Search

The technical–economic analysis of the hemodialysis water purification process, which uses reverse osmosis with sand, softeners, and granular-activated carbon as pretreatment steps, shows that the permeate conductivity exceeds 25 µS cm−1 at 25°C due to softeners failure and that the cost of cubic meter of water produced is 2.4 €. The purification unit generated brine with a conductivity above 5 mS.cm−1 and it is discharged into the sewer. Several brine valorizations are proposed; brine recycling and simulation with IMS design software reveal that it is possible to recycle 0.2 m3.h−1 of brine and achieve 83% conversion rate with a good quality of permeate. The residual of the first reverse osmosis brine is diluted by the second reverse osmosis permeate and is to be used for toilet flushing, landscape irrigation, and sterilization steam production. [ABSTRACT FROM AUTHOR]

In response to the escalating world water demand and aiming to promote equal opportunities, reverse osmosis desalination has been widely implemented. Desalination is however constantly subjected to fouling and scaling which increase the cost of desalination by increasing the differential pressure of the membrane and reducing the permeate flux. A bench-scale desalination equipment has been used in this research to investigate the mitigation of fouling and scaling. This study involved the performance of membrane autopsy for fouling characterisation with special attention to flux decline due to sulphate precipitation and biofouling. Visual inspection, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and microbiology tests (API) were performed. Results obtained showed the presence of diatoms, pseudomonas and polysaccharides as the main foulants causing biofouling. Analysis revealed sulphate deposits as well as aluminium, calcium and silica as the main elements contributing to inorganic scaling. Findings pointed out that the pre-treatment system of the small-scale reverse osmosis water treatment was inefficient and that selection of pre-treatment chemicals should be based on its compatibility with the membrane structure. The importance of characterisation for the verification of fouling mechanisms is emphasised. [ABSTRACT FROM AUTHOR]

Upgrading existing wastewater treatment plants (WWTPs) is a more challenging task than constructing new plants. The aim is usually to overcome overloading and to reduce pollution concentrations in the effluent. There are various methods that can be used to upgrade WWTPs. This article reviews some of the methodologies, such as inserting new tanks as additional treatment steps and modifying the WWTP by introducing new technologies. A number of effective technologies are reviewed in terms of their basic concepts, operational conditions, and treatment performances. Examples of WWTPs in China that have been successfully upgraded using these technologies are also highlighted. [ABSTRACT FROM AUTHOR]

In this study, a biological denitrifying process using a sequencing batch reactor (SBR) was employed to treat reverse osmosis (RO) concentrate with high conductivity produced from a coking wastewater plant. From the results, the average removal efficiencies for chemical oxygen demand, total nitrogen, and nitrate were 79.5%, 90.5%, and 93.1%, respectively. Different microbial communities were identified after sequencing the V1-V3 region of the 16S rRNA gene using the MiSeq platform, and the major bacterial phyla in the SBR system were Proteobacteria and Bacteroidetes. The main microorganisms responsible for denitrification were from the genera Hyphomicrobium, Thauera, Methyloversatilis, and Rhodobacter. Quantitative real-time PCR was used to quantify the absolute levels of denitrifying genes, including narG, nirS, nirK, and nosZ, during the start-up and stable operation of the SBR. The abundances of narG, nirK, and nosZ were lower during stable operation than those in the start-up period. The abundance of nirS at a concentration of 104-105 copies/ng in DNA was much higher than that of nirK, making it the dominant functional gene responsible for nitrite reduction. The higher nitrate removal efficiency suggests that biological denitrification using SBR is an effective technique for treating RO concentrate produced from coking wastewater plants. [ABSTRACT FROM AUTHOR]

In this paper, one nanoporous graphene grafting several zwitterionic polymer chains was designed as the osmosis membrane for seawater desalination. Using molecular dynamics simulation, the efficiency and mechanism of salt rejection were discussed. The simulated results showed that the zwitterionic polymer chains on nanoporous graphene can form the charge channel to block Na+ and Cl- ions pass through, and the slat rejection efficiency of functionalised graphene can reach to about 90%. In the simulation, the steric hindrance and electrostatic interaction are the main factors for the salt rejection. With time evolution, the charge channel formed by the soft polymer chains can decrease the effective pore area of membrane, leading to the increase of steric hindrance; the positive and negative centres of polymer chains can adsorb Na+ and Cl- ions under electrostatic interaction in the solution, contributing into the increase of charge density above the membrane. These conclusions are consistent with experimental report. Our designed osmosis membrane about the graphene is helpful for improving the potential application of defect graphene in water desalination and reducing the trouble of obtaining appropriate graphene sheet with small aperture. [ABSTRACT FROM AUTHOR]

Brine disposal from reverse osmosis (RO) systems remains a major challenge for the desalination industry especially in inland areas where discharge options are very limited. Solutions will entail the introduction of economic treatment processes that will alleviate the brine's negative impact on the environment and reduce its discharge volume. Such processes could act as an intermediary treatment process for the recycling of the brine through an additional RO stage which, for brackish water (BW) desalination, could lead to saving valuable water while reducing the amount of brine discharge. In this context, the study at hand attempts to evaluate the effectiveness of a one-step chemical process for the treatment of BWRO brine. This study seeks to determine optimal operating conditions relative to type, ratio, and dosage of alkalizing chemicals, pH and temperature, for substantially reducing the concentrations of scaling parameters such as calcium, magnesium, silica, and strontium. The results indicate that precipitation softening at pH = 11.5 using combined chemical dosages of NaOH and Na2CO3 in a ratio of 2:1 leads to substantial removal of calcium and magnesium (>95%) and moderately high removal of strontium and silica (>71%). [ABSTRACT FROM AUTHOR]

