Drinking Water Treatment Technologies Research Articles

Superior microplastic removal and gravity-driven membrane filtration optimization: The role of octadecyl-quaternium hybrid coagulant and molecular dynamics insights

Microplastics (MPs) contamination in surface water poses significant environmental and health threats, particularly in rural areas without centralized water treatment systems. Although pre-coagulated gravity-driven membrane (GDM) is a promising decentralized drinking water treatment technology, the impact of MPs on its performance has not been clearly understood yet. In this study, octadecyl-quaternium hybrid coagulant (OQHC) is proposed as an innovative solution for the efficient removal of MPs. Specifically, the effectiveness and mechanisms of OQHC in removing MPs are investigated, and the performance of a GDM pre-coagulated with OQHC is comprehensively evaluated. The findings reveal that OQHC achieves a superior MPs removal efficiency of 93.45 % in surface water, outperforming conventional coagulants such as PACl and AlCl3. Molecular dynamics simulations suggest that OQHC primarily removes MPs through hydrophobic interactions facilitated by its long octadecyl carbon (C18) chains, with humic acid (HA) enhancing the electrostatic interactions. Furthermore, the stability and permeability of GDM filtration pre-coagulated with OQHC are influenced by the cake layer’s zeta potential in the initial stage (0–90 h) and porosity in the late stage (90–120 h). Moreover, the presence of MPs increases the quantity of particles smaller than 6 µm, resulting in lower porosity of the cake layer and steeper flux decline rates during prolonged filtration. Overall, this study establishes OQHC pre-coagulated GDM filtration as a promising approach for addressing MPs contamination in surface water, offering an efficient solution for ensuring safe drinking water in rural areas.

SWASTIIK Technology for Drinking Water Treatment- Enhancing Water Disinfection Efficacy using Fennel Oil and Hydrodynamic Cavitation

Providing safe drinking water is of paramount importance for sustaining life. New technology, Safe Water and Sustainable Technology Initiative from Indian Knowledgebase (SWASTIIK), combining hydrodynamic cavitation and natural oils having antimicrobial properties, was evaluated for effective water disinfection using fennel seed oil for the first time. For model organism, E. coli., while acoustic cavitation (0.2% fennel oil) gave 100% disinfection in 10 minutes, for vortex diode cavitation device, the disinfection in 2 minutes was 70% and 99.6% at 0.5 and 1 bar P respectively. Process improvement with aeration yields 100% disinfection in just 1 minute. The cost, 0.25 Rs/m3 , confirmed cost-effectiveness. The hybrid approach showed highest per-pass disinfection and high cavitational yield of 236 CFU/mL/J. The oil after the treatment can be easily separated and recycled. The removal of oil was achieved using adsorption by activated carbon to restore the original taste and smell of the drinking water.

Improving household water treatment: using zeolite to remove lead, fluoride and arsenic following optimized turbidity reduction in slow sand filtration

Despite the United Nations 2030 agenda, large number of both urban and rural dwellers in low-income countries continue to lack access to improved water. Thus, increased effort is required towards enhancing low-cost drinking water treatment technologies especially for developing countries. Slow sand filter (SSF) is one of the most commonly used low-cost and efficient technologies for treating household drinking water. However, effectiveness of SSF is substantially affected by very high turbidity and relatively large amounts of dissolved heavy metals. To enhance removal of both turbidity and heavy metals, this study optimized sand bed depth (SBD) of SSF and investigated the potential of natural zeolite from Uganda for removal of lead, arsenite (As(III)) and fluoride ions from water. To remove lead ions, the zeolite was used in its natural form. However, to remove As(III) and fluoride, the natural zeolite was modified using hexadecyltrimethylammonium bromide solution. Removal of high turbidity was found to require a large optimal SBD. Furthermore, efficiency of treating synthetic turbid water increased with increasing initial turbidity. Variation of final turbidity with SBD was found to be best described by an exponential function. Optimal SBDs on top of an underdrain gravel layer of 0.2 m were 453, 522, 561, and 580 mm for turbidity of 60, 80, 100, and 120 NTU, respectively. Optimized SBD used achieve at least 95% efficiency in removing suspended particles from water with turbidity 120 NTU was found to save up to 35% of the total cost for acquiring sand volume required by a conventional SSF. For a particular zeolite mass, removal efficiencies of lead, As(III) and fluoride generally increased with increasing contact time. Removal efficiencies of lead, As(III), and fluorides were also shown to increase with increasing zeolite mass. Lead removal efficiencies using natural zeolite were 75 and 98% under 20 and 40 min, respectively. Removal of As(III) using modified zeolite mass was 91% within contact time of 10 min. Adsorption of fluoride on modified zeolite was 80% within 5 min. Adsorption of lead, As(III), and fluorides indicated promising potential of natural zeolites from Uganda for treating polluted water.

