Maximum esterification rate (3.59 mmolmin-1) and product yield (91%) were achieved for octyl decanoate synthesis. Fed-batch mode of operation allowed for the production of 1 M hexyl octanoate, while retaining enzyme activity over five days. Consecutive batch runs allowed for the cumulative production of 1.1 M hexyl octanoate after 4 cycles. CONCLUSIONS Medium engineering allowed to use miniemulsion systems for the synthesis of medium-chain alkyl esters and to increase the final concentration of the intended product. Through a fed-batch mode the enzyme stability and reutilization was tuned allowing long-term utilization of the free enzyme which could not be achieved through a repeated batch system.

Gemini-type cationic surfactant-directed synthesis of hollow ZSM-5 zeolite with intracrystalline mesopores and its application in the hydroxylation of phenol


BACKGROUND ZSM-5 zeolites are of great importance in industrial catalysis. However, the diffusion limitations caused by small pore opening restrict the extent of catalytic conversions over conventional ZSM-5. Many works have shown that mass transfer in zeolite channels can be improved by controlling the morphology or creating additional mesoporosity. Here, we further improve the catalytic performance by the creation of hollow structure and intracrystalline mesopores in ZSM-5 zeolite. RESULTS The characterization results demonstrated that hollow ZSM-5 with intracrystalline mesopores can be synthesized by using a simple one-step hydrothermal strategy with a commercial gemini-type cationic surfactant containing hydrophilic hydroxyl groups. Compared to the Fe-substituted conventional ZSM-5, the Fe-substituted hollow ZSM-5 with intracrystalline mesopores show remarkably enhanced catalytic performance in the hydroxylation of phenol. About 52.2% conversion of phenol can be obtained with almost 96.8% selectivity to dihydroxybenzenes. The catalytic activity remained almost unchanged after five cycles. CONCLUSION The newly created hollow structure and intracrystalline mesopores in ZSM-5 zeolite showed enhanced catalytic activity and reusability for the hydroxylation of phenol, which is higher than most reported systems. The prepared catalyst is a promising alternative material for the hydroxylation of phenol.

Continuous cell flocculation for recombinant antibody harvesting


BACKGROUND Integrated continuous production technology is of great interest in biopharmaceutical industry. Efficient, flexible and cost effective methods for continuous cell removal have to be developed, before a fully continuous and integrated product train can be realized. Here we describe the development and testing of such an integrated continuous and disposable set-up for cell separation by flocculation combined with depth filtration. RESULTS Screening of multiple flocculation agents, depth filters, and conditions demonstrated that the best performance was obtained with 0.0375% polydiallyldimethylammonium chloride (pDADMAC; a polycationic flocculation agent) in combination with Clarisolve® depth filters. Using this set-up, we achieved a four-fold decrease of filtration area relative to standard filtration without flocculation, with yields of ≥97% and DNA depletion of up to 99%. We accomplished continuous operation using a simple tubular reactor design with parallelization of the filtration. The reactor length was selected to allow a 13.2-minute residence time, which was sufficient to complete flocculation in batch experiments. Continuous flocculation performance was monitored on-line using focused beam reflectance measurement. Filter switch cycles based on upstream pressure were controlled by in-line pressure sensors, and were stable from one filter to the next. CONCLUSION We demonstrated that stable and efficient continuous flocculation associated with depth filtration can be easily accomplished using tubular reactors and parallelization. Continuous cell separation is essential for the development of fully continuous integrated process trains. Our cost-efficient disposable design run in continuous mode significantly reduces facility foot print, process costs and enables great flexbility.

Biofiltration of Formaldehyde, Acetaldehyde, and Acrolein from Polluted Airstreams Using a Biofilter


Aldehydes inhalation can adversely affect human and environmental health. This study was carried out to investigate the removal efficiency (RE) of three aldehydes including formaldehyde (FA), acetaldehyde (ACT), and acrolein (ACR) from airstream using a biofilter packed with a new mixture of compost-scoria-sugarcane bagasse. Influence of inlet concentrations (0.63-25.15 mg/m3), empty bed residence time (EBRT) (40, 80, and 120s), and bed height on the biofilter efficiency were measured for three separated 90-day period. The mean RE of FA, ACT, and ACR were 92.6±4.6, 85.3±6.2, and 86.3±5.7 %, respectively. The mean RE at EBRTs of 40, 80, and 120s was 84.9±6.1, 87.9±6.2, and 91.4±5.1 %, respectively. Results showed that the RE decreased with increasing inlet concentration, so that the minimum RE (80.2±4.7%) was observed at the inlet concentrations of 78.5-25.15 mg/m3. Also, more than 68% of the overall RE was occurred in section 1 of the biofilter, where the mean bacterial population (7.51 log10CFU/g) was higher than that in section 2 (7.02 log10CFU/g). Finally, due to the high RE and negligible pressure drop of the bed, it can be calculated that a biofilter with the same conditions is a satisfactory technique to remove aldehydes from polluted air.

Harvesting of microalgae Coelastrella sp. FI69 using pore former induced TiO2 incorporated PES mixed matrix membranes


BACKGROUND Extracellular polymeric substances and microalgae stimulate membrane fouling during harvesting. The objective of the study was to compare the effect of pore formers on TiO2 embedded polyethersulfone mixed matrix membranes MMMs to harvest Coelastrella sp. FI69. The study experimented with hydrophilic additive (polyethylene glycol), polyelectrolyte additive (polyethylenimine), inorganic additive (zinc chloride) and charged polymer (sulfonated polyetherether ketone (SPEEK)) as pore formers. RESULTS It was found that SPEEK/TiO2 combination enhanced the hydrophilic property on the PES membrane surface. Also, contact angle value (55.22°) was decreased to 1.38 times of a neat PES (76.63°) membrane Morphology studies indicated that the TiO2 particles dispersed well in PES membrane matrix along with pore formers. The existence of super hydrophilic TiO2 supported the restriction microalgae cell attachment on the membrane surface. The filtration of alginic acid sodium solution analysis showed that PES/SPEEK/TiO2 and PES/PEG/TiO2 membranes support higher flux with minimal fouling percentage. The microalgae filtration studies indicated that synergistic effect of both SPEEK and TiO2 on PES membrane exhibited higher water recovery percentage of 96 % and equilibrium flux of 66 L/m2h. CONCLUSION Fouling propensity is significantly reduced in modified membranes. Future research on scale-up of membranes for further microalgae dewatering applications is recommended.

Practical experiences from the bench-scale implementation of a bioprocess for fucoxanthin production


BACKGROUND A laboratory scale protocol for the production, primary recovery and partial purification of fucoxanthin via biomass production at low light intensities was previously reported. This proposed approach exploited the use of ethanol salt aqueous two-phase systems (ATPS) and ultrafiltration (UF) to deliver a 45% total recovery yield if all steps were implemented in a bioprocess. In this study, practical experiences derived from the bench-scale implementation of the previously characterized lab protocol are presented. RESULTS After the implementation of the process, a 47.5% fucoxanthin recovery was obtained, while 87.2% of the contaminant proteins were removed. CONCLUSION The findings reported here provide the required guidelines to facilitate the process scale-up in route for the potential commercial production and recovery of fucoxanthin.

Anaerobic Treatment of Sugar Cane Vinasse: Treatability and Real-Scale Operation


BACKGROUND Vinasse is a wastewater from the bioethanol production with a very high concentration of organic matter, usually from 40 to 80 gCOD/L. These features make this wastewater attractive for treatment in an anaerobic system. Anaerobic processes allow the valorisation of this highly polluting wastewater as an energy resource in an environmentally friendly way. RESULTS A multiscale approach was followed, using batch tests, continuous bench scale reactors, and a full-scale UASB reactor. Potential inhibition due to high potassium concentrations was evaluated. From batch tests was determined the IC50 of the potassium concentration around 6 g/L, but continuous reactors could adapt the biomass to this concentration level without removal efficiency decay. A load of 20 gCOD/L.d with chemical oxygen demand (COD) removal efficiencies between 60% and 80% were reached in bench scale UASB and EGSB reactors. Finally, a 100 m3 UASB reactor located in a distillery was tested under industrial conditions. A load of 0.6 kgCOD/kgV SS.d was achieved with a COD removal efficiency of 78%. CONCLUSION Although potassium was inhibitory for the inoculum, the sludge from a continuously operated reactor can be adapted to high potassium concentrations without affecting its performance. The real possibility of working with undiluted vinasse was also verified. For distilleries like the Uruguayan case, which produces 18000 m3 of bioethanol per year, 5x106 m3 of biogas per year, with 68% methane, could be expected, representing an energy potential of about one-third of the main fuel produced.

Lipase production by solid-state fermentation of olive pomace in tray-type and pressurized bioreactors


BACKGROUND Bioreactor type, sterilization and specific operational conditions are key factors for the scale-up of solid-state fermentation (SSF). This work deals with the lipase production by SSF of olive pomace (OP) at a traditional tray-type and pressurized bioreactors. Important aspects for SSF at bioreactors were studied, such as the need of sterilization and moisture content (MC) control. RESULTS At larger scale, there was no significant difference in lipase production between sterilized and unsterilized substrates, but MC control had significant impact. The production of lipase in a pressurized bioreactor, under air absolute pressure of 200 kPa and 400 kPa, was two-fold higher than in tray-type bioreactor using the same amount of substrate (500 g) and the same bed height. The protein content of substrate increased from 10 to 18% (w/w) after SSF and the fermented solid presented an antioxidant activity of 10 mmol Trolox kg-1. CONCLUSIONS SSF in pressurized bioreactor allowed to efficiently produce lipase with higher substrate bed height in contrast to that in tray-type bioreactor. The improvement of nutritional value of substrate by SSF indicates its potential applicability in animal feed.

Deep Eutectic Solvents: Designer Fluids for Chemical Processes


The increasing demand for multi-task green solvents has spurred the development of next-generation liquid media such as deep eutectic solvents (DESs), which have recently attracted increased attention. DESs are mixtures of salts and complexing agents, having freezing points lower than those of starting individual components. Similarly to ionic liquids, DESs exhibit distinctive properties such as chemical and thermal stability, biodegradability, non-flammability, and cost effectiveness. These features account for their wide range of applications, e.g., as extractants, reactants, catalysts, reaction media, additives, and lubricants. This review summarizes the recent research efforts directed at exploring the potential applications of DESs in various chemical processes. With the rapid publication on this new generation of solvents, other roles also are expected to be seen sooner or later.