A pilot-scale reverse osmosis (RO) followed behind a membrane bioreactor (MBR) was developed for the desalination to reuse wastewater in a PVC production site. The solution–diffusion–film model (SDFM) based on the solution–diffusion model (SDM) and the film theory was proposed to describe rejections of electrolyte mixtures in the MBR effluent which consists of dominant ions (Na+and Cl−) and several trace ions (Ca2+, Mg2+, K+and SO42−). The universal global optimisation method was used to estimate the ion permeability coefficients (B) and mass transfer coefficients (K) in SDFM. Then, the membrane performance was evaluated based on the estimated parameters which demonstrated that the theoretical simulations were in line with the experimental results for the dominant ions. Moreover, an energy analysis model with the consideration of limitation imposed by the thermodynamic restriction was proposed to analyse the specific energy consumption of the pilot-scale RO system in various scenarios. [ABSTRACT FROM PUBLISHER]

A monolithic copolymer hydrogel was synthesised by polymerising n-isopropylacrylamide and sodium acrylate in the presence of poly(sodium 4-styrenesulfonate) (PSSS) chains and studied as potential draw agent for forward osmosis (FO) process. The monolithic hydrogel synthesised from 19% NIPAM, 1% SA, and 15% PSSS at 60°C generated higher FO water flux and higher recovery rate than other hydrogels, due to improved membrane-hydrogel contact and water transport. In particular, the synthesised hydrogel draw agent achieved twice water flux compared with the particles. The monolithic hydrogel containing a smaller amount of water produced a higher water flux due to its high swelling pressure. [ABSTRACT FROM AUTHOR]

The membrane-based grey water treatment for grey water reuse and surfactant recovery is presented in this research paper. Grey water from washing machine discharges having turbidity and used surfactant was processed through the polymeric ultrafiltration (UF) membrane to remove the turbidity. The UF treated grey water is further purified by reverse osmosis (RO) membrane for surfactant recovery and water reuse. The surfactant trapped inside the RO spiral wound membrane module is recovered through various membrane physical regeneration techniques such as backwashing, simultaneous backwash–back-flush and ozone back-flush. Among this, backwash–back-flush is found to be effective process for surfactant recovery. The methodology for optimising surfactant recovery is captured by studying effect of various operating parameters such as feed detergent concentration, backwash pressure, backwash temperature and back-flush flow rate. By implementing optimal process conditions, the integrated UF and RO membrane process is able to produce 300 L of reusable pure water and 80 L of concentrated detergent solution and 20 L of turbid water while treating 400 L of grey water discharges. Maximum surfactant recovery of 82% is obtained while treating grey water which consists of 720 ppm of total dissolved solids (detergent) and 45 ppm of surfactant. The extent of UF and RO membrane fouling is determined by measuring the pure water flux before and after the grey water treatment. The membrane performance is found to be stable when membrane is regenerated by backwash–back-flush technique for RO and gravity backwash for UF membrane. [ABSTRACT FROM PUBLISHER]

This study aims to evaluate the effects of oilfield water (OW), treated by a hybrid process of electrocoagulation and reverse osmosis (EC–RO), on seed germination and early growth characteristics of sunflower (Heliantus annusL.). In the EC step, tests were conducted with 28.6 A m−2current density and 4 min. reaction time. In the RO step, the system was operated with 1 L min−1constant flow and 2 MPa, 2.5 MPa and 3 MPa feed pressures. In all feed pressures, RO polymeric membranes achieved very high removals of chemical oxygen demand (up to 89%) and oils and greases (100%) from EC-treated effluent. In best feed pressure (2.5 MPa), turbidity, total dissolved salts, electrical conductivity, salinity, toxic ions and sodium adsorption ratio values attained internationally recognized standards for irrigation water. Using EC–RO (feed pressure:2.5 MPa) treated OW, germinated sunflower seeds percentage (86 ± 6%), speed of germination (30 ± 2) and biomass production (49 ± 5 mg) were statistically similar to control (distilled water) results. Vigor index average values obtained using OW treated by EC–RO (3871)were higher than that obtained by OW water treated by EC (3300). The results of this study indicate that EC–RO seems to be a promising alternative for treatment of OW aiming sunflower crops irrigation, since the use of this treated effluent did not affect adversely seed germination and seedling development, and improved seedling vigor. Furthermore, OW treatment by EC–RO reduces sodium levels into acceptable standards values avoiding soil degradation. [ABSTRACT FROM PUBLISHER]

Several industrial processes, such as desalination or neutralization, generate brines defined as concentrated solutions of salts in water, usually NaCl, typically discharged in the vicinities of the desalination plant or factory. To reduce the environmental impact and promote the valorization of the wasted resources, alternatives must be sought. Among sustainable alternatives for the recovery of brines, the possibility of using Electrodialysis with Bipolar Membranes (EDBM) is of interest, because it allows recovering brines as useful acids and bases. This review focuses on the discussion of the technical aspects of the EDBM as a means to treat streams rich in NaCl from reverse osmosis desalination and industrial processes in order to complete the direct delivery of chemicals for self-supply. The main environmental issues associated with desalination brine disposal are presented. The state-of-the-art of valorization of brines by EDBM to acids and bases is completed. This work concludes with an in-depth discussion of the technical, techno-economic and economic barriers that prevent the widespread use of EDBM technology. [ABSTRACT FROM AUTHOR]

Techno-economic feasibility of water recovery from secondary effluents of an urban wastewater treatment plant (WWTP) for landscape irrigation was investigated considering two distinctive strategies: ultrafiltration (UF)/chlorination and UF/reverse osmosis (RO). Experimental performance evaluations were conducted separately for UF membranes and for different RO trans-membrane pressures. The quality of the effluent recovered by the UF/RO system was in accordance with the national and international guidelines. The produced reuse water was first class quality according to the national guideline for all parameters except sodium adsorption ratio (SAR), which can be eliminated readily by direct addition of KCl into the recovered water. Estimated field-scale costs indicated that UF/RO yielded a total cost of US$12,500,000–13,600,000 with annual operating cost being US$482,000–533,000 at 5–20 bar. The economic estimations guaranteed reimbursement with US$7,600,000–7,400,000 net present value, 0.22–0.39 year payback time, US$0.44–0.49/m3treatment cost, and a benefit/cost ratio of 0.57. [ABSTRACT FROM AUTHOR]

