Water Treatment Problems Research Articles

Screening of new adsorbents to remove algal organic matter from aqueous solutions: kinetic analyses and reduction of disinfection by-products formation.

The algal organic matter (AOM) is a problem in water treatment. Although the adsorption process is extensively applied to drinking water treatment, little information is known about the potential of new adsorbents to remove AOM. Herein, this work evaluated the removal of AOM and its main compounds (dissolved organic carbon (DOC), carbohydrate, and protein) by new adsorbents-mesoporous silica (SBA-16), graphene oxide material from citric acid (CA), and sugar (SU), and a composite of CA immobilized on sand (GSC). In general, the removal efficiencies followed the order of SBA-16 > CA > SU or GSC for DOC, carbohydrate, and protein. At environmental condition (5mg DOC·L-1 and pH 8), high removals were reported for SBA-16 (88.8% DOC, 80.0% carbohydrate, and 99.6% protein) and CA (70.0% DOC, 66.7% carbohydrate, and 89.7% protein), while moderate removals were found for SU (60.5% DOC, 47.9% carbohydrate, and 66.5% protein) and GSC (67.4% DOC, 60.8% carbohydrate, and 57.4% protein). Based on these results, further analyses were done with SBA-16 and CA. Both adsorbents' efficiencies decayed with the pH increment of the test water. Disinfection by-products reductions found using SBA-16 - trihalomethanes (58.2 to 94.7%) and chloral hydrate (48.7 to 78.8%) - were higher than the ones using CA-trihalomethanes (45.2 to 82.4%) and chloral hydrate (40.1 to 70.8%). This study showed the potential of applying these adsorbents for AOM removal, and further investigations are suggested to increase the adsorption capacity of these adsorbents.

Investigation of scale inhibition effect and mechanism of S-HGMF in the clean recirculating cooling water system

The formation of scales in a recirculating water system is a common problem in industrial water treatment; it seriously affects the production in various industries and pollutes the environment. Although conventional scale inhibition methods are effective, they are expensive and harm the environment. Herein, an advanced method is proposed to solve the scaling issue in recirculating cooling water systems using the superconducting high-gradient magnetic field (S-HGMF) treatment. The scale inhibition performance could be improved by changing the magnetic flux density, operation time, and flow rate. The results showed that S-HGMF could increase the number of hydrogen bonds in the recirculating cooling water, enhance molecular interaction, increase the thickness of the ion hydration shell, reduce the nucleation rate, stabilize the water quality, improve the solubility of scale-forming ions, and inhibit scale formation. The scale inhibition performance reached 8.10%. Interestingly, S-HGMF had a memory effect in that it could maintain the scale inhibition effect for some period after treatment completion. Moreover, S-HGMF changed the crystal structure of the scale and promoted the transformation of the scale to a metastable phase. Ultimately, calcite was transformed to aragonite to reduce the precipitation of hard scale (calcite), achieving the purpose of scale inhibition. As a physical method, the application of S-HGMF to inhibit scaling has great potential for industrial applications.

Effectiveness of pulse dosing of submicron super-fine powdered activated carbon in preventing transmembrane pressure rise in outside-in-type tubular and inside-out-type monolithic ceramic membrane microfiltrations