Sustainable approach to biotransform industrial sludge into organic fertilizer via vermicomposting: A mini-review


Currently, industrial sludge is generated in large amount annually. Industrial sludge is a solid or semi-solid material consisting of all compounds removed from wastewater, as well as any substances added to the biological and chemical operation units during the treatment process. The composition of sludge may vary considerably. Furthermore, distinctive treatment and disposal methods are necessary as sludge produced from different industries would have different characteristics. Therefore, processing and disposing of industrial sludge is a challenging and complex environmental problem. Landfilling, incineration and agricultural land application are the three most commonly employed methods for the disposal of industrial sludge. Among the three methods, the agricultural land application is a convenient and economical disposal alternative for industrial sludge. However, industrial sludge could have high putrescible content and pathogenic hazards. One possible way to ensure that the industrial sludge could be reused on agricultural land is by conditioning and stabilizing the sludge using a pretreatment process. One of the pretreatment processes which could be employed in this context is vermicomposting. Vermicomposting is an alternative for biological stabilization of organic wastes, with the addition of earthworms. Through vermicomposting, industrial sludge could be transformed into matured organic fertilizer or vermicompost in a shorter period. Thus, this paper reviewed the recent literature on utilizing the vermicomposting process to manage industrial sludge in order to assess the feasibility of this technology. The present review would also provide a brief overview of the production and treatment methods of industrial sludge.

Bio-degradation of polyethylene via complete solubilisation by the action of Pseudomonas fluorescens, bio-surfactant produced by Bacillus licheniformis and anionic surfactant


Background Long hydrocarbon (~CH2) chain, absence of polar bonds and highly hydrophobic nature of polyethylene, makes polyethylene one of most difficult environmental pollutants to degrade. In the present study, commercially available polyethylenes were treated with bio-surfactant produced by Bacillus licheniformis, anionic surfactant and bacterially treated with Pseudomonas fluorescens in a different combination to achieve higher biodegradation. Results Polyethylene was slightly oxidised by P. fluorescens in the first month and the oxidation of polyethylene induced by the bio-surfactant during second month was enhanced by the presence of lower amount of carbonyl groups as observed in FTIR analysis. During third month, highly oxidised polyethylene was entirely solubilised by the action of 10% SDS forming two layered liquid consisting of yellow oil like liquid as upper layer and aqueous colourless lower layer. Bio-degradable aliphatic acids, alcohols and short hydrocarbon molecules of 10-30 carbon chains were identified in GC-MS analysis in the aqueous solution. Weight-loss of 7.13 ± 0.05% was also observed in polyethylene samples which were treated with SDS in the first month, then bacterially treated with P. fluorescens in the second month and finally treated with bio-surfactant in the third month. Conclusions Polyethylene became biodegradable after complete solubilization in water by treating consecutively with Pseudomonas fluorescens in the first month, then with bio-surfactant in the second month and finally treating with 10% sodium dodecyl sulphate (SDS) at 60°C for third month. Simultaneous treatment of polyethylene with P. fluorescens, surfactant (SDS) and bio-surfactant has tremendous effect on the oxidation and biodegradation of polyethylene.

Simultaneous sequestration of nitrate and phosphate from waste water using a tailor made bacterial consortium in biofilm bioreactor


BACKGROUND Municipal wastewater that usually contains nitrate and phosphate as major contaminants, if discharged untreated affects health of environment and human population. Currently available treatment technologies to treat municipal wastewater lose the essential growth nutrients ‘P’ and ‘N’ during treatment. In this paper we present a strategy of simultaneous sequestration of nitrate and phosphate in biomass, by using a tailor made consortium in biofilm reactor. RESULTS The consortium comprising of 3 novel Bacillus strains in a fixed bed biofilm bioreactor maintained at ambient temperature showed reduction up to 94% of nitrate, 68% of phosphate, 93% of Chemical Oxygen Demand, 97% of Biochemical Oxygen Demand, 73% in Total Organic Carbon while maintaining an effluent pH of 6.8 ± 0.02. Response Surface Methodology revealed maximum reduction at a flow rate of 1.97 L/h with 306.04 mg/L and 19.62 mg/L of initial nitrate and phosphate concentrations respectively. The system was scaled up from 4.5 L to 220 L with the same retention time of 2 h and operated with consistent performance for over 212 days. CONCLUSION The treated waste water met the criterion for reuse as non-potable water for applications like irrigation and aquaculture, hence making it the fastest microbial process for simultaneous nitrate and phosphate removal from waste water

Effect of sludge age on the consortium of microorganisms microbial consortia developed in MFCs


BACKGROUND This work is focused on the assessment of the performance of mini-scale air-breathing microbial fuel cells (MFCs), by monitoring the evolution of the bio-electrogenic activity for a period of 40 days and by comparing the microorganisms populations developed in each of the MFC after this period. RESULTS Five MFCs were operated at sludge ages ranging from 1.4 to 10.0 days. Results showed the superb performance of the MFC operating under a sludge age of 2.5 days. Desulfuromonas, Syntrophothermus, Solitalea, Acholeplasma, Propionicimonas, Desulfobacula and Sphaerochaeta are proposed as potential responsible for the bio-electrogenic activity. CONCLUSIONS Microbial population analysis through Illumina amplicon sequencing demonstrated that despite all MFCs were seeded with the same mixed culture inoculum, the biological cultures developed in the suspension and the biofilm are completely different and depend strongly on sludge age.

A perspective on flotation: a review


The problem of fine particles processing has become important both in mineral processing and also for water and wastewater engineering. It is accepted, on the other hand, that the bubble–particle collection efficiency increases with decreasing bubble size. A decrease in bubble size can be obtained using different methods (dispersed-air, where electroflotation is included, and/or dissolved-air flotation), as discussed. Following an introduction of the subject, older Laboratory results are presented in this review paper (based on 4 decades of experience), explaining the above, giving further ideas and possibly, assisting the future researchers in the area. Examples given are: separation of fine mineral particles (such as pyrite and magnesite), and of metal ions (as chromium, arsenic, copper, zinc, germanium and so on); among the various available techniques, mention is given to ion, precipitate, adsorbing colloid, sorptive and biosorptive flotation - including certain comparisons for the same application. Attention on the metal ion flotation application deserves further study and work, mainly for selective removal.

Remediation of soil contaminated by PAHs and TPH using alkaline activated persulfate enhanced by surfactant addition at flow conditions


BACKGROUND Remediation of a soil polluted with fuel oil #2 and polycyclic aromatic hydrocarbons (PAHs) has been carried out by alkaline activated persulfate (PS). Furthermore, the effect of surfactant addition on the abatement of TPH and PAHs was studied. Accordingly, four runs were performed at flow conditions using: 1) only water, 2) only surfactant (15 g L−1 of Verusol-3), 3) activated persulfate (210 mM PS and 840 mM NaOH) and 4) surfactant (15 g L−1 Verusol) with activated persulfate (210 mM PS and 840 mM NaOH). RESULTS Washing with water was found to achieve a negligible desorption of the pollutants. Washing with surfactant or a combination of surfactant and oxidant completely removed the contaminants from soil, however only the addition of oxidant yielded an aqueous effluent without the pollutants. When adding activated persulfate alone (without surfactant), about 30% residual contamination remains in the soil. CONCLUSION Results suggest that the combined application of surfactant and alkali persulfate produces a significant improvement in the elimination of organic compounds such as fuel oil #2 and PAHs.

Mixing characteristics, cell trajectories, pressure loss and shear stress of tubular photobioreactor with inserted self-rotating helical rotors


BACKGROUND Tubular photobioreactors (TPBRs) have great potential in culturing microalgae, but their poor mixing properties make it difficult to increase the surface productivity. In our work, a TPBR with inserted self-rotating helical rotors, which have been studied for a decade by our team, was designed. RESULTS This paper aimed to show hydrodynamic behaviors of gas-liquid in a TPBR with inserted self-rotating helical rotors by computational fluid dynamics (CFD) and the visualization experiments. It could be concluded that with assembling self-rotating helical rotors into the TPBR, very remarkable mixing and particle cycle frequency could be achieved. Besides, the influences of rotor lead and liquid inlet velocity on the swirl number, gas holdup, pressure loss, cell trajectories and shear stress were also investigated. And it would be a better choice to select a rotor lead of 150mm and a liquid inlet velocity of 0.4~0.5m/s for microalgae with strong shear force tolerance. The microalgae cultivation experiments verified that helical rotors had a positive effect on the biomass productivity. CONCLUSION The results indicated that assembling the self-rotating helical rotors into TPBR was a feasible and effective method to improve the mixing performance and microalgae productivity.

Enzymatic Fructose Removal From D-Psicose Bioproduction Model Solution and the System Modeling and Simulation


BACKGROUND The rare sugar of D-psicose has important physiological functions, and has been allowed used as ingredient in foods and dietary supplements. It can be mass produced from D-fructose in industry. However, separation of D-psicose from D-fructose is difficult. RESULTS In this research, a reaction purification system consists of two continuous stirred tank reactors (CSTR) containing immobilized glucose isomerase (GI) and glucose oxidase (GOD), respectively, for D-fructose removal is constructed. Using this system D-fructose is transformed into gluconic acid and can be separated from D-psicose easily by using anion exchange resin. Modeling and simulation is made for this system and the model is verified by experiments and used in process predictions. CONCLUSION D-Psicose can be efficiently purified by using the reaction purification system. The final purity of the D-psicose is 91.2%, which purity meets the need for crystallization to obtain highly purified product. The mathematical model developed for this system can simulate and predict the process well, which is useful in process analysis, prediction, and optimization to save the time and costs compared with laboratory experiments.

Recovery of Butanol from Clostridium beijerinckii P260 Fermentation Broth by Supercritical CO2 Extraction


BACKGROUND Butanol is a superior biofuel to ethanol because of its blend properties and higher energy density. However, its recovery by distillation from the fermentation broth is energy intensive. For this reason, we studied butanol recovery by supercritical CO2 extraction from simulated and actual fermentation broths. Recovery of butanol by this technique has numerous advantages including being environmentally favorable, avoiding use of costly chemicals or membranes, and compatible with the microbial culture. RESULTS For the model solution extraction process, feed contained 7.00, 12.00, and 1.00 gL-1 acetone, butanol, ethanol (ABE), respectively, to mimic the actual concentrations obtained in the fermentation broth. In the extract phase, butanol concentration that was obtained ranged from 460.4 to 573.2 gL-1 with butanol selectivities ranging from 128 to 204.8. ABE recovery was also successfully demonstrated using actual fermentation broth of C. beijerinckii P260. CONCLUSION Supercritical CO2 was successfully used for recovery of all three (ABE) components. Fermentation broth raffinate (feed depleted in ABE after recovery) was also reused for a second fermentation thus allowing process water recycle.

