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Abstract: The aim of this work was to study the transmission of p-anisic acid through two different membranes, viz., commercially available nanofiltration membrane (NF-300) and a goat membrane. The p-anisic acid is a crystalline organic compound having vital applications in medical science for the treatment of Parkinson''s disease, hepatitis B and C viruses, liver diseases, post radiation treatment of breast cancer, and skin desquamation. The study of transmission (or rejection) of material and change in the permeate flux have been made with respect to changes in feed concentration, pH, cross flow velocity, time and temperature and found that the transmission of p-anisic acid is affected by the type of membrane, its pore size and structure of pores. Also a study pertaining to the mass transfer coefficient has been made and evaluated the same with different theories. Mass transfer of p-anisic acid is explained in a better way by the simple graphical theory. The transmission of p-anisic acid is affected by the membrane structure and its type. A higher transmission was observed through the goat membrane. Using nanosize particles the drug dosage can be reduced with better diffusion, further, toxicological aspects can also be reduced. [Copyright &y& Elsevier]

Abstract: Toxic cyanotoxins such as microcystins represent a human health risk in water bodies. Nanofiltration is an effective technology to remove these micro-contaminants from drinking water. However, long-term operational sustainability is necessary because of decreases in membrane fluxes over time and increasing operation costs. The rejection of natural organic matter (NOM) is a key issue regarding membrane fouling and flux decline, and is also of great importance in the water industry due to its relationship with public health. Therefore, this study aimed to analyse the effect of microcystins and NOM properties on membrane fouling and to understand the fouling mechanisms, using a series of experiments with different water types. Results showed that nanofiltration was capable of reducing low molecular weight NOM fractions from water and that these fractions were responsible for flux decline and membrane fouling. The adsorption of NOM onto the membrane surface was reduced in the presence of microcystins due to the hydrophobic character of microcystins, which are the first to be adsorbed on the membrane surface. Microcystins contributed to the rejection of smaller natural organic fractions by blocking the membrane pores and reducing NOM adsorption onto the membrane pores. [Copyright &y& Elsevier]

Abstract: Recently, for some membrane separation processes, the concept of threshold flux was introduced in substitution of the critical one. The new concept applies to all systems which trigger fouling formation from start of operation, even at very low operating conditions, and in particular to the purification of olive mill wastewater streams by membranes. The operation of a spiral-wound nanofiltration membrane module used to purify different pretreated olive mill wastewater streams and how pretreatments affect the threshold flux values and the threshold flux fitting parameters will be discussed. [Copyright &y& Elsevier]

Abstract: In this study, the municipal wastewater treated by biological methods was used for further treatment by nanofiltration method for wastewater reuse. For this purpose, different nanofiltration (NF) membranes, such as CK, NF-90, and NF-270 were employed. The quality analysis of product water was carried out using various analytical techniques. The results revealed that the NF-90 membrane can produce the best water quality compared to other two membranes. The CK membrane showed also a good rejection property after NF-90 membrane but its big inconvenience is that it gave a lower water flux. Despite the good water flux by NF-270, the permeate quality obtained with this membrane was not as good as obtained with the NF-90 and CK membranes. [Copyright &y& Elsevier]

Abstract: The goal of the present work is to illustrate the applicability of crossed mixture–process design to predict the rejection of the nanofiltration membranes when treating non-dilute solutions. The method used in this work is based on the use of mixture factors derived from the fractions of equivalents of the major ions present in solution combined with the total concentration as a process variable. In this way, polynomial models for permselectivity properties can be obtained. Model accuracy is improved by using pseudo-components to restrict the range of the composition variables to that expected for the feed water compositions. The experimental plan uses the D-optimal criterion. As an application example, the procedure was used to model the performance of the nanofiltration membrane NF270 (Dow-Filmtec) with ionic mixtures containing chloride, nitrate, sulfate, sodium and calcium. The experiments were carried out in a pilot plant with solutions of total concentration ranging from 2480 to 4050mg/L. The obtained polynomial models could satisfactorily describe individual ion rejection despite the solutions not being dilute. The polynomial models can be useful for design and operation purposes as an alternative to physical-based nanofiltration models. [Copyright &y& Elsevier]

Abstract: Modeling of mass transport through nanofiltration membranes has seen an increasing expansion over the last decades in view of proposing predictive tools. Many models were devoted to the prediction of separation by NF and the model proposed here is classically based on the extended Nernst–Planck equation and equilibrium partitioning at the interfaces. The key of such models lies in the estimation of the adjustable parameters. Hence, the feasibility of fully predictive models requires an accurate methodology to identify easily and quickly the input parameters. Among them, the two parameters governing electric and dielectric exclusions have aroused much scientific interest because of their difficult assessment. In this paper, a methodology based on membrane potential (MP) and tangential streaming potential (TSP) measurements is proposed to estimate their values. MP is used to identify the dielectric constant of ternary mixtures which are extrapolated to determine those of salt solutions. In this study, the membrane charge is supposed to vary along the pore length because of the concentration variation. The TSP method is thus implemented to correlate membrane charge and salt concentration via adsorption isotherms, which are introduced in the model to calculate the charge along the pore length. Finally, the ability of the Pore Transport Model (PTM) to predict salt rejections is investigated for two membranes and a satisfactory prediction is obtained. The methodology appears to be convenient for a preliminary estimation of separation performances. [Copyright &y& Elsevier]

