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Copyright: Copyright © 2018 Elsevier Ltd. All rights reserved.
 



Novel membranes for filtration of copper in wastewater

Fri, 13 Apr 2018 11:00:00 GMT

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The research article 'Design of reusable novel membranes based on bacterial cellulose and chitosan for the filtration of copper in wastewaters' will be published in Elsevier journal Carbohydrate Polymers.

Abstract

This study has been carried out to design novel, environmentally friendly membranes by in situ and ex situ routes based on bacterial cellulose (BC) as a template for the chitosan (Ch) as functional entity for the elimination of copper in wastewaters. Two routes led to bionanocomposites with different aspect and physico-chemical properties. The mechanical behaviour in wet state, strongly related to crystallinity and water holding capacity, resulted to be very different depending on the preparation route although the Ch content was very similar: 35 and 37wt% for the in situ and ex situ membranes, respectively. The morphological characterization suggested a better incorporation of the Ch into BC matrix through the in situ route. The cooper removal capacity of these membranes was analyzed and in situ prepared membrane showed the highest values, about 50%, for initial concentrations of 50 and 250mgL−1. Moreover the reusability of the membranes was assessed.

This is the first time that the whole 3D nano-network BC membrane is used to provide physical integrity for chitosan to develop eco-friendly membranes with potential applications in heavy metal removal.

Access the complete article on ScienceDirect.

 




Eaton helps wine to achieve stability

Wed, 11 Apr 2018 13:15:00 GMT

Eatons filtration cartridges ensure that all wine and sparkling wine produced by Hubert Sekt achieve microbiological stability.A leading supplier of sparkling wines and a variety of other wines and spirits exports its products to more than 100 countries around the world. They rely on filtration solutions from a filer supplier to achieve the microbiological stability of its end products with good cost efficiency. In 1825, in Bratislava, colonial goods and wine merchant Johann Fischer and physician Michael Schonbauer, launched the first company in Europe outside of France to produce sparkling wine, based on the original French formula from the Champagne region. In 1877, the company was taken over and successfully managed by the Hubert family. Today, Hubert Sekt is the market leader in Slovakia, producing sparkling wines, plus a variety of other wines and spirits. Filtration solutions from Eaton have been a permanent part of the company’s processes, which involve a filtration volume of approximately 16 million liters of wines annually. Different filter media are used on the three bottling lines. The lines for all sparkling and wine varieties are equipped with filter cartridges, while the spirits line is fitted with depth filter sheets. The beverage company had been testing cheaper options from competitors on the sparkling wine and other wine lines in the last two years, but found that the cheaper cartridges caused problems in terms of microbiological stability, filtration capacity and the service life of the cartridges. The challenge An essential factor in bottling filtration is the microbiological safety of the filtrates. If yeast and bacteria end up in the wine, the product may continue to ferment in the closed bottle, leading to changes in taste and secondary hazing, and possibly causing enormous pressure to build up in the bottle due to the accumulated CO2 inside. The microbiological safety of the filtrates must be ensured to avoid having to recall the finished product due to quality issues and to avoid potential injuries to employees and consumers due to exploding bottles. Collecting the bottles, filtering the product again and then refilling the bottles is also time- and cost-intensive and impacts the entire efficiency of the operation. Another aspect to consider is that the filtration process must be adapted to optimize the service life of expensive membrane filter cartridges. Blockages that occur early in the filtration process lead to bottling downtimes, reducing filter capacity and increasing process and material costs for filter cartridges. The high colloidal and microbiological burden makes filtering the products more difficult. Accordingly, it is essential to use membrane filter cartridges with high levels of bacterial retention (LRV >7 per cm²) and a good service life despite the tight filter material. Suitable pre-filter cartridges must be identified with the aim of optimizing filterability and protecting the membrane filter cartridges. These pre-filter cartridges predominately catch particles and colloids that could otherwise block the membranes prematurely. The membrane filter cartridges themselves act as final ”police filters,” separating out only the remaining microorganisms before bottling. The solution After a complete process analysis conducted by Eaton, an optimized filtration concept was developed and implemented. The analysis investigated the filterability of the wines, the flow speed, the pre-filtration stages of sparkling wines, other wines and service media, such as water and steam, and the cleaning process of the filter cartridges (regeneration). The new process solution is composed of an integrated approach of pre-filter and membrane filter cartridges, as well as water filter cartridges for the rinsing process and a steam filter cartridge for sterilization. Beco depth filter cartridges with a nominal retention rate of 0.6 µm are used as pre-filters. The layered wrapping of these cartridges a[...]



