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Different approaches have been suggested for the waste heat recovery of high-temperature exhausted gas of a solid oxide fuel cell (SOFC). In such systems, mostly gas turbine (GT) and organic Rankine cycle (ORC) are added as bottoming systems to the SOFC (Configuration 1). However, the SOFC-GT-ORC has a considerable amount of waste energy which can be recovered. In the present research, the waste energy of ORC in the heat rejection stage and the residual exhausted gas of the system were recovered by a thermoelectric generator (TEG) and a hot water unit, respectively. Then, the extra produced power in the TEG was directed to a proton exchange membrane electrolyzer and a reverse osmosis desalination unit (RODU) for hydrogen and potable water outputs. The performance of SOFC-GT, Configuration 1, and Configuration 2 was compared through a 4E (energy, exergy, exergy-economic, and environmental) analysis. In the best performance point, the exergy efficiency and unit cost of product (UCOP) of SOFC-GT were obtained as 69.41% and USD 26.53/GJ. The exergy efficiency increased by 2.56% and 2.86%, and the UCOP rose by 0.45% and 12.25% in Configurations 1 and 2. So, the overall performance of Configuration 1 was acceptable and Configuration 2 led to the highest exergy efficiency, while its economic performance was not competitive because of the high investment cost of RODU. [ABSTRACT FROM AUTHOR]

In this article to tackle the main concerns of today's world as fossil fuel shortage, environmental impacts of fossil fuels like global warming and atmosphere pollution as well as water scarcity, a novel power plant is designed. In this regard, the proposed plant comprises of biomass gasification unit, photovoltaic thermal collectors, a proton exchange membrane hydrogen production unit, as well as a reverse osmosis water purification plant. The plant is named as (biomass-fired combined cycle with photovoltaic, thermal collectors, hydrogen production, and reverse osmosis) BCPVHR and to assess its performance, energy, exergy, exergoeconomic, and environmental analyses are performed. The varying parameters are compressor pressure ratio and gas turbine inlet temperature. These two parameters' impact on energy efficiency, exergy efficiency, net generated power, fresh water production, total unit product cost as well and environmental index are assessed. The results are useful for adjusting the compressor pressure ratio and gas turbine inlet temperature. Please note that this plant is designed to be used completely or partially in sports facilities and can be a valuable endeavor for managing sports facilities to use renewable energy in their construction. Meanwhile, based on the priories of products different values of parameters can be used. Increasing the compressor pressure ratio raises the total unit product cost and the environmental index until 11.5 decreases and later increases. Increasing the gas turbine inlet temperature decreases the both total unit product cost and environmental index which reach 65 $/GJ and 65 kg/kWh, respectively. • A novel power plant is designed. • Plant comprises of biomass gasification unit and photovoltaic. • Plant uses proton exchange membrane for hydrogen production. • System uses reverse osmosis for water purification. • Energy, exergy, exergoeconomic, and environmental analyses are performed. [ABSTRACT FROM AUTHOR]

Reverse osmosis (RO) and nanofiltration (NF) membranes are widely used to remove ions from water, but the interdependencies among active layer pore size, thickness, surface charge, and membrane porosity and their influence on performance are not clear. In this study, we evaluated these parameters for two commercial RO and eight commercial NF membranes and demonstrated that membrane porosity can serve as a critical linkage between these membrane characteristics and membrane performance. Porosity was mainly determined by pore size (as opposed to permeability or thickness), and thicker, more porous membranes with smaller pores (including RO) had higher sodium chloride removal and less permeability. Membrane volume charge density increased with increasing porosity. Higher porosity membranes have greater inner pore surface area available to support a greater number of functional groups, which increases counterions and reduces co-ions in the membrane, thereby reducing ion flux and increasing ion removal. The Donnan Steric Pore Model was used to determine that the contribution of diffusion and electromigration flux to the total counterion flux declined with increasing porosity, whereas the contribution of convection flux increased. Co-ion flux was dominated by diffusion flux, with electromigration and convection flux contributing about 3% and 2% of the total co-ion flux, respectively. Accordingly, calculation of just the diffusion flux for the co-ion can yield a good rough estimate of ion flux using high-porosity (small pore) membranes. Controlling membrane porosity through pore size and thickness can help to tune permeate water flux and ion removal to targeted water treatment goals using the trends reported in this study. [ABSTRACT FROM AUTHOR]

Constraint optimization redundancy allocation problem (CoRAP) is a real-world, complex integer programming problem. Many researchers have used a variety of techniques to solve CoRAP. In the last two decades, evolutionary algorithms have been used by researchers to handle a variety of complex problems. Among these, the spider monkey optimization algorithm (SMO), which focuses on the behavior of monkeys, is one of the most promising and recent developments by researchers. In addition, no work has been undertaken in the context of solving CoRAP for water treatment plants so far. This paper proposed an integer programming problem, CoRAP for water treatment reverse osmosis (RO) plants subject to a cost constraint. The spider monkey optimization technique is applied to optimize the redundant units of the components of the plant, due to which the overall system reliability is maximized. A review of spider monkey optimization applications and modifications are also presented to investigate its performance. The same problem is solved by the heuristic algorithm, the branch and bound method and student psychology-based optimization technique to compare performance. The simulation work of spider monkey optimization, heuristic algorithms and student psychology-based optimization is implemented using MATLAB and the results for the branch and bound method are obtained using LINGO software. The findings demonstrate the better performance of spider monkey optimization. [ABSTRACT FROM AUTHOR]

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]

This document is a spotlight column from the journal Environmental Engineering Science, highlighting selected articles from the December 2023 to March 2024 issues. One article discusses a faculty mentoring program developed by the Association of Environmental Engineering and Science Professors (AEESP), which pairs junior faculty with mentors to support their professional development. The article emphasizes the importance of factors such as university type, personality, research area, parental and marital status, and race/ethnicity in the mentor-mentee pairing process. Another article explores the potential of vertical hydroponic systems using effluents from anaerobic membrane bioreactors to grow lettuce in urban areas with limited land access. The study demonstrates that proper lighting and knowledge of nutrient concentration are crucial for efficient lettuce growth. A third article investigates the role of membrane thickness and porosity in reverse osmosis (RO) and nanofiltration (NF) processes for desalination and wastewater treatment. The study finds that membrane porosity, determined by pore size and thickness, affects sodium chloride removal and ion flux. Lastly, a study evaluates sampling strategies for SARS-CoV-2 in wastewater treatment plants, highlighting the effectiveness of composite sampling for capturing overall community conditions and grab sampling for identifying specific outbreak locations. The information presented in these articles can be valuable for researchers and practitioners in the field of environmental engineering and science. [Extracted from the article]