Abstract: This study compared the filtration of produced water using two new and highly hydrophilic NF and RO membranes to assess toxicity removal efficiency in pre- and post-filtration samples for reuse as indirect potable water. The toxicity test was conducted using marine luminescent bacterium Vibrio fischeri to monitor changes in the level of light emission during exposure to unknown toxic substances present in the tested pre- and post-filtration samples of produced water. The results show that the quality of water obtained using the NF membrane was toxic at an effective concentration of 13.65% (EC50). However, the performance of NF membrane in rejecting 48% of total organic carbon indicates that it has high potential for use as a pretreatment for the RO membrane in treating produced water because this configuration will decrease the rate of fouling by organics. Toxicity test analysis further revealed that the RO-treated produced water was free of toxicity, whereby 100% of the effective concentration (EC50) caused no effects when exposed to V. fischeri. Therefore, converting produced water from a pollution source into a new water resource has been conclusively shown to be readily achievable, especially through the use of a combined membrane system rather than a single membrane. [Copyright &y& Elsevier]

Abstract: This study compared the filtration of produced water using two new and highly hydrophilic nanofiltration (NF) and reverse osmosis (RO) membranes to assess removal efficiency in pre-and-post-filtration processes, and to compare the quality of water obtained against standards for reuse as indirect potable water. The results show that NF membrane successfully attains 96% of overall drinking water standards, despite its inefficiency in removing boron, molybdenum and ammonia. The study also found that the NF membrane can be used as a pre-treatment for the RO membrane to produce high quality water and reduce contaminant concentrations, thereby minimizing the potential for fouling. In contrast, the produced water treated by the RO membrane successfully met the regulatory quality standards for drinking water, with the exception of the parameters for ammonia and molybdenum. The study concluded that treated produced water has potential for reuse as indirect potable water and that both of the hydrophilic NF and RO membranes studied are suitable for treating produced water to yield a promising source of water. [Copyright &y& Elsevier]

Abstract: This study describes the rejection of heavy metal ions using a commercial nanofiltration membrane (NF270). The effect of feed pH, pressure and metal concentration on the metal rejections and permeate flux and in some cases permeate pH was explored. The results showed that with all metals examined (except As (III)), when the feed pH is below the isoelectric point, the rejection increased. NF270 rejected almost 100% of copper ions at low concentrations, but decreased to 58% at the highest concentration examined. Using 1000mg/L concentration level, pH=1.5±0.2 and 4bar the rejection was 99%, 89% and 74% for cadmium, manganese and lead respectively. However at pH above the isoelectric point the average rejections decreased. NF270 was unable to retain As(III). The metals caused a flux decline due to membrane fouling in the order of severity: Cu2+ >Cd2+ ≈Mn2+ >Pb2+ ≈As3+. The correlation between adsorbed amounts of the metals onto NF270 with the normalised flux shows that as the amount increased the normalised flux decreased, except for arsenic that had a higher deposited amount and higher flux. The RMS roughness as obtained by AFM showed that roughness was decreased by membrane fouling. [Copyright &y& Elsevier]

Abstract: As nanofiltration is gaining more and more importance in the field of desalination, one has to address the many obstacles in order to achieve effective/efficient filtration. One such issue is biofouling and microbial attack to the membrane. This paper describes about the study on copper coating onto the membrane surface as biofouling protective layer. This is an attempt to come up with a new approach for desalination and an antimicrobial membrane. The work indicates that, the copper coated membrane can resist the possible microbial attack to some extent while maintaining good salt rejection and appreciable flux. SEM and EDX studies had shown the distribution of copper on the membrane surface. The copper coated membrane had shown the maximum salt rejection of about 96% for 3500ppm NaCl solution and also it had shown the pure water flux of 36Lm−2 h−1. [Copyright &y& Elsevier]

Abstract: Novel polyaniline (PANI)/phosphomolybdicacid (PMA) nanoparticles were prepared by simple protonation method and used to enhance the antifouling property of polyethersulfone (PES) ultrafiltration membranes. The prepared nanoparticle size around 30±3nm was confirmed by transmission electron microscopy and scanning electron microscopy analyses. Complete PMA incorporation with PANI was evaluated by Fourier transform infrared spectroscopy analysis. The surface charge of nanoparticles are average value is of −46mV. The contact angle, water flux and flux with rejection of protein of all membranes increased by increasing nanoparticle concentrations in the range of 0, 2, 3, 5 and 7wt.% into casting solution. Compared to pure PES membrane, the PES–PANI/PMA membrane exhibits better antifouling performance with very high (>98.8%) protein rejection rate. Especially, the 3wt.% PANI/PMA nanoparticles incorporated membrane shown superior results than other membranes. The roughness of PES–PANI/PMA membranes are remarkably enhanced due to the drastic enrichment of nanoparticle segments on the membrane surface. Bovine serum albumin (BSA) was used as a model protein to investigate the protein adsorption resistivity and permeation properties of all membranes. BSA ultrafiltration experiment showed that PES–PANI/PMA membranes had higher flux and better antifouling property than PES membrane. [Copyright &y& Elsevier]

Abstract: In an effort to reduce its environmental impact, the desalination industry constantly seeks more sustainable operational and maintenance practices. Based on the increasing number of large desalination plants using membrane technology, the resulting number of old reverse osmosis (RO) modules to be discarded is expected to become a critical challenge. Although the fate of old RO membranes has rarely been considered in the past, a wide range of opportunities can be considered for the potential reuse and recycling of the old modules. Reuse options include direct application of the old membranes within lower throughput systems (i.e. brackish water treatment) and chemical conversion into porous, ultrafiltration-like filters. Other options include, direct recycling of the various module components, and energy recovery through incineration. In addition to the remaining technical issues related to the feasibility of these proposed options, strategic and policy challenges will need to be addressed. However, the concept of product stewardship, already implemented in many parts of the world for electronic wastes and packaging, can provide guidelines for future policies for RO disposal. Finally, the framework for a life cycle assessment of the various disposal options is discussed which may provide guidance for the future implementation of these strategies. [Copyright &y& Elsevier]