Optimizing energy performance of pre-treatment depth filters

Wed, 11 Apr 2018 07:15:00 GMT

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The research article 'DRFM hybrid model to optimize energy performance of pre-treatment depth filters in desalination facilities' has been published in Elsevier journal Applied Energy.

Abstract

Rapid depth filtration is the dominant pre-treatment technology in seawater desalination industry today. Optimizing the pre-treatment filter’s energy performance provides economies of scale in the total energy usage of desalination facilities on a broader sense. However, this objective remains difficult to achieve by far. In this study, we develop a numerical algorithm, termed as Dynamical Rapid Filtration Model (DRFM), to simulate the effective clogging dynamics occurring inside a depth filter which depends on a multitude of controlled and non-controlled operating parameters. DRFM quantifies the filtration kinetics with a modified Yao’s model to represent the particle removal mechanisms occurring within the simulated filter. A unique length scale is also introduced to account for the particle size effect on the filter’s energy loss rate incurred, i.e. its energy performance, during its effective filtration stage. Concurrently, we performed an experimental study with a lab-scale depth filter to develop a model equation for measuring its total contaminant mass removal rate (Rc) due to effective clogging conditions. For a predicted Rc transient profile, good agreement is obtained between the experimental results and predicted values from DRFM.

We then extensively discuss on a novel DRFM hybrid model to optimize the filter’s energy performance which subsequently affects the filter’s optimized backwashing timing for achieving economies of scale. The simulation results from the hybrid model demonstrates on how various filter configurations can result in lower energy cost to effectively pre-treat each unit volume of intake seawater as compared to the current industrial average of 0.39 kWh/m3.

Finally, we include a cost analysis to demonstrate on how the obtained economies of scale alleviates a portion of the total energy cost for each unit volume of desalinated water.

Access the complete article on ScienceDirect.

 




The possibilities of hybrid meshes with GKD

Wed, 04 Apr 2018 12:00:00 GMT

The application-specific combination of different materials in one structure, hybrid meshes enable process improvements to be made. (© GKD)Whether the objective is to enhance the performance of components, reduce costs or counteract the limited availability of raw materials, reliable alternatives are much sought-after in many industrial applications. This article examines the greater process efficiencies possible through tailor-made structure using hybrid-mesh. Hybrid meshes is an application-specific combination of different materials in one structure enabling process improvements to be made. By combining the physical properties of the materials used, GKD’s mesh structures aim to realize optimization potential for individual customers with their customized performance spectrum and previously unknown product properties. Alongside all metals and polymers, materials such as aramid, ceramic, glass, natural products or textile fibers is also weaved. The manufacturer’s intention is to use all industrially weaveable materials for such hybrid combinations depending on each individual case. Monofilaments, multi-filaments or wires made of these materials can be weaved into single-, multi-ply, and if required even multidimensional, mesh structures. These expand the possible range of deployments and performance of conventional solutions. Possible applications Hybridization offers two possible applications for nonconductive basic mesh designs. As such, a matrix of conductive materials can be integrated to act as Faraday components in order to provide shielding from electromagnetic radiation. Electrostatic charging is avoided or dissipated using specific material combinations. This not only prevents the process-based risk of fire or explosion: in fluid and gas filtration these hybrid meshes also prevent electric fields from forming that negatively impact flow mechanisms or filtration rates. Hybrid meshes also offer added value in wear-intensive bulk-volume applications such as filtering process fluids. Here, perfectly tailored metal-plastic combinations can save costs while at the same time extending service lives. Moreover, an increased plastic content also reduces weight. For heavily loaded surfaces, for example the corners of filter leaves, resistance is improved through the partial use of hybrid mesh. To this end, warp or weft sections can be weaved in metal instead of in plastic. Solutions that combine a certain number of plastic wires with metal wires at defined intervals in the weft direction have proven effective in practice. Through the use of different materials in multi-ply meshes, properties are added at the exact points in the mesh at which they are required. In highly corrosive processes, hybrid meshes offer alternatives to structures made up of expensive raw materials with only limited availability such as Hastelloy or titanium. Here, a basic metal structure is combined with a polymer material such as PTFE in a YMAX weave which, unlike a pure metal structure, also achieves finer filtration rates more reliably.  Another positive effect is that material costs are lowered by around 50%. Process advantages Further typical examples of the process advantages offered by hybrid meshes are compatibility with flexing cycles to fit the process in question, mechanical strength, temperature resistance or surface properties individually adapted in line with adhesion properties or cleaning behavior. Furthermore, the plastic or elastic forming properties can be altered in certain directions by selecting specific materials and changing the diameter of the metallic cross section. This makes hybrid mesh appropriate as a high-performance shatter and fracture protection solution. The possibility to integrate desired materials into flat structures as meshes when shaping them is still relatively unknown. Because the material does not change during the weaving process, such hybrid meshes can offer a solution in[...]



