Search

Solar radiation experiments showed a shift in the composition of natural organic matter (NOM). Due to irradiation, the concentration of high molecular weight (HMW) molecules decreased, and that of the low molecular weight (LMW) fraction increased. Microbiological analyses showed that biodegradation was neglectable. To assess the consequences for water treatment processes, coagulation jar tests were performed by comparing the removal effectivity for NOM fractions from irradiated and unirradiated raw water. The degree of dissolved organic carbon (DOC) removal by coagulation was lower for irradiated waters. As primarily HMW organic compounds are removed by coagulation, the decrease in coagulation performance is attributed to the increase in the LMW concentration due to photochemical reactions induced by solar radiation. Flocs were about 15% larger for irradiated water. Possibilities to adapt water treatment to respond to changes in DOC composition and concentration are outlined. Ozonation-biofiltration is judged as the most promising treatment process to cope with climate change-related challenges in drinking water treatment.

Eutrophication has become a great concern in recent years with the algae blooms in source water resulting in a serious threat posing to the safety of drinking water. Chlorine dioxide (ClO2) has been served as an alternative oxidant for preoxidation or disinfection during drinking water treatment process due to its high oxidation efficiency and low risk of organic by-products formation. However, the generation of inorganic by-products including chlorite (ClO2−) and chlorate (ClO3−) has become a potential problem when applied in drinking water treatment. In this study, ClO2 preoxidation-assisted coagulation/precipitation process was applied to improve the raw water quality, especially algae, turbidity, chemical oxygen demand (CODMn), and UV254, and explore the formation mechanisms of inorganic by-products. It was found that the polymeric aluminum chloride (PAC) and ClO2 have shown the best raw water treatment performance with the optimal dosage of 10 mg/L and 0.8 mg/L, respectively. Moreover, the initial pH also has exhibited a notable influence on pollutants treatment and by-products generation. Due to the adverse influence of algae and natural organic matters (NOM) and the generation of by-products, it was significant to investigate their inhibition effect on the water quality and the production of ClO2− and ClO3− in the ClO2 preoxidation-assisted coagulation/precipitation process. Moreover, it was applicable of this process to apply for the algae-containing raw water (calculated as Chl.a lower than 50 μg/L) treatment with the ClO2 dosage of less than 0.8 mg/L to achieve optimum treatment performance and minimum by-products generation.

Raw water quality deterioration has affected capabilities of Conventional Water Treatment Processes (CWTP) in many countries. CWTP used at Morton Jaffray Water Treatment Works (MJWTW) in Harare have proven ineffective due to pollution. The study investigated the use of chlorine dioxide (ClO2) as an alternative pre-treatment chemical. Its effectiveness was compared to that of calcium hypochlorite (Ca(CIO)2) used at MJWTW. Grab raw water samples from MJWTW were collected between January and March 2020 and pre-treated with ClO2 and Ca(CIO)2 followed by jar tests with alum to determine pre-treatment effectiveness. Parameters analyzed included electrical conductivity (EC), total dissolved solids (TDS), total solids (TS), turbidity, chemical oxygen demand (COD), pH and total algae counts (TAC). The raw water had mean TDS (264 mg/L), TS (440 mg/L), turbidity (7.1 NTU), COD (85 mg/L), pH (7.9) and TAC (28.4 × 106 cells/mL). The optimum alum dosage without pre-oxidation was 80 mg/L. Pre-oxidation with 0.075 mg/L ClO2 reduced alum dosage to 60 mg/L. This ClO2 dosage was compared to a Ca(CIO)2 dosage of the same concentration and strength at 5 and 15-minutes contact time before alum dosage at 60 mg/L. The treated water quality parameter levels proved better performance for ClO2 compared to calcium hypochlorite. HIGHLIGHTS Raw water quality deterioration in Lake Chivero has complicated treatment and treatment costs.; Chemicals currently used have become ineffective including calcium hypochlorite, which creates risk of formation of carcinogenic compounds.; Chlorine dioxide was considered an an alternative as it has been used widely elsewhere, enhances coagulation compared to calcium hypochlorite, and thus is likely to be economic.

Long-distance water transfer projects are important for water allocation. To enhance our understanding of biofilm growth and changes in water quality during raw water transfer, raw water through a long-distance non-full culvert at flow rates of 1.4−2.0 m/s was studied. The results revealed that: (1) the biofilm total cell count (TCC) and heterotrophic plate count (HPC) were the highest at a flow rate of 1.5 m/s, which were 3.7 × 104 cells/cm2 and 1.1 × 103 CFU/cm2, respectively; (2) Proteobacteria had the highest relative abundance (RA) among all samples, and the RA in biofilm (78.85%) was higher than that in water (48%−59%); (3) when the pollutants and biofilm were partially shed, the total phosphorus (TP), permanganate index (CODMn), and dissolved organic carbon (DOC) increased by 0.011, 0.36, and 0.5 mg/L at most, respectively; and (4) dissolved oxygen (DO) was sufficient during non-full flow water transport and nitrification occurred. The highest removal rates of ammonium nitrogen (NH+4-N) and nitrous nitrogen (-N) reached 27.16% and 66.76%, respectively. At the flow rates of 2.0 m/s, the efficiency decreased to 10.47% and 41.25%, respectively, due to the shedding of biofilm. HIGHLIGHTS Raw water flow over a long-distance non-full culvert studied using an experimental model.; Flow rate influenced biofilm biomass, and resulted in different bacterial community structure in bulk water and biofilm.; Nitrification in the long-distance non-full culvert was only 0.54%–1.2% that in the simulation experiment.