Abstract: Zein-based microspheres and membranes were prepared by phase separation. Increasing the concentration of zein in the stock solution resulted in the formation of three different kinds of zein microstructures i.e. discrete microspheres, sponge-like microsphere membranes and continuous membranes. Zein single (ZS) membrane and zein composite (ZC) membrane were developed by spin coating zein solutions onto porous asymmetric alumina tablets. Both the ZS and ZC membranes effectively removed ethanol from dilute ethanol aqueous solutions via pervaporation. The pervaporation performances of the two membranes were evaluated using different process parameters, such as operating time, ethanol feed concentration and temperature. The separation factors for the ZS and ZC membranes were 3.2 and 3.4 respectively and the permeation fluxes were 0.62 and 0.73kg/m2 hr respectively for a feed solution with 3wt % ethanol–97wt % water at 25°C. In a ternary feed solution with 1wt % acetic acid–3wt % ethanol–96wt % water, the pervaporation performances were slightly lower compared with those for the binary feed system. Single gas permeation of N2 confirmed that the membranes were free of defects before and after pervaporation. The ZS and ZC membranes showed good hydrophobic properties and ethanol permselectivity, which can be explained by the Switch Effect. [Copyright &y& Elsevier]

Abstract: Using the immersion phase inversion process, polyvinylidene fluoride (PVDF) and graphene oxide (GO) dissolved in N, N-dimethylacetamide (DMAc) were combined to prepare organic–inorganic-blended ultrafiltration membranes. The prepared GO-blended PVDF membranes were characterized by several analytical methods, such as Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), contact angle measurements and permeation tests. Owing to the hydrophilic nature of GO, the GO-blended PVDF membranes appeared to be more hydrophilic and have higher pure water fluxes recovery ratio than the unblended PVDF membranes. The beneficial effects of adding GO to the PVDF membrane, in terms of mechanical strength, permeation properties, and anti-fouling performance, were also examined. The results show that, when the content of GO added in the casting solution was 0.20wt.%, the properties and structure of the blended membranes can be improved obviously. The permeability of the blended membrane increases by 96.4% with a slight change of retention; the tensile strength increases by 123%. Moreover, the contact angle decreases from 79.2° to 60.7°, which implies that the anti-fouling ability of the membrane is improved. [Copyright &y& Elsevier]

Abstract: Efficiency of two MBR systems (microfiltration and ultrafiltration) at producing reusable effluent was evaluated. The ultrafiltration MBR (0.034μm pore size) maintained recirculation sludge flow at six times the influent flow, and membranes were backwashed every 5minutes. The microfiltration MBR (0.4μm pore size) maintained recirculation sludge flow at four times the influent flow, and membrane-relax was applied after the production phase. Permeates of both systems were shown to be suitable for unrestricted reuse (based on Spanish reuse guidelines); however their colour and aerobic bacteria concentration may lead to their rejection for certain purposes. The capacity of the MBR systems to eliminate organic matter depends on the biological activity in the active sludge, and it is not affected by the type of membrane. The concentration of coliphages is one of the differentiating characteristics between the two systems in terms of the quality of the permeate. This concentration was higher in the microfiltration system, due to the larger pore size, a fact which also explained the higher concentration of aerobic bacteria and the different particle size distribution. Reuse of effluent from ultrafiltration MBR systems is more safety in view of its microbiological and physico-chemical quality. [Copyright &y& Elsevier]

Abstract: Ethanol fermentation from food waste decreases pollution and optimizes waste utilization. However, the high-energy consumption involved in the distilling process hinders the industrial application of ethanol fermentation. In the present study, pervaporation was adopted to resolve such a shortcoming. A flocculation–filtration unit was used for the treatment of the fermentation broth. The purpose was to decrease the amount of suspended solids (SS) and oil, which affected the pervaporation membrane used for ethanol separation from food waste broth. Seven kinds of flocculants at three pH levels were adopted to screen the best type and corresponding dosage. Then, a mixture of fiber-ball and quartz sand was used to treat the residue oil and SS. Considering the higher flux of the filtration process, 500mg/L sodium alginate in a raw fermentation broth was considered the best choice. After treatment, 94.74% of SS and 98.60% of oil in the fermentation liquid were removed. The effluent quality contained the desirable qualities of the inlet water in the pervaporation step. [Copyright &y& Elsevier]

Abstract: This work investigated the characteristics of algogenic organic matter (AOM) that was produced by blue-green algae grown under different nitrogen to phosphorus ratios (1N:1P, 1N:2P, 1N:10P, 2N:1P). Subsequently, the potential for AOM microfiltration (MF) membrane fouling under these scenarios was evaluated. The results showed that algae grew differently under various N/P ratios. Microcystis aeruginosa in 1N:10P and 1N:2P grew much better than those in 1N:1P. When constant phosphorous concentrations were maintained, no obvious effect was observed on the accumulation of algal intracellular organic matter. The amount of AOM released from M. aeruginosa was also affected by the N/P. AOM fraction analysis showed that the neutral hydrophilic fraction (N-HPI) was the main component of AOM; with lower N/P ratios, the proportion of hydrophilic AOM increased. Moreover, molecular weight (MW) distribution discrepancies existed among different AOMs. MF membrane fouling by AOM may also be influenced by N/P variations. AOM at 1N:10P exerted the strongest impact on membrane fouling, followed sequentially by 1N:2P, 1N:1P and 2N:1P. According to the analysis of the excitation–emission matrices (EEMs) and the MW distribution of membrane filtration, the membrane fouling potential of AOM seemed to be mainly associated with polysaccharide-like or protein-like substances of large MW. [Copyright &y& Elsevier]