Improvement in Lactone Production from Biotransformation of Ricinoleic Acid based on the Porous Starch Delivery System


BACKGROUND The natural gamma-decalactone (GDL) produced by the mean of microbial fermentation is an essential lactone compound as a Generally Recognized as Safe food additive. An effective control of the substrate ricinoleic acid (RA) concentration in the biotransformation medium becomes a bottleneck for the industrial manufacture of GDL. In this study, porous starch (P-S) was utilized as a carrier of RA to control its distribution in the medium. The effect of P-S on the biotransformation was evaluated and the mechanism was revealed. RESULTS Scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis indicated that the RA layer was formed on the surface of P-S, which increased the opportunity for interaction between microorganisms and the substrate. With P-S-embedded RA as a substrate, the yield of GDL increased to 3.36 g/L which was 17.5% higher than the control. In addition, the presence of P-S in this system exerted no negative effect on the viability of the microorganism. CONCLUSION This study is a new attempt of applying P-S as a delivery system in the biotransformation of GDL to increase its yield which indicates that the P-S-controlled release is a potential method of improving natural GDL production in the industrial scale.

Dealginated seaweed waste for Zn(II) continuous removal from aqueous solution on fixed-bed column


BACKGROUND The alginate extraction residue from Brazilian Sargassum filipendula was employed as biosorbent on Zn(II) removal through fixed-bed column in order to explore its adsorptive properties and to establish a new usage for this waste. RESULTS The best operating conditions were of 0.5 mL/min and 1.0 mmol/L (inlet concentration), providing the lower mass transfer zone and the higher uptake. Elution percentages of 52 and 73 % were obtained for the first and second desorption cycles, respectively, using CaCl2 as eluent. The Yan et al. model was more representative of the experimental data. Characterization revealed that ion exchange is involved between zinc ions and light metals (Ca, Na, K and Mg). It was observed a decrease in real and apparent densities of biomass, with an increase in particle porosity of the residue after process. CONCLUSION The study revealed that this biomass has potential for Zn removal from aqueous solution, encouraging its application as biosorbent in future studies involving multicomponent systems.

Enhanced NH3 capture by imidazolium-based protic ionic liquids with different anions and cation substituents


BACKGROUND Ionic liquids have become potential absorbents to treat exhausted gases containing NH3, which threatens the living environment of human beings. RESULTS In this study, 10 kinds of protic and conventional ILs were synthesized and characterized and their densities, viscosities and thermal decomposition temperatures were measured. The NH3 solubility in ILs from the VLE experiments revealed that the chain length of cations had little influence on the NH3 solubility of the protic ILs because of the high NH3 capacities in protic ILs resulting from protic hydrogen atom compared to the conventional ILs. Besides, the 2-H atom on the cation influenced the NH3 solubility in both protic and conventional ILs with different trends as the pressure increased. Considering the effect of anions with the same cation [Bim]+, the order of NH3 solubility in protic ILs was [Bim][NTf2] > [Bim][SCN] > [Bim][NO3]. Dynamic absorption of NH3 in [Eim][NTf2] preliminarily revealed that the absorption was fast under ambient pressure and through 5 cycles of absorption and desorption, the NH3 absorption ability kept stable. CONCLUSIONS The relationship between the NH3 solubility and the structures of both protic and conventional ILs were revealed, indicating the protic ILs as an alternative material for the treatment of NH3 - containing exhausted gases.

Hydrodynamic simulations and biological modelling of an Anammox reactor


BACKGROUND The design of anammox process reactors should be addressed to obtain maximum sludge retention and maximum removal efficiency, and also prevent microorganisms’ inhibition. The conventional biological models (Activated Sludge Models, ASM) are only focused to test the influence of operational parameters on the biological performance. This study integrated Computational Fluid Dynamics (CFD) and biological modelling (ASM) for the description of a novel anammox reactor configuration. RESULTS A full description of the hydrodynamics, the mixing degree of the system and biological performance within the overall reactor domain was obtained. The large recirculation of the system and the internal plates favoured the correct mixing of the overall system, despite a particular point of preferable way of flow in the inlet stream of the reactor. From the removal rates distributions calculated with the model, it was feasible to demonstrate that the 45% of the domain had a zero reaction order in respect with the ammonium substrate (nitrite was in excess). CONCLUSIONS The model integration was demonstrated to be a powerful tool for the design of an anammox reactor. It was useful to obtain information about the overall mixing in the system, determine death zones of flow, points of maximum and minimum removal efficiency.

Influence of Solvent Additives on the Aqueous Extraction of Tannins from Pine Bark: Potential Extracts for Leather Tanning


BACKGROUND Pine bark, which represents approximately 10 to 20% in weight of the tree trunk, is an abundant and low cost agro-industrial waste. In order to obtain condensed tannin-rich pine bark extracts (for future application in leather tanning/retanning processes), conventional aqueous extractions were performed, varying the type and amount of the solvent additive: sodium hydroxide (0.5, 1.0 and 1.5%, w/v), formic acid (0.5, 1.0 and 1.5%, v/v) and ethanol (5, 10 and 15%, v/v). Extractions were performed with and without the addition of sodium sulfite (1.0%, w/v). RESULTS The most favorable solvent additive in terms of total phenolics and condensed tannins was ethanol: extracts achieved 34.8% of gallic acid equivalents and 62.8% of catechin monohydrate equivalents. Moreover, the favorable pH values (~3.5) of the resultant aqueous solutions and their relatively low viscosities are suitable for subsequent tanning applications. CONCLUSIONS The results of this study suggest that the high added-value aqueous extracts of Pinus pinaster bark, which were achieved with small amounts of ethanol, have appropriate characteristics for leather tanning, and therefore they may be used as eco-friendly tanning agents to partially replace chromium salts, thus reducing some of the environmental impacts typically associated with leather industry.

Improving the photo-reduction of CO2 to fuels with catalysts synthesized under high pressure: Cu/TiO2


BACKGROUND In previous studies the enhanced activity of TiO2-based catalysts synthesized in supercritical medium for photocatalytic reduction of CO2 has been proved. RESULTS In this case, Cu/TiO2 photocatalysts are synthesized by hydrothermal methods in supercritical CO2. Two titanium precursors [titanium tetraisopropoxide and diisopropoxititanium bis(acetylacetonate)], two alcohols (ethanol and isopropyl alcohol), and one metal precursor (Cu (II) acetylacetonate) have been used in the synthesis. Catalysts produced have shown improved properties in comparison to the commercial reference catalyst (Degussa P-25, Evonik). CONCLUSIONS Specifically, it has been found that Cu/TiO2 catalysts may yield methane production rates 20 times larger than that of commercial TiO2 catalyst without diminishing CO production rate (about 5 times higher than that of commercial catalyst). This result has been mainly imputed to both the formation of oxygen vacancies during the synthesis in supercritical medium and the high capacity of copper to adsorb and activate CO2 molecules, while preventing CO molecules from reoxidation, and avoiding the competitive reaction of hydrogen formation.

Liquid-Liquid Extraction of Biopharmaceuticals from Fermented Broth: Trends and Future Prospects


Biopharmaceuticals are one of the most important groups of biotechnological products, representing one-quarter of all pharmaceutical sales, and providing suitable and efficient medical care for many previously untreatable diseases. However, their production and purification usually require complex processes, resulting in extremely expensive final products. Thus, the development of newer, simpler and cheaper methods for biosynthesis and purification of these biocompounds, as well a proper integration between these stages, are crucial to reduce their commercial costs and increase the scale of biopharmaceuticals’ medical use. One solution for this concern relies on the proper integration between upstream and downstream processing applying liquid-liquid extraction systems as an intermediate stage. Recently, several works reported that a proper choice of liquid-liquid systems like aqueous biphasic systems (ABS) can be a suitable platform to simplify, reduce the number of the downstream stages, improve the recovery and purification yields, and consequently, decrease the biopharmaceuticals’ manufacturing costs. This review will explain the general concept of biopharmaceuticals, the main ways to their production and purification methods, in particular, exploring the use of ABS as effective and integrative platforms for their recovery and purification, and provide further insights into the future trends and prospects in the field.

Shaken flasks by resonant acoustic mixing in the biosynthesis of alginate by Azotobacter vinelandii with non-Newtonian rheological characteristics


BACKGROUND Orbitally shaken flasks in polysaccharide-producing bacterial cultures usually present oxygen limitations because of non-Newtonian rheological characteristics of the resulting culture broth and bacterial respiration. Here, we present the production of alginate by Azotobacter vinelandii using a novel alternative mixing technology (resonant acoustic mixing, RAM) to increase oxygen transfer. RESULTS No significant differences were observed in biomass growth (3.43 ± 0.61 g · L−1) with RAM frequencies between 5 and 20 g, but higher specific growth and sucrose consumption rates were found at higher frequencies (15 and 20 g). The highest alginate production (9.13 ± 0.63 g · L−1) was obtained in 20 g cultures, in which no oxygen limitation was detected, whereas intracellular reserve polymer poly-β-hydroxybutyrate (PHB) production was favored at low shaking frequencies (5 and 10 g), in which dissolved oxygen tension were zero for a long culture time. Cultures behave pseudoplastically, with an apparent viscosity that increases until the end of the exponential phase, and the alginate monomer ratio was approximately 1.0 in all cultures. CONCLUSION RAM can maintain elevated oxygen transfer rates, even in non-Newtonian high-viscosity cultures, as in the case of alginate production by A. vinelandii.

Purification of influenza virus-like particles using sulfated cellulose membrane adsorbers


BACKGROUND Vaccines based on virus-like particles (VLPs) are an alternative to inactivated viral vaccines that combine good safety profiles with strong immunogenicity. In order to be economically competitive, efficient manufacturing is required, in particular downstream processing, which often accounts for major production costs. This study describes the optimization and establishment of a chromatography capturing technique using sulfated cellulose membrane adsorbers (SCMA) for purification of influenza VLPs. RESULTS Using a design of experiments approach, the critical factors for SCMA performance were described and optimized. For optimal conditions (membrane ligand density: 15.4 μmol cm−2, salt concentration of the loading buffer: 24 mM NaCl, and elution buffer: 920 mM NaCl, as well as the corresponding flow rates: 0.24 and 1.4 ml ml−1), a yield of 80% in the product fraction was obtained. No loss of VLPs was detected in the flow through fraction. Removal of total protein and DNA impurities were higher than 89% and 80%, respectively. CONCLUSION Use of SCMA represents a significant improvement compared to with conventional ion exchangers membrane adsorbers. As the method proposed is easily scalable and reduces the number of steps required compared to conventional purification methods, SCMA could qualify as a generic platform for purification of VLP-based vaccines.