Residence time and the concentration of microorganism in the ozone contactor: a CFD simulation on chamber deflectors.

Disinfection is an important step in deep drinking water treatment technology. This study applies computational fluid dynamics to investigate and optimize the hydrodynamics inside the ozone contactor. ANSYS Fluent was used to solve all the control equations. A step method is used to simulate the residence time distribution. The mean residence time is simulated under the Eulerian framework. The deflectors are installed in chambers to direct flow. The deflectors allow for a more uniform flow and a longer mean residence time within the contactor. The baffling factor showed that the deflectors could reduce the short-circuit effect in the contactor and improve the disinfection efficiency by 34.6% compared to the original reactor. The Morrill factor coefficient is improved by 22.8% compared to the original reactor. According to the Aral-Demirel index, contactors with deflectors are significantly better than other baffle-type contactors. The presence of the deflectors increased the microbial inactivation efficiency from 95.3 to 96.5%. The optimal deflector height should be controlled between 30 and 60 mm.

Structure and principle of operation of the apparatus for introducing chlorine into the process pipeline

The article discusses the study of swirling flow in technological pipelines. It examines the nature of the swirling flow, presenting the experimental velocity distribution and pressure inside the pipe in graphical and tabular form. The scope of the study includes the displacement of liquid and gas, as well as the purification of natural waters using ozone and chlorine. The article analyzes the existing technological processes for the preparation of drinking water from surface water sources in Uzbekistan. Due to the significant volumes of water consumption for economic activities, the issue of drinking water disinfection is crucial. In addition to traditional disinfection methods, modern researchers are focusing on developing innovative technologies for this process. The article also studies the features of water formation and its qualitative composition, with an analysis of the reliability of the existing drinking water treatment technology.

Why do low-cost point-of-use water treatment technologies succeed or fail in combating waterborne diseases in the field? A systematic review

In a world where the consequences of inequalities in access to safe drinking water persist, Household Drinking Water Treatment Technologies (HDWT) remains the most readily available and promising alternative solution to prevent waterborne diseases. While successful cases of combating waterborne diseases with HDWT have been documented, there are also reports of failures in reducing water-related illnesses. Understanding the reasons behind these inconsistent results is crucial. This work aimed to identify and critically discuss barriers, enablers, and technology delivery strategies for HDWT-based interventions to improve drinking water safety. Data from 147 articles covering Solar Disinfection, Chlorination, Flocculation-Disinfection, BioSand Filter, and Ceramic Water Filter were extracted from a total of 11,982 systematically retrieved records. Among the identified factors, 77 barriers and 76 enablers were distributed across different domains: psychosocial (37.7, 47.4%), promotion (22.1, 26.3%), technology (28.6, 10.5%), economic (9.1, 14.5%), and environmental (2.6, 1.3%) for barriers and enablers, respectively. Technology delivery strategies primarily included water education and technology promotion, training for technology usage, provision of HDWT through donation or promotional sale, donation of safe water storage, technical assistance, and the use of a diarrhea control diary. All barriers and enablers affect the initial adoption, regular, and sustained use of HDWT and should be considered when planning and implementing interventions. The health impacts of interventions decreased over time since HDWT adoption. Adequate user training, HDWT donation, and high compliance are important predictors of success for HDWT-based interventions. In general, identifying and exploring the listed enablers can help overcome many of the reported limitations.