Abstract: Destruction of coalescer filters by coke particles is an important concern faced with polyolefin units of petrochemical plants. A lot of fund and time is wasted for reclogging/substituting the coalescer filters. In the current work, γ-Al2O3 based ceramic microfiltration membrane was utilized to remove coke particles from petrochemical wastewaters before introducing to the coalescers. Perfect elimination of coke particles from oily wastewaters was achieved. Influence of temperature and some operating conditions such as filtration time and reusability was examined. Analysis results showed that the extent of volatile organic compounds (VOC) was not noticeably changed after the process; however, suspended solids were effectively retained by the ceramic membrane. The results indicated that most of the light organic compounds (e.g. gasoline) passed through the membrane but the troubling coke particles did not. By increasing temperature, the flux was increased due to viscosity reduction as well as solvents diffusivity enhancement. Microfiltration was performed at constant trans-membrane pressure of 15bar, cross-flow velocity of 2m/s and various temperatures (20–80°C). Moreover, reusability of the membranes was examined using HCl, NaOH and SDS as eluting agents. Normal flux recovery was obtained utilizing NaOH whereas HCl did not suggest an acceptable flux recovery. [Copyright &y& Elsevier]

Abstract: The influence of air bubble flow rate (ABFR), hydraulic retention time (HRT), mixed liquor suspended solid (MLSS) concentration, and pH on the performances of modified polyvinylidene fluoride (PVDF) was investigated in submerged membrane ultrafiltration (SMUF).The refinery wastewater process was conducted using an experimental set-up consisted of an SMUF reservoir, a circulation pump, and an aerator. For SMUF, operated at vacuum pressure, deposition and accumulation of suspended solids on membrane surface were prohibited with continuous aeration. The process performance was measured in terms of the membrane water flux and chemical oxygen demand (COD) removal efficiency. The air bubbles flow rate was controlled at 1.2–3.0mL/min while HRT was manipulated in the range of 120–300min. MLSS and pH solution were controlled at 4.5g/L and 6.5, respectively. Results from response surface methodology (RSM) have demonstrated the improvement in water flux and COD removal, achieving 145.7L/m2 h and 90.8%, respectively. By using pH at 6.50, the optimized conditions achieved for refinery wastewater treatment were 2.25mL/min, 276.93min, 4.50g/L for ABFR, HRT and MLSS concentration, respectively. [Copyright &y& Elsevier]

Abstract: This study describes the influence of polyethersulfone (PES) sublayers on the performance of polyamide (PA) reverse osmosis membranes. Asymmetric polymeric sublayers were synthesized by using the DIPS technique (Diffusion Induced Phase Separation). Sublayers are optimized mainly with respect to hydrophilicity, permeability and rejection potential by adjusting synthesis procedures. Parameters that were found to have an influence are the type of solvent (DMF and NMP were used), the air humidity, processing time, and concentrations of polymer. By carefully controlling these parameters, it was possible to prepare a range of sublayers with different characteristics, in the ultrafiltration–nanofiltration area. To visualize membrane surface characteristics, both scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements were performed. In addition, titanium (TiO2) nanoparticles were assembled with polyethersulfone (PES) membranes at ultralow concentrations of nanoparticles to characterize TiO2/PES composite membranes and evaluate their permeate flux and solute rejection. Subsequently, a polyamide top layer was added by interfacial polymerization using typical reagents both in the aqueous and in the organic phase. The membrane performance was evaluated in terms of flux and salt rejection. Experimental design was performed in order to obtain the importance of some experimental variables during the polymerisation process. It was found that depending on the type of sublayer used in the procedure, a different membrane performance could be obtained. [Copyright &y& Elsevier]

Abstract: The frequent detection of pesticides in water sources is of great concern to the public, to authorities and all those involved in potable water production, wastewater treatment and reuse, due to potentially adverse health effects associated with these compounds, even at very small concentrations. In view of problems inherent in conventional processes, for removing various pesticides and the multitude of other synthetic micropollutants, significant research efforts have been invested for developing effective potable water treatment methods based on membranes. The growing interest in such processes is justified on account of the high and stable water quality they can achieve, although their cost effectiveness needs improvement. Therefore, influenced also by social and legislative pressure for more stringent potable water quality regulations, membrane processes such as nanofiltration (NF) and low-pressure reverse osmosis (LPRO) are under development for broad applicability. The scope of this paper is to review our current understanding, gained from laboratory research, pilot and industrial-scale activity, regarding pesticides removal by membrane processes. A rather thorough discussion of pesticides rejection by membranes is provided, highlighting the prevailing mechanisms and main factors involved. Finally, an outline is provided of outstanding issues, both at the scientific and technological level, which require further investigation. [Copyright &y& Elsevier]

Abstract: Addition of nanoparticles to polymer solution in membrane fabrication process has the potential to improve membrane separation performance. Recently, the mechanical and chemical modifications of TiO2 nanoparticles have shown to provide improvements in reducing the nanoparticles agglomeration and fouling in flat sheet membranes. In this study, hollow fiber PES membranes with 2wt.% mechanically and chemically modified TiO2 were fabricated. The effect of chemical and mechanical modifications on the titania nanoparticles was compared with the effect of mechanical modification only and membranes without nanoparticles additives. The results showed that the migration of nanoparticles toward outer layer only occurred after mechanical modifications, whereas the migration and size of agglomerations reduced significantly after both the chemical and mechanical modifications of particles. Higher thermal resistance, stiffness and lower elasticity were observed in fibers made with chemically and mechanically modified particles. Enhancement in initial pure water flux due to lower intrinsic membrane resistance and bigger pore size was also observed. While the rejection of BSA remained similar and lower overall ultrafiltration resistance was observed, the benefits of particles modifications on flux recovery after cleaning of hollow fiber membranes was not observed, possibly due to a significant change in pore structure and initial permeabilities. [Copyright &y& Elsevier]