A review of graphene-based separation membranes

Wed, 04 Apr 2018 11:45:00 GMT

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Graphical abstract.

The research article 'A review of graphene-based separation membrane: Materials, characteristics, preparation and applications' has been published in Elsevier journal Desalination.

Abstract

Membrane desalination has become an important solution to global water problems. Graphene-based materials have excellent advantages in the desalination process due to their intriguing features, including single atomic layer structure, large specific surface area, hydrophobic property, rich modification approaches, etc. After an introduction of membrane, graphene and graphene oxide (GO), this review systematically summarizes the current progress and gives an insight into the graphene-based separation membranes (GBSMs). The applications of the pressure-driven graphene-based membranes are introduced and their performances are listed and analyzed. By molecular dynamics simulation (MDS), the researchers predict the excellent performances of GBSMs, including high water flux, good salt rejection, etc. which have been verified in subsequent experiments. We believe that the application of graphene-based materials in pressure-driven membrane is worthy of further exploration. Several researchers have prepared electric-driven membranes with graphene-based materials, since their good stabilities and water-retention. However, graphene is not efficient in forward osmosis membrane area for now. In spite of the shortcomings like weak mechanical strength of single layer graphene, difficult to prepare nanopores on graphene film and hard to integrate with polymer, we hold the opinion that graphene-based films still have great research value especially in the membrane separation technology.

Access the complete article on ScienceDirect.

 




Fibrous ceramic membrane for dust removal

Wed, 04 Apr 2018 07:15:00 GMT

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The research article 'Highly porous fibrous mullite ceramic membrane with interconnected pores for high performance dust removal' has been published in Elsevier journal Ceramics International.

Abstract

Porous fibrous mullite ceramic membranes with different content of fibers were successfully fabricated by molding method for dust removal. The properties of the samples, such as microstructure, porosity, bulk density and mechanical behavior were analyzed. Owing to the highly porous three-dimensional structure of ceramic membranes, all the samples exhibited low density (lower than 0.64g/cm3), high porosity (higher than 73%), low linear shrinkage (lower than 1.0%) and low thermal conductivity (lower than 0.165W/mK). Significantly, the as-prepared porous ceramic membrane possessed of enhanced dust removal efficiency with almost 100% for 3–10µm, 97% for 1.0µm, 87% for 0.5µm and 82% for 0.3µm dust particles in diameter from dust-laden air passed through the test module. Moreover, the pressure drop was lower than 80Pa when the airflow linear velocity reached 1.25mmin−1. The results indicated that the ceramic membranes prepared in this work were promising high efficiency dedusting materials for the application in gas filtration field.

Access the complete article on ScienceDirect.

 




Thin film nanocomposite membranes incorporating graphene quantum dots

Wed, 28 Mar 2018 11:30:00 GMT

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The research paper 'Thin film nanocomposite membranes incorporated with graphene quantum dots for high flux and antifouling property' has been published in Elsevier's Journal of Membrane Science.

Abstract

Thin film nanocomposite (TFN) membranes incorporated with graphene quantum dots (GQDs) were fabricated with enhanced water permeability and antifouling property. Owing to the small size, stable dispersion and active functional groups, GQDs were embedded into polyamide (PA) layer during the interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC) in a facile way. The surface chemical features and morphologies of the resultant TFN membranes were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), water contact angle, zeta potential, scanning electron microscope (SEM) and atomic force microscopy (AFM) measurements. The surface roughness of the TFN membranes decreased and the surface hydrophilicity of the TFN membranes enhanced with the increase of the GQDs content. According to nanofiltration (NF) experiments, the highest water flux of the TFN membranes reached up to 102.0L/(m2h) under operation pressure of 0.2MPa, which was nearly 6.8 times as much as that of the pristine PA membrane. The TFN membranes also exhibited excellent antifouling performance that the steady water flux of the as-fabricated membrane under harsh fouling condition was about 4 times as much as that of the pristine PA membrane. This study may present a useful attempt of using carbon materials in fabricating high flux and antifouling membranes.

Access the complete article on ScienceDirect.