In this study, a multivariate 23 experimental design was applied to optimize the operational conditions (seed mass, salt concentration, and pH) to employ Ceratonia siliqua L. (carob) and Moringa oleifera Lam (moringa) as coagulating/flocculating agents for water treatment. Currently, the coagulation stage in water treatment uses aluminium compounds, due to the characteristic reaction to natural alkalinity in raw water, and for its low market value. Considering that aluminium effects on human health are not sufficiently studied to acknowledge its toxicity, and its significant environmental impacts, it is suitable for the studies to search for alternatives to be employed in the water treatment that will be distributed to human consumption. This study was carried out with raw water of high turbidity level, 83.7 NTU. The raw water collected was also characterized according to pH, colour, Total Organic Carbon (TOC), Dissolved Organic Carbon (DOC), and Dissolved Organic Matter (DOM), with values of 6.7, 178 NTU, 6.80, 2.45 and 138.58 mg/L, respectively. The optimized results showed that with 2 g of seed, 0.5 mol L-1 of NaCl, and pH 11.0 In these conditions, moringa coagulant reached 90%, 86%, 6%, 67%, and 81% for turbidity, colour, DOC, TOC, and DOM removal, respectively, whereas the carob coagulant achieved 85%, 76%, 5%, 55.6%, 66.7%, respectively for the same parameters' removal. Both coagulants presented lower sludge formation, 1.1 mL L-1 for moringa coagulant, and 1.1 mL L-1 for carob coagulant. The results could be considered promises, and natural polymers carob and moringa can be suggested as alternatives agents in coagulation/flocculation stages for water treatment.

The present work reports the effect of antibacterial activity of Murraya koenigii leaves extract to improve the quality of drinking water collected from Moradabad Uttar Pradesh, India and its rural area. The five different water samples were collected and characterized for their properties. During this work, examination of treated and untreated sample water for heavy metals and microbial counts has been done. The curry leaves (Murraya koenigii) show antibacterial property and its extract has been applied in different volumes (5–25 mL) to improve the quality of drinking water and producing safe bacteria-free water for multiple usages. The water samples A, B, C, D, E were also analyzed for metals like Pb, Cr, Cu, Zn, and Cd contents. The total microbial count (TBC) was identified by the pour plate method and membrane filtration method on R2A agar media plates. The biological oxygen demand (BOD) for 5 days and CFU/mL (colony-forming unit/mL) indicated a significant decrease in the reduction of microbial count and biological oxygen demand. This gives evidence for the antibacterial activity of curry leaves extract. During the treatment of raw water samples with extract Pb, Cr, Cu, Zn, and Cd were also coagulated to the maximum extent. The results showed the significant decrease, up to 95% in the microbial counts. Treatment with curry leaves extract also helped in the coagulation of the heavy metals like lead, copper, chromium etc. present in the treated water samples. In control water samples, total bacterial count (TBC) was found to be more than 800 CFU/mL but the total bacterial count in the treated samples was reduced significantly to low value depending on the volume of the extract used. The overall performance of extract was found satisfactory for treating drinking water. This will be an economical and ecofriendly safe method to obtain bacteria-free drinking water at a small and large scale.

The drinking water treatment plants (DWTPs) in the developing countries urgently need an efficient pre-treatment for nitrate (NO3−) removal to cope with the increasing NO3−pollution in raw water. An upflow sludge blanket (USB) reactor applied for NO3−removal from domestic wastewater may be adopted by the DWTPs. However, studies on the optimal carbon-to-nitrogen ratio (C/N) and operation of USB reactor at short hydraulic retention times (HRT) for high-rate polluted raw water pre-treatment are lacking. In this study, we first investigated the optimal C/N for biological NO3−removal in a sequencing batch reactor (SBR). An USB reactor was then operated with the optimal C/N for pre-treating synthetic raw water contaminated with NO3−(40 mg N L− 1) to monitor the NO3−removal performance and to examine opportunities for reducing the HRT. After operating the SBR with designed C/N of 4, 3 and 2 g C g− 1N, we selected C/N of 3 g C g− 1N as the optimal ratio due to the lower carbon breakthrough and nitrite (NO2−) accumulation in the SBR. The USB reactor achieved complete NO3−and NO2−removal with a lower designed C/N of 2 g C g− 1N due to the longer sludge retention time when compared with that of SBR (10 d). The high specific denitrification rate (18.7 ± 3.6 mg N g− 1mixed liquor volatile suspended solids h− 1) suggested a possible HRT reduction to 36 min. We successfully demonstrated an USB reactor for high-rate NO3−removal, which could be a promising technology for DWTPs to pre-treat raw water sources polluted with NO3−.

Dissolved organic matter (DOM) has detrimental effects on drinking water treatment, distribution water quality and human health. In this study, four methods (dissolved organic carbon (DOC), potassium permanganate index (CODMn), ultraviolet (UV) absorbance and fluorescence excitation emission matrix (EEM) spectroscopy measurements) were utilized to investigate the spatiotemporal variations in DOM in two conventional drinking water supply systems (DWSSs) for the purpose of assessing the applicability of various technologies for DOM monitoring. Results showed that in the water samples, DOM was dominated by hydrophilic and low molecular weight substances. The fluorescent fraction of DOM was composed of humic-like components C1 and C2 and protein-like component C3, and was mainly from autochthonous sources. DOC, CODMn, UV absorbance and DOM fluorescence exhibited identical behavior, with high values in the raw water, decreased levels in the treated finished water and no significant changes during distribution. The order of removal efficiency in the drinking water treatment was fluorescence > UV absorbance > CODMn > DOC. Among the analyzed spectral parameters, UV absorbance at 270 nm (UV270) exhibited the best correlation with CODMn, a standard regulatory measurement. The findings suggest that fluorescence EEM spectroscopy is a sensitive tool for assessing the DOM removal efficiency of drinking water treatment and that UV270 may be used as a surrogate for CODMn for monitoring DOM levels in DWSSs. This study highlights the importance of combining multiple techniques for DOM monitoring, and enhances the understanding of amounts, composition and sources of DOM and their variations in conventional DWSSs.