The potential of the carbon nanotube (CNT) membrane has been highly strengthened in water treatment during the last decade. According to works published up to now, the unique and excellent characteristics of CNT outperformed conventional polymer membranes. Such achievements of CNT membranes are greatly dependent on their fabrication methods. Further, the intrinsic properties of CNT could be a critical factor of applicability to membrane processes. This article provides an explicit and systematic review of the progress of CNT membranes addressing the current epidemic—whether (i) the CNT membranes could tackle current challenges in the pressure- or thermally driven membrane processes and (ii) CNT hybrid nanocomposite as a new generation of materials could complement current CNT-enhanced membrane. [ABSTRACT FROM AUTHOR]

Desalination technology, and reverse osmosis in particular, is used by several island authorities in Greece to address water scarcity. However, this is a highly energy-intensive technique, requiring the consumption of significant quantities of fossil fuels. The case of Syros Island is presented, to demonstrate the strong water–energy link in the operation of desalination plants. The article also discusses the use of renewable energy sources as a means for reducing the energy intensity of desalination. [ABSTRACT FROM AUTHOR]

Membrane technology is the dominant process in water treatment. However, the operation cost of membranes cannot be decreased unless the amount of fouling, the “Achilles heel” of membranes, and energy consumed are cut. The high energy requirements in commercial nanofiltration, reverse osmosis and forward osmosis technologies lead researchers to develop new membrane designs having high flux values with high salt rejection values. The purpose of this review is to present the inadequacies of the membrane processes by considering studies related to fouling and energy minimization. In this respect, lipid bilayers, block copolymers, aquaporin Z proteins and aligned carbon nanotubes can be the base to build biomimetic membranes. Such studies are summarized due to their remarkable properties in fouling control. Furthermore, the review describes the membrane design strategies and points the limitations hindering commercialization. Additionally, it is hoped that this review will trigger further needed studies. [ABSTRACT FROM PUBLISHER]

Arsenic (As) contamination of groundwater reservoirs is a global environmental and health issue given to its toxic and carcinogenic nature. Over 170 million people have been affected by As due to the ingestion of As-contaminated groundwater. Conventional methods such as reverse osmosis, ion exchange, and electrodialysis are commonly used for the remediation of As-contaminated water; however, the high cost and sludge production put limitations on their application to remove As from water. This review critically addresses the use of various agricultural waste materials (e.g., sugarcane bagasse, peels of various fruits, wheat straw) as biosorbents, thereby offering an eco-friendly and low-cost solution for the removal of As from contaminated water supplies. The effect of solution chemistry such as solution pH, cations, anions, organic ligands, and various other factors (e.g., temperature, contact time, sorbent dose) on As biosorption, and safe disposal methods for As-loaded biosorbents to reduce secondary As contamination are also discussed. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are relatively well-known organic pollutants and due to their carcinogenic and mutagenic properties their presence in the environment still attracts a lot of attention. According to literature reports and own research, PAHs presence in wastewaters is common. It was confirmed that PAHs are the components of municipal landfill leachate. Membrane techniques are one of the most interesting ways of removing PAHs from leachate. The purpose of this article is to monitor PAHs concentration changes during the membrane (reverse osmosis - RO) leachate treatment processes. In the first stage of testing leachates were filtrated on the sand bed (pre-filtration). After the pre-filtration they were directed to the membrane module for the main filtration. Sixteen PAHs listed by EPA were analyzed. The results with information on PAHs concentration in leachate samples were presented using HPLC with fluorescence detection (FLD). The changes in PAHs concentration were determined in leachate samples before and after pre-filtration as well as after RO. The decrease of PAHs concentration in the samples was observed after these processes. The total concentration of 16 PAHs in raw municipal landfill leachates amounted to 23.64–26.95 μg/L. The research confirmed the high efficiency in removal of PAHs while using a reverse osmosis (59–72%). Including the pre-filtration, the overall level of removed PAHs reached 81–86%. The average PAHs concentration after pre-filtration and RO was in the 4.46–4.99 μg/L range. The municipal landfill leachate with a high concentration of PAHs should be cleaned before it is discharged into the environment. [ABSTRACT FROM PUBLISHER]

A combined three-stage system, (1) coagulation (2) zeocarbon filtration and (3) membrane filtration, a combination of microfiltration (MF) and reverse osmosis (RO), was investigated for reclamation of tunnel construction wastewater having a salinity of 10.8–12.9‰ and a concentration of suspended solids (SS) in the range of 264–1084 mg/L. The initial stages – coagulation, zeocarbon filtration and MF – served as a precursor to RO membrane filtration to successfully reduce water contaminants to less than 0.2 nephelometric turbidity units (NTU) of turbidity, thereby minimizing the potential for fouling. The RO system subsequently removed over 99% of remaining pollutants including ionic substances, resulting in less than 0.02 NTU turbidity, less than 0.04 mg/L total nitrogen (TN) and less than 0.01 mg/L total phosphorus (TP). Also, addition of an RO system markedly reduced high salt concentrations (high chloride (Cl−) concentrations) in the wastewater, exceeding 99% salt elimination. Thus, reclaimed water from our combined system met and exceeded currently regulatory quality standards for wastewater reuse (turbidity ≤ 2.0 NTU; TN ≤ 10 mg/L; TP ≤ 0.5 mg/L; Cl− ≤ 250 mg/L). [ABSTRACT FROM PUBLISHER]