Abstract: Recently nanofiltration (NF) is gaining more importance for water treatment. It is replacing the conventional method of water treatment due to advantages of NF membranes over RO system. In this work, we are discussing the preparation of NF membrane for desalination of sea water. We herein report the synthesis of polymer, by the reaction of p-amino benzoic acid (PABA) and poly isobutylene-alt-maleic anhydride (PIAM) and its blend membrane preparation with polysulfone (PSf). The new membranes were characterized by SEM images, surface wettability to investigate the hydrophilic nature of the membrane, water swelling, pure water flux, molecular weight cut-off and salt rejection of the membranes. The membranes showed nano size (<50nm) pores in SEM image, and the contact angle data revealed that membrane surface is moderately hydrophilic. Membrane with 70:30 (PSf:modified PIAM) composition has shown good salt rejection of 96% at 200kPa for 3500ppm of NaCl solution with a pure water flux of 38.36Lm−2 h−1. [Copyright &y& Elsevier]

Abstract: The effect of inorganic and organic additives in polyethersulfone (PES) membranes was investigated for the possible enhancement in ultrafiltration performances. Tetraethylorthosilicate (TEOS) and polyethyleneimine (PEI) were chosen as inorganic respective silica precursor and organic additive based on their potential to promote hydrophilicity in PES membranes. With the addition of TEOS and PEI in PES casting solution, the viscosity and hydrophilicity were increased.In addition of TEOS in PES, the SiO2 particles were homogeneously dispersed in PES matrix, a large amount of on the SiO2 particles generated, and led to an improvement in the hydrophilic property. Characterizations of membranes by FTIR and X-ray Diffraction (XRD) confirmed that the PES suffered a transform from various functional groups due to the addition of TEOS. The 40% of water permeability was found by 5% addition ion of TEOS and PEI repressively. The top surface and cross-section morphology of PES membranes changed from dense-like structure to finger-like macrovoids structure with increasing TEOS and PEI content. Protein solution separation was investigated using lysozyme and bovine serum albumin (BSA) with the concentration of 1000ppm. The observed sieving coefficient of protein decreased exponentially with increasing contents of TEOS and PEI in PES membranes. [Copyright &y& Elsevier]

Abstract: The biosand filter (BSF), intermittently operated household slow-sand filter, was modified by introducing a 10-cm thick layer of iron oxide-coated sand. Long-duration (about four months) tests were conducted to compare the performance of the modified BSF (MBSF) with the conventional BSF in terms of their efficiency in removing bacteria and turbidity under different operating conditions. Filters were charged daily with 20L or 40L natural canal water (turbidity 10.0±1.2 NTU; faecal coliforms 365±251 MPN/100mL; pH 8.4±0.4) or seeded tap water (turbidity 14.7±4.3 NTU; Escherichia coli 3850±736CFU/mL; pH 7.9±0.3). Results showed that the performance of MBSF in terms of faecal coliform and E. coli removals was better by at least one-log10 unit throughout the filter operation. The mean bacterial removal was low for BSF for the first month (90.0%), while it was 99.3% for MBSF during the same period. Bacteria and turbidity removals increased with time as filter ripening (maturation) occurred in both the filters. No significant difference was observed in turbidity removal between BSF and MBSF, and mean effluent turbidity was around 1 NTU for BSF and MBSF representing >90% removal. When daily charge was increased from 20L to 40L, a reduction in bacterial removal was noted in both the filters indicating the influence of operating conditions. Effluent physico-chemical quality remained within the guideline values for drinking water. [Copyright &y& Elsevier]

Abstract: The devastating earthquake of 2005 severely damaged over 4000 water and sanitation schemes in northern Pakistan. The present study aimed at testing a low cost household sand filter (HSF) in treating low quality drinking water in disaster-hit areas of northern Pakistan. Two villages were randomly selected for practical demonstration of a low cost drinking water treatment system in earthquake affected areas. The on-site performance of HSF was monitored during the operational period. The data was collected on people perceptions of water quality and handling of the household sand filter (HSF) through in depth focus group discussions, questionnaire and interviews. The results showed that pre-treatment values of drinking water for Escherichia coli, total coliforms and turbidity were 101cfu/100ml, 73cfu/100ml and turbidity 44 and 16 NTU, respectively. After HSF operation for 10days, 97% reduction in E. coli, total coliforms and turbidity was evidenced. More than 67% of the respondents perceived turbidity as a prime water quality issue responsible for ill health consequences. It was concluded that the designed HSF was efficient in improving drinking water quality for illiterate communities and its success and dissemination to poor communities were prone to locally available construction materials. [Copyright &y& Elsevier]

Abstract: A substantial variation in characteristics arises from the use of dye-house wastewater. Such a dye-house effluent is heavily polluted and has to be treated before discharge and/or reuse. The pre-treatment is needed in order to avoid high operational costs as a consequence of frequent membrane fouling. Therefore, the aim of this research was to study the appropriateness of dead-end ultrafiltration (UF), with or without a flocculation pre-treatment, with the emphasis on colour and chemical oxygen demand (COD) removal. The dyes employed in the dyeing processes were disperse dyes for polyester fabrics, as well as metal-complex dyes for the dyeing of polyamide fabrics. The removal efficiencies for colour and COD were studied using several ultrafiltration membranes. Two hydrophobic and one hydrophilic commercial UF membranes were selected. [Copyright &y& Elsevier]

Abstract: Accumulation of particulate matter and microorganisms present in wastewater as biofilm on the surface of filters can lead to clogging of the media. If clogging of filters occurs, they need to be temporarily decommissioned before they can be operated again. The mechanisms causing clogging may only be delineated through destructive sampling of a filter. The aim of this study was to characterise the build-up of biofilm in the upper layer below the surface of polishing filters intermittently loaded with effluent from a novel horizontal flow biofilm reactor used for the treatment of domestic-strength wastewater. Three filter media were used: crushed glass, sand, and a shallow podzolized soil. The parameters used to measure biofilm build-up were: soil water retention, total phosphorus (Tot-P) content and loss on ignition (LOI). The LOI and Tot-P deposition near the filter surface were lowest in the glass filters. Soil water retention curves indicated that biofilm formation mainly occurred in the uppermost 0.03m depth below the filter surface and gradually decreased with depth. This indicates that measurements of volumetric water content using time domain reflectrometry probes may be used as an in situ proxy for measurements that would normally require the destructive sampling of a filter. [Copyright &y& Elsevier]