Introduction: Reverse osmosis (RO) is a method for purifying water. Ir separates water from incrustations, through semi-permeable membranes; absorption of scales can cause damage to the membranes, affecting the process. Injecting antifouling removes and inhibits its overproduction. The objective of this scientific article is to learn about antiscalants, using as a method the bibliographic review of previous works that have operated with these, through the analysis of their processes and conclusions, to study how they vary from each other and which one implies better results. Objective: To analyze the most common antifoulings today through a bibliographic review, where compounds that have metaphosphates and polymers as a chemical base are studied. Materials and Methods: The review of 3 original publications that posed as the main topic the use of different antiscalants and their action on the membranes of reverse osmosis equipment was carried out. The reviewed articles were published in the 2018-2021 period, taking into consideration the quality and nature of the publications. Results and Discussion: According to the comparative analysis of the chosen antiscalants, the effect they have with respect to the membranes of reverse osmosis equipment was monitored. To analyze the results, aspects of function, dosage, injection point and conclusions obtained from each one were considered. Conclusions: Compared to phosphinocarboxylic acid and the modified base, sodium hexametaphosphate has shown better results in the industry with respect to reverse osmosis membranes in water purification processes. [ABSTRACT FROM AUTHOR]

Reduction coagulation filtration using ferrous iron (Fe(II)‐RCF), or reduction filtration using stannous tin (Sn(II)‐RF), for the removal of hexavalent chromium (Cr(VI)) from drinking water represent attractive alternatives to ion exchange or reverse osmosis. With a new maximum contaminant level for Cr(VI) anticipated in California, this study sought to expand on previous research by applying Fe(II)‐RCF and Sn(II)‐RF to multiple groundwaters under a variety of reductant dose and reduction time scenarios. Four different granular filter media were also tested for removal of total chromium (Cr(T)) following Cr(VI) reduction to trivalent chromium (Cr(III)). Sodium hypochlorite, instead of aeration, was used to oxidize excess Fe(II) to Fe(III) prior to filtration, with minimal Cr(III) to Cr(VI) reoxidation. Sn(II)‐RF was also able to achieve Cr(T) and Cr(VI) treatment goals without dedicated reduction time prior to filtration. Results of this study were used to develop more up‐to‐date, feasibility‐level, 20‐year annualized cost estimates. [ABSTRACT FROM AUTHOR]

Antibacterial properties of engineered materials are important in the transition to a circular economy and societal security, as they are central to many key industrial areas, such as health, food, and water treatment/reclaiming. Nanocoating and electrospinning are two versatile, simple, and low-cost technologies that can be combined into new advanced manufacturing approaches to achieve controlled production of innovative micro- and nano-structured non-woven membranes with antifouling and antibacterial properties. The present study investigates a rational approach to design and manufacture electrospun membranes of polysulfone (PSU) with mechanical properties optimized via combinatorial testing from factorial design of experiments (DOE) and endowed with antimicrobial silver (Ag) nanocoating. Despite the very low amount of Ag deposited as a conformal percolating nanocoating web on the polymer fibers, the antimicrobial resistance assessed against the Gram-negative bacteria E. coli proved to be extremely effective, almost completely inhibiting the microbial proliferation with respect to the reference uncoated PSU membrane. The results are relevant, for example, to improve antifouling behavior in ultrafiltration and reverse osmosis in water treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] Capacitive deionization (CDI) technologies have the potential to become cost-competitive alternatives to reverse osmosis for the treatment of brackish waters. In this study, we report our findings on the effect of co-ion sorption and faradaic side reactions on our ion exchange resin functionalized desalination electrodes which passively capture salt and reject it upon charging. This system, which we previously reported on and refer to as electrically regenerated ion exchange (ERI), avoids the use of expensive ion exchange membranes in an effort to save costs. Surprisingly, we find that, compared to a reference CDI system, ERI electrodes capture salt most effectively at low applied voltages (0.5 mg/cm3 at 0.8 V). Both CDI and ERI systems also seem to suffer from co-ion sorption effects which negatively impact salt adsorption. However, Faradaic side reactions at higher voltages (1 V and 1.2 V) which we track via pH measurements, serve as a detriment to CDI but seem to facilitate the functionality of ERI. [ABSTRACT FROM AUTHOR]

Background: Non-condensable gases (NCGs) are all gases that do not undergo liquefaction during the saturated steam sterilization process. During a sterilization cycle, the NCGs presence inside the chamber is one of the biggest threats to the sterilization process compromising process validation and product quality. Methods: In this work, 170 testing of NCGs concentrations performed between September 2016 and August 2021 were carried out by Orionce Serviços de Metrologia Ltda (Barueri, SP, Brazil), according to EN285:2015 procedure. For steam generation, the types of water used were softened water (SW), one-step reverse osmosis (RO), purified water (PW), and water for injection (WFI). The data obtained were analyzed using Minitab® software, version 18.1, to identify a relationship between the water quality used for steam generation and the concentration of non-condensable gases determined into equipment qualification. Findings: From total tests performed, 109 tests passed, and 61 tests failed, representing 64.2% and 35.8%, respectively. A higher failure rate was observed in terms of concentration of non-condensable gases in systems that used purified water for steam generation (64.7%), followed by softened water (55.6%), one-step reverse osmosis (42.9%), and water for injection (7.6%). Conclusion: System processes using WFI for steam generation showed better results for steam quality approvement, in terms of NCGs concentration, compared to softened, purified, or reverse osmosis water treatments in the concentration of non-condensable gases in steam used for sterilization processes of industrial utilities. [ABSTRACT FROM AUTHOR]

The article highlights the need to reassess the innovation pipeline for membranes used in desalination and water treatment. Topics include examines despite extensive research to optimize membrane chemistry, morphology, and module designs, reverse osmosis (RO) membranes used for seawater desalination over 50 years ago remain the industry standard.

The article presents a study which analyzed the arsenic (As), ammonia (NH3), and iron (Fe) concentrations in the drinking water treatment plant (DWTP) wastewater stabilization pond (WSP) system of five sequential ponds in Saskatchewan. Also cited are the elevated concentrations of contaminants like heavy metals, metalloids, and ammonia in DWTP wastewaters, and the use of groundwater as a source water of the DWTPs.