Two antibacterials, amoxicillin trihydrate and cefuroxime axetil spiked into wastewater were completely removed by sequential wastewater treatment plant's membranes, which included activated sludge, ultrafiltration (hollow fibre and spiral wound membranes with 100 and 20 kDa cut-offs), activated carbon column and reverse osmosis. Adsorption isotherms in synthetic water which employed activated carbon and micelle–clay complex (octadecyltrimethylammonium–montmorillonite) as adsorbents fitted the Langmuir equation.Qmaxof 100 and 90.9 mg g–1, andKvalues of 0.158 and 0.229 L mg–1were obtained for amoxicillin trihydrate using activated carbon and micelle–clay complex, respectively. Filtration of antibacterials in the ppm range, which yielded variable degrees of removal depending on the volumes passed and flow rates, was simulated and capacities for the ppb range were estimated. Stability study in pure water and wastewater revealed that amoxicillin was totally stable for one month when kept at 37°C, whereas cefuroxime axetil underwent slow hydrolysis to cefuroxime. [ABSTRACT FROM PUBLISHER]

This work focused on wastewater reclamation of secondary treated ethylene chemical plant effluent, which contained high conductivity and high organic concentration. To reduce the cost and improve operation stability, a biological aerated filter-ultrafiltration-reverse osmosis (BAF-UF-RO) process was proposed. The feasibility and effectiveness of BAF loaded with a novel non-sintered fly-ash ceramsite (NSFC) as a pretreatment method of a dual membrane system were investigated in detail. The results showed that the CODCr, turbidity, NH3-N and the silt density index (SDI) in the effluent from the BAF were reduced to 24.2 mg/L, 12.17 NTU, 0.42 mg/L and 7.52, respectively, and most of the organic compounds were biodegraded. The BAF-UF-RO process was stable with a recovery rate of 75%, and the desalination rate was up to about 97.5%. Compared with the UF-RO process, the operating pressure and backwash frequency decreased from 1.12–1.26 Mpa and 3 times/d to 0.94–0.98 Mpa and 2 times/d, respectively. After continuous operation for four months, there appeared to be no need for chemical cleaning of the RO membrane. Moreover, the analysis results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy proved that there was only slight membrane fouling, which was mainly colloidal blocking caused by refractory organic compound. [ABSTRACT FROM PUBLISHER]

Desalination of brackish groundwater has emerged as a major option to overcome water scarcity, since quantity and quality of surface water is not appropriate for the continuously growing water demand of two-thirds of the world’s population. Photovoltaic (PV) solar energy powered reverse osmosis (RO) system can be the best option in secluded and isolated areas of the world that are suffering from a shortage of electricity energy and drinking water. This technique is likely to be the lowest energy demanding technology among other desalination techniques. Further, adopting measures like energy recovery devices, hybrid pretreatment process, and battery-less system reduces overall cost of the system. But, the capital cost of the system is still too high to support this technology competitively in the market. In the present paper, a review of the PV-RO systems employed for drinking water treatment in non-electrified rural areas of developing countries has been provided. The status of development in the last few years, along with the attempts towards finding rational solutions for cost reduction are also summarized. [ABSTRACT FROM AUTHOR]

In this study, we discuss the preparations of cellulosic membranes from cellulose acetate (CA), cellulose triacetate (CTA) and cellulose acetate blend (CAB) [blending of CA and CTA] systems and their potential for concentration of simulated ammonium-diuranate (ADU) effluent solution (only uranium and ammonium nitrate) by FO. The membranes are prepared using casting solution of polymers in mixed solvent systems with gelling in ice-cold water followed by annealing in 80°C hot water. Prepared membranes are characterized in terms of separation performance (tested under brackish water reverse osmosis test condition), water contact angle and surface average roughness. The performance of the membranes are evaluated in terms of volume reduction factor using solution of 40,000 ppm of NH4NO3and 20 ppm uranium as feed and 320000ppm of NH4NO3as draw solution. It is found that the volume reduction factor increases in the order of CTA

Greater use of reverse osmosis (RO)-based processes in municipal wastewater reclamation presents the water industry with a major challenge regarding the sustainable management of the resultant RO concentrate (ROC) generated. This has promoted interest in investigating different approaches for the cost-effective treatment of ROC to reduce the risks associated with its disposal or reuse. This review highlights and discusses research on the treatment of ROC generated mainly from domestic wastewater. Methods employed for the treatment of municipal ROC are predominantly physicochemical processes, although biological processes with varying degrees of success in terms of the removal of organic content have also been reported. Relatively little attention has been paid to the quantification and removal of micropollutants. Due to the recalcitrant nature of some of the organics in ROC, advanced oxidation processes (AOPs) have been demonstrated to be the most effective for breaking down various pollutants and improving the biodegradability of the ROC. UV/H2O2, electrochemical oxidation, and ozonation are among the most studied AOPs for the treatment of ROC, and some have investigated posttreatment changes such as effect on molecular weight distribution and biodegradability improvement. Although these treatments appear to be promising, high energy consumption and the formation of harmful by-products during oxidative treatments are challenges that are yet to be fully addressed. Most studies have been conducted at laboratory scale and therefore large-scale investigation should be carried out to validate the effectiveness of these technologies. [ABSTRACT FROM AUTHOR]

The diversity of the bacterial community developed in different stages of two reverse osmosis (RO) water reclamation demonstration plants designed in a wastewater treatment plant (WWTP) in Tarragona (Spain) was characterized by applying 454-pyrosequencing of the 16S rRNA gene. The plants were fed by secondary treated effluent to a conventional pretreatment train prior to the two-pass RO system. Plants differed in the material used in the filtration process, which was sand in one demonstration plant and Scandinavian schists in the second plant. The results showed the presence of a highly diverse and complex community in the biofilms, mainly composed of members of the Betaproteobacteria and Bacteroidetes in all stages, with the presence of some typical wastewater bacteria, suggesting a feed water origin. Community similarities analyses revealed that samples clustered according to filter type, highlighting the critical influence of the biological supporting medium in biofilm community structure. [ABSTRACT FROM AUTHOR]