 




Dynamic membrane filtration of landfill leachate

Wed, 21 Mar 2018 06:55:00 GMT

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The research article 'Assessment of dynamic membrane filtration for biological treatment of old landfill leachate' has been published in Elsevier's Journal of Environmental Management

Abstract

This study investigated the behaviour of dynamic membrane (DM) filtration for the treatment of stabilised landfill leachate in a bench-scale pre-anoxic and aerobic submerged dynamic membrane bioreactor (DMBR). Four meshes with different openings (10, 52, 85 and 200μm) were tested to support the development of DM. Differences were observed among the meshes in supporting the development of the cake layer constituting the DM. The treatment of landfill leachate had an impact on sludge characteristics resulting in deteriorated filtration performance of the DM. Effluent turbidity was often higher than 100 NTU for larger mesh pore size (85 and 200μm). Low effluent turbidity was achieved with meshes with 10 and 52μm (13±2 and 26±4 NTU, respectively) although at membrane fluxes lower than 10L m− 2 h−1. The bioreactor exhibited a moderate organics removal of 50–60% and an ammonia oxidation between 80 and 90%. Incomplete nitrification was observed due to increased concentrations of free ammonia and free nitrous acid, with nitrite effluent concentrations up to 1062 mgNO2--N L−1. Due to the large presence of refractory organic matter in landfill leachate, denitrification was limited resulting in a total nitrogen removal of approximately 20%.

Access the complete article on ScienceDirect.

 




Evaluation of ultrafiltration membranes for treating poultry processing wastewater

Wed, 14 Mar 2018 09:15:00 GMT

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The research paper 'Evaluation of ultrafiltration membranes for treating poultry processing wastewater' has been published in Elsevier's Journal of Water Process Engineering.

Abstract

The US poultry industry produces over 60 billion gallons of poultry processing wastewater (PPW) per year which requires treatment prior to discharge. In this work, nine different commercially available ultrafiltration membranes, having different nominal molecular weight cut-offs (10–300kDa) and made of different polymeric materials (polyethersulfone and regenerated cellulose), were screened for treating PPW streams obtained from bird washer and chiller operations. Wastewater samples were treated for recycling and reuse purposes. Bird washer wastewater was found to cause more fouling as it contained higher biochemical oxygen demand (BOD), chemical oxygen demand (COD), fat, oil and grease (FOG) and total suspended solid (TSS) compared to the chiller wastewater.

The presence of suspended particles can lead to plugging of the membrane pores. Thus, it is important to select the most appropriate membrane (pore size, polymeric material, flux, etc.) that minimizes fouling and maximizes contaminate rejection. For the feed streams considered here, membranes with 30kDa nominal molecular weight cut-off provided the most stable performance in laboratory scale tangential flow filtration. Larger pore size membranes displayed rapid flux decline most likely due to entrapment of smaller particulate matter within the membrane structure. These particles were excluded from the smaller pore size membrane by size exclusion. The particle size distribution of the feed stream affected the level of contaminate rejection. Significant removal of BOD (up to 93%), COD (up to 94%), TSS (up to 100%) and FOG (up to 100%) was obtained for both wastewater streams.

Access the complete article on ScienceDirect.

 