Efficient adsorption/reduction of aqueous hexavalent chromium using oligoaniline hollow microspheres fabricated by a template-free method


BACKGROUND Uniform and well-dispersed hollow microspheres of oligoaniline were synthesized by a facile and template-free method in alkaline medium. The morphology of oligoanilines was controlled from hollow to hard microspheres, by simply changing the volumes of alkaline medium. SEM, TEM, XRD, FTIR and physical adsorption of nitrogen were used to characterize the products. Hexavalent chromium ion uptake experiments were run with these aniline oligomers. RESULTS Adsorption experiments showed that the removal of chromium ions was strongly dependent on the initial pH of the solution. The pseudo-second-order kinetic and Langmuir isotherm models were well correlated to the experimental data. The adsorption of Cr(VI) and synergistic reduction to Cr(III) were confirmed by analyzing remnant chromium in the liquid and XPS detection of the exhausted adsorbent. A redox/pseudo-protonation process was recommended as the mechanism to explain the Cr(VI) removal. The adsorbed chromium ions could be desorbed by NaOH solution. The higher desorption efficiency of 96.2% was achieved by using 1.0 M NaOH as the desorption agent. CONCLUSIONS It was observed that the hollow microsphere were the most effective adsorbent in the three adsorbents and its removal efficiency reached to 99% to remove 60 mg/L Cr(VI). The facile fabrication, efficient removal of Cr(VI) and simple regeneration offered an option to remove Cr(VI) contamination from natural water and industrial wastewater.

Mined pyrite and chalcopyrite as catalysts for spontaneous acidic pH adjustment in Fenton and LED photo-Fenton like processes


BACKGROUND The Fenton-based processes have been extensively studied for the treatment of pollutants contained in olive mill wastewater (OMW). These processes have some limitations, such as the need of acidic pH control, the generation of a sludge, and the separation of soluble iron species. Mined pyrite (FeS2) and chalcopyrite (CuFeS2) avoid the problem associated to the sludge formation and the acidic pH adjustment. The catalytic activity of pyrite and chalcopyrite was investigated for the Fenton and LED (light emitting diode) photo-Fenton like oxidation of tyrosol and in the treatment of aqueous mixtures containing phenolic compounds. RESULTS The highest mineralization of TY (85.0%) and lowest Fe leaching (0.89 mg L-1) was obtained by using chalcopyrite and the LED photo-Fenton like process (0.50 mM of TY initial concentration and 19.0 mM of H2O2 stoichiometric dosage). Complete degradation of the phenolic pollutants and a mineralization of 98.0% was also achieved. CONCLUSION Mined chalcopyrite can be an appropriate photo-Fenton like catalyst in the degradation of phenolic compounds found in OMW because it can provide a high TOC removal, proper acidic pH conditions, low leaching of iron species and a small spontaneous formation of H2O2. However, the catalyst stability must be improved to minimize the leaching of metals.

A novel modeling approach for evaluating microbial mechanism and design of contact stabilization process


BACKGROUND The paper offered a novel interpretation for the microbial mechanisms and evaluated the assets of contact stabilization (CS) using multi-component modelling. A model structure re-defining microbial processes was adopted, where the function of the contact tank was limited to the utilization of soluble substrate fractions and that of the stabilization tank essentially involved endogenous decay and removal of the adsorbed particulate substrate. RESULTS The model was used to simulate the microbial behaviour and performance of the CS in comparison with a conventional activated sludge system (CAS), at an SRT range between 6-15 d. The results were confirmed by a stoichiometric description of the process using relevant mass balance relationships, which identified the role of major parameters on system behaviour and performance. A rational design procedure of the process was proposed based on modelling and process stoichiometry. CONCLUSION CS process could achieve effective carbon removal in a much smaller footprint and/or aeration volume with respect to CAS, due to its ability to work at significantly higher volumetric organic loadings; its flexibility to be operated at much higher SRT as compared with CAS with the same HRT, allowed minimizing sludge production and sustaining a microbial composition also supporting nitrification. However, process stoichiometry reflected that the CS process, despite its significant advantages, should not be considered as a suitable candidate for maximizing sludge harvest and energy recovery.

Improved photocatalytic hydrogen production from methanol/water solution using CuO supported on fluorinated TiO2


BACKGROUND Photocatalytic water splitting constitutes an attractive alternative for the hydrogen generation because it is considered as a clean and environmental friendly process. TiO2 semiconductor has been widely used in photocatalysis, however its efficiency is limited due to the high recombination of the charge carriers. Many methods have been proposed to enhance the TiO2 photoactivity, including the modification with nonmetal ions and the coupling with other semiconductor oxides. In this work, a series of CuO/TF photocatalysts with different CuO content were synthesized by impregnation of fluorinated TiO2 (TF) powder. These materials were characterized by several techniques and were studied in the hydrogen production reaction from a methanol/water solution under UV irradiation. RESULTS The impregnation of the TF powder with Cu(NO3)2•H2O leads the generation of crystalline and mesoporous materials and the existence of copper in the form of CuO. HRTEM results indicated the formation of heterojunctions between TiO2 and CuO phases. CuO(1.0)/TF photocatalyst was four times more active than the TiO2 and fluorinated TiO2 support. CONCLUSIONS The coexistence of fluoride and CuO species on the TiO2 improves the photocatalytic properties of the semiconductor and the reduction of the H+ ions to H2 is considerably better than that achieved with the TiO2, TF and CuO/TiO2 materials.

The effect of hot water pretreatment on the heavy metal adsorption capacity of acid insoluble lignin from Paulownia elongata


Background Biorefinery processes utilize carbohydrates from biomass in order to produce biochemical and biomaterials. Lignin as the byproduct after biorefinery needs to be studied for applications. This study evaluated how hot water pretreatment, a typical biorefinery process, will impact on the heavy metal adsorption capacity of lignin. Results Paulownia elongate acid insoluble lignin was tested for its heavy metal adsorption capacities with Pb(II), Cu(II) and Cd(II). Hot water pretreatment was conducted on the lignin with both water and dilute acetic acid solution. Samples with both increased and decreased adsorption capacity were observed after the pretreatment, while samples with long duration of pretreatment encountered a substantial loss in the adsorption ability. Depolymerization and condensation lignin reaction schemes under acidic environment were summarized and applied to explain the capacity changes. NMR analysis was performed to quantify the functional groups in the lignin samples. Changes in the amount of functional groups were found in the samples after pretreatment. Conclusion Hot water pretreatment can either increase or decrease the adsorption capacity of lignin depending on the treatment duration. Lignin byproducts after treated under acidic and high temperature environment with long duration is no longer suggested to be used as a heavy metal adsorbent.

A new source for developing multi-functional products: Biological and chemical perspectives on subcritical water extracts of Sambucus ebulus L.


BACKGROUND For obtaining bioactive fractions from plant material subcritical water is notably advantageous in comparison to any other technique. Excellent solvating properties and selectivity combined with finely tuned reactivity of subcritical water enable exploitation of plants potentials. Herein subcritical water extraction was used for recovery of bioactive compounds from leaves, roots and fruits of Sambucus ebulus L. Obtained extracts were characterized in terms of biological and chemical fingerprints. RESULTS AND DISSCUSION Results obtained by using several antioxidant assays that focused on different mechanisms showed that subcritical water extracts of Sambucus ebulus were proved to be powerful antioxidants. Enzyme inhibitory effects were tested against α-amylase, α-glucosidase and tyrosinase, and the results showed anti-diabetic potential of the extracts as well as its possible use in case of skin disorders. Antiproliferative properties were detected on three cell lines (A-549; LS-174T; HeLa) and showed prominent cytotoxicity against all tumor cell lines. Obtained inhibitory concentrations were in the range 0.58-8.10 µg/mL. Generally, the leaves SCW extracts exhibited stronger biological activities with higher levels of phenolic compounds compared to roots and fruits of Sambucus ebulus. Gallic acid, catechin and caffeic acid were identified as major components in these extracts and these components seem to relate with observed biological activity. CONCLUSION The obtained results suggest that Sambucus ebulus has a high potential for preparing new phyto-pharmaceuticals and functional food ingredients.

Energy efficient harvesting of Arthrospira sp. using ceramic membranes: Analyzing the effect of membrane pore size and incorporation of flocculant as fouling control strategy


BACKGROUND Biomass harvesting is an important issue in commercialization of algal biofuel production. In the present study focus has been given to develop a robust ultrafiltration membrane on low cost ceramic substrate for efficient harvesting of Arthrospira sp. Effect of the membrane pore size and flocculant addition as fouling reduction strategy was undertaken. The study represents a comparative analysis in terms of flux, fouling, volume reduction factor (VRF) and energy consumption of different processes, viz. microfiltration (MF), ultrafiltration (UF), guar gum induced bioflocculation followed by MF and bioflocculation followed by UF, respectively. RESULTS MF process showed higher volume reduction factor (11.11) and concentration factor (12.5) with stabilized flux of 230 Lm-2h-1 at optimized conditions. In terms of fouling, the UF membranes were less prone to fouling with a flux recovery of about 93% during long term operation. Incorporation of bioflocculant caused significant reduction in fouling of both the MF and UF membrane. Energy uptake in MF process was lower (0.908 kWh/m3) than that of the UF process (2.625 kWh/m3). Among the various processes permeate from the UF showed the highest CO2 dissolution capacity (657+7 mg/L), hence could be reused for algal cultivation with negligible reduction in growth. CONCLUSION The present study reveals that clay-alumina based ceramic MF and UF membrane can be effectively used in harvesting of algal biomass with suitable fouling control strategy based on the algal species and required biomass concentration. The developed processes show potential in view of less energy consumption compared to the other existing processes.