In the lowlands of Nepal (Terai), the WHO drinking water guideline concentration of 10 μg/L for arsenic (As) is frequently exceeded. Since their introduction in 2006, iron-assisted bio-sand filters (Kanchan filters) are widely used to treat well water in Nepal. The filters are constructed on the basis of As-removal with corroding zero-valent iron (ZVI), with water flowing through a filter bed of iron nails placed above a sand filter. According to several studies, the performance of Kanchan filters varies greatly and depends on the size of the iron nails, filter design, water composition, and operating conditions, leading to concerns about their actual efficiency. This study examined 38 Kanchan household filters for which insufficient As-removal was reported, to evaluate the reasons for limited removal efficiency and to define measures for improved performance. The measured arsenic removal ranged from 6.3% to 98.5%. The most relevant factors were the concentrations of As and Fe in the raw water, with the best removal efficiency observed for water with low As (123 µg/L) and high Fe (5.0 mg/L). Although the concentrations of other elements, pH, flow rates, and contact time with ZVI also played a role, the combined evidence indicated that the reactivity of the frequently drying nail beds between filtrations was insufficient for efficient As-removal. Optimized filters with added top layers of sand and raised water outlets with flow restrictions to keep nails permanently immersed and to increase contact times, should be able to achieve higher and more consistent arsenic removal efficiencies.

Using raw water from a shallow water supply reservoir located in the lower Yangtze River region, the removal efficiencies of conventional treatment on dissolved organic matter (DOM) and disinfectio...

Based on the principles of mass conservation, momentum, and energy, an improved version of the Desalination pipeline called Improved Desalination Pipeline System (IDPS) has been studied in the present paper. The main features of IDPS are the high transfer rate and the high raw water production rate. IDPS works with the help of thermal gradient generated due to the temperature difference between the seaside/destination. Heat injection has also been used to increase the efficiency of IDPS. In the condensation part, the heat pipe concept is adopted to facilitate the vapor-liquid process. The main portion of heat injected to the IDPS is recovered by generating electrical power using water flow due to available water head. To show the efficiency of IDPS, a case study is performed from Bandar Abbas (seaside) to Mount GNU (the destination) located30 km away with 2347 m height. The results show that IDPS does not necessarily require large diameter pipes for greater efficiencies. The energy consumption for distillation and transferring1 m3 of water is about 6.6 Kwh. In addition to the distilled transferred water, a significant amount of water is distilled on the site, which is about 25% of the transferred water.

Geosciences and geoethics emerge at the core of a globally increasing demand of resources and the risk of scarcity for the new generations, promoting social, economic and environmental awareness, better management of resources and our commitment to environmental issues. According to the United Nations World Water Assessment Program, water consumption rates increased in the last decades and this trend is likely to continue over the coming years. Driven by climatic hazards due to human activities or by the denaturation of freshwater sources, in certain regions of the planet, water is becoming increasingly scarce, already facing water supply deficits, water resources must be saved as much as possible. The industrial sector accounts for a considerable volume of freshwater consumption, lagging behind the agriculture sector. Nonetheless, the global annual water used in industry is expected to increase and, particularly, much of this increase will occur in developing countries, experiencing rapid industrial progress. The present work deals with a case study of the intervention and adaptation of a wastewater treatment process of a food company. Through a water pinch analysis, within the concept of circular economy, it is envisaged to improve the efficiency of the water management system through a reduction in water and energy use and also wastewater generation. The introduction of new stages in the treatment process is proposed to allow the reuse of treated wastewater and to reduce raw water consumption from natural sources. This research points to the use of phytoremediation processes combined with ion exchange columns, packed with a mix of cationic and anionic resins. The results were promising and point to an intervention proposal with a reduction of up to 55% in the consumption of raw water and a 45% reduction in the volume of treated wastewater sent for discharge.

Securing safe and sustainable supplies of drinking water is a major challenge for the government and scientific community, especially in times of climate change and dynamic urban and economic development. A typical water supply system comprises an intake, transmission, treatment, and distribution works. Satisfactory performance of water treatment plant (WTP) and availability of residual chlorine in the water distribution network (WDN) is necessary for the planning, management, and operation of the water supply system. Particularly in India, water shortages and poor water quality continue to be a major challenge in domestic and industrial sectors. The performance of the WTP depends on the raw water quality and unit processes involved in water treatment. The raw water quality fluctuates due to daily and seasonal changes in weather conditions, variations in water dam level, demands by consumers, heavy rainfall floods, industrial effluents, and agricultural activities. In the present paper, performance evaluation of WTP in farthest zones in WDN, namely Sant Tukaram Nagar at Nigdi WTP, Pimpri Chinchwad Municipal Corporation (PCMC), Maharashtra, India, is investigated. Artificial Neural Network (ANN) was implemented to predict the performance of WTP with correlation coefficient (R) 0.986. Feed Forward Neural Network (FFNN) Water Quality Model was developed using the Levenberg–Marquardt Training Algorithm and Bayesian Regularization Training Algorithm.