Membrane fouling is still a major problem in water treatment that uses membrane separation. In this study, submicron-sized super-fine powdered activated carbon (SSPAC) was applied in a pulse/continuous dose to ceramic-membrane microfiltrations of two very different types: a submerged tubular membrane system that enabled vacuum-driven, outside-in filtration and a monolithic membrane system that enabled pressure-driven, inside-out filtration. Constant-flux filtration with repeated hydraulic backwashing was performed using diluted secondary-treated municipal wastewater and natural river water, and the effect and mechanism of membrane fouling mitigation were investigated. Pulse dosing with SSPAC alleviated a rise of transmembrane pressure (TMP) more than continuous dosing in the submerged tubular membrane system because of the effects, inter alia, associated with precoating the SSPAC layer as well as adsorption, by which soluble membrane foulants were effectively removed. Moreover, pulse-dosed SSPAC combined with a coagulant formed a precoat layer on the membrane that was easy to peel off with hydraulic backwashing. Continuous dosing of SSPAC was inferior to pulse dosing of SSPAC in terms of water quality, and some SSPAC was left on the membrane surface after hydraulic backwashing. In the monolithic membrane system, however, the superiority of pulse dosing of SSPAC was not observed: pulse and continuous dosing of SSPAC led to similar reductions of TMP rise. The SSPAC layer was unevenly distributed along the length of a channel and between channels in the monolithic membrane.

Partnership helps Flowserve solve challenging problems in the water treatment sector

In the USA, Flowserve Corp has entered into a non-exclusive partnership agreement with Gradiant Corp to help address the most challenging problems in water and wastewater treatment.

Treatment of formation water at oil fields using granular filters with varying particle sizes

Purpose. Increasing oil recovery from reservoirs, reducing water content, and decreasing costs by pumping formation water effectively cleaned of suspended solids allows you to get a picture of the uniform distribution of water over the reservoir and, in general, the quality maintenance of reservoir pressure in productive reservoirs. Methodology. The study on water treatment issues for maintaining reservoir pressure at existing oil fields has a variety of approaches. Therefore, the methods of analysis, review, comparison, modeling, experiment were used in the work. The analysis method made it possible to divide the problems of approaches to the formation water preparation for its injection into the reservoir into many elements, which made it possible to learn their properties, connections and relationships. This method contributes to a more detailed structuring of the problem of water treatment. The analogy method uses the study of the technology of preparation of reservoir water with suspended solids. Based on the data, an effective technology was studied for treating formation water from suspended solids and injecting it into a productive formation. Findings. The experiments carried out reflect the high-quality water preparation using the developed new industrial sand-gravel filter made of granular materials with variable particle sizes in the vertical direction, taking into account the rational parameters of the column height of the filter working area. The regularities were studied and the process of formation water preparation without suspended solid particles was improved on the basis of the theoretical and experimental studies carried out on a special laboratory unit. The dependence of the reservoir permeability in the bottomhole zone of injection wells on the size of solid suspended particles in the injected water was determined, and rational filter parameters were established for preparing injected water without suspended solid particles into the reservoir using granular materials with a variable fraction and water supply from the bottom up. Originality. An effective technology for deep purification of formation water from suspended clay particles is proposed by using filters made of granular materials with a variable particle size. The technical result of the invention is to increase the efficiency of purification of industrial waste and industrial formation waters with suspended solids. Practical value. A new method for deep formation water treatment is proposed, which ensures the capture of suspended solids. The results of experiments on establishing the regularity of the process of formation water filtration with suspended clay particles through a porous medium with variable pore sizes and granular particles are presented. A recommendation has been developed for choosing rational parameters and operating modes of a new filter for formation water treatment.