Water purification improvement using moringa oleifera seed extract pastes for coagulation follow scoria filtration

Currently, millions of people are exposed to dangerous levels of chemical and biological water pollution in drinking water due to source contamination. The rising of populations and industrialization or agricultural wastewaters were causes of water contaminations. The aim of this study was to design, develop and performance evaluation of point of use drinking water purification technology using MoringaOleifera seed coupled followed by scoria coag-filtration media. Experimental laboratory based aquas solution of contaminated water was prepared for evaluations. Moringa Oleifera seed coagulation/flocculation and sedimentation tests were carried out using jar test with the batch experiment. The potential treatment of the sequential ordered unit process stages were evaluated by the determination of physicochemical parameters of the water; such as turbidity, Color, PO4−3, Fe+3 and F−concentration. The factor that affects the purification where coagulant doses, pH, and contact time. Based on this, the physicochemical parameter analysis indicated that turbidity from (150-8NTU), PO4−3 (20–5.95 mg/L), Fe+3 (7–2.93 mg/L) and F− (9–2.83 mg/L), Moringa Oleifera seed dose (10–40 mL/L) extract paste. The maximum pollutant removal efficiency was achieved at 35 mL/L of Moringa Oleifera seed extractdose, within 6.5–7.5 pH range. Then VSco filtration was conducted after jar test under small column experiment as a function of contact time (0, 2, 4 h s). The VSco removal capacity showed that the removal of turbidityfrom (8–2.54NTU), PO4−3 (5.95–1.07 mg/L), Fe+3 (2.93–0.43 mg/L) and F− (2.83–1.94 mg/L) were achieved after 4hr detention time. The percent removal of turbidity, PO4−3, Fe+3 and F− increases remarkably with increasing of their initial concentration. At an initial concentration of turbidity (150NTU), PO4−3 (20 mg/L), Fe+3 (7 mg/L) and F−(9 mg/L), the removal efficiency were 98%, 84%, 85% and 60% respectively. Therefore, we recommend Moringa Oleifera seed –Vscoas an economic, efficient and simple Point of Use drinking water treatment technology.

Developing Cost-Effective and Efficient Drinking Water Treatment Technology for the Removal of Salinity and Suspended Solids

Although a variety of economical water treatment options are available, rural residents struggle to have safe drinking water. Therefore, developing cost-effective and efficient drinking water treatment technology for the removal of selected ionic compounds and suspended solids is necessary. The present study aims to establish a cost-effective water treatment method by employing the following adsorbents Graphene Sand Composite (GSC), GSC with Moringa Oleifera seeds, Phyllanthus emblica seeds, Strychnos potatorum seeds, tea waste, sawdust, coal, coconut charcoal, and clay pot (an indigenized filter). X-ray diffraction of GSC confirms SiO2 nanoparticles, a broad peak centred at 22.5°, Graphene peaks are found at 26.73 (200), 45.8 (110) and 54.959 (222). In FT-IR, graphene oxide has a strong and wide O-H/ Si-OH stretching vibration peak at 3444 cm-1. In the Raman spectrum, the graphitic vibration band from its first-order scattering of E2g photons using sp2 carbon appeared at 1589 cm-1. Moreover, the graphitic vibration band contributes to the presence of stretching C-C bond; which is common in all sp2 carbon systems. Water’s pH, TDS, hardness, and chloride content also increased considerably in a few adsorbents. Fabricated pots with an indigenous filter using GSC and Moringa oleifera seed as filter disc has also been designed and evaluated in the present study. In this research, 100% salinity removal is achieved using GSC as an adsorbent. While there is an interesting rise trend in fluoride and calcium content to 33% and 39%, respectively. The reason for the rise in fluoride and calcium can be studied further.

A challenge in washing water with the sun: 24h of SODIS fails to inactivate Acanthamoeba castellanii cysts and internalized Pseudomonas aeruginosa under strong real sun conditions.

Despite access to drinking water being a basic human right, the availability of safe drinking water remains a privilege that many do not have and as a result, many lives are lost each year due to waterborne diseases associated with the consumption of biologically unsafe water. To face this situation, different low-cost household drinking water treatment technologies (HDWT) have been developed, and among them is solar disinfection (SODIS). Despite the effectiveness of SODIS and the epidemiological gains being consistently documented in the literature, there is a lack of evidence of the effectiveness of the batch-SODIS process against protozoan cysts as well as their internalized bacteria under real sun conditions. This work evaluated the effectiveness of the batch-SODIS process on the viability of Acanthamoeba castellanii cysts, and internalized Pseudomonas aeruginosa. Dechlorinated tap water contaminated with 5.6 × 103 cysts/L, contained in PET (polyethylene terephthalate) bottles, was exposed for 8h a day to strong sunlight (531-1083W/m2 of maximum insolation) for 3 consecutive days. The maximum water temperature inside the reactors ranged from 37 to 50°C. Cyst viability was assessed by inducing excystment on non-nutrient agar, or in water with heat-inactivated Escherichia coli. After sun exposure for 0, 8, 16 and 24h, the cysts remained viable and without any perceptible impairment in their ability to excyst. 3 and 5.5 log CFU/mL of P. aeruginosa were detected in water containing untreated and treated cysts, respectively, after 3days of incubation at 30°C. The batch-SODIS process is unable to inactivate A. castellanii cysts as well as its internalized bacteria. Although the use of batch SODIS by communities should continue to be encouraged, SODIS-disinfected water should be consumed within 3days.