Neural network modeling and the back-propagation concept were utilized to develop data-driven models for predicting reverse osmosis (RO) plant performance and finding control strategies. Considering different commissioning times, the process of three RO plants was successfully modeled using an artificial neural network (ANN). Moreover, long-term forecasting of performance degradation was developed. Time (h), transmembrane pressure (TMP; bar), conductivity (µs/cm), and flow rate (m3/h) were utilized as ANN inputs. The effects of operating time and TMP on performance at mean values of feed conductivity and flow rate were investigated using three-dimensional figures. Genetic algorithm (GA) was employed to find optimum paths of TMP, feed flow rate, and control strategies during a specific period of time. The RO plant was monitored for 5000 h corresponding to the results generated by GA (optimum paths), and experimental results were compared to the prediction made by the model. The differences strongly implied the robustness of the ANN model. [ABSTRACT FROM AUTHOR]

In this paper, a thorough investigation has been done to evaluate the effects of different pollutants on membrane performance by autopsy. Autopsy was performed on fresh and fouled reverse osmosis (RO) membrane elements from a distillery spent wash treatment plant by different analyses, such as field emission scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy and X-ray diffraction, to identify the cause of poor performance of an RO plant. Results obtained from the analysis of membranes indicate that a mixture of colloids and organic matters (polysaccharides and amines) along with the presence of multivalent ions (Ca, Mg, Fe and SO4) causes membrane fouling, which in turn affects membrane performance. Possible measures to improve treated effluent quality and mitigate fouling have been suggested for this particular case study. [ABSTRACT FROM AUTHOR]

The present study aims at evaluating a small-scale brackish water reverse osmosis (RO) process using parameter optimization. Experiments were carried out using formulated artificial groundwater, and a predictive model was developed by using response surface methodology (RSM) for the optimization of input process parameters of brackish water RO process to simultaneously maximize water recovery and salt rejection while minimizing energy demand. The result of multiple response optimization along with analysis of variance for RSM predictions showed that the optimal water recovery (19.18%), total dissolved solids rejection (89.21%) and specific energy consumption (17.60 kWh/m3) occurred at 31.94 °C feed water temperature, 0.78 MPa feed pressure, 1500 mg/L feed salt concentration and 6.53 pH. Furthermore, confirmation of RSM predictions was carried out by an artificial neural network (ANN) model trained by RSM experimental data. Predicted values by both RSM and ANN modelling methodologies were compared and found within the acceptable range. Finally, a membrane validation experiment was carried out successfully at proposed optimal conditions, which proves the accuracy of employed RSM and ANN models. Present methodology can be used as a generalized way for the optimization of different RO membranes available in the market in terms of increased water recovery and salt rejection with least energy consumption to make it commercially competent. [ABSTRACT FROM PUBLISHER]

The significant percentage of the world water consumption devoted to industrial use, along with an increasingly higher environmental concern of society, has awaken the interest of industry on using municipal reclaimed water for replacing fresh water use coming from utilities or natural resources. Depending on the type of industry and the specific application, water must meet certain quality requirements. Therefore, those water quality standards that are required for those most relevant industrial applications wherein the use of reclaimed water has noticeably been reported are herewith reviewed. Although the use of internal water treatments for recycling and reusing their own effluents has recently and widely been reported within many industrial sectors worldwide, the substitution of fresh water by reclaimed municipal wastewater has yet to be extended much. The increasing proportion of municipal wastewater reclamation plants that rely on membrane filtration technologies versus the total number of reclamation facilities that are distributed worldwide is also assessed within this review, including the discussion of their main related drawbacks. [ABSTRACT FROM AUTHOR]

Dynamic filtration permits to increase permeate flux and membrane selectivity, as compared to crossflow filtration. It consists in creating the shear rate by a disk rotating near the membrane or by rotating or vibrating the membrane, avoiding the need for large feed flow rates. The benefits of high shear rates are important in microfiltration and ultrafiltration, but they are even larger in nanofiltration (NF) and reverse osmosis (RO). The reduction in concentration polarization by high shear rate can increase the permeate flux by a ratio of 3 to 5 as compared to a spiral wound module and augments also solutes rejection as their diffusive transfer through the membrane is reduced by a factor of 4 to 5. This paper describes available dynamic filtration modules suitable for NF and RO and reviews the treatment of dairy effluents, desalination, oil emulsions, and oligosaccharides recovery using a rotating disk module or a VSEP module with vibrating membranes and compares their performances with those of crossflow filtration. These examples confirm the high potential of dynamic NF and RO when operated at high shear rate and high TMP. The availability of large rotating NF ceramic membrane disks could permit the fabrication of highly efficient modules. [ABSTRACT FROM AUTHOR]

Reverse osmosis (RO) membranes have been used extensively in water desalination plants, waste water treatment in industries, agricultural farms and drinking water production applications. The objective of this work is to impart antibacterial and antifungal activities to commercially available RO membrane used in water purification systems by incorporating biogenic silver nanoparticles(AgNPs) synthesized usingRosa indica wichurianahybrid leaf extract. The morphology and surface topography of uncoated and AgNPs-coated RO membrane were studied using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Elemental composition of the AgNPs-coated RO membrane was analyzed by energy-dispersive X-ray spectroscopy (EDAX). The functional groups were identified by Fourier Transform Infrared spectroscopy (FT-IR). Hydrophilicity of the uncoated and AgNPs-coated RO membrane was analyzed using water contact angle measurements. The thermal properties were studied by thermogravimetric analysis (TGA). The AgNPs incorporated RO membrane exhibited good antibacterial and antifungal activities against pathogenic bacterial strains such asE. coli, S. aureus, M. luteus, K. pneumoniae,andP. aeruginosaand fungal strains such asCandida tropicalis, C. krusei, C. glabrata, and C. albicans. [ABSTRACT FROM AUTHOR]