In this research paper, profit analysis of a Water Treatment Reverse Osmosis (RO) Plant is carried out by using the Regenerative Point Graphical Technique (RPGT) under specific conditions for system parameters. The paper analyzes the behavior of a water treatment RO plant consisting of subunits namely Multimedia filter (MMF), Cartridge filter (CF), High-pressure pump (HPP), RO System (ROS). The system is in a working state when all subunits are in good condition. A repair facility is accessible for all subunits. Availability of the plant, Busy Period of the Server (BPS) and Expected number of inspection by the repairman (ENIR) is calculated by using the RPGT technique. Finally, numerical analysis is carried out for calculating the performance measures and their comparisons. [ABSTRACT FROM AUTHOR]

The clean water and energy are both the most important needs of mankind. The increasing population and the necessity to meet the need for freshwater requirements make the desalination process a popular topic. The reverse osmosis is one of the most popular technique for desalination. The main advantages of the reverse osmosis over other desalination techniques are the lower energy consumption and the robustness to the salinity of feedwater. The ambient conditions are the key parameters affecting the efficiency of desalination process. On the other hand, the design parameters of a reverse osmosis desalination plant also play an important role in the process. In this paper, both ambient conditions and the design parameters are investigated. The contributions of the study are to determine variation the specific power consumption and related total power requirement of single stage reverse osmosis desalination plant model with the ambient conditions and design parameters. The effects of design parameters and ambient conditions for power requirements are given in the results section. The simulation studies are performed at constant production rate in order to see the effects of each parameter to product properties. The increase in seawater temperature for constant seawater salinity decreases the power consumption while increasing the salinity of final product. The results indicated that design parameters should be optimized according to the size of the designed system and salinity of feedwater. Also, a case study is performed for a point at Marmara Region, Turkey. [ABSTRACT FROM AUTHOR]

Nanoporous graphene (NPG) shows tremendous promise as an ultra-permeable membrane for water desalination thanks to its atomic thickness and precise sieving properties. However, a significant gap exists in the literature between the ideal conditions assumed for NPG desalination and the physical environment inherent to reverse osmosis (RO) systems. In particular, the water permeability of NPG has been calculated previously based on very high pressures (1000-2000 bars). Does NPG maintain its ultrahigh water permeability under real-world RO pressures (<100 bars)? Here, we answer this question by drawing results from molecular dynamics simulations. Our results indicate that NPG maintains its ultrahigh permeability even at low pressures, allowing a permeate water flux of 6.0 l/hbar per pore, or equivalently 1041 ± 20 l/m²-h-bar assuming a nanopore density of 1.7 × 1013 cm-2. [ABSTRACT FROM AUTHOR]

This study reviewed the most common methods for removing lead ions from industrial wastewater and municipal wastewater. Most of the research done was reviewed using traditional methods such as chemical precipitation, ion exchange, reverse osmosis, oxidation, evaporation, electric-dialysis, membrane filtration, and solvent extraction. These operations were related to several restrictions, that comprised the treatments to be limited to a definite concentration of the Lead (II) ions. Similarly, disadvantages complicated the production of huge quantities of dangerous waste although very high costs. This means these operations were very costly. For these reasons, to utilize the agricultural waste and low-cost adsorbents operation can be considered as eco-friendly. Currently, agricultural waste and natural materials are present in a huge quantity, and that is very damaging to the environment. Therefore, adsorption is an alternate operation for eliminating Lead (II) ions. According to the increased quality of adsorption operations, like the properties of improved adsorptive, increase availability, and cost-effectiveness, the operation is economical option for eliminating Lead(II) ions. [ABSTRACT FROM AUTHOR]

Constituents in the feed of reverse osmosis (RO) processes pass into the product by two mechanisms: diffusion through the membrane and advection through defects in the system. While minerals and tracers pass via both mechanisms, pathogens pass only via advection. Using mass and flow balances, a rigorous model is developed to characterize the response of both viruses and tracers in RO systems. The model is used to assess several tracers being considered today. Early virus testing and the commercial requirements of desalination are reviewed, leading to the conclusion that some degree of advection can be expected to be present in RO systems but that commercial incentives can be expected to maintain pathogen removal due to defects somewhat greater than 4.0 log. Model results suggest that the best tracers currently in use can detect defects near this log reduction value but that there is still room for improvement. [ABSTRACT FROM AUTHOR]

Membranes used for water treatment are subject to organic fouling, caused by organic matter in source water. Characterizing organic matter has the potential to improve fouling prediction since the development of an organic fouling layer on the membrane is dependent on the specific characteristics of the organic matter. A field study was performed at a full‐scale reverse osmosis water treatment plant that treats secondary wastewater effluent for industrial reuse at a power plant. Samples were collected at various points within the treatment process and were analyzed for turbidity, total organic carbon (TOC), conductivity, and fluorescence Excitation Emission Matrices (EEM). Parallel factor analysis (PARAFAC) was used to generate representative fluorescence measurements of the organic matter. Results indicate that TOC and fluorescence measurements were effective in differentiating between two observed fouling periods at multiple locations within the treatment plant. However, none of the water quality measurements were effective in tracking treatability of organic matter throughout pretreatment. The results of this case study provide important information about the relationship between fluorescence NOM signals and membrane fouling that can be used in future online detection systems. Practitioner points: TOC and fluorescence measurements were effective in differentiating between the high fouling and low fouling periods.Water quality measurements were not effective in tracking changes in organic matter throughout pretreatment.Implementation of online fluorescence monitoring of fouling potential could be used for real‐time process control. [ABSTRACT FROM AUTHOR]

Water‐stressed communities are beginning to consider alternative sources of water supply augmentation. We provide a comparison of water conveyance and potable water reuse over a range of water demands. On a unit basis (US$/1,000 gal) and under current practice, water reuse is generally less costly at low flow rates (<10 mgd) as compared with water conveyances of 20 miles or more. This is true especially for advanced water treatment schemes that are based on biologically activated carbon (BAC). At greater distances (>100 miles), treatment schemes that are based on reverse osmosis (RO) also become cost competitive. Similarly, both BAC‐based and RO‐based reuse schemes have a lower or comparable carbon footprint on a unit basis (g CO2‐equiv/1,000 gal) for a flow rate of 20 mgd. In spite of public reluctance, managers would do well to consider reuse in their portfolio of water supply options. [ABSTRACT FROM AUTHOR]

In this study, the wastewater treated by the membrane bioreactor (MBR) process at the wastewater treatment plant of ITOB Organized Industrial Zone was used as the feed solution for further desalination by nanofiltration (NF90) and reverse osmosis (BW30) membranes. The effect of chemical cleaning to control the membrane fouling during long-term repeated uses of both NF and RO membranes were investigated. The water permeability values were obtained using deionized water as the feed solution after five cycles of desalination-membrane cleaning-permeability tests. Water permeability values changed from 3.93 L/m2·h·bar to 1.35 L/m2·h·bar for BW30 and 7.76 L/m2·h·bar to 2.65 L/m2·h·bar for NF90. The permeability tests were also carried out by using MBR effluent as the feed solution for better evaluation of fouling effects for MBR treated wastewater on desalination performance of NF and RO membranes. An optimal cleaning strategy was suggested throughout the study. Unlabelled Image • Effects of fouling on permeate flux of NF and RO processes are investigated. • Mini-pilot scale long-term membrane tests were performed. • An efficient membrane chemical cleaning strategy was established to control fouling. [ABSTRACT FROM AUTHOR]