Water quality events such as increases in stormwater or wastewater effluent in drinking water sources pose hazards to drinking water consumers. Stormwater and wastewater effluent enter Lake Mead—an important drinking water source in the southwest USA—via the Las Vegas Wash. Previous studies have applied machine learning and online instruments to detect contamination in water distribution systems. However, alert systems at drinking water intakes would provide more time for corrective action. An array of online instruments measuring pH, conductivity, redox potential, turbidity, temperature, tryptophan-like fluorescence, UV absorbance (UVA254), TOC, and chlorophyll-a was fed raw water directly from Lake Mead. Wastewater effluent, dry weather Las Vegas Wash, and storm-impacted Las Vegas Wash samples were blended into the instrument inlets at known ratios to simulate three types of adverse water quality events. Data preprocessing was conducted to correct for diurnal patterns or instrument drift. Supervised machine learning was conducted using previously published models in R. Ninety-nine models were screened on the raw data. Eight high-performing models were evaluated in-depth and optimized. Weighted k-Nearest Neighbors, Single C5.0 Ruleset, Mixture Discriminant Analysis, and an ensemble of these three models had accuracy over 97% when assigning test set data among three classes (Normal, Event, or Maintenance). The ensemble detected all event types at the earliest timepoint and had one false positive that was not a lag error (i.e., consecutively following a true positive). Omitting Maintenance, the Adaboost model had over 99% test set accuracy and zero false positives that were not lag errors. Data preprocessing was beneficial, but the optimal methods were model-specific. All nine water quality variables were useful for most models, but UVA254 and turbidity were most important.

Groundwater is a viable alternative when access to surface water resources is limited. Iron and manganese are known ions in soil and naturally in groundwater sources. However, human activities also are responsible. To identifying the best module for removing manganese and iron in the water treatment plant (WTP) of Mazandaran, 516 samples were taken from raw and treated water. The concentration of manganese, iron, was measured by atomic absorption spectrophotometry, and turbidity was used with the nephelometry method. The water pollution index (WPI) was applied for categorizing the status of pollution in treated water. The effect of seasonal temperature and backwashing (At flow rates of 3.5, 9.2, and 15.3 m h-1) on the sand filter efficiency was also investigated. The highest concentrations of manganese, iron, and turbidity in raw water were 0.744, 6.70 mg L-1, and 41.8 NTU, and in treated water were 0.67, 1.09 mg L-1, and 5.58 NTU, respectively. The mean concentration of manganese and iron in raw and treated water were 0.24 ± 0.1, 0.93 ± 0.91, 0.105 ± 0.06 and 0.18 ± 0.14 mg L-1 respectively. The WPI statuses in drinking water were excellent for manganese and iron in 95.74 and 53.88 % of the samples and very poor in 1.16 and 12.01 % of the samples, respectively, and its classification for drinking water for manganese and iron was excellent ˃ good ˃ extremely polluted ˃ polluted and the concentration of iron was more than manganese in treated water. The study of temperature’s effect on sand filters showed that the removal efficiency in warm seasons was higher than in cold seasons. Also, the turbulence in the backwash with the 9.2 m h(− 1) rates, is lesser than other speeds, and in this flow, after 270 s, the turbidity decreases to less than 10 NTU. Spearman correlation comparison showed that the parameters amounts after filtration decreased significantly (p ≤ 0.0001) in comparison to raw water. The results showed that module #1 that used open-aeration and chlorine as oxidations, was most effective in removing iron and manganese. In the end, the WTP couldn’t diminish the parameters completely and need subsidiary units.

2-Methylisoborneol (2-MIB) is one of the most common taste and odor (T&O) compounds in waterbodies and causes complaints from drinking water consumers. This is a case study of two water treatment plants taking the raw water from Lake Tai, the third largest lake in China. The relationships between the 2-MIB concentration and algae density, light change and nutrients of the raw water for the most recent four years were comprehensively investigated. The yearly variation pattern of the 2-MIB concentration in the raw water is closely related to the algae cell density. Both values reached peaks in July or August with concentrations as high as ∼500 ng/L and ∼1000 × 104 count/L, respectively. For the diurnal 2-MIB variation, the concentrations increase from 5 to 6 am, reach a peak value at ∼12 p.m., and then gradually decrease and achieve the lowest value at night. These results further confirm that 2-MIB is highly related to algae cell activity (e.g., photosynthesis). In addition, 2-MIB exists both inside and outside algae cells (i.e., intracellular and extracellular or bound and dissolved 2-MIB, respectively), and the percentage of the extracellular/dissolved portion was as high as 60% during the study period. Conventional water treatment processes (usually referrings to coagulation sedimentation and sand filtration, CSF) in WTPs have extremely unstable 2-MIB removal efficiencies (from −20% to >95%), which is mainly related to the existing forms of 2-MIB. The intracellular/bound portion can be effectively removed by CSF, especially sand filtration, while advanced water treatment processes are required to remove the dissolved 2-MIB. An ozone-activated carbon process is recommended, and the 2-MIB removal rate can reach 100%. This research has great theoretical and engineering value for treating water containing T&O compounds.

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.