Technology trends in membrane filtration use

Thu, 08 Mar 2018 17:15:00 GMT

Membrane filtration technology is widely utilized across various industries. Image courtesy of ShutterstockA significant amount of resources are allocated in the research and development of membrane filtration technology.  However, it remains unclear how closely research goals align with solving industry needs. Sepideh Jankhah, Ph.D, P.Eng. examines the history, evolution and R&D trends in this area. Since 2001, a significant amount of resources have been allocated each year to the research and development (R&D) of membrane filtration technology. However, it remains unclear how closely research goals align with solving industry needs. This article examines the history and evolution of membrane filtration technology applications and investigates R&D trends in this area based on peer-reviewed literature. Interestingly, it appears that research and industry needs are converging at a similar pace, though the leading party varies by area of application. Membrane filtration history Membrane filtration technology is widely utilized across various industries: water and wastewater treatment, food and beverage processes, pharmaceutical and medical applications, chemical processing, and other industrial separation or purification applications. The history of membrane separation goes back to the early 1700’s, when the word osmosis was first used to describe the permeation of water through a diaphragm. Filtration technology has evolved from osmosis to electrodialysis, gas filtration, and membrane distillation, contributing to the invention and improvement of countless industrial products, processes and applications. Membrane filtration is now commonly used to concentrate fruit juices, remove contaminants from water and wastewater, and harvest cells for antibiotic production. Membrane filtration technology has several advantages over conventional separation technologies (i.e. coagulation and sedimentation, sand filtration, dissolved air floatation, etc.). These advantages include improved product quality, increased separation capacity, lower risk factor, smaller footprint and generally lower chemical usage.  The global demand for membranes is expected to grow 8.5% annually, reaching $26.3 billion in 2019.2 The US market alone is expected to grow 7.9% annually, reaching $6.2 billion in 2018. Growth may be intensified due to global water shortages, increasingly stringent guidelines for drinking water and wastewater discharge quality, a drop in the cost of membrane production and operation, and recent advancements in the membrane technology. Major membrane applications Water and wastewater treatment account for more than 50% of industrial membrane usage, followed by food and beverage processes (21%) and pharmaceutical and medical applications (9%).  Over the next five years, pharmaceutical and medical applications are expected to be the fastest growing markets. This trend is driven by increasing purity standards and expanding medical applications for this technology. Water treatment (including desalination) and food and beverage processing are expected to maintain steady growth.3 R&D data trends were derived from the number of peer reviewed journal articles published between 2001-2016 and sorted by primary application area, as mined from the Engineering Village Database. During the last decade, trends in research application observed closely align with industrial applications. Water and wastewater R&D represents 40%, followed again by food and beverage at 34%. For industry, emphasis has been placed on the development of gas separation processes and desalination. Meanwhile, R&D has focused on pushing the boundaries of technology. Additional resources have been allocated to conduct research on such topics as membra[...]



Electrolysis technique for fouling control with low-pressure membrane filtration

Wed, 07 Mar 2018 15:45:00 GMT

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The research article 'Periodic electrolysis technique for in situ fouling control and removal with low-pressure membrane filtration' has been published in Elsevier journal Desalination.

Abstract

Electrically conductive membranes and their application for desalination pre-treatment and water purification have an exceptional performance due to self-cleaning of fouling deposits by the application of external electric fields. However, the effectiveness of existing conductive membranes is hampered by their common applications. The current approach aims to better understand the in situ fouling mitigation and enhanced flux by employing two different electrically conductive coated feed spacer configurations during filtration of humic acid at concentrations of 8, 12, 16 and 20ppm. Periodic electrolysis was applied for a duration of 2min with three intervals of 30, 45 and 60min. A comparison of both the feed spacers was made in terms of the effect of the applied potential and interval time on enhancement of water flux, as well as the required energy consumption at four different concentrations. In terms of enhanced flux and energy consumption, feed spacer A (2×2mm aperture size) revealed better results than feed spacer B (3×2mm), which may be attributed to a greater conductive area. The reported technique shows a major advantage of in situfeed spacer self-cleaning, thus providing a continuous and non-destructive approach for the mitigation of surface fouling.

Access the complete article on ScienceDirect.

 




Household unit for treatment of contaminated drinking water

Mon, 26 Feb 2018 07:00:00 GMT

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The research paper 'House hold unit for the treatment of fluoride, iron, arsenic and microorganism contaminated drinking water' has been published in Elsevier journal Chemosphere.

Abstract

A first of its kind hybrid electrocoagulation-filtration prototype unit was fabricated for the removal of fluoride, iron, arsenic and microorganisms contaminated drinking water. The unit comprised of 3 chambers, chamber A consisting of an inlet for the water to be treated and an outlet for the treated water along with one block of aluminum electrodes. Chamber B consisted of ceramic membrane filtration assembly at the bottom over a metallic support which filters the flocs so produced in chamber A and chamber C consisting of space to collect the treated water. Operating parameters were maintained as current density of 625 A m−2 and an electrode distance of 0.005m. Contaminated drinking water containing mixture of fluoride (10mgL−1), iron (25mgL−1), arsenic (200μgL−1) and microorganisms (35CFUml−1) was used for the experiment. A removal of 98.74%, 95.65%, 93.2% and 100% were obtained for iron, arsenic, fluoride and microorganisms, respectively. The apparatus and method made it possible to efficiently treat contaminated drinking water to produce drinkable water as per WHO specification. By-products obtained from the electrocoagulation bath were analyzed using SEM, EDX and XRD and explained.

Access the complete article on ScienceDirect.

 




Anti-fouling membranes for oily wastewater treatment

Tue, 20 Feb 2018 10:30:00 GMT

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The research article 'Antifouling membranes for oily wastewater treatment: Interplay between wetting and membrane fouling' has been published in Elseiver journal Current Opinion in Colloid & Interface Science.