Comparative study of rice husk biochars for aqueous antibiotics removal


BACKGROUND Antibiotics are widely used for the treatment of several bacterial infections in humans and animals, but it might be released into water sources due to incomplete metabolism in humans or discharge from drug manufacturers. RESULTS The removal efficiency of three antibiotics was enhanced with increasing biochar dosage. The adsorption of three antibiotics by RH700 was much higher than RH300 and RH500, which might be due to the larger surface area and adsorption pore volume of RH700 (211.76 m2/g and 6.25 nm, respectively). In addition, the adsorption capacity was greatly affected by the solution pH, background electrolyte and humic acid. The kinetics experience data were well fitted by the pseudo-second order kinetic model. The maximum adsorption capacities of tetracycline hydrochloride (TC), doxycycline hydrochloride (DC) and ciprofloxacin (CF) based on Langmuir model by RH700 at 318 K were 80.9, 85.2 and 36.1 mg/g, respectively. RH700 exhibited high affinity for antibiotics mainly ascribing to chemical interaction between oxygen-containing functional groups (phenolic hydroxyl group, carboxyl and alkoxy groups) of biochar surface and TC, DC and CF. CONCLUSION The rice husk biochar produced at high temperature could be applied as potential adsorbent for removal of antibiotics from water.

Metabolic strategies for microbial glycerol overproduction


Glycerol has wide applications in the chemical, pharmaceutical, and food industries for manufacturing of an array of chemicals, drugs, food and beverages, personal care items, lubricants, adhesives, emulsifiers, plastics, and other products.

Development of synthetic perfluorinated photobioreactor system for simultaneous carbon dioxide separation and promotion of microalgae growth and productions


BACKGROUND CO2 is the primary impurity in many fuel gases and may reduce the efficiency of fuel combustion and generate a lot of incomplete residues in the product, leading to energy waste and environmental issues after emission. Currently although plants/microalgae-mediated approaches have been widely used for CO2 separation/digestion, they are usually emphasized on CO2 removal efficacy for purpose of environment protection, but showed less consideration to subsequent CO2 manipulation for cell culture that restricts their effectiveness thereafter. To address above issues, the perfluorinated photobioreactor system (PPBRS) that enabled CO2 separation and controlled microalgae cultivation was developed in this study. RESULTS Results showed that the PPBRS provided > 85% CO2 separation efficiency from 60%-N2/40%-CO2 within 5 days by using perfluorocarbon as the CO2 absorbent; whereby the Nannochloropsis oculata cultured with 20 mL min−1 perfluorocarbon containing 2% CO2 isolated from the gas mixture exhibited 2-fold higher cell concentration and yielded 1.8-, 2.5-, and 2-fold (P < 0.05 for all) increased productions of biomass, lipid, and eicosapentaenoic acid, respectively, compared to the group with air aeration without PFC for 5 days. CONCLUSION With advantages that perfluorocarbon is recyclable and all the procedures including CO2 extraction, collection of purified gas, and delivery of isolated CO2 to cell culture are in continuous process without need of additional handling, the PPBRS provides an efficacious, easy-to-use, and cost-effective means for simultaneous CO2 separation and enhanced microalgae productions that is highly applicable for use in the industry.

Hydrogenolysis of glycerol to 1,2-propanediol in a continuous flow trickle bed reactor


BACKGROUND Hydrogenolysis of glycerol to glycols in continuous flow three phase reactors is of practical importance due to the need to give value to huge amounts of surplus glycerol. Thermodynamic and kinetic aspects must be revised for a proper design. The system was studied in a trickle-bed reactor using copper chromite and Cu/Al2O3 as catalysts. RESULTS Phase equilibrium and flow pattern were verified. Solid, liquid and gas phases were present, with the liquid phase in “trickling” flow. Catalysts were characterized by ICP, nitrogen sortometry, XPS, XRD, TPR and pyridine-TPD. The average reaction rate was found to be practically constant at different process conditions. A theoretical analysis indicated that the resistance to the transfer of hydrogen from the gas to the liquid phase dominated the overall kinetics. Selectivity to 1,2-propanediol varied with temperature, with a maximum at 230 °C (97 %). Selectivity was a function the catalyst acidity. When the pressure was increased the selectivity to 1,2-propanediol was increased, up to 97% at 14 bar. Higher pressures did not modify this value. CONCLUSIONS Optimum reaction conditions for maximum selectivity to 1,2-propanediol with Cu-based catalysts are 230 °C and 14 bar. System kinetics are however dominated by the gas-liquid mass transfer resistance.

Enhancement of biomass retention in an EGSB reactor used to treat 1-methoxy-2-propanol


BACKGROUND An expanded granular sludge bed (EGSB) reactor is commonly used in anaerobic treatment of industrial wastewater. To develop applications to remove solvents, the granular sludge retention within the reactor must be improved. RESULTS This work evaluated the addition of chitosan as a strategy to enhance granulation in an EGSB reactor used to treat a wastewater containing 1-methoxy-2-propanol and ethanol. Two reactors, one with chitosan supplementation and other without chitosan (control), were operated in parallel. Greater particle size was obtained in the reactor with chitosan. The retention of solids within the reactor was clearly improved. Moreover, the settling properties were clearly enhanced in the first stages (days 0–44) in terms of settling velocity and sludge volume index. The required time to obtain 80% removal of 1-methoxy-2-propanol was shortened from 38 days to 22 days when chitosan was supplemented. CONCLUSIONS The addition of chitosan is a promising alternative to enhance granulation in EGSB reactors that are used to treat glycol ethers. A single addition rapidly improves the settling properties of the granular sludge; this method could be used as an operational strategy when partial degranulation occurs. This work provides useful guidelines on the enhancement of biomass retention while operating an EGSB.

Polyphenols extracted from red grape pomace by a surfactant based method show enhanced collagenase and elastase inhibitory activity


BACKGROUND The aim of this study is to separate polyphenols from grape pomace using a surfactant-based separation, Colloidal Gas Aphrons (CGA) and to investigate their inhibitory activity against skin relevant enzymes, collagenase and elastase. Ethanolic (EE) and hot water crude extracts (HWE) were produced first and then the CGA generated using TWEEN20 were applied resulting in polyphenols enriched fractions (CGA-EE and CGA-HWE, ethanol and hot water extracts derived fractions respectively). RESULTS Both crude extracts inhibited the enzymes in a dose-dependent manner however, further extraction by CGA led to fractions with higher inhibitory efficiency against collagenase. Although gallic acid was the main component of the CGA-HWE, others such as kaempferol must have contributed to its potency which was over six times more than gallic acid's. The CGA-EE was found to be about four times more efficient than its crude extract and over six times more efficient than gallic acid in collagenase's inhibition; quercetin was the major polyphenol in this fraction. CONCLUSION It is evident that ethanol and hot water extraction processes led to different polyphenols composition and thus different inhibitory activity against collagenase and elastase. Further separation with CGA increased the inhibitory potency of both extracts against collagenase. Overall the results here showed the potential application of the CGA fractions from grape extracts in cosmetics.

Prediction of overall glucose yield in hydrolysis of pretreated sugarcane bagasse using a single Artificial Neural Network: Good insight for process development


BACKGROUND In this work, it was used a single Artificial Neural Network (ANN) to model the overall yield of glucose (YGLC) as a function of a wide range of operation conditions of both pretreatment and enzymatic hydrolysis. RESULTS The model was validated experimentally and presented good predictions of YGLC. Sensitivity analysis using the ANN model indicated that most of the operating parameters, except for pretreatment time, were statistically significant (p-value < 0.05). Experiments showed that the processing of sugarcane bagasse (in natura) results in a satisfactory glucose yield of 69.34 % when pretreated for 60 min with low initial biomass concentration and acid concentration (10 % and 1.0 % w/v), and followed by enzymatic hydrolysis for 72 h with 3.0 % w/v substrate loading and 60 FPU/gWIS enzyme concentration. CONCLUSION This study demonstrated how pretreatment and enzymatic hydrolysis data can be used to parameterize a single ANN model. Acceptable predictions of YGLC are achieved in terms of RSD, MSE and R2. Supported by the model, this study provided a good insight for process development.

In situ purification of periplasmatic L-asparaginase by aqueous two phase systems with ionic liquids (ILs) as adjuvants


BACKGROUND L-asparaginase (ASNase) is an important biopharmaceutical used to treat the acute lymphoblastic leukemia (ALL) and lymphosarcoma. Considering its main use in cancer therapy, the most important request for ASNase production is the need for a highly pure biopharmaceutical obtained in the final of the downstream process, which is considered as the crucial step in its production. RESULTS This work proposes the use of polymer-salt aqueous two-phase systems (ATPS) based on polyethylene glycol and citrate buffer, with ionic liquids (ILs) as adjuvants, combined with the permeabilization of cell membrane using n-dodecane and glycine for the in-situ purification of periplasmatic ASNase from Escherichia coli cells. The process proposed was optimized (polymer molecular weight, pH, tie-line length/mixture point, presence, nature and concentration of the adjuvant). The results show that ASNase partitions mostly to the PEG-rich phase, due to hydrophobic interactions between both PEG and enzyme. Remarkably, the addition of 5 wt% of 1- butyl-3-methylimidazolium methanesulfonate, [C4mim][CH3SO3] as adjuvant lead to high recoveries [87.94 ± 0.03 (%)], purification factors (20.09 ± 0.35), and a final specific activity SA = 3.61 ± 0.38 protein, from a crude enzyme extract with a SA = 0.18 ± 0.05−1 protein. Moreover, better results were achieved when a prepurification step consisting of an ammonium sulfate precipitation was combined with the optimized ABS, achieving an increased SA = 22.01 ± 1.36−1 protein and PF = 173.8. CONCLUSIONS A novel integrated downstream process was successfully implemented for the in-situ purification of ASNase from fermentation broth.

Evaluation of a low-cost magnesium product for phosphorus recovery by struvite crystallization


Background The development of a cost-effective process of struvite crystallization requires the selection of appropriate sources of alkali and magnesium. In this study, the effectiveness of two industrial grade products, MgO and Mg(OH)2, as magnesium and alkali sources to recover phosphorus as struvite were investigated and compared in a first set of experiments. Subsequently, the use of industrial Mg(OH)2 was compared in two different struvite crystallization systems, an upflow fluidized bed reactor (FBR) and a continuous stirred tank reactor (CSTR) coupled to a settler tank. Results At the same operational conditions, the consumption of MgO was higher than Mg(OH)2 consumption. Moreover, industrial Mg(OH)2 consumption for FBR and the CSTR operation was 1.6 and 1.1 1 mol Mg added∙mol P precipitated-1, respectively. This difference was caused by the high mixing intensity and the higher contact time between the Mg(OH)2 slurry and the influent in the CSTR, favouring the conversion. Conclusions Both industrial grade magnesium products are two promising options for struvite crystallization. However, Mg(OH)2 was more effective than the starting material, MgO, to recover phosphorus. Struvite crystallization by adding an industrial grade Mg(OH)2 could be economically viable with regard to alternative physico-chemical P removal processes using metal salts, increasing the attractiveness of this P recovery process.