Compounding Challenges

Protecting public health by ensuring communities have safe, sufficient water isn't easy on a good day, but lately it seems like water and wastewater systems have had an uphill climb. The vital water infrastructure that communities depend on was designed to serve the present day while anticipating future needs. Unfortunately, in many cases the challenges of today are much greater than were imagined decades ago. The foundational issues are still there and water supply and treatment problems still need to be solved, but local and large-scale disasters are happening at an alarming pace, making the estimation of future needs more difficult. At times, we seem to be tracking some of the worst-case projected scenarios. Earthquakes, tornados, hurricanes, super high winds, fires, floods, deep freezes, heat waves, (mega)droughts—they're growing more frequent, more intense, and at times, they can follow in succession and even overlap. It isn't just nature that's highly variable these days. Political transitions can shake up priorities, and instability leads to general distrust in government. Anger at the federal and state/province level can carry over to local units, and it seems as if science hasn't been this distrusted in a long time. All of this can make dialog hard and collaboration untenable. Social issues, which go hand in hand with financial matters, are not as straightforward as we'd like to think since they are tethered to politics, too. Community expectations continue to grow, which is great, but it means more time, transparency, and training to properly meet those expectations. With increasing connectedness and technology come increasing security issues, and now bad actors can attack a utility's physical assets as well as its network-based controls and data. How about a global pandemic and all its associated health and safety adversity? Add to that supply chain issues, labor issues, inflation, global conflicts, and more. With so many disasters and difficulties to keep in mind at any one time, it can feel overwhelming. But while the issues are significant, the water industry is working to address them, and water professionals need to consider how systems will respond to a few at once and/or challenges that follow close after one another. Journal AWWA can help by highlighting how utilities are anticipating and responding to the many challenges facing them and their communities. This month's Journal AWWA features timely topics, including lead service line replacement, water quality modeling, and mitigating climate change. Please consider sharing your perspectives and experiences with water professionals everywhere by writing me at journaleditor@awwa.org.

Insights into recent advances of chitosan-based adsorbents for sustainable removal of heavy metals and anions

With globally increased human population and industrialization, the natural sources of water are reduced and then contaminated. Therefore, development of advanced technologies for the efficient water treatment is becoming of the scope of each of the nation. One of the cost-effective and well-known technologies for wastewater treatment is adsorption of contaminants by natural biopolymer like chitosan (CS) due to its unique features such as availability, biodegradability, biocompatibility, eco-friendly and low-cost production. However, Cs suffers considerable limitations such as low adsorption capacity, low surface area and limited reusability. Thence, this review intended to provide an overview for recent advances of chitosan-based adsorbents that established better adsorption activities towards various hazard heavy metals, including: As(III), As(V), Cu(II), Cr(VI), Pb(II) and Cd(II) ions. In addition, the capabilities of chitosan-based adsorbents for the adsorptive removal of anions including phosphates and nitrates were discussed. Besides, the suggested adsorption mechanisms of these contaminants onto chitosan-based adsorbents and the research conclusions for the optimum conditions of the adsorption processes were explained in light of the currently reported studies. Furthermore, to emphasize the foremost research gaps and future potential trends that could inspire further researchers to find out the best solutions for water treatment problems.

Research on zero discharge treatment technology of mine wastewater

In order to solve the problem of mine water treatment in the production process of coal mine enterprises, the source and characteristics of mine water are introduced, and the zero discharge technology of mine water is studied and applied in engineering, the zero discharge technology of mine water includes three stages: pretreatment, concentration and reduction, and evaporation and crystallization. The results show that: for the mine water with TDS mass concentration of 3200 mg/L, coagulation clarification process is used for pretreatment, reverse osmosis+DTRO is used for concentration and reduction, MVR is used for evaporation and crystallization, the TDS concentration of concentrated water after treatment is 142000 mg/l, the recovery rate of the system is 84.5%, and the TDS of final water production is about 418 mg/l, which meets the design and reuse requirements. The sodium sulfate produced in the evaporation crystallization stage is about 4.9 t/h, and its purity is 99.12%, which can be used as chemical raw material.

Research and results of mathematical modeling of block ion-exchange water treatment plants operating modes and regeneration

The problem of water treatment at thermal power plants using ion-exchange technologies is a multi-parameter task. Mathematical modeling is essential for research and optimization of ion exchange technology. The analysis of hydrodynamic processes during the operation of ion-exchange filters was carried out according to the developed mathematical model. Also, a physicochemical analysis of the composition of the water treatment plant solutions under real conditions was carried out. It is shown that in the cationite and anionite filters, the flow movement occurs mainly in a mixed hydrodynamic mode. This mode of regeneration and the filter design do not allow achieving the minimum consumption of the reagent for regeneration, the minimum volume of wastewater and the maximum output of demineralized water. The mixed mode of the anion exchange filter operation allows division of the outgoing solution flow into fractions, which can be successfully used in the TPP water cycle.