Abstract

Oily wastewater is an extensive source of pollution to soil and water, and its harmless treatment is of great importance for the protection of our aquatic ecosystems. Membrane filtration is highly desirable for removing oil from oily water because it has the advantages of energy efficiency, easy processing and low maintenance cost. However, membrane fouling during filtration leads to severe flux decline and impedes long-term operation of membranes in practical wastewater treatment. Membrane fouling includes reversible fouling and irreversible fouling. The fouling mechanisms have been explored based on classical fouling models, and on oil droplet behaviors (such as droplet deposition, accumulation, coalescence and wetting) on the membranes. Membrane fouling is dominated by droplet-membrane interaction, which is influenced by the properties of the membrane (e.g., surface chemistry, structure and charge) and the wastewater (e.g., compositions and concentrations) as well as the operation conditions. Typical membrane antifouling strategies, such as surface hydrophilization, zwitterionic polymer coating, photocatalytic decomposition and electrically enhanced antifouling are reviewed, and their cons and pros for practical applications are discussed.

Access the complete article on ScienceDirect.

 




Mobile water treatment units

Wed, 14 Feb 2018 12:45:00 GMT

Pall Water's Aria FAST mobile water treatment unit deployed in Cisco, Texas.As emergencies arise, it is important for plants to prepare for the unplanned. The best way is by having a plan in place. This article looks at how mobile systems can provide an economical solution that can be deployed, installed, and operated quickly to ensure a sustainable supply of high quality water. From industrial operations and power production, to the treatment and distribution of municipal water to the masses, water is arguably the most important resource on the globe. Over time, worldwide water shortages and mounting regulations have challenged municipal and industrial facilities to increasingly implement sustainable methods for efficient water treatment. When a natural disaster or mechanical malfunction occurs, the need for an adequate solution and immediate response is critical. Crisis scenarios Advancements in technology have helped mobile membrane filtration systems emerge and provide high quality water in these crisis scenarios. While it is worth noting that these systems are also a very effective long-term solution, the value proposition is deeply rooted in emergency response situations as these automated, self-contained units can be rapidly deployed and are capable of producing water on-site within hours of arrival. Regardless of the quality and source of water, as well as whether a solution is needed short- or long-term, mobile membrane filtration units have been proven as the most effective, ideal water treatment solution for use across the globe. As emergencies or supplemental capacity issues inevitably arise, it is important for plants to prepare for the unplanned. Both municipal and industrial operators need to react immediately to restore services in order to provide safe, reliable water to their customers, or meet water supply demand while abiding by regulations, respectively. Emergency water need In June 2016, the City of Cisco, Texas experienced heavy rains that ultimately submerged the city's water treatment facility and all of its equipment. Personnel at the plant worked around the clock to provide water to the city's 6,500 residents, which included two wholesale customers that purchased bulk water from the city for surrounding rural communities. However, even with the efforts of the team, the plant completely ran out of water within days following the flood. The city needed to immediately identify and implement a solution to provide the residents and wholesale customers with safe, reliable water. The City of Cisco quickly selected a containerized mobile membrane system due to how quickly the trailer could be deployed and the unit's ability to meet water quality regulations. Within 72 hours of the flood, the automated water treatment trailer and technician had arrived on-site and the unit was producing water for the city hours later. With turbidity levels of the existing water reaching 50 times higher than normal, the unit was able to produce water that met drinking standards. The system was staffed continuously in the first few weeks in order to get control over raw water, install a temporary chlorination system to further treat water and eventually deploy a more permanent chlorine system. The water remained under boil water notice for nearly three weeks due to the vast infrastructure repair that needed to be completed, such as repairing every electrical and control panel, restoring functionality of tanks and pumps, and rebuilding pre-treatment chemical feeds from scratch. The speed of this deployment, which was made possible due to the mobile water treatment trailer, was critical, as within hours of arriving on-site, the trail[...]



Dynamic membrane for micro-particle removal in wastewater treatment

Wed, 14 Feb 2018 08:30:00 GMT

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The research paper 'Dynamic membrane for micro-particle removal in wastewater treatment: Performance and influencing factors' has been published in Elsevier journal Science of The Total Environment.