The development of cleaning strategies for RO membranes processing highly charged wastewaters requires knowledge about foulant composition. The objective of this study was to characterize the fouling layer that formed on RO membranes processing swine wastewater pretreated by a mechanical solid-liquid separator (LF) and aerobic biofiltration (AE). The two LF effluents represented swine wastewater concentrated three (LF1) and four (LF2) times with BW30 (36 bar) and SW30 (60 bar) membranes, respectively. Flux decline was slightly higher with LF2-SW30 (37.1%) than LF1-BW30 (31.8%) after 20 h of filtration. The fouling layer had significantly higher protein concentration on LF2-SW30 than on LF1-BW30, but both had similar microbial content and inorganic composition. The AE effluents were concentrated by a factor of 7 and processed at pH 5.75 (AE1) and 8.07 (AE2) with BW30 membranes. Both AE effluents had higher calcium but lower suspended solids and organics than the LF effluents. They generated significantly higher flux decline and biofouling than LF1. High flux decline was also associated with increased protein attachment for AE1 and inorganic fouling for AE2. A mechanical separator may be adequate to prepare swine wastewater for RO filtration but the aerobic pretreatment would allow for a higher volumetric concentration of the effluent. [ABSTRACT FROM PUBLISHER]

An excess of 31 million m3/y of tertiary-treated wastewater is expected in Muscat, Oman, by 2015. This paper addresses the technical and cost estimation of managed aquifer recharge after reverse-osmosis treatment. The results indicate that the project is appealing from an economic perspective. The total cost varies between USD 0.353 and USD 0.550 per cubic metre, depending on the cost of electricity, the interest rate and the life span of the project. The project may face rejection from domestic users, who may be unwilling to accept mixing treated wastewater with the current water supply due to health risks. An alternative to indirect potable reuse is the installation of a separate network to service industrial users. [ABSTRACT FROM AUTHOR]

Drinking water of acceptable quality has become a scarce commodity. The standard high-capacity desalination methods such as multi-stage flash evaporation and multi-effect evaporation, vapour compression and reverse osmosis are reliable in the range of about 100–500,000 m3/day fresh-water productions. However, the wide-scale implementations of these methods face numerous technological, economic and political barriers and these methods are not used in decentralised regions with a poor infrastructure due to their permanent need of qualified maintenance and electricity supply. In this paper, various low-capacity solar thermal desalination systems, with fresh-water output production in the range of 10–150 l/day for the use in rural areas, are reviewed and classified based on five technological aspects such as the development of the technology of the systems, the applicability of high-capacity thermal desalination technologies, the enhancement of solar heat collectors, the hybridisation of thermal desalination technologies and heat recovery processes. Most of the reviewed systems are in the research stage and have not cleared economic feasibility such as the price per cubic metre of water that may stimulate the decision-maker to direct these studies into the actual commercial applications to find a solution to the water scarcity problem in isolated and remote areas. Although many of the developed systems have several novel and valuable features, more efforts are required for further investigating more efficient, economic and applicable solar energy-driven low-capacity desalination systems. [ABSTRACT FROM PUBLISHER]

The efficiency of Al-Quds Waste Water Treatment Plant (WWTP), which includes sequential elements as activated sludge, ultrafiltration, activated carbon column and reverse osmosis, to remove spiked ibuprofen, a non steroid anti inflammatory drug (NSAID), was investigated. Kinetic studies in pure water and in the activated sludge indicated that the drug was stable during one month of observation. Besides, the overall performance of the integrated plant showed complete removal of ibuprofen from wastewater. Activated carbon column, which was the last element in the sequence before the reverse osmosis system, yielded 95.7% removal of ibuprofen. Batch adsorptions of the drug by using either activated charcoal or composite micelle-clay system were determined at 25°C and well described by Langmuir isotherms. Octadecyltrimethylammonium (ODTMA) bromide and montmorillonite were used to prepare the micelle-clay adsorbent, for which the adsorption kinetics are much faster than activated charcoal. Results suggest that integrating clay-micelle complex filters within the existing WWTP may be promising in improving removal efficiency of the NSAID. [ABSTRACT FROM AUTHOR]

Membrane-based industrial desalination/demineralization plants generate a considerable amount of discarded membranes. This work studies the effects of the chemical treatment with potassium permanganate solutions in combination with chemical cleaning of three years old composite polyamide/polysulfone reverse osmosis membranes (8″ modules) in order to make them reusable in other applications than reverse osmosis and to increase their life cycles. The performance of membranes with 60 cm2was evaluated in terms of water permeate flux and salt rejection, two properties that can be easily measured in industrial systems. Potassium permanganate treatment degraded the selective layer, improving the water permeate flux of at least 15% from its initial value at the expense of decreased salt rejection. The formation of a manganese oxide layer was detected which reduced subsequent oxidative treatment efficacy. Citric acid was used as a cleaning agent after the oxidation steps, removing part of the manganese oxide layer; the result was an enhanced oxidative process, which increased the permeate flux even more and decreased the loss of salt rejection. Furthermore, to verify the stability of the treatment, the membrane was submitted to a long-term oxidizing experiment. [ABSTRACT FROM PUBLISHER]

Boron removal from geothermal water and its reverse osmosis (RO) permeate was examined by a novel synthesized monodisperse porous poly(GMA-co-EDM) resin containing N-methyl-D-glucamine. The optimum resin concentration was found to be 4 g L−1 and the kinetic data were found to follow a pseudo-second-order kinetic model. According to the correlation coefficients for diffusional kinetic, the rate controlling step was particle diffusion. [ABSTRACT FROM AUTHOR]