Ballast water management: technology choice comparing TODIM and THOR 2

This paper approaches the problem of ballast water treatment in ships. This has been identified as one of the four greatest threats to the world’s oceans. Solutions that have been considered for solving the problem are alternative water treatment technologies. In the case study reported in this paper three major water treatment technologies have been evaluated with the help of twenty-six criteria, quantitative as well as qualitative by using two discrete multicriteria methods, TODIM and THOR 2. The THOR 2 consists of the axiomatic evolution of the THOR method and both THOR 2 and THOR are made available through the THOR Web platform. Five groups of evaluation criteria are then considered: practicality; biological effectiveness; cost/benefit ratio; time frame for the implementation of standards; and environmental impact of the process' sub-products. In this paper a case study on choosing a ballast water treatment technology is presented. Three alternative ballast water management technologies are proposed by experts in the field and are evaluated with the help of twenty-six criteria, quantitative as well as qualitative. Each ballast water management method is described by a list of twenty-six attributes or criteria. After setting the problem in a clear way and consulting different experts, the two separate applications of both TODIM and THOR 2 are performed. What is denoted as Management Method #1 is indeed chosen as the best alternative according to both methods. The conclusion is that those two methods, although conceptually and analytically quite different, lead essentially to the same main results. Two other applications of both TODIM and THOR have indeed confirmed the convergence of results in spite of the conceptual and technical differences between the two methods. This suggests that formulating a decision problem in a correct, clear-cut way can be at least as important as the technical characteristics of the method per se.

Carbon‐Fiber Cloth Decorated with 3D Flower‐Like GO/WO3 Quantum Dots/TiO2 Microsphere with High Photocatalytic Activity under Natural Sunlight

AbstractNanopowder photocatalyst suffers two serious problems (low photocatalytic efficiency, easy aggregation, and difficult recycling) in water treatment. For solving these issues, a 3D flower‐like graphene oxide (GO)/WO3 quantum dots (QDs)/TiO2 microsphere (FWGT) with excellent photocatalytic property is synthesized by a hydrothermal method which can degrade 100% Rhodamine B (RhB) within 10 min under solar light irradiation. Meanwhile, a carbon‐fiber cloth/FWGT (CF/FGT) membrane is constructed by decorating the FWGT microsphere on the surface of the carbon‐fiber cloth. CF/FGWT membrane displays better photocatalytic activity compared with carbon‐fiber cloth/flower‐like GO/TiO2 microsphere (CF/FGT) membrane, which the reaction rate constants of CF/FGWT membrane are 3.52 times higher than that of CF/FGT membrane. Moreover, the CF/FGWT membrane shows a little quality loss (about 1.7%) after several recycles, indicating the novel flexible photocatalytic membrane has great potential for purifying water.

Fabrication of highly permeable and anti-fouling performance of Poly(ether ether sulfone) nanofiltration membranes modified with zinc oxide nanoparticles

Membrane fouling is one of the challenging bottleneck problems in waste water treatment by membrane process. The present study constructed a nanofiltration membrane based on the zinc oxide nanoparticle (n-ZnO) integrated Poly(ether ether sulfone) (PEES) membranes. The developed membranes were characterized by X-ray diffraction (XRD), attenuated total reflectance - fourier transform infrared spectroscopy (AT-FTIR), atomic force microscopy (AFM) and scanning electron microscope (SEM) coupled with energy dispersive X-ray (EDX) analysis. Pure water flux, contact angle, molecular weight cut-off, mean pore size and porosity were determined to investigate the influence of n-ZnO on the properties of the membranes. The characterization showed asymmetric configuration of membranes after n-ZnO incorporation. This incorporation also enhanced the hydrophilicity of PEES membrane. The fouling-resistant potential of the membranes was investigated by the model foulant humic acid (HA) and an enhanced anti-fouling irreversible property with a corresponding flux recovery rate of 92.43 % was noted for the prepared membrane. The rejection performance and permeability of HA was 98.03 % and 166.73 L m−2 h−1, respectively, owing to the hydrophilic nature of ZnO particles. Further, modified PEES membrane exhibited superior separation performance for monovalent and divalent anions. PEES/n-ZnO hybrid membrane assisted nanofiltration is an effective process for the improvement of membrane performance and anti-fouling property, demonstrating its immense use in water reclamation.