Membranes with suitable nanopores and tunable charge characteristics are highly desired for their good application prospects in specific membrane-based separations. This study focused on the synthesis of polyamide (PA) composite membranes with tunable pore size and perm-selectivity. Trimellitic anhydride chloride (TAC) with an anhydride group, was introduced as the co-reactant of trimesoyl chloride (TMC) to form PA film via interfacial polymerization with m -phenylenediamine on the surface of the polysulfone substrate membrane. Due to the chemistry character difference (the number of functional group and acylation activity) between TMC and TAC, the structure and physico-chemistry properties of the PA film could be tailored through the control of TAC concentration. As a result, the nanopore radius of the membrane varied from <0.32 to 1.14 nm, along with the improved water permeability from 2.3 to 9.8 L m−2 h−1 bar−1 and selectivity of Na 2 SO 4 /NaCl from 2.2 to 4.9. This study provided a facile and effective approach for the fabrication of tailor-made membrane with tunable nanopore and ion selectivity designed at a molecular level. • PA-TFC membranes were fabricated with mixed organic phase monomers of TMC and TAC with an anhydride group. • The pore size (from RO to NF range) and charge of the membrane were tailored through varying the TAC content. • Enhanced perm-selectivity could be attained by the control of TAC content. [ABSTRACT FROM AUTHOR]

Wastewater reclamation and reuse became essential to meet the more restrictive discharge limits and to overcome the water scarcity issue. Industrial wastewaters treated by membrane bioreactor (MBR) systems generally include high amounts of salinity, nutrients as nitrogen and phosphorus, heavy metals, hardness, etc. which in most cases, do not fit with discharge and reuse limits. Membrane processes like nanofiltration (NF) and reverse osmosis (RO) are widely adopted for secondary effluent treatment producing high-quality water. Since untreated brine can damage the environment, this work focused on reduction of amount of concentrate by working in membrane-in-series configuration. Tests with two membrane-in-series (NF90 + NF90, BW30 + BW30, BW30 + NF270 combinations) were performed as the concentrate stream of the first one was fed to the second one. Water recoveries were over 80% in each experiment. Water fluxes of 44.0, 41.4 and 73.4 L/m2.h were obtained with NF90 + NF90, BW30 + BW30, BW30 + NF270 combinations, respectively. Also, salinity rejections represented by electrical conductivity were 92.9%, 97.4% and 42.9% for NF90 + NF90, BW30 + BW30, BW30 + NF270 configurations, respectively. Permeates of BW30 + BW30 and NF90 + NF90 combinations seem to be useable for agricultural irrigation although soil permeability is an important issue, not only ion concentrations and salinity of water used. • Three different membrane pairs were tested for concentrate reduction in desalination of MBR effluent. • Product waters of NF90 + NF90 and BW30 + BW30 were useful for irrigation. • Water recoovery was over 80% with no significant flux drop. [ABSTRACT FROM AUTHOR]

We present a multi-objective analysis of the optimization of seawater reverse osmosis (RO) desalination systems, considering economic, power requirement, and exergo-economic factors. Exergy flow for each stream and exergy destruction for each equipment in the RO network is included in the model. The exergo-economic unit cost (EUC) for the final product is considered as an objective function. An enhanced version of the augmented epsilon constraint method, AUGMECON2, is utilized to solve the multi-objective optimization problem, which allows for lexicographic optimization for other objectives if alternative optimum solutions exist. Redundant iterations are avoided through the use of the bypass coefficient. Results show that the Pareto solutions for permeate split design are located below the normal design. Fixed cost dominates the exergo-economic unit cost. The power cost has the greatest share of water cost, while pass 1 has the greatest share of exergy destruction. The throttling valves and blending of different salinity streams (final product mixer and first pressurization stage mixer) could cause non-negligible exergy destruction. The fixed cost for each equipment, exergy rate, and EUC for each flow rate are analyzed, in order to provide insights into the system. Unlabelled Image • Economic, energy, exergo-economic analysis are considered simultaneously. • Redundant iterations of MOO problems are avoided by bypass coefficient. • Fixed cost dominates exergo-economic unit cost. • Exergo-economic analysis is performed to get an insight view of the system. • Blending of different salinity streams causes non-negligible exergy destruction. [ABSTRACT FROM AUTHOR]

Brackish water (BW) desalination represents an untapped potential for augmenting water resources by the reliable technology of reverse osmosis (RO). There is a significant economic incentive to operate the process at the highest possible water recovery. A high recovery has the important advantage of reducing the amount of concentrate waste stream whose safe disposal is of significant environmental concerns. The degree of RO water recovery possible with a given raw water is dictated by the scaling problem. To overcome this hindrance, a variety of processes have been developed for conditioning the concentrate emanating from the primary RO unit for additional permeate production by a secondary RO unit. This paper provides a critical review of the treatment technologies that enable intensification of the water recovery in BWRO desalination by the intermediate concentrate demineralization techniques. The principles of each technique as well as its strength, weaknesses, technology readiness level, and economics are discussed. Extensive application of ICD technologies requires overcoming challenges such as lowering energy demand and total cost and reducing membrane scaling and use of chemicals. • Current and emerging intermediate concentrate demineralization (ICD) technologies are reviewed. • High recovery BW desalination is achieved by applying ICD technologies between consecutive RO stages. • Selection of ICD technology depends on water quality, treatment capacity and costs. • Challenges and future perspectives of these ICD technologies are discussed. [ABSTRACT FROM AUTHOR]

Renewable energy driven desalination has been proven to be a sustainable, economic and environmental friendly solution for the water deficiency problems in remote areas. However, one of the most important issues is the determination of the optimal configuration so that the system meets the water load at the minimum cost. In this paper, five different configurations of a sea water desalination system powered by photovoltaics were examined at autonomous mode. Αn island in Cyclades, Aegean sea, Greece, was used as a typical case study for the installation of such systems. Then, a comparison among the different configurations was realized in order to determine the optimum technical and economic system, by minimizing the total system installation and operation cost for 20 years lifetime, which then compared in economic terms with the water transportation practice. The present study shows that the application of a photovoltaic powered seawater reverse osmosis desalination unit that incorporates water storage, a small capacity battery bank and an energy management system, is technically feasible to produce fresh water. According to the optimal sizing results, the implementation of an energy management system designed on the basis of Fuzzy Cognitive Maps presents the lowest cost and lowest power losses. • Various energy management systems have been implemented and tested for a PV-SWRO desalination system. • A technical and economic evaluation of alternative configurations for a PV-SWRO desalination plant has been performed. • An autonomous PV-SWRO desalination plant with an EMS based on FCM is technically feasible and economically a sustainable. [ABSTRACT FROM AUTHOR]