Water suppliers face increased pressure to explain the relative health risks from non-regulated xenobiotics that may be present in recycled water, including pharmaceuticals and personal care products (PPCPs) and endocrine disrupting compounds. This report reviews their occurrence, fate, and recent human health risk assessments for potable and non-potable water reuse. The most effective advanced treatment for PPCPs is reverse osmosis (RO) followed by advanced oxidation. During soil aquifer treatment, the majority of PPCPs are attenuated relatively quickly (within 100 days), yet some are persistent and can migrate to the underlying groundwater at low concentrations. Recently, several investigations have assessed the potential human health risks associated with xenobiotics in recycled water, focusing on exposure from drinking water (e.g., planned and unplanned indirect potable reuse) and non-potable reuse (e.g., exposure via recreational, occupational, and irrigation-related activities at sites utilizing recycled water). Risk assessments conducted over the last 10 years have found no adverse human health effects or significant risks. Though advanced treatment of wastewater that is discharged or recycled may not be required to protect public health, it may be necessary to prevent potential effects on exposed biota and to address, to some degree, the public's perception of water reuse. [ABSTRACT FROM AUTHOR]

It has been difficult to produce physically and chemically pure nanoparticles from a particle solution in deionized (DI) water by atomization due to residue from impurities in the DI water. In this study, we show that further purification of DI water by reverse osmosis (RO) membrane filtration under high pressure (900 psi) substantially reduces solvent impurities when submicrometer and nanosized particles are atomized. Comparison of size distributions among several types of DI water showed that the production of residual particles significantly decreased by a factor of ∼11 (by number) after the RO filtration of regular DI water from commercially available DI water. Mixing states of aerosolized particles produced from particle solutions were examined by using the hygroscopicity tandem differential mobility analyzer technique and transmission electron microscopy/energy dispersive spectroscopy. We found that residual particles were externally mixed with particles of interest during the aerosolization and drying process and that impurities in DI water can beadded onto the target particles (i.e., internally mixed). By removing impurities in DI water by the RO filtration, the effect of impurities for the production of clean nanoparticles was significantly reduced, suggesting that the atomization method can still be a promising tool to produce pure nanoparticles in a simple and inexpensive way. [ABSTRACT FROM AUTHOR]

The purpose of this bench-top study was to demonstrate the feasibility and effect of applying ozone and ozone/peroxide upstream of reverse osmosis (RO) membranes as a means of controlling organic fouling during reuse applications. A series of ozone or ozone/peroxide doses was applied to surface water and a membrane bioreactor (MBR) filtrate using a HiPOx® reactor skid, with ozone-to-dissolved organic carbon ratios of approximately 0.25 to 1.75. Results from the flat-sheet testing indicate that both ozone- and ozone/peroxide-treated waters, even at the lowest ozone dose of 1.5 mg/L, fouled the membranes less than the MBR filtrate and surface control waters while both treated and control waters maintained consistent levels of salt rejection throughout the tests. [ABSTRACT FROM PUBLISHER]

This paper reports the optimisation and validation of an analytical method for the determination of the residual concentration of the prescription antibiotics metronidazole, trimethoprim, sulfamethoxazole, azithromycin, clindamicyn, clarithromycin, erythromycin-H2O, roxithromycin and tylosin in wastewater and advanced treated wastewater. The method applied was used in a study of removal efficiency of these compounds at a full scale operational water reclamation plant using microfiltration-reverse osmosis (MF-RO) (Kwinana, Western Australia). The analytical procedure involves off-line solid-phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) operated in multiple reaction monitoring mode. Method validation included determination of linearity, accuracy, precision, method limits of quantitation (MLQs), reproducibility and matrix effect. SPE recoveries were generally higher than 89% for both pre- and post-RO water, except for erythromycin which yielded approximately 50% recovery. The overall precision of the method was better than 16% RSD (relative standard deviation), for all compounds and matrices. MLQ ranged between 23-53 ng L-1 and 2.5-31 ng L-1 for pre- and post-RO water, respectively. In-house reproducibility expressed as RSD was generally better than 10%. Inter-laboratory tests revealed a generally good agreement between concentrations of antibiotics reported by all participants. Results demonstrate that MF/RO treatment is capable of removing antibiotics present at relevant environmental concentration in secondary effluent (from the low to mid ng L-1 range) to below MLQs (2.5-31 ng L-1), and more importantly, three to six orders of magnitude below the health guideline values developed for this project. Estimated RO rejections ranged between >91 and 99%. [ABSTRACT FROM AUTHOR]

Submarine disposal of mine tailings is a relatively recent technology that holds the promise of solving the recurring problems that the mining industry has had with tailings disposal. Implementation of this technology is however contingent upon the pre-treatment of the tailings, particularly those in the aqueous phase. One of the best-known methods to eliminate dissolved metal ions from an aqueous phase is reverse osmosis (RO). In this study, effluent water from mines was passed through a variety of RO membranes and the efficacy of removal was measured. RO was found to be an extremely effective method for cleaning mine effluent, and in the absence of cost limitations, can provide a significant solution to the mine tailings problem. [ABSTRACT FROM AUTHOR]

Electrodialysis (ED) was studied as a technology to concentrate NaCl from SWRO reject in order to be reused in the chlor-alkali industry. A mathematical model was developed based on Nernst-Planck equations to predict the performance of the Barcelona ED pilot plant. Several of the model parameters were obtained experimentally and others were taken from the literature. The model was able to accurately predict the NaCl concentration reached, the time required to reach maximum concentration, and production overflow as a function of the operation conditions. In this article, the mathematical model is fully described and validated with preliminary experimental results obtained. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the variability of manganese concentrations in drinking water (daily, seasonal, spatial) for eight communities who participated in an epidemiological study on neurotoxic effects associated with exposure to manganese in drinking water. We also assessed the performance of residential point-of-use and point-of-entry devices (POE) for reducing manganese concentrations in water. While the total Mn concentrations measured during this study were highly variable depending on the location (< 1 - 2,700 μg/L), daily or seasonal variations were minimal. Flushing the tap for 5 minutes did not significantly reduce total manganese concentration for 4 out of 5 sampling locations. The efficiency of reverse osmosis and ion exchange for total Mn removal was consistently high while activated carbon provided variable results. The four POE greensand filters investigated all increased (29 to 199%) manganese concentration, indicating deficient operation and/or maintenance practices. Manganese concentrations in the distribution system were equal or lower than at the inlet, indicating that sampling at the inlet of the distribution system is conservative. The decline in total Mn concentration was linked to higher water residence time in the distribution system. [ABSTRACT FROM AUTHOR]