In order to use purified wastewater on watering green spaces of Agadir city, we conducted this study to assess the bacteriological and physicochemical quality of treated wastewater in Mzar treatment plant. To realize these objectives, we analyzed four types of waters: raw water (RW), decanted water, purified water and purified water treated by the ultraviolet radiation (PWUV). The biologically analyzed parameters are fecal coliforms (FC) and fecal enterococci (FE). The physicochemical parameters are: pH, electrical conductivity, chemical oxygen demand (COD), five-day biological oxygen demand (BOD5) and total suspended solids (TSS). The results showed a high level of bacterial contamination in all types of waters, and the average loads of FC were between 4.71 × 106 CFU/100 mL (RW) and 1.45 × 103 CFU/100 mL (PWUV), while loads of FE were between 2.62 × 105 CFU/100 mL (RW) and 7.92 CFU/100 mL (PWUV). The physicochemical parameters show a pH close to neutrality and a high electrical conductivity (3261 μS/cm) in PWUV. In all stages of wastewater treatment, values of COD, BOD5 and TSS were under the limit values recommended by Moroccan standards. Except for the electrical conductivity and FC, all the studied parameters were under the limit values requested by the Moroccan standards. The microbiological quality of PWUV is unstable, and if these waters are reused, they can affect the microbiological and physicochemical quality of green spaces and groundwater.

A new in-situ pre-enrichment system was developed for trace analysis of radioactive Cs in environmental water such as rivers, ponds, and seas, where the radioactive Cs is separated into suspended substances (SS) and dissolved substances (DS). The SS component was collected as the enrichment slurry by cross-flow filtration, thereby compact systems were realized. The DS component was collected in a small cartridge filled with a non-woven fiber with immobilized adsorbent nanoparticles. The recovery rate was estimated at around 95%. The size distribution of the SS and the concentration of radioactive Cs after enrichment were the same as that of the raw water before enrichment. The condensed SS can be used for other evaluations such as ignition loss. From the field test at a pond in the Fukushima-area, the Cs concentration of the SS was found to be 4–5 times higher than that of the sediment in the same pond. The organic content estimated by ignition loss was also three times higher.

Environmental degradation has increased, mainly as a result of anthropogenic effects arising from population, industrial and agricultural growth. Water pollution is a problem that affects health, safety and welfare of the whole biota which shares the same environment. In Goiânia and metropolitan region, the main water body is the Meia Ponte River that is used for the abstraction of water, disposal of treated wastewater and effluents. In addition, this river receives wastewater from urban and rural areas. The aim in this present study was to evaluate the quality of raw water by some physical, chemical and toxicological tests. The physicochemical results found high levels of turbidity, conductivity, aluminum, phosphorus and metal iron, manganese, copper and lithium when compared to the standards of the Brazilian legislation. The values found of toxicity demonstrated a high degree of cytotoxicity and genotoxicity. Therefore, it was concluded that the Meia Ponte River has been undergoing constant environmental degradation, causing the poor quality of its waters. Thus, measures for the prevention and recovery should be adopted for the maintenance of the Meia Ponte River.

Calibrated adsorption-based passive samplers were used for time-integrative monitoring of microcystins (MCs) in three full-scale drinking water treatment plants (DWTPs) in the Czech Republic during two vegetation seasons (Jun-Nov), in parallel with traditional discrete sampling. MCs were detected in epilimnetic water samples at concentrations up to 14 mu g/L, but their levels in raw water in DWTPs were below 1 mu g/L WHO guideline value for drinking water. Conventional treatment technologies (coagulation/filtration) eliminated cyanobacteria and intracellular toxins but had a limited removal efficiency for extracellular toxins. MCs were regularly detected in final treated water, especially in DWTPs equipped only with the conventional treatment, but their concentrations were below the quantitation limit of discrete sampling (

The occurrence of pharmaceuticals in the drinking water is a growing concern in China. In this study, we determined the concentration and distribution of 59 selected pharmaceuticals in raw, finished, and tap water samples from 79 drinking water treatment plants (DWTPs) in 15 cities, encompassing seven large river basins in China, using solid-phase extraction pretreatment and ultra-high-performance liquid chromatography–tandem mass spectrometry analysis. Forty-seven pharmaceuticals were detected in raw water samples, with detection rates of 1.27–96.20% and average concentrations of 0.09–128.87 ng/L. Forty-three pharmaceuticals were detected in finished water samples, with detection rates of 1.27–96.20% and average concentrations of 0.07–59.17 ng/L. Forty-two pharmaceuticals were detected in tap water samples, with detection rates of 1.27–94.94% and average concentrations of 0.07–58.43 ng/L. Purification methods implemented by DWTPs are capable of removing some pharmaceuticals from water treatment systems; however, low concentrations of pharmaceuticals were detected in drinking water, raising concerns about the possible human health implications of long-term exposure to low-dose pharmaceuticals. The detection and quantification of pharmaceuticals in municipal water samples presented in this study represent the most extensive analysis of commonly used pharmaceuticals and personal care products located in Chinese river basins.

Complying with the demands of drinking water supply whilst minimizing environmental impact poses a great challenge in water management. This study investigates the potential of withdrawal management of drinking water reservoirs to alleviate the disruption of the river continuum by a reservoir dam with respect to temperature and discharge. The aim is the identification of an optimal withdrawal strategy to provide a near‐natural discharge temperature and flow for the downstream river without jeopardizing drinking water production. First, we identify the applicability of new withdrawal regimes for raw water security and downstream river demands. Second, we search for an ideal withdrawal regime in scenario simulations using a numerical reservoir model (“General Lake Model”). The scenarios on a drinking water reservoir in Germany demonstrate that we are able to derive an optimized reservoir management. The numerical model is provided for operators as a simple and efficient tool for optimizing the withdrawal strategy within reservoir management.