On the West Coast of South Africa, there is an abundance of brackish groundwater. Reverse Osmosis membrane systems are used to make the borehole water fresh. Unfortunately, the salts that are removed from the water, precipitates on the membrane surface, thus, decreasing the overall process efficiency. In this study, the use of Zn2+ ions as an anti-scalant was investigated in terms of feasibility in the treatment of brackish water influent. Experimental tests were conducted on a bench scale unit, followed with a pilot plant thereafter. Three commercial membranes were exposed to natural groundwater scaling. The first, commercial anti-scalant treatment, second, anti-scalant treatment with Zn2+ ions and the third, untreated. The results, after a period of close to 5 months, showed that the flux of the membranes treated with commercial (32.78 L·m−2·h−1) and zinc (30.80 L·m−2·h−1) ions anti-scalant was higher than the untreated membrane flux (25.56 L·m−2·h−1), which decreased continuously. Unlabelled Image • Maximum concentration of Zn ions generated in the electrolytic was obtained at a potential difference of 2 volts. • The use of Zn2+ improved anti-scaling capacity of the membrane when treating brackish water • Scaling of the membrane in the pilot plant was minimized with the use of commercial anti-scalant as well as Zn ions. • SEM and OM analyses showed that deposits on the membrane surface were minimized with the use of both anti-scalants tested [ABSTRACT FROM AUTHOR]

We propose a new approach to desalination of water whereby a pressure difference across a vapor-trapping nanopore induces selective transport of water by isothermal evaporation and condensation across the pore. Transport of water through a nanopore with saline water on one side and pure water on the other side under a pressure difference was theoretically analyzed under the rarefied gas assumption using a probabilistic framework that accounts for diffuse scattering from the pore walls as well as reflection from the menisci. The analysis revealed that in addition to salinity, temperature, and pressure difference, the nanopore aspect ratio and the probability of condensation of a water molecule incident on a meniscus from the vapor phase, known as the condensation coefficient, are key determinants of flux. The effect of condensation coefficient on mass flux becomes critical when the aspect ratio is small. However, the mass flux becomes independent of the condensation coefficient as the pore aspect ratio increases, converging to the Knudsen flux for long nanopores. For design of a nanopore membrane that can trap vapor, a minimum aspect ratio is derived for which coalescence of the two interfaces on either side of the nanopore remains energetically unfavorable. Based on this design criterion, the analysis suggests that mass flux in the range of 20–70 g/m2 s may be feasible if the system is operated at temperatures in the range of 30–50 °C. The proposed approach further decouples transport properties from material properties of the membrane, which opens the possibility of engineering membranes with appropriate materials that may lead to reverse osmosis membranes with improved flux, better selectivity, and high chlorine resistance. [ABSTRACT FROM AUTHOR]

Management of coalbed methane (CBM)-produced water is a crucial part of the water–energy nexus, especially as CBM is projected to play a key role as a bridge fuel in major economies. In this paper, we consider one management technique, i.e., desalination of CBM-produced water to generate potable water. We discuss a confluence of geographic, sociotechnical, regulatory, and other circumstances that could make this concept viable for select coal-bearing regions. Having said that, for maximizing benefits, it is prudent to take a synergistic view targeting multiple objectives (water access, health, environmental impacts, and ease of waste management). Thus, we make design recommendations and suggest a system-evaluation framework for making sustainable decisions related to produced-to-potable water systems. For instance, a key question is whether such systems should be centralized or decentralized—and this paper highlights crucial tradeoffs that are present in both the cases. [ABSTRACT FROM AUTHOR]

Abstract A new concept to concentrate seawater up to 200 g/kg for producing vacuum salt using a reverse osmosis (RO) system hybridized with an electrodialysis (ED) system is presented. The RO system operates up to pressures of 120 bar and concentrates seawater up to 120 g/kg with the ED system concentrating RO brine to 200 g/kg. A parametric analysis to minimize the specific cost of brine concentration was conducted. Parameters varied were: the degree of RO-ED hybridization, ED current density, electricity prices and water prices. Optimal hybrid RO-ED designs reduced brine concentration costs by 33–70 % over standalone ED systems, with revenue generated from water co-production further subsidizing costs by 1–6 %. Optimizing ED current density reduced costs the most. Including a crystallizer, the total reduction in production cost over a standalone ED-crystallizer system was 19–55 % , with the production cost for a typical case being $111/tonne-salt. The proposed RO-ED-crystallizer (REC) systems were found to be techno-economically feasible in Cyprus, Japan, Kuwait, Saudi Arabia, and the USA. At a road transportation distance of 735 km, REC based seawater vacuum salt was competitive with conventional vacuum salt. REC systems may open up the potential of small-scale decentralized salt production. [ABSTRACT FROM AUTHOR]

Abstract Background Lead exposure represents a significant human health concern that often occurs with little warning to the consumer. Water lead levels can be mitigated by point-of-use (POU) devices such as reverse osmosis, distillation, or activated carbon with lead reduction media. Objectives This study assessed a partial cost-benefit of residential installation of POU devices to reduce lead concentrations in drinking water and examined the economic impact at the community level based on exposures reported in Flint, Michigan. Methods We calculated the individual consumer breakeven point for each lead abatement option by subtracting the lifetime cost of device installation and maintenance from the lifetime cost of lead exposure through its impact on intelligence (IQ) and lifetime earnings. This approach was then extrapolated to the community level based on reported lead exposures in Flint, Michigan. Results Based on operating POU device costs, lead absorption from water, and economic losses associated with reduced IQ, initial water lead levels associated with consumer breakeven points for reverse osmosis (7.31 µg/L), activated carbon (3.73 µg/L), and distillation (12.0 µg/L) were calculated. For example, an individual consuming water with 25 µg/L of lead, similar to the 90th percentile of concentrations measured in Flint, Michigan, would have an expected blood lead level of 1.25 µg/dL, a corresponding loss of 0.641 IQ points, and a lifetime economic earnings loss of $14,284. Over 70 years of continued use, activated carbon with lead reduction media is the least expensive device to maintain and operate as compared to reverse osmosis and distillation. Conclusions Infrastructure failures related to drinking water are unpredictable and exposure to contaminates can have significant economic ramifications. POU devices represent a cost-effective option to reduce the impact of lead exposure, particularly when water lead concentrations exceed regulated levels. Highlights • Reverse osmosis, activated carbon, and distillation effective for lead removal. • Point-of-use devices can be cost effective for lead removal over a lifetime. • Lead exposure from drinking water decreases IQ and lifetime earnings. [ABSTRACT FROM AUTHOR]