Abstract: This study focused on quantitative chemical analysis of organic fouling of ultrafiltration membranes by protein (bovine serum albumin-BSA) in the presence of a polysaccharide (alginic acid-AA). Filtration experiments were performed in a dead-end cell with two microporous membranes. Prior to the filtration experiments, the ultraviolet-visible absorbance spectra of 140 solutions with various BSA and AA concentrations were used to calibrate a partial least square (PLS) model for estimating BSA concentration. This model, which had a validation error of less than 0.7mg BSA/l, was used in the filtration experiments to estimate the concentration of BSA in the feed and permeate solutions, as well as in a solution containing the BSA fouling removed by simple water rinsing. These measurements, together with a mass balance of the different fractions of the filtration process, were used to estimate the reversible and irreversible fouling. Direct analysis of the fouled membrane was done by photoacoustic spectroscopy (FTIR-PAS), and a PLS model was used to estimate the amount of BSA present on the membrane. The fouling estimated from the FTIR-PAS spectra by PLS correlated well with the estimates from the mass balance approach, with typical errors of less than 10% of the range investigated. [Copyright &y& Elsevier]

Abstract: In this study, the surface charged and structural information of sulfonated polyethersulfone nanofiltration membrane are acquired through the analysis on the relevant electrochemical impedance spectroscopies (EIS) expressed in terms of dispersions of the impedance with frequency (1KHz–1MHz). The measurements are performed in the different electrolyte solutions (NaCl, MgCl2, LaCl3, KCl, K2SO4, and K3PO4) with different concentrations ranging from 1×10−4 mol/L to 6×10−3 mol/L. After that, the corresponding equivalent circuit as a theoretical model is set up. Experimental results indicate that the resistance of active layer is influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. For different cations and anions，the corresponding resistances of the active layer take on a sequence of SO4 2− >Cl− >PO4 3- and Na+ >La3+ >Mg2+，respectively, which is in well agreement with the variation trend of ion retention, especially for monovalent and divalent ions. Furthermore, the thickness of the active layer in the working state is estimated from the capacitance values and compared with the result obtained by SEM. On the basis of the above, it is reasonable to think that EIS can be used for online analysis in membrane process. [Copyright &y& Elsevier]

Abstract: Microfiltration was used to clarify pomegranate juice using two polyvinylidene fluoride membranes with pore sizes of 0.22 and 0.45μm. Changes were studied in the chemical properties of the juice after passing through each membrane. Characteristics such as turbidity changed for both membranes (more than 95%). The permeate flux decreased over time as a result of membrane fouling. The degree of decline in the membrane with pore size of 0.22μm was greater than another one. In both membranes, fouling resistance increased over time from 5×109 m2/kg to 4.43×1010 m2/kg for 0.22μm and to 1.29×1010 m2/kg for 0.45μm after 45min. This increase had a sharp slope in the first stages of the testing. Fouling index changes over time showed similar behavior. Scanning electron microscopy images showed that the cake layer had the greatest impact on membrane fouling after processing by preventing turbid components from entering pores. [ABSTRACT FROM AUTHOR]

Abstract: Treatment of olive mill wastewaters (OMW) by membrane techniques were investigated in this study. For this purpose, OMW was centrifuged, and filtered via UC010 ultrafiltration membrane followed by filtration through NP010, NP030, and NF270 nanofiltration membranes, and XLE and BW30 reverse osmosis membranes. Besides, skipping the ultrafiltration step, the centrifuged OMW was filtered through NP010 and NP030 membranes in order to evaluate the performance of the centrifuging process as a pretreatment option. For the OMW percolated through ultrafiltration membranes, the membrane fluxes reached values of up to 21.2, 5.2, 28.3, 15.5, and 12.6Lm− 2 h− 1 for NP010, NP030, NF270, XLE, and BW30 membranes, respectively. The maximum COD removal efficiencies obtained at 10bars were 60.1%, 59.4% and 79.2% for NP010, NP030, and NF270 nanofiltration membranes, respectively, while they were 96.3% and 96.2% for XLE and BW30 reverse osmosis membranes, respectively. Besides, conductivity removal efficiencies obtained at 25bars were 93.2% and 94.8% for XLE and BW30 membranes, respectively. Obtained efficiencies are higher than those obtained in the treatment of OMWs with other treatment methods. Thus, it was concluded that membrane processes are a good alternative for the treatment of OMWs. Additionally, the centrifuging process was found to be a promising pretreatment method. [Copyright &y& Elsevier]

Abstract: The retention of Cu(II)– and Ni(II)–nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA) complexes in dilute solutions ([M-chelate]=0.5mM) by ultrafiltration in presence of polyethylenimine (PEI) or chitosan 10mM was studied. Metal retentions larger than 98% were observed for PEI in the pH-range of 4–9. The excellent metal retention resulted from the combination of covalent binding and electrostatic interactions. The metal retention was studied at pH 7 as a function of the Cu-chelate/PEI ratio and has shown that the more encapsulating the chelate was, the lower was the retention. Electrolysis at pH 2 was used to precipitate Cu ions and to regenerate PEI with electrolytic yields in the range of 40–50% depending on the mixture composition. [Copyright &y& Elsevier]