Removal behaviors and mechanism of polystyrene microplastics by coagulation/ultrafiltration process: Co-effects of humic acid

Microplastics (MPs) have been detected in drinking water, which could absorb or accumulate humic acid (HA) and threaten the water quality. Coagulation-ultrafiltration (CUF) is a common drinking water treatment technology, but its behavior and mechanism of removing MPs and MPs-HA remain unclear. In this study, the removal mechanism of polystyrene (PS)-MPs coagulated by Al- and Fe-based salts with or without HA was investigated to optimize the CUF process. The results showed that Al-based salt (92.7 %) was better than Fe-based salt (91.2 %) in the removal efficiency of PS or HA, and the optimal coagulants dosage of PS-HA composite system (12 mg·L−1) was higher than that of the individual PS system (9 mg·L−1). Moreover, the coagulation mechanism was studied by Fourier transform infrared spectroscope (FTIR) and X-ray photoelectron spectroscopy (XPS). The oxygen group in PS and PS-HA was the main binding site of Al and Fe hydrolysate, and the effects of charge neutralization, adsorption bridging, and sweep flocculation became weaker in turn at the optimal dosage. In addition, the cake layer formed by coagulation and the presence of HA alleviated the irreversible membrane fouling by intercepting flow and re-adsorption. This study guides the improvement of the traditional drinking water treatment process to remove MPs.

Evaluating the hidden costs of drinking water treatment technologies

Drinking water treatment technologies are largely evaluated on the basis of metrics such as contaminant removal efficiency, capital costs and health impacts. However, the potential for safe water technologies to lead to positive health outcomes depends greatly on user satisfaction, consistent and sustained operation, and financial viability. In this Perspective, we argue for the importance for engineering, public health and economics researchers to assess the ‘hidden’ costs of drinking water treatment technologies, including affordability, labour burden, user acceptance, and the (often) gendered nature of these. Neglecting these factors results in an underestimation of the full costs of drinking water treatment technologies and an overestimation of the potential for treatment options that require substantial behaviour change and time to succeed. Here we present a set of user-centric evaluation criteria for water service providers, practitioners, governments and other stakeholders to consider when deciding which drinking water treatment technologies to implement, scale up or take to market. Drinking water treatment technologies are typically evaluated on the basis of narrow evaluation criteria, such as contaminant removal efficiency. This Perspective proposes additional user-centric criteria to evaluate the hidden and often gendered costs of water treatment technologies, including affordability, labour burden and user acceptance.

Pilot-scale biofiltration of 1,4-dioxane at drinking water-relevant concentrations