Abstract In this investigation, a polygeneration scheme integrating local desalination units with CCHP systems, providing cold, heat and power for Kish twin towers as well as providing a portion of the fresh water demand of the island, is proposed and evaluated in terms of energy, environment, and economy aspects. The proposed system is compared to the conventional CCHP and desalination system adopting the separate production system as the reference. Here, two types of desalination technologies, namely multi-effect distillation (MED) and reverse osmosis (RO) processes, are used to provide desalinated water. A genetic algorithm is implemented to determine the optimal operating parameters. It results in that in the polygeneration system the yearly average power generation efficiency, the annual primary energy saving ratio (APESR) and the annual total cost saving ratio (ATCSR) of the whole system increase by 3.45%, 9.73%, and 6.49%, respectively, compared to the conventional system. Using the MED process can increase the ATCSR from 9.8% to 16.0%, depending on the fresh water market price. Moreover, the carbon dioxide emission (CDE) decreases by 1460.5 tons each year, compared to the reference. It is also indicated that 93.87% of the MED input heat can be recovered for domestic hot water (DHW) provision. Highlights • The integration of local desalination and CCHP units has been investigated. • The effects of the combination on the performance of each unit have been evaluated. • A new way for integrating the MED unit with the CCHP system has been optimized. • The integration mainly improves the part-load performance of the CCHP system. • Adopting MED process can considerably improve energy and economic performance of the whole system. [ABSTRACT FROM AUTHOR]

Abstract Two dimensional (2 D) layered materials with special properties provide opportunities to design energy-efficient membranes for water desalination. A negatively charged layered graphene analogue, molybdenum disulfide (MoS 2) was synthesized through liquid exfoliation. A novel thin film nanocomposite (TFN) reverse osmosis (RO) membrane was successfully fabricated with prepared laminar MoS 2 as fillers in the organic phase through interfacial polymerization of m -phenylenediamine and trimesoyl chloride monomers. The laminar MoS 2 nanosheets were observed by transmission electron microscopy (TEM), and the nanosheets were dispersed in the polyamide (PA) matrix as well as on the membrane surface. The properties of the resultant TFN membranes were effectively modified by taking the advantage of two dimensional features, i.e., the negative charge and the hydrophilic sites of layered MoS 2. Compared to a classical TFC membrane, the MoS 2 incorporated TFN membranes were found to have an increased salt rejection and higher water flux. Moreover, 0.01 wt% MoS 2 -TFN membrane showed a superior fouling resistance against proteins as foulants. The antifouling behavior of this TFN membrane was observed by field-emission scanning electron microscopy (FE-SEM). Stability tests demonstrated that there was a loss of MoS 2 in the initial 2 h filtration, but the process is stable in the long-term. Graphical abstract Unlabelled Image Highlights • Negatively charged layered MoS 2 was prepared through liquid exfoliation. • Laminar MoS 2 nanosheets were successfully incorporated in the polyamide matrix and modified the membrane surface. • MoS 2 -TFN RO membrane showed decreased selective layer thickness, increased surface hydrophilicity and surface roughness. • MoS 2 -TFN RO membrane exhibited high perm-selectivity and improved fouling resistance. [ABSTRACT FROM AUTHOR]

Abstract As water shortage has increasingly become a serious global problem, desalination using seawater reverse osmosis (SWRO) is considered as a sustainable source of potable water sources. However, a major issue on the SWRO desalination plant is the generation of brine that has potential adverse impact due to its high salt concentration. Accordingly, it is necessary to develop technologies that allow environmentally friendly and economically viable management of SWRO brines. This paper gives an overview of recent research works and technologies to treat SWRO brines for its beneficial use. The treatment processes have been classified into two different groups according to their final purpose: 1) technologies for producing fresh water and 2) technologies for recovering energy. Topics in this paper includes membrane distillation (MD), forward osmosis (FO), pressure-retarded osmosis (PRO), reverse electrodialysis (RED) as emerging tools for beneficial use of SWRO brine. In addition, a new approach to simultaneously recover water and energy from SWRO brine is introduced as a case study to provide insight into improving the sustainability of seawater desalination. Highlights • This manuscript describes the pilots (SWRO-PRO and SWRO-MD) built under the project of Global MVP (GMVP). • SWRO-PRO pilot plant (240 m3/d) based on spiral wound module incorporated the energy recovery device inside the pilot so as to monitor the energy saving. • MD pilot plant (400 m3/d) using hollow-fiber membrame/module unlike other pilot plants. [ABSTRACT FROM AUTHOR]

Abstract Several fouling indexes, such as silt density index (SDI), have been applied in the reverse osmosis (RO) process to predict the fouling tendency, design the pretreatment process, and optimize the cleaning cycles. However, the forward osmosis (FO) process has no reliable method, as yet, that relates fouling with its performance. This study utilized the concept of fouling reversibility to develop a fouling index for the FO process simulation. The osmotically driven reversibility index (ORI) was determined by measuring the flux recovery after the physical cleaning or flushing cycle. The protocols of ORI measurement were developed systematically by determining the proper operation mode, cross-flow velocity for physical cleaning, and draw solution type and concentration. The applicability of ORI was examined by investigating the FO process in treating secondary effluents from various full-scale wastewater treatment plants. The results demonstrated that the normalized final flux by fouling in FO was closely correlated to the ORI measurements with high statistical reliability (R2 = 0.84). After conducting a long-term stable FO operation, it is deduced that the ORI is a useful evaluation parameter for continuous FO and its cleaning cycles in which periodic flushing is normally utilized to exploit and enhance the fouling reversibility of FO. Graphical abstract fx1 Highlights • An osmotically-driven reversibility index (ORI) was developed for FO process. • ORI simulates FO fouling reversibility and its operational protocol was constructed. • High correlation of ORI and FO fouling was obtained using various real wastewaters. • ORI is a useful evaluation parameter for continuous FO and its cleaning cycles. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Introduction of the environmental impacts index on RO system. • Choosing the optimum configuration and ORC fluid from 4E+D point of view. • The benefit of low grade heat losses to reduce the environmental impacts of RO. • Water-Energy-Environmental nexus. Abstract This paper presents the concentration disposal index (CDI) concept extension for increasing the Water–Energy-Environmental nexus and reducing the environmental impacts of RO system brine. This non-dimensional index introduces the difference between the density of brine flow and raw water tank in recovery. This concept is utilized in main engine system of the ship. Different configurations of Organic Rankine Cycle (ORC) and working fluids are studied at the outlet of high temperature thermal source (280 °C), based on Energy analysis (1E), Exergy (2E), Economic (3E) and environmental impacts (4E) in order to produce desalinated water (4E+D). The output power from ORC is used as the driver of RO high pressure pump. Based on the waste heat in system, the sources are used for preheating of RO system pump inlet water. These sources are: Lubricating oil, air cooler and jacket cooler and ORC condenser. The key parameters in optimization are: (1) the ORC configuration choice, (2) the working fluid of Rankine cycle based on thermal source, (3) the RO system optimum design, (4) the membrane selection among the DOW company membranes, (5) the pinch and approach temperatures of the Waste Heat Recovery (WHR), (6) the reduction of environmental impacts of RO brines, (7) the selection of Energy Recovery Device (ERD). Determination of these parameters is done according to system optimization by genetic algorithm (GA). In order to consider the CDI function impact, once the system is considered with two objectives based on exergy efficiency of the entire cycle and the unit product cost (UPC) and then is considered by three objectives; the two mentioned ones and the CDI function. The results of these two optimizations indicate that, utilizing CDI reduces the ultimate concentration of the brine and increases the buoyancy force for faster mixture. In three-objective optimization, the ORC configuration is chosen with the recuperator, the R245ca working fluid, the two-stage RO system and the SW30XLE-400i membrane for both of stages. [ABSTRACT FROM AUTHOR]