Study of electrostatic parameters of aqueous suspensions for solving the tasks of water treatment and selection of optimal filter media

Relevance of research. At present, there is a need for a comprehensive study of both physical and chemical parameters of substances, which is the primary source of deteriorating treated water quality, as well as the relevant physical properties of the actual filter media to determine the mechanism of their interaction. Such a parameter of purified water as turbidity is closely related to the electrostatic properties of the colloids contained in water. For a more detailed experimental study of this interaction, an operating water treatment facility was chosen. A preliminary study of the conditions at the Communal Enterprise "Chernivtsivodokanal" in the city of Chernivtsi, Ukraine made it possible to identify the typical problems that need to be immediately addressed. The study revealed that the main indicator that is critical for the purification of these waters is turbidity, and one of the main growing concerns to be addressed is the replacement of the filter media.
 Research results. To select optimal filter media, a comprehensive study of the electrostatic parameters of all components in the water treatment process was carried out. Experimental studies of physical quantities that are key to this process were performed. The relationship between the turbidity parameters of the studied waters and the ζ-potential of the colloids contained in them was shown. Seasonal changes in the hydrochemical composition of the treated waters were studied. The connection between electrochemical parameters of clay particles and the processes of their sedimentation in aqueous suspension is given. The dependences of turbidity on time and the ratio of average turbidity values to the minimum and maximum ones at the water intake of the Dniester-Chernivtsi water supply system during 2005-2015 were reviewed and presented. The dynamics of changes in the parameters of turbidity and ζ-potential in the structures of the technological chain of water treatment during the periods of summer-autumn floods and low-water winter period was studied. The effect of the coagulant used at the studied water treatment facility on the electrostatic parameters of the purified colloidal particles, in particular, on changing the structure of the electric double layer of clay particles, which lead to the coagulation and reduction in the treated water turbidity, was analyzed. The optimal conditions of using polystyrene foam and zeolite filter media were determined. Ion exchange properties enabled the zeolite to efficiently remove fine colloidal particles with positively charged cores out of the purified aqueous suspension, which were not completely covered with a layer of potential-forming ions. However, they produced impact only in the short-term initial stage of filtering. Therefore, they cannot be recommended for using for long-term water treatment processes at water treatment facilities. This phenomenon is due to the limited ion exchange adsorption properties of zeolite. The effective filtration of colloidal particles through zeolite in the year-round mode of operation at the studied water treatment facility is mainly associated with the developed outer surface of its grains, which provides mechanical interception and retention of colloidal particles.
 Conclusions. The connection between the turbidity parameters and colloids ζ-potential of the purified aqueous suspension for the conditions of water quality formation in the upper reaches of the Dniester River has been established. The determined values of the ζ-potential of colloids enabled to find out that the polystyrene foam filter media is more expedient to use during the flood periods, and the application of the zeolite media has a higher efficiency during the low-water periods. The ion exchange properties of zeolite can ensure a high level of water purification during floods; however it can be only efficient at the initial stage of filtration. Effective mechanical interception and retention of colloidal particles in the year-round regime is provided by the developed surface of its grains. The combined polystyrene foam and zeolite filter media is recommended to use to solve the problems of water treatment throughout the year.