Simultaneous removal of selenite and phenol from wastewater in an upflow fungal pellet bioreactor


BACKGROUND The simultaneous treatment of selenite and phenol containing wastewater in batch and continuous systems, inoculated with pellets of Phanerochaete chrysosporium, was evaluated in this study. RESULTS Synthetic oil refinery wastewater containing 15 mg L-1 selenite and 100 - 600 mg L-1 phenol was used in batch incubations for 5 days. Orange-red colored pellets developed during selenite incubations in the presence of up to 400 mg L-1 of phenol, which confirms the formation of elemental selenium with removal efficiencies ranging from 57 - 78.5% and 75 - 90.8% for, respectively, phenol and selenite. Continuous experiments in two upflow fungal pelleted bioreactors (30 oC, pH 4.5, hydraulic retention time of 16.7 h) fed the synthetic oil refinery wastewater containing phenol or phenol with selenite were performed for 38 days. The maximum removal efficiency of phenol in the fungal bioreactor was 100% (up to day 26). CONCLUSION The selenite mass balance showed the overall maximum removal efficiency of selenite in the presence of phenol was 67.3%. The critical phenol and selenite loading rates of the upflow bioreactors were ~12 and 4.3 mg L-1.h-1, respectively.

Polyethyleneimine grafting and Cibacron Blue F3GA modifying poly(methylmethacrylate) magnetic microspheres for protein adsorption


BACKGROUND Polyethyleneimine (PEI) had attracted wide interest due to not only its good hydrophilicity but also its high density of amino groups across the polymer chain. In order to study deeply the effect of PEI as spacer arm on dye ligand modification and further protein adsorption, poly(methylmethacrylate) (PMMA) magnetic microspheres were fabricated, grafted with PEI, and further modified with an affinity dye-ligand, Cibacron Blue F3GA (CB). RESULTS CB density of these CB-PEI-PMMA microspheres was determined to be 370.7 μmol/g for CB-PEI 600-PMMA, 355.2 μmol/g for CB-PEI 1800-PMMA, and 317.6 μmol/g for CB-PEI 70000-PMMA microsphere, respectively. Moreover, bovine serum albumin (BSA) adsorption capacity of PEI-PMMA and CB-PEI-PMMA microspheres increased greatly compared with PMMA microspheres. Furthermore, the effects of temperature, BSA initial concentration, pH and ionic strength on BSA adsorption were studied. And CB-PEI 70000-PMMA microspheres exhibited the maximum adsorption of 103.6 mg/g. CONCLUSION The results demonstrated the versatility of PEI as spacer arm. The information obtained from the present work could be utilized for rational design of carriers for protein adsorption or enzyme immobilization.

Microbial community dynamics reflect reactor stability during the anaerobic digestion of a very high strength and sulfate-rich vinasse


BACKGROUND Microbial community dynamics during the anaerobic digestion of vinasse has been little studied. However, having knowledge about it is essential for early detection of reactor operational difficulties to apply preventive actions. This research studies the microbial community dynamics in the anaerobic digestion of vinasse, linking to experimental observations about product yields and organic matter degradation. RESULTS Methane and sulfide yields decreased with increasing SO42-/COD ratio, while the fraction of organic matter degraded by sulfate reducing bacteria increased from 4.5 ± 0.3% to 27.1 ± 0.6%. The archaeal community showed that acetoclastic Methanosaetaceae were little affected by the increase of the SO42-/COD ratio, in contrast to the Methanomicrobiales and Methanobacteriales population, which decreased during the experiment. The total bacterial diversity was influenced mainly by substrate composition, showing that the increase of the SO42-/COD ratio above 0.10 shifted the bacterial community to a lower richness. CONCLUSION These results provide knowledge on the dynamics of the microbial communities, which can be useful to control de anaerobic digestion of sulfate-rich vinasses, showing that reactor stability equates to the higher ratios between total methanogens and total bacteria gene copy numbers, whereas operational difficulties can be associated to lower bacterial richness and higher community organization.

Synthesis, characterization and evaluation of amphoteric chitosan-based grafting flocculants for removing contaminants with opposite surface charges from oilfield wastewater


BACKGROUND Contaminants in wastewater generated from oilfield with either negative or positive surface charges is normally very difficult to remove by traditional flocculants owing to their strong pH-dependence and high health risks. Natural polymer flocculants, especially chitosan-based flocculants have attracted much interest for their environmental friendliness, excellent flocculation efficiencies and cost-effectiveness recently. RESULTS A series of amphoteric chitosan-based grafting flocculants (CM-chi)-g-PDMDAAC (denoted as CgPD) were successfully synthesized by grafting diallyl dimethyl ammonium chloride (DMDAAC) onto carboxymethyl chitosan (CM-chi) with different grafting ratios. By carboxymethyl and grafting modification, the dramatically increased water solubility of chitosan was obtained. The physicochemical structure of CgPD products was characterized by 1H NMR and elemental analysis proving that DMDAACC was grafted onto CM-chi appropriately. Flocculation effect of CgPD was studied in kaolin and hematite suspensions with opposite surface charges. The results confirmed that these CgPD flocculants demonstrated an excellent performance in flocculation window, optimal dosage and pH sensitivity. In addition, CgPD was proven to be applicable as flocculants in water treatment on oilfield site. CONCLUSION These biodegradability flocculants, CgPD can effectively remove contaminants with opposite surface charges from oilfield wastewater with low optimal dosage, wide flocculation window, low pH sensitivity and less environmental impacts than traditional flocculants.

From ion exchange resins to polymer-supported reagents: an evolution of critical variables


The concept of immobilizing ligands onto cross-linked polymer supports is presented as an evolution of a concept that begins with ion exchange resins and evolves into ion-selective polymers, polymer-supported catalysts, and the general area of polymer-supported reagents. Each of the four categories of polymers is defined by a set of major variables {electrostatic attraction (for ion exchange resins); steric, geometric, and electronic factors (for ion-selective polymers); attracting and orienting reactants, and stabilizing the transition state (for polymer-supported catalysts); and binding reactants with weak or strong forces (for polymer-supported reagents)} and of minor variables {pH, concentration, competing ions, counterions, ionic strength, hydrophilic/hydrophobic interactions, hydration energies, and polymer crosslink level}. The rational design of each category will require identifying the relationships between major and minor variables and applying the principles inherent to complexity science will be an important focus of future research. © 2017 Society of Chemical Industry

Comparison of Cyanex 272 and Cyanex 572 for the separation of Neodymium from a Nd/Tb/Dy mixture by pertraction


BACKGROUND Recovering Nd(III) from waste magnets is an alternative method to satisfy the increasing demand for this metal. For this reason, the separation of Nd from a mixture containing Nd/Tb/Dy in chloride media using Cyanex 272 and Cyanex 572 has been evaluated. RESULTS Using Cyanex 272 and Cyanex 572, the metals are transported in the order Dy(III) > Tb(III) > > Nd(III) in all conditions studied. The optimum feed conditions to achieve Nd(III) separation are: Cyanex 272: pH 2 and Cyanex 572: pH 1.5 with 1.2 mol L-1 HCl as a receiving agent for both carriers. CONCLUSION The results obtained suggest that Cyanex 572 is a better carrier than Cyanex 272 for separating Nd(III) from a mixture containing Nd/Tb/Dy. © 2017 Society of Chemical Industry

Pilot scale production of extracellular thermo-alkali stable laccase from Pseudomonas sp. S2 using agro waste and its application in organophosphorous pesticides degradation


Background Laccases are multicopper oxidases that are able to oxidize various aromatic or nonaromatic compounds owing to their multifarious applications. However, till now only a few bacterial laccases have been isolated and characterized. Hence there is an urgent need to study an extracellular thermo-alkali stable laccase. Results In the present study, an extracellular thermo-alkali stable laccase was produced from Pseudomonas sp. S2 in a 100 L bioreactor using agro waste (potato peel). Production was 17-fold higher than in the control. The enzyme (S2LAC) was purified 12.16 ± 1.6-fold to homogeneity with specific activity of 1089.70 ± 16.8 U mg−1 and molecular mass of 38 kDa. The temperature and pH for maximum enzyme activity were 80 °C and 9.0, respectively. The metal ions Na+, K+, Pb+2, Ca+2, Cu+2 and Co+2 enhanced enzyme activity. The purified enzyme showed maximum specificity to Pyrogallol > PPD > L-DOPA > Hydroquinone. The S2LAC was able to degrade organ-phosphorous pesticide including dichlorophos, chlorpyrifos, monocrotophos and profenovos upto 45.99 ± 0.3%, 80.56 ± 0.6%, 75.45 ± 1.3%, 81.84 ± 0.6%, respectively, in the absence of any mediator. Conclusion S2LAC produced using agro waste was stable and capable of degrading organophosphorous pesticides making it attractive for industrial applications. © 2017 Society of Chemical Industry

LYTAG-driven purification strategies for monoclonal antibodies using quaternary amine ligands as affinity matrices


BACKGROUND Monoclonal antibodies are becoming a leading class of biopharmaceuticals but to increase their accessibility by the general population, new production processes must be developed in particular for the downstream processing. RESULTS In this work, an alternative and innovative affinity chromatographic method using quaternary amine matrices is proposed. Separation is driven by the dual affinity ligand LYTAG-Z, composed of a choline binding polypeptide (LYTAG) and the synthetic antibody binding Z domain. A two-elution method was developed for the purification of mAbs and the performance of different anion exchangers containing quaternary amines that act as choline analogues – CIMmultus Q, Q Sepharose and gPore Q – were tested and compared, with both CIMmultus Q and Q Sepharose allowing a recovery of more than 94% of mAbs from a CHO cell supernatant with a purity greater than 95%. An integrated platform combining an initial affinity extraction step for the clarification and capture of mAbs and a subsequent chromatographic separation using Q-matrices for the polishing of mAbs is also proposed. LYTAG-Z triggers the extraction of 94.7 ± 1.7% mAbs to the PEG-rich phase, as opposed to 26.9 ± 0.6% in the absence of the ligand, using 7% PEG 3350 and 6% dextran 500 k. Further purification using Q Sepharose allowed a mAb recovery of 95.3 ± 1.4% with a purity level of 91.4 ± 13.0%. CONCLUSION An integrated platform based on two purification steps – affinity extraction and affinity chromatography – results in an overall process yield of 90%, allowing the processing of mAbs directly from a non-clarified CHO cell culture. © 2017 Society of Chemical Industry