Abstract Recent progress in reverse osmosis (RO) technology is not limited to RO membrane materials, module designs and RO process optimization. It involves prior feed treatment which directly impacts RO system performance. The ongoing challenges of membrane fouling in RO membranes can be addressed by increasing the operational efficiency through the use of correct pretreatment options which can mitigate organic and inorganic fouling by selectively rejecting contaminants prior to reaching the RO unit. Highly polluted water resources have put critical stress on the existing conventional pretreatment techniques, whereby membrane pretreatment has emerged as a promising alternative. This paper provides an overview of the development and current trends in conventional and non-conventional RO pretreatment techniques whereby the techniques are critically reviewed to inform readers of potential improvements in such areas. This paper addresses the major drawbacks of conventional pretreatment methods which have necessitated the use of membrane pretreatment techniques. Special attention is given to microfiltration, ultrafiltration and nanofiltration methods and their development in terms of advanced membrane materials based on ceramics and self-cleaning membranes. Studies from laboratory scale standalone systems, pilot scale and large scale integrated systems for performance, cost and ecological analysis have been reviewed to familiarize readers with the many factors which need to be analyzed for selection of the appropriate pretreatment method(s). The critical review in this paper will help researchers focus more on the areas which have room for further development for cost-effective and advanced RO pretreatment techniques. Highlights • Reverse osmosis (RO) pretreatment continues to be one of the most challenging aspects of RO plants. • Membrane pretreatment capital and operational cost is higher than conventional pretreatment. • Membrane pretreatment water production cost is smaller than conventional ones due to improved permeate quality. • Ultrafiltration system with minimal prior pretreatment can reduce the cost of the overall RO process. • Integrated pretreatment systems incorporating nanofiltration saved up to 25–30% energy. [ABSTRACT FROM AUTHOR]

Abstract In the context of decentralised brackish water treatment in development applications, the influence of water quality on membrane separation was investigated with real waters. High ionic strength (low net driving pressure) on fluoride (F) retention by nanofiltration (NF) and reverse osmosis (RO) was investigated over a wide pH range (2–12). Further, the influence of pH on the permeation of natural organic matter (NOM) fractions, in particular low molecular weight (LMW) neutrals, was elucidated. Natural and semi-natural waters from Tanzania with similar F concentrations of about 50 mg L−1 but varying NOM and inorganic carbon (IC) concentration were filtered with an NF and RO, namely NF270 and BW30. F retention by NF270 for the feed water with highest ionic strength and IC concentration was lower and attributed to charge screening. This parameter further reduced at high pH due to co-ions (F− and CO 3 2−) interactions and combined (synergistic) effect of high salt concentration and pH on F. High NOM resulted in higher membrane zeta potential in comparison with low NOM natural water. However, there was no significant difference in F retention due to the fact that F retention enhancement was annulled by deposit formation on the membrane. The fraction of NOM found in NF/RO permeates was dominated by LMW neutrals. This was attributed to their size and uncharged nature, while their higher concentration at low pH remains unexplained. More humic substances (HS) of higher molecularity and aromaticity permeated the NF270 when compared with BW30, which can be explained with the different membrane molecular weight cut off (MWCO). The study highlights the complexity of treating tropical natural waters with elevated F and NOM concentrations. In order to develop appropriate membrane systems that will achieve optimal F and NOM removal, the influence of water quality parameters such as pH, NOM content, ionic strength and IC concentration requires understanding. Seasonal variation of water quality as well as operational fluctuations, which occur in particular when such treatment processes are operated with renewable energy, will require such challenges to be addressed. Further, given the high permeability of low molecular weight (LMW) organics significant permeate side fouling may be expected. Highlights • Real tropical waters with different IS, IC, NOM but similar F content treated by NF/RO. • At high IS & pH, F retention decreases due to IC speciation, pH and salt effect. • No enhancement effect of high NOM on F retention was observed. • A discrepancy between permeate NOM measured by TOC analyser and LC−OCD was observed. • According to LC−OCD results, LMW neutrals accounted for 60–90% of permeate NOM. [ABSTRACT FROM AUTHOR]

Abstract Swine wastewater treatment plant has become one of the main sources of antibiotic resistance genes (ARGs). Membrane treatment processes are promising solutions for removal of the emerging contaminants. However, limited studies have investigated the effects of nanofiltration and reverse osmosis treatment in removing ARGs in swine wastewater. In this study, the presence and the fate of common ARGs including sul 1, sul 2, tet A, tet M and tet W, as well as intI 1 and 16S rRNA gene, were investigated in a medium-sized (6500) pig farm wastewater treatment plant (WWTP) equipped with conventional biological treatment and advanced membrane processing system. All of the genes were detected with highly abundance in the raw sewage. The biological treatments of the swine wastewater treatment plant did not reduce the quantity of the ARGs. As expected, nanofiltration and reverse osmosis treatment reduced the absolute gene copy number of ARGs efficiently (4.98–9.52 logs removal compared to raw sewage). Compared to the reverse osmosis effluent, however, the absolute abundance of ARGs in the artificial wetland increased by 1.00–2.06 logs. Meanwhile, the relative abundance of sulfonamide resistant genes were basically unchanged, while tetracycline resistance genes (tet A, tet M and tet W) decreased by 0.88, 3.47, 2.51 log, respectively. The results demonstrated that advanced membrane treatments are capable of removing various kinds of ARGs efficiently, as well as some common nitrogen and phosphorus contaminants. This study suggested a mature alternative method for the removal of ARGs from livestock wastewater. Graphical abstract Image 1 Highlights • Swine sewage presents high content of ARGs. • Nanofiltration and reverse osmosis reduces ARGs, nitrogen and phosphorus contaminants. • The abundance of ARGs in artificial wetland increased. [ABSTRACT FROM AUTHOR]