It was confirmed experimentally that a Roughing Filter (RF) is effective as a pre-treatment system for Slow Sand Filter (SSF) with coagulant dosing and mixing with raw water. This RF system can pre-treat high turbidity raw water (1,000 NTU) to generate low turbidity (10 NTU) pre-treated water for SSF treatment. In the experiment, the types of filter media, height of the filter media, filtration rate and coagulant dosing were varied and the characteristics of each item were evaluated and the design guidelines were formulated. Water Treatment Plants (WTPs) consisting of pre-treatment with RF followed by SSF to treat river water were designed and constructed in Myanmar based on the design guidelines, and the operational performance was confirmed as effective to generate treated water with a turbidity under 5 NTU, which is in compliance with the WHO guideline despite the rather short working period of about one year. Sand scraping of SSF at a frequency of about once in every one to two months was implemented to maintain the design filtration rate.

Exposure to aluminium (Al) is inevitable in the daily life because of its abundance in the environmental media through natural processes. Meanwhile, several studies have reported a positive association between Alzheimer’s disease and a higher level of Al ingestion through drinking water. The present study is the first of its kind in Malaysia which predicts the human health risk of Al ingestion via drinking water at the Langat River Basin, Malaysia. Water samples were collected during 2015–2016 from the four stages of drinking water supply chain at the basin to determine the concentrations of Al by the Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The determined mean concentration of Al in river 2.50E−01 ± 1.89E−01 mg/L crossed the Malaysian drinking water quality standard of 0.2 mg/L. The higher concentration of Al in the Langat River might be due to natural weathering of Al-bearing minerals. The mean Al concentrations in the treated water by the treatment plants, household’s tap and after filtration water, respectively, were found to be within the Malaysian drinking water quality standard. This study suggests that there is no potential human health risk of Al ingestion through drinking water (HQ = 3.81E−03 ± 1.82E−03) at 95% confidence level in the basin because the hazard quotient (HQ) value is less than 1. However, the authorities need to be careful of excessive ingestion of Al via drinking water because the water treatment plants in the basin follow the conventional method to treat raw water. The turbidity in the tropical Langat River changes very frequently; thus, the doses of Al2(SO4)3 for water disinfection are very crucial. Therefore, reverse osmosis technology can be introduced in the treatment plants because the United States Environmental Protection Agency has recommended that it can remove all types of metal > 90% from treated water.

This work summarises the results of calcium and magnesium ion removal from raw water feeding an industrial steam generation system. The cations were precipitated with sodium phosphate before separation of the solids by dissolved air flotation, with micro and nanobubbles. Studies were done at bench scale and validated at pilot scale (raw water feed = 1 m

Society's increasing use of chemicals poses a challenge for drinking water producers. Accepted concentrations for per- and polyfluoroalkyl substances (PFASs) in finished water are lower than ever before with new regulations often enacted based on findings made possible by improved analytical techniques and correspondingly justified health concerns. Nanomembrane filtration removes compounds, including PFASs, based primarily on size-exclusion, however, treatment and/or disposal of PFAS laden membrane concentrate remains a challenge. This study combined feedwater nanofiltration with granular activated carbon (GAC) and anion exchange (AIX) for concentrate treatment. Nanofiltration removed PFAS concentrations on average by 99% including some PFASs with molecular weights smaller than the membrane nominal cutoff of 270 Da, indicating membrane rejection mechanisms additional to size-exclusion. Treatment of raw water and concentrate was compared in column tests. AIX showed up to threefold greater half-time of saturation than GAC, however with a higher rate of decreasing efficiency, while GAC removed approximately 20% of incoming PFAS concentrations consistently after treatment of 15 000 bed volumes (BVs). Overall, GAC and AIX removed 2.6-fold and 4.1-fold more PFAS mass per adsorbent volume from the concentrated retentate than from raw water indicating that the combination of nanofiltration with GAC or AIX increases the efficiency of the adsorbent materials in comparison to only using GAC or AIX filters.

Quantitative microbial risk assessments (QMRA) was conducted for 10 drinking water facilities located in Canada. Monthly risk estimates were based upon a suite of reference pathogens for the raw water, as well as detailed process assessments that considered the variability treatment at individual treatment facilities. The majority of the facilities (9 out of 10) maintained risk levels significantly below the World Health Organization's target of 10−6 DALY per person per year. Cryptosporidium was shown to be the most significant contributor for microbial risk at all locations. Potential treatment specific failure scenarios were evaluated; most treatment facilities were capable of withstanding partial filtration and disinfection failures as a result of the multi-barriers employed.

The objective of this study was to determine the applicability of the laboratory flocculation test (Jar Test) for a solid contact clarifier. Cohesivity, a parameter characterizing the sludge blanket can be established by determining the Sludge Cohesion Coefficient (SCC) by conducting a Sludge Cohesion Test (SCT). A series of laboratory tests were performed using the Jar Test and SCT. Considering the large number of variable parameters involved with natural raw water, sludge samples were prepared using synthetic raw water with varying turbidity and coagulant dose combinations. A comparison was made between the optimum coagulant dose obtained using the two tests. Highest SCC observed at the optimum coagulant dose was within the range of 0.6–3.3 m/hr. Low SCC values indicate a light and fragile sludge blanket whereas high SCC values indicate a quick settling consistent blanket. With increasing raw water turbidity, the optimum coagulant dose given by SCT is lower than that of the Jar Test. Hence, at higher raw water turbidity occurrences, it may be possible to operate the upward flow solid contact clarifiers with lower coagulant dose. A significant quadratic relationship is observed between the optimum coagulation doses with R2 = 0.9 and α < 0.05.

This paper discusses raw water quality results for the raw water from Vaalkop dam reservoir in South Africa. A time series analysis was conducted for various parameters over a prolonged period of time. The analysis indicates that apart from conductivity and coliform counts, most parameters were below their recommended threshold levels for the greatest part of the study period.