Abstract: Polyethersulfone (PES) membranes with nano-porous surface were fabricated by addition of potassium perchlorate (KClO4) as an additive in the casting solution. The membranes were prepared from PES/polyvinylpyrrolidone (PVP)/KClO4/dimethylacetamide (DMAc) via phase inversion induced by immersion precipitation technique. Mixture of water and isopropyl alcohol (IPA) was used as coagulation medium. The viscosity of PES casting solution increased with addition of KClO4. The contact angle measurements demonstrated that the hydrophilicities of membrane enhanced by increasing the KClO4 concentration in the casting solution. According to SEM analysis, it was found that the addition of KClO4 had a significant influence on structure of the membrane skin layer and the sub-layer. Membranes with dense surface and sub-layer were formed at this condition. The surface AFM images indicated that the addition of KClO4 in the casting solution resulted in nano-structure membranes with surface small pore size. The effect of KClO4 on the membrane performance was investigated using cross-flow filtration of pure water and non-skim milk as feeds. The pure water flux through the prepared membranes declined by adding 1, 3 and 5wt.% of KClO4 in the casting solution. On the other hand, milk water permeation and protein rejection of prepared membranes were improved. [Copyright &y& Elsevier]

Abstract: Three macrofiltration processes were evaluated as a first stage of tertiary treatment of municipal wastewater. The processes studied were pressure sand filter (PSF), disc filter (DF) and mesh filter (MF). The performance of each process was assessed by analysing the effluent for suspended solids, turbidity, E. coli, nematode eggs and particle distribution analysis. In all processes, the quality of the effluent with respect to suspended solids and turbidity was found to be dependent on the influent, with the PSF achieving the best results. The effluent particle analysis likewise indicated a superior retention capacity by PSF, while the DF and MF presented an increase in small particles. All effluent contained E. coli and pathogenic nematode eggs were not detected. However, other types of nematode eggs were observed, so the presence of this pathogen in effluents cannot be discarded. Costs analysis reveal than DF and MF present a higher cost than PSF, owing to the high power consumption. These technologies may be applied as pre-treatment of tertiary disinfection process, pointing up the PSF as the most effective process, allowing direct water reuse for uses with lower quality demands. [Copyright &y& Elsevier]

Abstract: The results shown in this paper are part of a study to investigate the use of nanofiltration membranes for the recycling of phosphorus from sewage sludge. It especially contains the results of an experimental study about the influencing factors pressure, pH and feed composition on the selectivity of nanofiltration membranes for phosphoric acid and multivalent cations. For the use of pretreated sewage sludge an effective pressure of 11bar could be identified as an effective operational point. The selectivity turned out to increase with decreasing pH which was studied in a pH-interval of pH 1–4. An increasing concentration of multivalent cations in the feed solution had a negative effect on the permeability of phosphoric acid. Accordingly it could be observed that the nanofiltration worked significantly more effective with sewage sludge ash eluates of the concentration 10g/l than eluates of the concentration 100g/l. [Copyright &y& Elsevier]

Abstract: Sand filters systems are widely used around the world for on-site and small communities wastewater treatment. Their treatment efficiency depends on several parameters like the media used, temperature, wastewater characteristics, hydraulic and organic loads. One of the most important design parameter in relation to treatment efficiency and sustainability (clogging phenomena) is the sand characteristics and its implementation. To precise the impact of sand implementation on hydraulic and biological behaviors, a study has been done in laboratory columns (surface 0.1m2) in relation to physical and mechanical characteristics of the sand. Two sands (d10 0.42 and 0.8 mm) as well as two implementations (natural compaction and 100% proctor compaction) have been studied during 8 months fed with synthetic wastewater. The weight of the columns was followed continuously and it allowed the following of different parameters (media humidity, infiltration rate, drainage flow). Other parameters linked to biological activity (treatment efficiency (BOD5, COD, SS, nitrogen forms, etc.), oxygen content of the porous gas phase) were followed on a daily basis. The results give information on the importance of media implementation on treatment efficiency and gas and water transfers within the sand filter. Physical parameters, like particle size distribution, are not the only ones to be determinant on biological and hydraulic behaviors of sand filters. If sand compaction can be detrimental in terms of clogging for fine sands, it can be beneficial for coarser sands. This has to be known to avoid bad design and clogging risks. [Copyright &y& Elsevier]

Abstract: This study was conducted to (1) determine appropriate conditions for nitrogen removal by a combined constructed wetland (CW) system and (2) evaluate the effects of hydraulic loading rate (HLR), nitrogen loading rate (NLR), effluent recirculation, plant uptake, and seasonal change on the removal efficiency of nitrogen. A three-stage experimental CW system consisting of a vertical flow-gravel filtration (v-GF) bed without plants, a horizontal-subsurface flow (h-SSF) bed planted with Iris australis, and a vertical-subsurface flow (v-SSF) bed planted with Phragmites australis in series were fed with primary-treated domestic wastewaters. The beds with plants produced effluents of better quality than the v-GF bed without plants. It was observed that the average removal efficiencies increased as the HLR (from 100 to 30 L/m2 d) decreased and the recycle ratios (to 100%) increased. The average removal efficiencies in the summer period were found higher of approximately 6% for the v-GF and h-SSF beds and 11% for v-SSF bed. Nitrogen removal by plant uptake was very low and only 3% (Iris) to 7%(Phragmites) of the N-input compared to other mechanisms such as nitrification and denitrification. The volume-base first-order nitrification and denitrification removal constants (1/d) were 0.388 and 0.785 for the h-SSF bed, and 0.412 and 0.293 for the v-SSF bed, respectively. [Copyright &y& Elsevier]