Abstract One possible contender to replace conventional reverse osmosis schemes is an energy solution where inexhaustible resources work together with a reverse osmosis plant. Based on the experience of an existing wind-powered desalination scheme run for more than 15 years by Soslaires Canarias S.L., the final objective of this paper is to propose improvements to the scheme so as to achieve a reduction in the cost of water (through restrained capital expenses) for the sake of greater feasibility and efficiency. The cost of the scheme is evaluated assuming a combined use of a reverse osmosis desalination plant and wind energy, using, for this purpose, the (exclusive) information provided by the industrial partner. Results showed that by carrying out the actions suggested in this paper, this scheme would be able to reduce its cost of water (COW) by about 0.022 EUR per cubic meter for the current LCOE of wind turbine technology in the study area (about 6 c€/kWh for the southeast of the island of Gran Canaria, Spain). This would mean that with an additional total capital investment cost of 196 000 € (from the current scheme of Soslaires Canarias S.L.), and supposing an average membrane life expectancy of 10 years for the current state-of-the-art membranes, a net present value of 74 360.95 €, a profitability index of 1.3794, and a 224.4881% internal rate of return would be achieved. Graphical abstract Typical cost structure for RO seawater desalination. Image 1 Highlights • Several configurations of desalination plants based RES have been simulated. • Cost of water has been considered as the central element of the evaluation. • In case of carrying out the actions suggested COW would be reduced. [ABSTRACT FROM AUTHOR]

Fluoride contamination of groundwater has become a major concern worldwide, resulting in serious medical conditions such as dental and skeletal fluorosis. Consequently, the WHO recommends that drinking water should not contain more than 1.5 mg/l of fluoride. Various defluoridation techniques such as coagulation, reverse osmosis, activated alumina adsorption, and biosorbent adsorption have been developed. Adsorption through the activated alumina and biosorbent process is not cost effective and has regeneration problems, and the reverse osmosis process has the high initial cost which makes it unacceptable for developing countries. Coagulation is a commonly employed field technology for defluoridation, which involves the addition of aluminum salts, lime, and bleaching powder followed by rapid mixing, flocculation, sedimentation, and filtration but suffers from a limitation of high residual aluminum in treated water. This paper critically reviews the recent developments in the coagulation technique for defluoridation along with its comparison to other defluoridation techniques. The review describes the pertinent gaps in the process and throws open suggestions for extending research by citing the recent studies which may lead to the revival of the process. The description about the suspension of alumino-fluoro complexes that constitute a substantial part of the residual aluminum after alum treatment has been narrated in the paper that helps in a deeper understanding of the defluoridation mechanism. To make the process highly suitable for communities, appropriate technological interventions, such as converting it to a continuous mode of operation, replacing alum with poly-aluminum chloride (PAC), and attaching a micro-filtration unit in series of the existing process, can be done. Also, using PAC as a coagulant with sand filtration has to be considered for making the process more efficient. [ABSTRACT FROM AUTHOR]

Abstract As potable reuse guidelines and regulations continue to develop, the presence of N -nitrosamines is a primary concern because of their associated health concerns. In this study, bench-, pilot-, and full-scale tests were conducted to focus on the occurrence and treatment of N -nitrosomorpholine (NMOR) in United States (U.S.) potable reuse systems. Out of twelve U.S. wastewater effluents collected, ambient NMOR was detected in eleven (average = 20 ± 18 ng/L); in contrast, only two of the thirteen surface water and stormwater samples had NMOR. Across all of these samples maximum formation potential by chloramination produced an average increase of 3.6 ± 1.8 ng/L. This result underscores the need to understand the sources of NMOR as it is not likely a disinfection byproduct and it is not known to be commercially produced within the U.S. At the pilot-scale, three potable reuse systems were evaluated for ambient NMOR with oxidation (i.e., chlorination and ozonation), biofiltration, and granular activated carbon (GAC). Both pre-oxidation and biofiltration were ineffective at mitigating NMOR during long-term pilot plant operation (at least eight-months). GAC adsorbers were the only pilot-scale treatment to remove NMOR; however, complete breakthrough occurred rapidly from <2000 to 10,000 bed volumes. For comparison, a full-scale reverse osmosis (RO) potable reuse system was monitored for a year and confirmed that RO effectively removes NMOR. Systematic bench-scale UV-advanced oxidation experiments were undertaken to assess the mitigation potential for NMOR. At a fluence dose of 325 ± 10 mJ/cm2 , UV alone degraded 90% of the NMOR present. The addition of 5 mg/L hydrogen peroxide did not significantly decrease the UV dose required for one-log removal. These data illustrate that efficient NMOR removal from potable reuse systems is limited to RO or UV treatment. Highlights • Surface waters and wastewaters typically did not form NMOR under chloramination. • Ozone-BAC did not significantly remove NMOR during pilot-plant operation. • Limited sorption of NMOR was observed during GAC pilot-plant operation. • Low pressure UV removed NMOR at doses lower than those required for NDMA. • Significant removal of NMOR in potable reuse is limited to RO or UV treatment. [ABSTRACT FROM AUTHOR]

Abstract The robustness of reverse osmosis (RO) against polar organic micropollutants (MPs) was investigated in pilot-scale drinking water treatment. Experiments were carried in hypoxic conditions to treat a raw anaerobic riverbank filtrate spiked with a mixture of thirty model compounds. The chemicals were selected from scientific literature data based on their relevance for the quality of freshwater systems, RO permeate and drinking water. MPs passage and the influence of permeate flux were evaluated with a typical low-pressure RO membrane and quantified by liquid chromatography coupled to high-resolution mass spectrometry. A strong inverse correlation between size and passage of neutral hydrophilic compounds was observed. This correlation was weaker for moderately hydrophobic MPs. Anionic MPs displayed nearly no passage due to electrostatic repulsion with the negatively charged membrane surface, whereas breakthrough of small cationic MPs could be observed. The passage figures observed for the investigated set of MPs ranged from less than 1%–25%. Statistical analysis was performed to evaluate the relationship between physicochemical properties and passage. The effects of permeate flux were more pronounced for small neutral MPs, which displayed a higher passage after a pressure drop. Graphical abstract Image 1 Highlights • Strong size-passage correlation for neutral hydrophilic organics (log D <2). • Weaker size-passage correlation for moderately hydrophobic organics (log D >2). • Passage of cationic organics was higher than that of anions of comparable size. • Low permeate flux resulted in increased passage of small neutral polar organics. • Higher salt and organic passage observed for at least 5 h following a pressure drop. [ABSTRACT FROM AUTHOR]

Introduction: In this study, we investigated contaminants in sediments of reverse osmosis water systems in Iraqi households. These filters are imported from the US and Taiwan and are available in the Iraqi market. The rate of environmental pollutions in residues of the water filters was examined by measuring alpha particles emission rates and the concentration of heavy metals. Material and Methods: In this study, we measured the rate of alpha particles emission using CR-39 detector. Heavy elements were measured using an atomic absorption spectrometer. Results: The highest value of cadmium was found in Ghadeer district and the lowest cadmium value in Alswag district. The highest value of lead was found in Ghadeer district and the lowest in Aljameha. The emission rates of alpha particles were found to be the lowest in the sediments of Ghadeer district, and the highest values were found in Khan Almkhdhar. Conclusion: The average concentrations of dissolved Cd and Pb were higher than the safe limits for Iraq specifications and the world standard limit. [ABSTRACT FROM AUTHOR]