Construction of fungi-microalgae symbiotic system and adsorption study of heavy metal ions

Harvesting and immobilization are problem in microalgae water treatment. Here, mycelial pellets (Aspergillus fumigatus) and Synechocystis sp. PCC6803 comprised a fungi-microalgae symbiotic system (FMSS) of hypha-pellet flocculant auxiliary microalgae solidification. Optical and scanning electron microscopy (SEM) revealed that green particles were attached to fungal mycelia. A 98% adsorption and immobilization efficiency of mycelium pellets to microalgae was evident. Under the condition of 108 cells/mL logarithmic phase microalgae and no fungal culture medium, the symbiotic system had higher stability and better Cd(II) adsorption efficiency (98.89%, 37.3 mg g−1). Meanwhile, the symbiotic system prolonged the growth cycle of microalgae in the adsorption. After Cd(II) ion stimulation, the content of total extracellular polymeric substances (EPS) in the FMSS was significantly higher than that in the control group, and the change of extracellular polysaccharide was more obvious. High performance anion exchange chromatography-pulsed amperometric detection (HPAEC-PAD) showed that the monosaccharide composition of extracellular polysaccharides increased. Three dimensional excitation emission matrix (3D-EEM) spectrum analysis showed the peak intensity of protein fluorescence changed with the treatment of heavy metals. FTIR spectra showed that the functional groups (such as OH, CONH) of EPS participated in the adsorption process. The findings showed that the key components of EPS, extracellular polysaccharides and extracellular proteins, played an important role in the symbiotic system to cope with the stress of heavy metal and resist the toxicity of heavy metal. The preliminary data can inform development and utilization of engineering strains and gene transformation.

Retraction: A study on the impact of contaminated water treatment problems in the Fukushima Daiichi Nuclear Power Plant Accident reconstruction process

Retraction: A study on the impact of contaminated water treatment problems in the Fukushima Daiichi Nuclear Power Plant Accident reconstruction process

Approaches to herbicide (MCPA) pollution mitigation in drinking water source catchments using enhanced space and time monitoring

Freshwater occurrences of the selective acid herbicide 2-methyl-4-chloro-phenoxyacetic acid (MCPA) are an ongoing regulatory and financial issue for water utility industries as the number and magnitude of detections increase, particularly in surface water catchments. Assessments for mitigating pesticide pollution in catchments used as drinking water sources require a combination of catchment-based and water treatment solutions, but approaches are limited by a lack of empirical data. In this study, an enhanced spatial (11 locations) and temporal (7-hourly to daily sampling) monitoring approach was employed to address these issues in an exemplar surface water source catchment (384 km2). The spatial sampling revealed that MCPA was widespread, with occurrences above the 0.1 μg L−1 threshold for a single pesticide being highly positively correlated to sub-catchments with higher proportions of ‘Improved Grassland’ land use (r = 0.84). These data provide a strong foundation for targeting catchment-based mitigation solutions and also add to the debate on the ecosystems services provided by such catchments. Additionally, of the 999 temporal samples taken over 12 months from the catchment outlet, 25% were above the drinking water threshold of 0.1 μg L−1. This prevalence of high concentrations presents costly problems for source water treatment. Using these data, abstraction shutdowns were simulated for five scenarios using hydrometeorological data to explore the potential to avoid intake of high MCPA concentrations. The scenarios stopped abstraction for 4.2–9.3% of the April–October period and reduced intake of water containing over 0.1 μg L−1 of MCPA by 16–31%. This represents an important development for real-time proxy assessments for water abstraction in the absence of more direct pesticide monitoring data.

Characterization of the Bacterial Biofilm Communities Present in Reverse-Osmosis Water Systems for Haemodialysis.