Bank filtration is a cost-effective and sustainable method of improving surface water quality for drinking water production. During aquifer transit, natural biodegradation and physiochemical filtration improve the quality of the raw water by removing sediments, pollutants, and pathogens. Strict regulations prohibit the use of substances that can be used to estimate aquifer residence times to define water protection areas for bank filtration. In this study, we present a novel measurement and modeling framework for deriving mean aquifer residence times for bank filtrate using the natural tracer radon-222. The method is intended for application in the drinking water sector, where extraction wells are screened over the entire aquifer and pumps are operated at high production rates. Mean aquifer residence times are estimated using composite residence time distributions that account for flow path mixing and non-uniform residence times with multiple components including bank filtrate, shallow groundwater, and deep groundwater. The mathematical framework is demonstrated for a drinking water production facility. Radon activities for the six monitored extraction wells ranged between 4,400 and 8,400 Bq/m³. Estimated mean aquifer residence times for the wells range from5 days to 110 days and strongly depend on i) the type of residence time distribution model (exponential, gamma or piston flow), ii) the mixing ratio between bank filtrate and local groundwater, and iii) the heterogeneity in the groundwater endmember. By accounting for mixing processes, we can show that radon can be used beyond the "5-fold half-life" (~20 days) commonly described in the literature as the upper limit for age dating purposes for radon. This method provides a simple and cost-efficient way to quantify residence times of bank filtrate on a regular basis without any addition of external substances to the aquifer.

The aim of our study is based on the characterization of the effluents treated by the M’zar plant, the monitoring of its purification performance after each treatment stage and the benefits of treated wastewater reuse in Souss-Massa region. Physico-chemical and bacteriological analyses were performed monthly from May 2019 to September 2020 on four types of water: Raw Water (RW), Settled Water (SW), Filtered Water (FW) and Purified Water treated by ultraviolet radiation (PWUV). After treatment, the pH values were close to neutrality and the concentrations of COD, BOD5, SM and bacteriological parameters were below the limits recommended by Moroccan standards, with a satisfactory abatement rate (between 97.5% and 100%), with the exception of electrical conductivity, which recorded very high values (3.7 dS/cm in PWUV) due to the salt discharged by the fish industries. In fact, the treated wastewater is rich in nitrates (289.24 mg/L in PWUV) and their reuse in agriculture can therefore contribute to making significant savings in terms of fertilization (2.08 t/day of nitrogen with a daily flow of 30,000 m3/day). Furthermore, a daily quantity of 2 to 5 tons of sludge is discharged, containing 40% to 60% of dry volatile matter, which results in the biogas production of 1275 m3/day/decanter.

Due to climate change, population growth, industrialization, urbanization, and water contamination, it is becoming more difficult to secure and supply clean and safe drinking water. One of the challenges many water utilities often face is the taste and odor (T&amp, O) problem in drinking water treatment plants, mostly associated with geosmin and 2-MIB. These representative T&amp, O compounds are mainly produced by the metabolism of blue-green algae (cyanobacteria), especially in summer. In this study, the correlation between algae blooms and T&amp, O compounds was identified in the intake and raw water of a large-scale water treatment plant in the Republic of Korea. The removal efficiency of geosmin and 2-MIB by each treatment process was intensively evaluated. According to the obtained results, ozonation and granular activated carbon (GAC) adsorption were more effective for removing the troublesome compounds compared to other water treatment processes, such as coagulation/flocculation, filtration, and chlorination. Because of their seasonal concentration variation and different removal rates, optimal operation methods need to be developed and implemented for drinking water treatment plants to solve the T&amp, O problems.

PURPOSE: Coagulation and flocculation are the prominent processes and unit-operations in water treatment plants. One of the most challenging operations in water treatment process is determining of the coagulant dose. METHOD: The Jar-test method is usually used to determine the coagulant dose. Considering that this traditional method is time consuming, associated with human error and highly affected by raw water quality fluctuations. In this study, artificial fuzzy neural network (ANFIS) according to subtractive clustering (SUB) method was applied in order to determine the optimal dose of coagulant in the water treatment plants. RESULTS: Adopting SUB method tend to moderate the number of rules and the interconnections besides enhancing the model responsibility and smart model recognition. The amount of pH, turbidity of raw water influent, alkalinity, temperature, and electrical conductivity were collected as input data. CONCLUSIONS: The results of modeling by ANFIS with correlation coefficients of 0.85 and 0.84 and RMSE 1.32 and 1.83, respectively, for alum and polyaluminum chloride (PAC) coagulant dose, indicated that ANFIS is an effective method for determination of the optimal coagulation dose in the water treatment plant.