1,4-Dioxane is a drinking water contaminant of emerging concern. Because conventional and many advanced drinking water treatment technologies are ineffective for 1,4-dioxane removal, cost-effective technologies for the removal of 1,4-dioxane at drinking water-relevant concentrations are needed. In this research, a gravity-fed, cometabolic biofiltration system was developed to degrade 1,4-dioxane that was spiked into coagulated, settled surface water at a concentration of ∼10 µg/L. Objectives were to determine whether cometabolic degradation of trace levels of 1,4-dioxane can be sustained using n-butane as primary substrate and whether filter media properties and empty bed contact time (EBCT) affect biofiltration efficiency. A mixed culture of bacteria derived from the Cape Fear River basin and previously enriched using isobutane served as inoculum for biologically active filters. Two granular activated carbons (GACs) with different grain sizes and one carbonaceous resin were used as attachment media, and n-butane served as the primary substrate for biologically active filters. Non-inoculated controls with the same media were evaluated in parallel to distinguish between biological and adsorptive removals of 1,4-dioxane. For the duration of the pilot study (>3 months), 1,4-dioxane was degraded in inoculated biofilters receiving n-butane. In control filters containing larger and smaller grain GAC, 1,4-dioxane broke through completely within 750 and 1250 bed volumes, respectively, corresponding to 15 to 30 days of operation at an EBCT of 30 min. 1,4-Dioxane removal increased with increasing EBCT in all biologically active filters. At an EBCT of 30 min, the biologically active GAC filter containing the larger-grain GAC removed on average 87% of 1,4-dioxane at pseudo steady-state. When the hydraulic loading rate was decreased to achieve an overall EBCT of 60 min, 1,4-dioxane was removed to <1 µg/L in the biologically active GAC filter containing the larger-grain GAC. Activity-based labeling showed the presence of catalytically active monooxygenases in backwash water from biologically active filters that degraded 1,4-dioxane. Amplicon sequencing results showed that while taxa shifted after the initial inoculation of biologically active filters, taxa in biologically active filters remained more similar to the inoculum than those in the non-inoculated control filters. Overall, results of this research demonstrate that cometabolic degradation of 1,4-dioxane at trace levels is possible for extended periods of time in inoculated biofilters that receive n-butane as primary substrate.

Adsorption of Fluoride onto Acid-Modified Low-Cost Pyrolusite Ore: Adsorption Characteristics and Efficiencies.

Fluoride concentrations in the groundwater continue to be a major cause for concern in Thailand, particularly in the country's north and west. The process of removing fluoride through adsorption has captured the attention of the abundance of ore in the mining industry. For the purpose of this investigation, the utilization of the adsorbent pyrolusite, which is a manganese mineral largely composed of MnO2, was a major component. Lab-scale experiments were conducted to investigate the efficacy of original pyrolusite ore (PA-1) and acid-modification PA (PA-2) created as low-cost adsorption materials for fluoride removal. The results of the adsorption rate in both PAs showed a fast rate of adsorption within 60 min of reaching equilibrium. According to the results of the adsorption capacity (qe) tests, PA that had been treated with an acid solution (PA-2) had the capacity to contain more fluoride (qe&amp;nbsp;= 0.58 mg/g) than the PA that had been used initially (PA-1) (qe = 0.11 mg/g). According to the findings of an isotherm, primary adsorption behavior is determined by the effect that surface components and chemical composition have on porous materials. This is the first current study that provides a comparison between pyrolusite from Thailand's mining industry and basic modified pyrolusite regarding their ability to remove a fluoride contaminant in synthetic groundwater by an adsorption process. Such an approach will be able to be used in the future to protect the community from excessive fluoride concentrations in household and drinking water treatment technology.

Sanitary Hygiene of Refilled Drinking Water Depots during the Covid-19 Pandemic

The Coronavirus-19 (Covid-19) pandemic requires people to behave cleanly and healthily to increase the need for clean drinking water. Based on a survey conducted by the Bengkalis District Health Office, it was found that 55% of the people used drinking water from refill depots. The purpose of this study was to determine the Sanitation Hygiene of Drinking Water Depots during the Covid-19 Pandemic in Bengkalis, Riau. This research method is a quantitative descriptive analysis using secondary data from the Bengkalis Health Service for a depot that has sanitation requirements for drinking water depots according to the reference. The research location is in Bengkalis District with a sample of 40 drinking water depots and analyzed for four parameters of drinking water depot sanitation inspection: place, equipment, handlers, and drinking water quality standard certificates. Sanitation hygiene inspection was obtained for the parameters of the place, equipment, and handlers with 100% achievement and only 25% certificate of water quality standard and proper hygiene. It is necessary to innovate drinking water treatment technology for drinking water sources that are healthy, guaranteed, cheap, and free from disease and to support the PHBS and STMB programs during the Covid-19 period.