An immobilized and highly stabilized self-sufficient monooxygenase as biocatalyst for oxidative biotransformations


BACKGROUND The requirement for expensive cofactors that must be efficiently recycled is one of the major factors hindering the wide implementation of industrial biocatalytic oxidation processes. In this research, a sustainable approach based on immobilized self-sufficient Baeyer–Villiger monooxygenases is discussed. RESULTS A bifunctional biocatalyst composed of an NADPH-dependent cyclohexanone monooxygenase (CHMO) fused to an NADP+-accepting phosphite dehydrogenase (PTDH) catalyzes ϵ-caprolactone synthesis from cyclohexanone, using phosphite as a cheap sacrificial substrate for cofactor regeneration. Several immobilized derivatives of the fused enzyme have been prepared with high immobilization yield (97%); the one obtained by affinity adsorption on Co-IDA (Co: cobalt chelated; IDA: iminodiacetic acid) support has shown to be highly stable affording average yields of 80% after 18 reaction cycles. CONCLUSIONS The immobilized self-sufficient monooxygenase has demonstrated to be able to perform Baeyer–Villiger oxidation with efficient cofactor recovery and biocatalyst recycling. The proposed biocatalytic process offers access to valuable molecules with high atom economy and limited waste generation. © 2017 Society of Chemical Industry

Process design of carbon dioxide and ethane separation using ionic liquid by extractive distillation


BACKGROUND Carbon dioxide and ethane easily form a binary azeotrope under liquefied conditions. An extractive distillation process for the separation of carbon dioxide and ethane using the ionic liquids [bmim][Tf2N], [emim][Tf2N] and [emim][EtSO4] as solvents was explored. The thermodynamic and physical property parameters of each ionic liquid and their thermo-physical properties that correlated with the experimental data were used to create the ionic liquid components and conduct the process simulation. RESULT Based on the analysis of its physical properties and relative volatilities, [emim][Tf2N] is the best option as a solvent for extractive distillation separation compared with other ionic liquids. Based on the sensitivity analysis optimization procedure, the minimum total annual cost, carbon dioxide emissions and thermodynamic efficiency were calculated. Compared with traditional extraction distillation, the total annual cost and carbon dioxide emissions of the process using [emim][Tf2N] as a solvent decreased by 62% and 31%, respectively. The thermodynamic efficiency (η) of the electricity generated from hydropower increase by 0.7%. CONCLUSION The results show that an ionic liquid extractive distillation process using an ionic liquid as the entrainer performs better than a process using traditional organic solvents in terms of economics. Due to the non-volatility of ionic liquids, a flash tank was used instead of a solvent recovery column to efficiently realize solvent recovery. © 2017 Society of Chemical Industry

Activation of Candida antarctica lipase B in pressurized fluids for the synthesis of esters


BACKGROUND The objective of this work was to evaluate the activation of Candida antarctica lipase B (CALB) in pressurized CO2 or liquefied petroleum gas (LPG) and, thereafter, to evaluate the synthesis of esters using activated CALB as a biocatalyst. Before activation, CALB was immobilized in polyurethane. For the esterification reactions, mechanical or ultrasonic agitations were studied. The stability of CALB after reuse cycles was also evaluated. RESULTS Before activation, the enzymatic activity of immobilized CALB was 789 U g-1. After activation in pressurized CO2 and LPG, the activities increased to 2486 U g-1 and 1413 U g-1, respectively. Consequently, the residual activities of CALB after activation in pressurized CO2 and LPG were 315% and 179%, respectively. For the best condition of reaction under ultrasonic agitation, oleic acid conversion was 51.2% when using non-activated CALB. Otherwise, oleic acid conversions were 66.5% and 77.1% when using CALB activated in LPG and CO2, respectively. This biocatalyst maintained more than 80% of its residual activity when reused for up to 13 cycles. CONCLUSION Activation of CALB in pressurized CO2 provided enzymatic activities 1.76 times higher than activation in pressurized LPG did. Immobilized CALB had good performance as a stable biocatalyst for esterification reactions under ultrasonic agitation. © 2017 Society of Chemical Industry

Antimicrobial effects of pulsed electromagnetic fields from commercially available water treatment devices – controlled studies under static and flow conditions


BACKGROUND Pulsed-electromagnetic field (PEMF) devices are marketed and utilized for the non-chemical management of biofouling, with little scientific validation of their effectiveness. Proof-of-principle studies were carried out previously to systematically investigate the effect of two such commercial devices on the culturability of bacteria under controlled static (i.e. non-flowing) conditions and anti-microbial effects were demonstrated. However, such effects were small and an expanded investigation, using these devices and including the effect of flow, was deemed necessary. RESULTS The effect of the electromagnetic fields generated by the same two commercial devices on the bacterial culturability of Escherichia coli and Pseudomonas fluorescens under flow conditions has been contrasted with previous static results. It has been found that the effectiveness of PEMF exposure depends on waveform, extent of flow, type of bacteria and PEMF exposure duration. CONCLUSION Both stimulatory and inhibitory effects are observed that are uniquely dependent upon device type (i.e. a range of parameters including waveform), species of microorganism, presence and degree of flow and PEMF exposure time. For both devices and both microorganisms, stimulatory effects are uniformly observed for one device under static conditions and inhibitory effects are uniformly observed for the other device at low flow and for the former at high flow. © 2017 Society of Chemical Industry

Ultrafiltration of whey: membrane performance and modelling using a combined pore blocking–cake formation model


BACKGROUND Ultrafiltration has been considered as a ‘green’ technique to treat different industrial wastewaters, such as whey in the dairy industry. However, fouling is one of the major drawbacks in the industrial implementation of this process. Thus, in this work, the performance of ultrafiltration membranes was investigated in terms of permeate flux and protein rejection when treating different whey model solutions. Modelling of permeate flux was performed combining two main fouling mechanisms (complete pore blocking and cake formation) by a time-dependent pore blocking parameter. RESULTS Results demonstrated that high protein concentration and the presence of calcium salts in the feed solution favoured permeate flux decline. The combined model was appropriate to describe the main fouling mechanisms, with fitting accuracies higher than 0.960. Model parameters were correlated with both calcium and protein concentration and the developed model was successfully validated with an additional fouling test. CONCLUSION All the membranes tested were suitable for carrying out whey protein separation, with rejection indexes greater than 99%. The combined model and the statistical correlation of model parameters with calcium and protein concentrations were useful to predict permeate flux decline when the ultrafiltration of a new whey model solution was performed. © 2017 Society of Chemical Industry

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 h-1) and succinate productivity (2.7534, 6.0772, 5.5661 mmol g-1DW h-1), 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. © 2017 Society of Chemical Industry

Enzymatic ring-opening polymerization (ROP) of polylactones: roles of non-aqueous solvents


Aliphatic polyesters such as polylactides (PLAs) and other polylactones are thermoplastic, biodegradable and biocompatible polymers with the potential to replace petro-chemical-based synthetic polymers. A benign route for synthesizing these polyesters is through the enzyme-catalyzed ring-opening polymerization (ROP) reaction; this type of enzymatic process is very sensitive to reaction conditions such as solvents, water content and temperature. This review systematically evaluates the crucial roles of different solvents (such as solvent-free/in bulk, organic solvents, supercritical fluids, ionic liquids, and aqueous biphasic systems) on the degree of polymerization and polydispersity. In general, many studies suggest that hydrophobic organic solvents with minimum water contents lead to efficient enzymatic polymerization and subsequently high molecular weights of polyesters; the selection of solvents is also limited by the reaction temperature, e.g. the ROP of lactide is often conducted at above 100 °C, therefore, the solvent typically needs to have its boiling point above this temperature. The use of supercritical fluids could be limited by its scaling-up potential, while ionic liquids have exhibited many advantages including their low-volatility, high thermal stability, controllable enzyme-compatibility, and a wide range of choices. However, the fundamental and mechanistic understanding of the specific roles of ionic liquids in enzymatic ROP reactions is still lacking. Furthermore, the lipase specificity towards l- and d-lactide is also surveyed, followed by the discussion of engineered lipases with improved enantioselectivity and thermal stability. In addition, the preparation of polyester-derived materials such as polyester-grafted cellulose by the enzymatic ROP method is briefly reviewed. © 2017 Society of Chemical Industry

Screening of glycoside hydrolases and ionic liquids for fibre modification


BACKGROUND This study elaborates the possibility to apply combined ionic liquid (IL) and enzyme treatments for pulp fibre modification. The approach involves swelling of fibre surfaces with 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 dimethylphosphate ([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. © 2017 Society of Chemical Industry

Improvement of the bioelectrochemical hydrogen production from food waste fermentation effluent using a novel start-up strategy


BACKGROUND Food waste is a valuable source of hydrogen by dark fermentation. Dark fermentation effluent contains volatile fatty acids that can be further converted into more hydrogen using microbial electrolysis cells (MECs). In this process, the anodic potential (Ean) has a significant influence on the MEC performance as well as the effluent composition. The objective of this study was to evaluate the effects of variation of the anode potential and substrate composition (food waste fermentation effluent) on the performance of hydrogen production using two-chamber MECs. RESULTS Colonization was conducted using an Ean of 0.5 V vs Ag/AgCl. After 38 days, the Ean had decreased to 0.3 V, resulting in an increase in the hydrogen production rate (from 287 to 482 mL H2 L-1cat d-1). A maximum hydrogen production rate of 685 mL H2 L-1cat d-1 was observed when effluent that contained the highest acetate concentration was utilized. Cathodic hydrogen recovery was higher than 93%, and hydrogen yield was greater than 873 mL H2 g-1 COD. CONCLUSION The start-up strategy in which Ean is decreased after the formation of an electroactive biofilm resulted in increased hydrogen production. The composition of the food waste fermented effluent influences the hydrogen production rate. © 2017 Society of Chemical Industry

Cork processing wastewaters components fractioned by ultrafiltration membranes – studies of antioxidant and antitumoral activity