Abstract: The removal of faecal coliforms (FC), Escherichia coli, somatic coliphages and F-specific bacteriophages was monitored over a period of 2 years in two vertical flow constructed wetlands (VFCWs) and four intermittent sand filters (ISFs) that treat pond effluent. Tracer tests (NaCl) were performed to estimate the hydraulic retention time (HRT) of the filters. The contribution of Phragmites australis to the removal of the faecal indicators was examined. The effect of media characteristics (depth, type of sand), hydraulic load and water application schedule on disinfection was also addressed. Planted and non-planted vertical sand filters were equally effective in removing microorganisms. The disinfection capacity was very sensitive to the depth and operation of the filters. HRT was the key parameter regarding filter disinfection capacity. Bacterial indicators were removed at a higher rate than viral ones. Somatic coliphages were removed at higher rates than F-specific bacteriophages. [Copyright &y& Elsevier]

Abstract: Two parallel pilot-scale biological filters which used manganese sand and silica sand as media respectively were tested for the removal of iron and manganese from drilled well water in Harbin. Iron and manganese oxidizing bacteria were isolated and used as inoculums for filter start-up. Manganese sand filter and silica sand filter can remove 3–6 mg/L of ferrous iron 0.9 mg/L and 0.6 mg/L of manganese respectively under the operation conditions of DO (5 mg/L), pH 7.2, and flow rate 3.9 m/h. The kinetics analysis indicated that the iron removal versus flow rate followed the first-order reaction. This kinetics model also demonstrated that a manganese sand filter had higher removal efficiency than a silica sand filter. Gallionella sp. was found in the backwashing water after 6 months of operation. [Copyright &y& Elsevier]

Abstract: This study describes the treatment of textile wastewater by various combinations of physicochemical and membrane processes. The basic physicochemical treatment consists in coagulation/flocculation (CF) with different coagulant and flocculant concentrations. The parameters analyzed prior and after treatment are turbidity, chemical oxygen demand (COD) and absorbance (Abs). The optimal process parameters for CF are 5 for pH, 100 mg/l for coagulant (Al2(SO4) 3) of 100 mg/l and 4 mg/l for flocculant. This simple treatment by CF was inefficient concerning COD reduction and dyes deterioration. It was therefore combined with microfiltration (MF) or ultrafiltration (UF) on one hand and adsorption on powdered activated carbon (PAC) on the other. The CF/MF, CF/UF and CF/PAC combinations ensure a COD removal of 37%, 42% and more than 80% respectively and a color reduction of 65%, 74% and 50% respectively. [Copyright &y& Elsevier]

Abstract: The objectives of this study were the investigation of the performance of an advanced treatment system, for the reclamation of secondary municipal effluents, and the study of the environmental quality of treated effluents. The secondary effluents from a conventional activated sludge process were fed to an advanced wastewater treatment system, consisting of a moving-bed sand filter, a granular activated carbon adsorption bed and ozone disinfection. The performance of this plant was evaluated by measuring the physicochemical, microbiological and ecotoxicological characteristics of reclaimed water. Sand filtration resulted in about 45% turbidity removal, while carbon adsorption enhanced mainly the removal of organic content, i.e. the total organic carbon removal exceeded 80%. The quality of treated effluents, obtained after ozonation by an ozone dosage of 26.7 mg/L, was found to comply with the respective US EPA proposed guidelines for urban reuse, food crop irrigation and recreational impoundments. However, a high ozone dose caused adverse effects on bacterium V. fischeri, possibly due to the formation of secondary oxidation byproducts. The annual cost of overall tertiary treatment process was evaluated to 0.24 €/m3, indicating the relatively high cost of these processes. Nevertheless, such processes are required in order to produce an effluent, with a high reuse potential. [Copyright &y& Elsevier]

Abstract: The objectives of this research were to evaluate two different processes using for wastewater reclamation in a hightech industrial park area in Taiwan. The major units of the first AC-RO-IE system included sand filter, an activated carbon (AC) bed, microfiltration module, a reverse osmosis (RO) membrane and ionic-exchange (IE) columns. The second DAF-AC-RO system was comprised of coagulation/flocculation, dissolved air flotation (DAF), an activated carbon bed, microfiltration module and reverse osmosis membrane units. This study was carried out at a pilot-scale plant in situ that operated for approximately 1 year. According to the long-term experimental results, both the AC-RO-IE and the DAF-AC-RO processes illustrated excellent performances on inorganic and organic contaminant removal. Comparing the removal efficiency of the filtration-AC units in the AC-RO-IE system with the coagulation-DAF-AC units in the DAF-AC-RO system, the removal efficiency of TDS, SiO2 and COD increased by 19.8%, 70.1% and 44.4% in the latter system, respectively. In addition, the combination of PAC-coagulation and DAF units could improve hardness removal, modify the form of dissolved silica, and reduce the SDI and MFI values. It showed good potential as a pretreatment unit in wastewater reclamation processes. Therefore, based on the reclaimed wastewater quality and process operational stability, the DAF-AC-RO system was suggested as a potential process for further application. [Copyright &y& Elsevier]

The management of residual sludge is an important subject. New environmental laws require the elimination of this waste by only two ways: incineration and agricultural use. In order to reach this goal, mechanical dewatering can be used as a first step due to its low energy cost. However, the final moisture content reached through this method is not generally sufficient and drying becomes obligatory. In this work we studied the first step: mechanical dewatering. Some experiments were carried out on a laboratory filtration-compression cell and the use of the Ruth relationship approach was tested in order to characterise slurry in filtration. We also studied the second step: thermal dewatering. From laboratory convective drying experiments, a macroscopic approach in terms of kinetics curve and drying potential was developed. This criterion, which groups a set of external conditions into a unique parameter (temperature, relative humidity, air velocity), allows for easy classification of different operating strategies. [Copyright &y& Elsevier]

Analyzes the fouling characteristics of wastewater effluent organic matter isolates from nanofiltration and ultrafiltration membranes. Size exclusion chromatography; Fourier transform infrared spectroscopy; Total sugars analysis.

Studies the effect of temperature on the retention of model substance and substances in industrial streams in nanofiltration. Pure water permeability; Pretreatment of nanofiltration membranes.