Sources, characteristics, and in situ degradation of dissolved organic matters: A case study of a drinking water reservoir located in a cold-temperate forest

Dissolved organic matter (DOM) plays a pivotal role in the biogeochemical cycles of elements and the regulation of forest ecosystem functions. However, studies on the regional and seasonal characteristics of DOM in cold-temperate montane forests are still not comprehensive. In this study, samples of water, soil, and sediment from different sites in the forest drainage basin were collected, and their DOM was characterized by an excitation-emission matrix and parallel factor analysis (EEM-PARAFAC). The results showed that terrestrial-sourced humic-like substances were the dominant DOM in the studied reservoir and inflowing rivers. The quality and quantity of DOM exhibited spatiotemporal variations with the influence of terrain and monsoonal precipitation. The average concentration of dissolved organic carbon (DOC) in the wet season was 11.62 mg/L, which was higher than that in the dry season (8.18 mg/L). Higher humification index (HIX) values were observed in the wet season and upstream water than in the dry season and reservoir water. Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) was used to further develop a molecular-level understanding of the in situ degradation process of DOM. The results indicated that photodegradation rather than biodegradation may play a dominant role in the in situ degradation of terrestrial-sourced humic-like substances under natural conditions. The biodegradability of DOM was enhanced after the in situ degradation process. Additionally, a significant decrease in the precursors of disinfectant byproducts in DOM was observed after in situ degradation. To our knowledge, this is the first study of the sources, characteristics, and in situ degradation of DOM in a reservoir in a cold-temperate forest. These findings help better understand the quality, quantity, and biogeochemical process of DOM in the studied reservoir and may contribute to the selection of drinking water treatment technologies for water supply.

Controlling the formation of halogenated byproducts in the chlorination of source waters by oxidative pre-treatment with the Fe(II)/Fe(III)-S(IV)-air system.

Breakpoint chlorination is a generally accepted method for removing ammonium ion from source waters in drinking water treatment technologies. This process is often accompanied by the formation of halogenated organic byproducts. The presence of these compounds in potable water is of primary concern. In this paper, we demonstrate that the concentration of the precursors of the halogenated species can sufficiently be decreased by oxidizing the organic pollutants with the Fe(II)/Fe(III) - S(IV) - air system. Pre-oxidative treatment of the source waters results in a substantial reduction of chemical oxygen demand, while the ammonium ion concentration remains unaffected. The breakpoint chlorination produces substantially less trihalomethanes (THMs) and adsorbable halogenated organic compounds (AOXs) in oxidatively pre-treated source waters than in raw waters. These results offer a possibility to improve drinking water treatment technologies for better controlling the formation of antagonistic byproducts. It is demonstrated that reaching the regulated concentration levels of THMs is feasible with this method even in source waters containing organic pollutants at relatively high concentration levels. The main advantage of the procedure is that the reagents used for the oxidative pre-treatment are converted into non-toxic products (Fe(III) and SO42-) by the end of the process.

Biological nitrate removal from a drinking water supply with an aerobic granular sludge technology: An environmental and economic assessment

Nitrate pollution of groundwater, mainly from agricultural applications, is a widespread water quality problem in many countries. The aim of this study was to identify and compare the main environmental impacts and costs associated with removing nitrate from groundwater under a conventional treatment technology and a technology based on a biological treatment process (denitrification using aerobic granular sludge). The analysis focused on the first real-world experience of an industrial-scale implementation of said technology, applied to the drinking water supply in a small town in Spain. The methods selected for the environmental and economic evaluations were life cycle assessment and cost-effectiveness analysis, respectively. The drinking water treatment technologies under study were a conventional reverse osmosis plant and a plant using a biological treatment called ecogranularwater. The analysis of these two drinking water production processes was divided into two phases: structure and water treatment. This study demonstrates that the biological technology produces drinking water in a more environmentally-friendly, cost-effective way, and with lower energy costs. The greatest environmental impacts from the reverse osmosis technology occurred in the water treatment phase due to the high levels of energy consumption (up to 1.68 kWh m−3 higher than with the ecogranularwater technology). In the structure phase, the biological technology contributed more than reverse osmosis in all impact categories, with values ranging from 91% in freshwater ecotoxicity to 98% in stratospheric ozone depletion. The cost of producing 1 m3 of water was estimated as 43% lower with the ecogranularwater technology compared to reverse osmosis. In order to further lessen the environmental impact of the biological technology, efforts should be focused on reducing and optimizing energy use and making improvements to the design of the structure. This biological technology proved a good alternative for small and medium-sized municipalities with problems of nitrate-polluted water. The decision to apply technological innovations in drinking water treatments to remove nitrates can be supported by environmental and economic studies.