Abstract

Dynamic membranes (DMs) have been of great interest in recent years because they can reduce energy consumption and costs during wastewater treatment. Dynamic membranes are a promising technology for the removal of low-density, non-degradable micro-particles, such as plastics, which are an increasingly prevalent wastewater contaminant. These micro-particles are not easily removed via conventional sedimentation and result in increased operation and maintenance costs in downstream unit processes. In this study, DMs were formed on a 90μm supporting mesh through filtration of a synthetic wastewater. The impact of influent flux (solid flux) and influent particle concentration on DM performance was investigated. The effluent turbidity was reduced to <1 NTU after 20mins of filtration, verifying the effective removal of micro-particles by the DM. Transmembrane pressure (TMP) and total filtration resistance increased linearly with filtration time, and were highly correlated (R2>0.998). TMP ranged from 80 to 180mm of water head, and total filtration resistance ranged from 2.89×10−9m−1 to 6.52×10−9m−1 during DM filtration. In general, an increase in influent flux and influent particle concentration corresponds with increasing TMP and filtration resistance, as well as a rapid reduction in effluent turbidity due to swift formation of a DM on the supporting mesh.

Read the full text on ScienceDirect.

 




High-efficiency hollow fiber design to enhance filtration performance

Wed, 07 Feb 2018 12:00:00 GMT

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The research paper 'High-efficiency hollow fiber arrangement design to enhance filtration performance by CFD simulation' has been published in Elsevier journal Chemical Engineering and Processing - Process Intensification.

Abstract

For increasing the shear stress on a membrane surface to reduce the fouling caused by solid deposition to improve the membrane filtration operation, various hollow fiber arrangements in a filter channel were investigated using computational fluid dynamics. In the simulation process, the velocity and pressure distributions and the effect of shear stress distributions on the membrane surface were analyzed under various hollow fiber arrangements and operating parameters, including fiber diameter (D), transverse pitch (ST), and longitudinal pitch (SL). These parameters lead to a dimensionless Reynolds number Re and the related friction coefficient CfD, which can be used to identify the relationship between different operating conditions.

The study results indicated that CfD of the staggered arrangement was approximately 1.5 times greater than that of the aligned arrangement under the same operating conditions. The fouling tendency in the staggered arrangement was less and more favorable than that in the aligned arrangement, and with a higher SL/D ratio and lower ST/D ratio. With the results from this study, a design direction for optimal geometry to prevent membrane fouling and reduce power consumption was proposed, and can be used as the basis for hollow fiber membrane module design in the future.

Read the full text on ScienceDirect.

 




Advanced process control for UF membrane water treatment system

Tue, 30 Jan 2018 12:30:00 GMT

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The research article 'Advanced process control for ultrafiltration membrane water treatment system' has been published in Elsevier's Journal of Cleaner Production.

Abstract

Dead-end ultrafiltration (UF) has been considered as a more energy efficient operation mode compared to cross-flow filtration for the production of drinking/potable water in large-scale water treatment systems. Conventional control systems utilize pre-determined set-points for filtration and backwash durations of the constant flux dead-end UF process. Commonly known potential membrane fouling parameters such as feed water solids concentrations and specific cake resistance during filtration were not taken into considerations in the conventional control systems. In this research, artificial neural networks (ANN) predictive model and controllers were utilized for the process control of the UF process. An UF experimental system has been developed to conduct experiments and compare efficiencies of both the conventional set-points and ANN control systems. The novelty of this study is to utilize commonly available on-line and simple laboratory analysis data to estimate potential membrane fouling parameters and subsequently utilize the ANN control system to reduce water losses. Reduction of water losses were achieved by prolonging filtration duration for feed water with low turbidity using the ANN control system. This advanced control system would be of interest to operators of industrial-scale UF membrane water treatment plants for the reduction of water losses with existing facilities.

Read the full text on ScienceDirect.

 




Nanofiber membranes with honeycomb-like textures

Mon, 22 Jan 2018 07:45:00 GMT

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The research article 'Honeycomb-like polysulphone/polyurethane nanofiber filter for the removal of organic/inorganic species from air streams' has been published in Elsevier's Journal of Hazardous Materials.

Abstract

Nanofiber nonwoven filters, especially those prepared by electrospinning, are of particular interest because of their high filtration efficiency. However, existing electrospun filters suffer from inherent limitations in that both strengths and filtration resistances of the filters leave much to be desired. Herein, we present a novel nonwoven filter that is composed of polysulphone and polyurethane nanofibers. By mimicking the honeycomb structure, a heterogeneous distribution of both fiber diameter and fiber density has been achieved. Compared with nanofiber nonwovens with plain architectures, the honeycomb-like nonwovens possess higher filtration efficiency (∼99.939%), better mechanical strength (∼105.24Ng−1) and improved quality factor (∼0.04Pa−1). The filtration efficiency against both inorganic and organic aerosols is guaranteed through the nanofiber surface geometry and the intrinsic charge-retention capacity of polysulphone. Since the production of this nanofiber filter does not need multistep procedures and can be easily scaled up on a needleless electrospinning device, we anticipate that the strategy of endowing nanofibers with honeycomb texture and charge-retention capacity may lead to the development of advanced fiber filters.