The present work aimed to study the origin of foulant material recovered on membranes used in water treatment. Firstly, sugar signatures were assessed from the monosaccharide composition. As results were not conclusive, a statistical approach using discriminant analysis was applied to the sugar data set in order to predict the origin of the foulant material. Three groups of various origins (algal, microbial, continental dissolved organic matter) were used as sugar references for the prediction. The results of the computation showed that the origin of reverse osmosis (RO) seawater foulant material is influenced by both the location of the water sources and the season. RO brackish water and nanofiltration river water foulant materials had a terrestrial origin. Secondly, bacteriohopanepolyol signatures indicated that RO seawater foulant material had a marine signature, RO brackish water foulant material had both a marine and a terrestrial origin and the nanofiltration river water foulant material contained only a terrestrial signature. [ABSTRACT FROM AUTHOR]

A membrane based treatment strategy was developed for the possible recycling of rinsing wastewater from indigo dyeing to the process itself. Performances of three different nanofiltration (NF) (NF 270 and NF 90, Dow Film Tech, USA and NF 99, Alfa Laval, Denmark) and two different reverse osmosis (RO) (HR 98 PP and CA 995 PE, Alfa Laval, Denmark) membranes were investigated with wastewater collected from the first post-rinsing tank of indigo dyeing process of a denim manufacturing plant. Dead-end microfiltration with a 5 µm filter was employed to remove coarse particles and minimize fouling of further NF and RO membranes. For NF and RO, a lab scale plate-and-frame membrane module was operated at a pressure of 5.07 bar and at a 0.62 m/s cross-flow velocity. The permeate quality from all the tested NF and RO membranes was acceptable for reuse in terms of COD and color. However, only the permeate from HR 98 PP RO and NF 90 membranes were with an acceptable conductivity. On the other hand, NF 270 membrane was superior to all the other NF and RO membranes in terms of the permeation rate. Flux declines obtained for all membranes were higher than 50% but fouling was not considerable and completely reversible. The good performance of NF 270 in terms of permeate quality (permeate conductivity, color, and COD values were 4.3 mS/cm, 8 Pt-Co, and 87 mg/L, respectively) together with a higher flux makes this membrane preferable over the other membranes to recycle denim textile rinsing wastewaters. [ABSTRACT FROM AUTHOR]

To conduct the health-effect studies described in subsequent articles in this series, concentrated aqueous mixtures of disinfection by-products were required for the two water treatment trains described in the preceding article (Miltner et al., 2008). To accomplish this, the finished drinking waters from each treatment train were sent through cation-exchange resin columns to remove hardness and free chlorine. Reverse osmosis membranes were then used to concentrate approximately 2400 L of each finished water down to approximately 18 L. The resulting volumetric concentration factors for the chlorinated and ozonated/postchlorinated waters were 136- and 124-fold, respectively. The concentrates were spiked with select disinfection by-products (DBPs) that were lost during the concentration effort. The results, along with the rationale for choosing the method of concentration, are presented. After reintroduction of a select list of lost DBPs, the concentration methodology used herein was able to produce concentrates that retained large percentages of the DBPs that were in the initial finished drinking waters. Further, the distributions of the DBPs in the concentrates matched those found in the finished drinking waters. [ABSTRACT FROM AUTHOR]

This research details the effects of ozone pretreatment on flux of a reverse osmosis membrane. Initial tests were conducted to determine the effects of ozonation on solids removal, turbidity, and chemical oxygen demand concentrations using various doses on a simulated surface water. These initial tests showed that the best reduction of solids in the 2-5 microns range was at 0.30 mg/L of ozone. Next, a series of bench scale tests was run for 62.5 hours using a standard reverse osmosis system under constant pressure with three pre-ozonation doses and a no ozone baseline dose. Temporal models were developed using the flux data from these tests to determine the effects of operating hours and ozone dosage on flux. It was found that the laboratory data were not linear and followed power law models. Statistical analysis was used to determine the significance of each ozone dose on the four developed models. The change in flux over the 62.5 operating hours with an ozone dosage of 0.30 mg/L showed the lowest flux change. Last, the models were tested using Hermia's filtration models and resistance versus time data to determine the type of membrane fouling that existed. It was concluded that the major fouling was pore blockage. This work demonstrated that ozone pretreatment is effective prior to use with reverse osmosis since it shows a better solid and organic removal rate as well as decreased flux and resistance changes over time. [ABSTRACT FROM AUTHOR]

Inorganic arsenic causes cancer, and millions of people worldwide are exposed to arsenic-contaminated water. Regulatory standards for arsenic levels in drinking water generally do not apply to private domestic wells. Reverse osmosis (RO) units commonly are used by well owners to reduce arsenic concentrations, but may not always be effective. In a survey of 102 homes in Nevada, 19 used RO devices. Pre- and post-RO filtration arsenic concentrations averaged 443 μg/l and 87 μg/l, respectively. The average absolute and percent reductions in arsenic concentrations after filtration were 356 μg/l and 79%, respectively. Postfiltration concentrations were higher than 10 μg/l in 10 homes and higher than 100 μg/l in 4 homes. These findings provide evidence that RO filters do not guarantee safe drinking water and, despite regulatory standards, some people continue to be exposed to very high arsenic concentrations. [ABSTRACT FROM AUTHOR]

Investigates the removal of arsenic from groundwater using point-of-use reverse osmosis and distilling devices. High concentrations of arsenic in the groundwater of the northeastern and southwestern coast areas of Taiwan; Selection of three commercially available reverse osmosis systems and two distillers to test their removal efficiency of arsenic from synthetic and real ground water; Percentage of arsenic removal for the distilled systems.