BACKGROUND Cork processing wastewater is an environmental problem due to its high content of organic matter, such as sugars and non-biodegradable compounds such as polyphenols (PPs), namely tannins. Membrane technology aimed at valorisation of the wastewaters components, concentrate stream, and simultaneously offer a pre-treatment of the wastewater, permeate stream. In this work, the identification of bioactive PPs was also envisaged. 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-1. CONCLUSION The process reported demonstrates that PPs compounds can be recovered from cork effluent and further reused as high-value bioactive compounds. © 2017 Society of Chemical Industry

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 of C. tyrobutyricum fermentation was observed at 1.2 g L-1 of furfural, while HMF showed less severe effects, and 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 at concentrations higher than 0.3 g L-1 and HMF at 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. © 2017 Society of Chemical Industry

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-1, 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-1. 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-1 and productivity of 1.743 g L-1 h-1 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 significantly 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. © 2017 Society of Chemical Industry

Kinetic characterization of Scenedesmus quadricauda under low irradiation conditions


BACKGROUND The kinetic parameters of a model culture of Scenedesmus 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 the retrieval of accurate kinetic data. Biomass and oxygen yields were also assessed. RESULTS A maximum specific CO2 uptake rate of 0.015 ± 0.002 gCO2 g-1VS 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 g VS g-1CO2 and 0.211–0.505 gO2 g-1CO2, 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. It was 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 obtained are useful for determining whether or not to implement a given microalgal-based process under low irradiance conditions. © 2017 Society of Chemical Industry

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


BACKGROUND Membrane separation is a 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 research into 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. First, 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. 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 retains relatively stable dye–oil–water permeation flux (about 27.5 L m-2 h-1) and high rejection rates (up to 99%) after six cycles of experiments under visible-light irradiation. Overall, the photocatalytic membrane opens up new avenues for the treatment of wastewater. © 2017 Society of Chemical Industry

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


BACKGROUND The release of natural estrogen 17 β-estradiol (E2) to the aquatic environment is a matter of 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 for E2 adsorption by AnGS was also analyzed. RESULTS The E2 adsorption efficiency of AnGs with ZVI was 48% higher than that without ZVI. The optimal conditions for high E2 adsorption efficiency (92.21%) and high equilibrium adsorption capacity (4.92 µg g-1 VSS) were rZVI/AnGS 1.33, pH 6, and temperature 25°C. E2 adsorption by ZVI/AnGS was a spontaneous and exothermic process, well described by the Freundlich isotherm. CONCLUSION The addition of a suitable amount of ZVI enhanced E2 adsorption by AnGS. © 2017 Society of Chemical Industry

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) constructed wetland (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 to treat OMW economically. © 2017 Society of Chemical Industry

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


BACKGROUND Disposable bioreactors based on orbital shaking technology have been employed extensively for mammalian cell culture, which proved to be less expensive and more flexible compared with mechanical stirred-tank bioreactors. However, it is difficult to evaluate flow parameters quantitatively since the flow field in bioreactors is complicated. RESULTS The flow characteristics of shaking bioreactors with a wide conical bottom under different shaking frequencies and filling volumes were simulated by CFD method. The validity of the simulation model was investigated by comparing simulated free-surface shapes and liquid levels with experimental results, and the CFD simulation results were shown to be 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 a positive effect on mass transfer coefficient (kL); the volumetric mass transfer coefficient (kLa) decreases with filling volume because of the combined effect of a and kL; the average shear strain rate (SSR) increases significantly with frequency, while it decreases with filling volume. Results also show that the SSR of shaking bioreactors is mainly distributed in low range which is acceptable for cell cultivation. © 2017 Society of Chemical Industry

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) is considered a promising green chemical process for numerous catalytic esterification reactions. Rendering novel structured CD packings is particularly desirable but remains challenging. RESULTS A microfibrous-structured HZSM-5 solid acid catalyst is proposed as CD packing and its separation and esterification reaction efficiency for producing ethyl acetate from acetic acid and ethanol are demonstrated. 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 packing is 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 packing provides a unique combination of instantaneous distillation and desired catalytic properties with respect to stability, adequate acidic sites and high mass/heat transfer, and therefore works 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. © 2017 Society of Chemical Industry

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 Pichia 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, compared with 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. © 2017 Society of Chemical Industry

Novel aspects and future trends in the use of aqueous two-phase systems as a bioengineering tool


Traditionally, aqueous two-phase systems (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 gaining 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. © 2017 Society of Chemical Industry

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


BACKGROUND Sodium oxalate is a key organic contaminant in alumina industry, which diminishes 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 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 dissolved oxygen (DO) set-points. RESULTS The results revealed that oxalate removal rates (33–111 mg h-1 g-1biomass) linearly correlate with OUR (0–70 mg O2 h-1 g-1biomass) in the N-supplemented reactor. However, in the N-deficient reactor, a linear increase of oxalate removal was recorded only with DO up to 3 mg L-1. Surprisingly, anaerobic oxalate removal was evident even in the presence of DO (up to 8 mg L-1) 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. © 2017 Society of Chemical Industry

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 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 a novel natural source for synthesis of TiO2 nanoparticles and were found to be effective for the degradation of toxic methyl orange dye. This green synthesis of TiO2 nanoparticles is beneficial for hazardous wastewater remediation to clean up the environment. © 2017 Society of Chemical Industry

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


BACKGROUND This article reports the synthesis and characterisation 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 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-1. 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. © 2017 Society of Chemical Industry

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-1, 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-1 d-1) 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-1 NH4+-N, however, 1500 mg L-1 NH4+-N caused decrease in reduction efficiency. Optimum nitrate loading rate was determined as 146 mgNO3-N L-1 d-1 at molar N/S ratio of 0.42, corresponding with 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 succeeded in a single reactor configuration at S/N ratio of 0.42. The developed process has the potential to be used in lab-scale applications. © 2017 Society of Chemical Industry

Enantioseparation with liquid membranes


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 have been known for almost four decades and have been used for optical resolutions, no comprehensive review has been published about the use of this technology for enantioseparations. 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. 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 a 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. © 2017 Society of Chemical Industry

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. © 2017 Society of Chemical Industry

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 2×2 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 owing 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. © 2017 Society of Chemical Industry

Struvite precipitation and COD reduction in a two-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 olive mill wastewater (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, a 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 by 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 two-step process together with a significant reduction of the COD of initial raw wastewaters. © 2017 Society of Chemical Industry

Study of 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 in breakthrough sulfur capacity was not very significant for the cokes except for the first regeneration cycles. From 400–600 °C, the higher the regeneration temperature was, the better the desulfurization activity of the cokes after regeneration. 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 promoted the removal of SO2. CONCLUSION The deposition of sulfate resulted in a significant decrease in the sulfur capacity of activated coke after the first two regeneration cycles. However, the residual amount of sulfate on the activated coke after regeneration declined with increasing regeneration temperature. Moreover, the phenolic hydroxyl and carboxyl groups did not disappear after regeneration, resulting in the desulfurization activity of cokes remaining relatively stable during subsequent desulfurization cycles. © 2017 Society of Chemical Industry

Suitability of pyrolusite as additive to activated coke for low-temperature NO removal


BACKGROUND Pyrolusite was used as additive to prepare coal-based activated coke (AC) for low-temperature NO removal. The pyrolusite modified AC was prepared by a blending method, and the denitrification performance was evaluated in a lab-scale simulated fixed-bed reactor. RESULTS The blending of pyrolusite promoted the specific surface area and pore structure of AC, even though the MnO2 and Fe2O3 showed inhibitory effects when blended separately. Both the basic and acid sites of AC-Mn(x) increased owing to the participation of the blended MnO2 during the activation, while the blending of Fe2O3 showed an 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 operating temperature adaptability and stability of catalysis activity of AC-P10 are good. 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 Pyrolusite is suitable to prepare the AC-based denitrification catalyst (AC-P(x)) for SCR NO removal because the Mn and Fe contained in the pyrolusite showed a synergistic effect. © 2017 Society of Chemical Industry

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 applied to 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-1 and 1.39 U g-1 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 while, 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. It is foreseen that this data will be helpful regarding the production of fungal pectinases or other acid-induced enzymes. © 2017 Society of Chemical Industry

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


BACKGROUND Conductive membranes, such as carbon material modified membrane and nickel metal film could be used for membrane fouling mitigation and energy generation during filtration. However, it is necessary to simplify the preparation process and reduce the cost for practical application. Here, a conducting polymer polypyrrole was polymerized on PVDF membrane surface for conductive membrane preparation via vapor phase polymerization. RESULTS After modification, the pure water flux was reduced from 3393.26 ± 222.99 L m-2 h-1 to 569.48 ± 150.82 L m-2 h-1. The contact angle was 58.63° for blank membrane after 8 s of delay, which was reduced to 27.53° for modified membrane. During short-term filtration, the modified membrane maintained high, stable flux and low effluent turbidity. The fouling of conductive membrane can be mitigated by 1 V cm-1 of electric filed during long-term filtration. Better effluent properties were obtained from modified membrane, which were improved further when an electric field was applied. CONCLUSION It is concluded that the conductive membrane has a smoother and more hydrophilic surface, resulting in better anti-fouling and effluent properties with the assistance of an electric field. © 2017 Society of Chemical Industry

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. This review summarizes 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. © 2017 Society of C[...]

Effect of the organic loading rate on 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 and 12.5 g COD L-1 d-1) for the treatment of tequila vinasses. The reactor performance was correlated with the microbial dynamics to elucidate the specific role of the microbial communities in the degradation pathways that govern the process. RESULTS The PBR was operated for 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-1 CODadded, respectively. Meanwhile, the highest volumetric methane production rate of 3.03 L CH4 d-1 L-1 was reached at the highest OLR, 12.5 g COD L-1 d-1. 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 the PBR is a promising and robust configuration that allows treating higher OLRs than currently reported technologies. © 2017 Society of Chemical Industry

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 γ'- 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 with 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 separati[...]

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


BACKGROUND High cell density in cultures of microalgae is a key factor to recover biomass and extract metabolites of interest. A 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, and lipid, protein and carbohydrate productivity of the microalgae Nannochloropsis oculata. RESULTS Results show that the FBTR promotes the highest cell density for both culture media, achieving 525 ± 1.84×106 cell mL-1. With AM in the 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 operating regimen, this being higher in the FBTR. CONCLUSION The use of AM in both operating modes, FBTR and SCR, increased the cell density and improved the lipid content of N. oculata. A good option would be to combine both culture modes; 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. © 2017 Society of Chemical Industry