Read the full text on ScienceDirect.

 




Status of solar thermal-powered desalination technologies

Fri, 19 Jan 2018 10:15:00 GMT

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The research paper 'Solar thermal-powered desalination: A viable solution for a potential market' will be published in Elsevier journal Desalination.

Abstract

This paper deals with an assessment of solar thermal-powered desalination technologies in order to identify key issues for developing market opportunities. The topic of selecting the best solar desalination solution is analysed, case by case, considering different scenes: i) Rural communities with limited fresh water demand; ii) Regions with high demands of both, water and electricity and iii) Intermediate water demands. Detailed analyses of solar thermal-driven desalination – i.e. distillation and Reverse Osmosis (RO) - in comparison to solar PV/RO are presented. The quantitative assessment performed highlights that membrane distillation systems, when fully developed, will have market opportunities at very small-capacity seawater desalination systems. Besides that, dish concentrators coupled to micro gas turbines in case of limited water demand is a promising option. A single unit could produce about 10 m3/h of fresh water from seawater and several units could be coupled to drive the same desalination plant. Moreover, the only stand-alone systems with market opportunities for intermediate water production are based on reverse osmosis driven by parabolic troughs or linear Fresnel concentrators by means of organic Rankine Cycles. Finally, water demands over 25,000 m3/d require both, a solar power plant and a reverse osmosis desalination plant.

Read the full text on ScienceDirect.

 




The role of filtration in orange juice production

Wed, 17 Jan 2018 12:00:00 GMT

Food processing in a Dow Water & Process Solutions installation.The bitterness in orange juices due to limonin develops after the extraction from oranges and is referred to as delayed bitterness, becoming a serious economic problem for the citrus industry. But scientific developments have helped producers to overcome this problem. In Chinese tradition, the orange is widely considered a symbol of good fortune. Perhaps this is due to its health benefits, as its high concentration of Vitamin C neutralizes free radicals that cause chronic diseases, like cancer and heart disease. However, the sweet taste of orange juice is down to more than just good fortune, but good chemistry. At the beginning of the 20th century, oranges were consumed principally as fresh, whole fruit. It was only in 1916, when California growers found themselves with an overabundance of oranges, that orange juice became more widely popular and solidly established itself as a key player in the global beverage industry. However, orange juice back then wasn’t the sweet-tasting nectar that we know today. One of the biggest problems throughout the juice’s commercial history was controlling taste, as orange juice loses taste over time and can also be extremely bitter. The compound that is primarily responsible for bitterness in navel orange juice is limonin. In fact, the development of unpleasant flavours is a consequence of food processing that results in the thermal degradation of components. As a matter of fact, the intact fruit barely contains limonin. Delayed bitterness Bitterness due to limonin in a variety of citrus juices is generally referred to as delayed bitterness, and it’s a major problem of the citrus industry worldwide. In fact, only a very small amount of this compound is needed to render the juice unpalatable. Although the sensitivity to limonin among individuals varies, generally most people will perceive bitterness in orange juice when its concentration is about 5 parts per million (ppm), and will consider an orange juice to be unpalatable when its concentration is about 10 ppm or higher. However, a nonbitter precursor limonoat A-ring lactone is present in the insoluble fruit sections and passes into the juices after its preparation and is converted to limonin under acidic conditions. Scientific advances in the second half of the century allowed orange juice producers to alter the taste such as by removing bitterness. Today, annual orange juice production is expected to reach 1.7 billion liters, the equivalent of 680 Olympic-sized swimming pools. It has become a really popular product within the drinks department, as orange juice is perceived as ‘healthy’ by consumers. So, how is orange juice made and how is the bitterness issue solved? First, oranges are harvested and shipped to the processing facility, where they are washed and screened before being squeezed for juice extraction. Citrus juices have natural bitter components, such as limonin and naringin, and removal of these bitter molecules is important for taste and shelf life stability. During the squeezing process, the orange rind emits a bitter flavour into the juice, so before it can be bottled and commercialized, the juice passes through a resin column to remove the bitterness. Ion exchange resin technology is used to optimize this removal process. Polymeric adsorbent resins, such as DOW Amberlite FPX66, help to debitter the juice by removing components through hydrophobic interaction. Ultrafiltration diverts[...]