Biofilm in reverse osmosis (RO) membranes is a common problem in water treatment at haemodialysis facilities. Bacteria adhere and proliferate on RO membranes, forming biofilms, obstructing and damaging the membranes and allowing the transfer of bacteria and/or cellular components potentially harmful to the health of haemodialysis patients. Our aim was to characterize the bacterial community associated to biofilm of RO membranes and to identify potentially pathogenic bacteria present in the haemodialysis systems of two dialysis centres in Chile. The diversity of the bacterial communities present on RO membranes and potable and osmosed water samples was evaluated using Illumina sequencing. Additionally, bacteria from potable water, osmosed water and RO membrane samples were isolated, characterized and identified by Sanger’s sequencing. The molecular analyses of metagenomics showed that the phyla having a greater relative abundance in both dialysis centres were Proteobacteria and Planctomycetes. Pseudomonas, Stenotrophomonas, Agrobacterium, Pigmentiphaga, Ralstonia, Arthrobacter, Bacteroides and Staphylococcus were bacterial genera isolated from the different samples obtained at both haemodialysis centres. Pseudomonas spp. was a bacterial genus with greater frequency in all samples. Pseudomonas and Staphylococcus showed higher levels of resistance to the antibiotics tested. Results demonstrated the presence of potentially pathogenic bacteria, showing resistance to antimicrobials on RO membranes and in osmosed water in both dialysis centres studied.

Formation of mine water composition and analysis of treatment methods

Formation of mine water inflow compositions is discussed, and the methods of mine water treatment are described. Mine water has different chemistry depending on hydrological, geological and geotechnical factors, as well as on depth of mining. Formation of mine water on higher horizons takes place under the influence of oxidation processes, while reduction processes are typical of lower levels. With an increasing depth, hydrocarbonate water changes into carbonate-sulfate and sulfate-hydrocarbonate water. The main pollutants of mine water are identified, the methods of mine water treatment are reviewed, the criteria of application of mine water treatment methods are specified, and the advantages and disadvantages of the methods are described. In terms of the Kirov Mine, the structure of mine water treatment facilities is considered. It is found that equipment included in the process flow chart ensure good removal of various size suspended solids from water and partially remove iron ions (when its oxidation goes to an insoluble form). However, some heavy metals remain in mine water. This fact is proved by the background concentrations observed in the places of mine water discharge in the Inya river. In the Inya water river, some contaminants exceed MAC, namely, total iron, manganese, copper, ion nitrite, etc. The authors describe the treatment methods and equipment used in coal mines in Kuzbass. There is a wide range of mine water treatment methods, but the technologies in application mainly reduce to mechanical purification which enables efficient removal of suspended solids, oil products, bacterial pollution and, partly, iron. In compliance with the requirements to mine water treatment quality, mines should modernize treatment facilities and introduce new advanced technologies, i.e. provide an integrated solution of the mine water treatment problem, and should anticipate usability of treated mine water and dregs.

Performance and cost comparison of a gravity-driven free-end membrane and other water filtration systems for household water treatment

Abstract Various types of gravity-driven membrane (GDM) systems have been developed to solve household water treatment problems. A gravity-driven free-end membrane (E-GDM) system was developed to mitigate the deposition of cake on the membrane more effectively than other commercialized GDM systems. The E-GDM system was manually operated with permeability of 12.94 and 1.75 L/m2/h/kPa for a kaolin suspension and a wastewater treatment plant influent sample, respectively, showing the highest average permeability and flow rate among all GDM systems. The GDM systems tested in this study met the daily minimum water requirement of a five-person family, except for a case in which wastewater treatment plant influent is filtered using a commercialized GDM system. According to permeability data from an accelerated cleaning test, the E-GDM system can be expected to guarantee 79,858 L of safe drinking water during its lifetime. The annual cost of the E-GDM system was assessed to be US$5.71 per household, which allows household water treatment in low- and middle-income countries.

Disinfection By-Products (DBPs) Control Strategies in Electrodisinfection

Chemical water treatment problems such as disinfection by-products (DBPs) generation have urged on the search for better water treatment technologies such as electrochemical water technologies that have been applied successfully in different water/wastewat...