Groundwater-Based Drinking Water Supply in Sri Lanka: Status and Perspectives

Drinking water is largely from groundwater in Sri Lanka, so quality management is of great concern. In order to achieve the 6th goal of United Nations (UN) Sustainable Development Goals (SDG), more efforts are being undertaken to secure drinking water quality. In this paper, the current status, challenges and opportunities of groundwater quality management and improvement in Sri Lanka were reviewed and discussed, based on previous studies. There are Ca-HCO3 type, Ca–Mg-HCO3 type and Na–SO4–Cl type groundwater dominated in the wet zone, intermediate and the dry zone, respectively. Elevated levels of hardness, fluoride, DOC, and alkalinity, and salinity are reported in the groundwater in the dry zone controlled by geology and arid climate. Although groundwater in some regions contain significant levels of nitrates, arsenic, cadmium and lead, the majority remain at acceptable levels for drinking purposes. As for treatment technologies, existing membrane-based drinking water treatment technologies such as RO (Reverse Osmosis) stations can produce safe and clean drinking water to the community, but this has still a limited coverage. To achieve a safe drinking water supply for all, especially in rural communities of Sri Lanka under the 6th goal of the UN SDG, more efforts in building up the infrastructure and man power are needed to monitor and assess groundwater quality regularly so as to develop management strategies. Research and development can be directed towards more cost-effective water treatment technologies. Protection of groundwater from being polluted, and educational and awareness programs for the stakeholders are also essential tasks in the future.

Removal of Dissolved Organic Matter in Drinking Water Using Active Microorganisms (EM)

Conventional treatment methods are used in the treatment of drinking water to protect human and environmental health. These methods can be named aeration to increase the amount of oxygen, precipitation, chemical treatment, filtration, chlorination for disinfection. Besides, iron and manganese removal operations are performed in places where the hardness is very high depending on the geographical location, iron and manganese removal operations are performed in cases where the iron and manganese content is high. Drinking, and drinking water treatment technologies in Turkey are generally the same. The conventional methods used are briefly described as ventilation, coagulation, flocculation, precipitation, sand filtration, and chlorination. In recent years, it has been observed that in addition to these methods, ozone has been used for primary disinfection purposes, activated carbon adsorption for advanced purification purposes, reverse osmosis studies have been performed. Conventional treatment plants are usually built when there is the use of superficial water sources. In settlements where spring or well water is used in a certain area, the water is only available by the chlorination process. The purpose of drinking water treatment is to be clear, colorless, odorless, disease-causing organism-free, free of chemicals harmful to health, and suitable for domestic use. The treatment technologies used in drinking water treatment plants vary depending on the properties that are desired to be found in purified water, as well as the properties of raw water. Physical, chemical, and biological purification, which is one of the classical methods used in the purification process, may be insufficient in the face of dissolved organic matter. This encourages us to look for new methods of combating dissolved organic matter.

Adapting a drinking water treatment technology for arsenic removal to the context of a small, low-income California community

Small, low-income, and rural communities across the United States are disproportionately exposed to arsenic contaminated drinking water because existing treatment solutions are too expensive and difficult to operate. This paper describes efforts to overcome some barriers and limitations of conventional iron electrocoagulation (Fe-EC) to enable its use in the rural Californian (U.S.) context. Barriers and limitations of Fe-EC's application in rural California considered in this work include: 1) Frequent labor intensive electrode cleaning is required to overcome rust accumulation, 2) Electrolysis durations are long, reducing throughput for a given system size, and 3) Waste needs compliance with California standards. We report results from an investigation for overcoming these limitations via a field trial on a farm in Allensworth, a small, low-income, rural community in California. Our strategies to overcome each of the above barriers and limitations are respectively, 1) operating the Fe-EC reactor at high current density to result in sustained Fe production, 2) operating at high charge dosage rate with external H2O2, and 3) characterization of the arsenic-laden waste, and are discussed further in the paper. Main findings are: (1) Fe-EC removed arsenic consistently below the federal (and state) standard of 10 µg/L, (2) high current density failed to sustain Fe production whereas low current density did not, (3) electrolysis time decreased from > 1 hour to < 2 min with H2O2 dosing of 5 mg/L at higher charge dosage rates, (4) dilution of As-sludge is required to comply with State's non-hazardous waste status, and (5) discrepancies were observed between lab and field results in using current density to overcome labor-intensive electrode cleanings. Finally, implications of overcoming limitations to scale-up of Fe-EC in relevant California communities are discussed.