[EN] The Mediterranean region is a climate change hotspot, especially concerning issues of hydrological planning and urban water supply systems. In this context, the Jucar River Basin (Spain) presents an increase of frequency, intensity and duration of extreme meteorological phenomena, such as torrential rains, droughts or heat waves, which directly affect the quantity and quality of raw water available for drinking. This paper aims to analyze the effects of climate change on the raw water quality of the Jucar River Basin District, which mainly supplies the city of Valencia and its metropolitan area, in order to adapt drinking water treatments to new conditions and opportunities. For this purpose, we used observed data of water quality parameters from four stations and climate drivers from seven Earth system models of the latest Coupled Model Intercomparison Project-Phase 6. To model water quality (turbidity and conductivity) in the past and future scenarios, this study employs a backward stepwise regression taking into account daily values of mean temperature, maximum temperature, total rainfall and minimum and maximum relative humidity. Results showed that the model performance of the water quality simulation is more adequate for short moving-average windows (about 2-7 days) for turbidity and longer windows (about 30-60 days) for conductivity. Concerning the future scenarios, the most significant change was found in the projected increase of conductivity for the station of the Jucar river, between 4 and 11% by 2100, respectively, under the medium (SSP2-4.5) and pessimistic (SSP5-8.5) emission scenarios. The joint use of these types of management and monitoring tools may help the managers in charge of carrying out the different water treatments needed to apply a better plan to raw water and may help them identify future threats and investment needs to adapt the urban water supply systems to the changing conditions of raw water, such as turbidity or conductivity, as a consequence of climate change., This research was co-funded by the Agencia Valenciana de la Innovacio, through the study "Aplicacion de los servicios climaticos para el desarrollo de una estrategia de adaptacion al cambio climatico de los sistemas urbanos de abastecimiento" (INNTA3/2020/14), as well as by EIT Climate-KIC, financing the CRISI-ADAP-II project (EIT-CKIC-TC_2.13.7_190799), and supported by the Ministry for the Ecological Transition and the Demographic Challenge (MITECO) of the Spanish Government under the "IMpacts of climate change on wetlands Affected by GroUndwAter (IMAGUA)" project.

Conventional drinking water treatment is inefficient in removing a large fraction of known organic micropollutants (OMPs). Therefore more efficient treatment approaches are needed to limit exposure to OMPs via drinking water. Here, the OMP removal performance of a combination of ozonation/no ozonation and two types of granular activated carbon (GAC) was tested in a one-year pilot-scale study, alongside a study of full-scale treatment. The raw water was lake water with low ambient concentrations of OMPs. In total, 29 of 99 targeted OMPs (per- and polyfluoroalkyl substances (PFASs), pharmaceuticals and other OMPs) were detected (mean n-ary sumation OMPs = 57 +/- 16 ng L-1). Only a few OMPs were consistently removed in the full-scale process, while ozonation in the pilot experiment effectively removed 72% of detected compounds to levels

The formation of disinfection by-products (DBPs) during drinking water treatment has been associated with various health concerns but the total DBP exposure is still unknown. In this study, molecular level non-target analysis by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to study non-volatile DBPs, and how their composition changes during water distribution in four drinking water treatment plants (DWTPs) in Sweden using different types of raw water and disinfection processes. The largest portion of tap water DBP compositions were detected also at the DWTPs, highlighting that these DBP formulae were rather stable and contribute to human DBP exposure. Yet the number of detected DBPs decreased 14-48% between drinking water treatment and consumer taps in the three plants in which no mixing of water from other DWTPs in the distribution system occurred showing active DBP processing in the water distribution network. While considerable amounts of bromine-containing DBPs were detected upon chemical disinfection in some DWTPs, few of them were detected in the tap water samples, likely due to debromination by hydrolytic reactions. The overall fewer non-volatile DBPs detected in tap waters, along with changed distribution among chlorine and bromine DBPs, demonstrate that DBP mixtures are highly dynamic and that DBP measurements at DWTPs do not adequately reflect exposure at the point-of-use. Clearly, more knowledge about changes of DBP mixtures through the distribution system is needed to improve DBP exposure assessments. Funding Agencies|FORMASSwedish Research Council Formas; Swedish Research Council for Sustainable Development [2013-1077]

There is growing worry that drinking water can be affected by contaminants of emerging concern (CECs), potentially threatening human health. In this study, a wide range of CECs (n = 177), including pharmaceuticals, pesticides, perfluoroalkyl substances (PFASs) and other compounds, were analysed in raw water and in drinking water collected from drinking water treatment plants (DWTPs) in Europe and Asia (n = 13). The impact of human activities was reflected in large numbers of compounds detected (n = 115) and high variation in concentrations in the raw water (range 15-7995 ng L−1 for ∑177CECs). The variation was less pronounced in drinking water, with total concentration ranging from 35 to 919 ng L−1. Treatment efficiency was on average 65 ± 28%, with wide variation between different DWTPs. The DWTP with the highest ∑CEC concentrations in raw water had the most efficient treatment procedure (average treatment efficiency 89%), whereas the DWTP with the lowest ∑177CEC concentration in the raw water had the lowest average treatment efficiency (2.3%). Suspect screening was performed for 500 compounds ranked high as chemicals of concern for drinking water, using a prioritisation tool (SusTool). Overall, 208 features of interest were discovered and three were confirmed with reference standards. There was co-variation between removal efficiency in DWTPs for the target compounds and the suspected features detected using suspect screening, implying that removal of known contaminants can be used to predict overall removal of potential CECs for drinking water production. Our results can be of high value for DWTPs around the globe in their planning for future treatment strategies to meet the increasing concern about human exposure to unknown CECs present in their drinking water., This work was supported through projects funded by the Swedish Research Council Formas SafeDrink (grant numbers 222-2012-2124) and LakePOPs (grant number 2016-01173). We thank all participating DWTPs for assistance in sampling and sample shipping. We would also like to acknowledge the following participants for coordinating the local sampling: Juliane Hollender (Eawag, Swiss Federal Institute of Aquatic Science and Technology, Switzerland), Tim Boogaerts, Adrian Covaci and Pieter Joos (Toxicological Center, University of Antwerp, Belgium), Rita Binetti (Researches and Controls Laboratories, Drinking Water Department Società Metropolitana, Italy) and Sara Castiglioni (Mario Negri Institute for Pharmacological Research, Italy).

In Panama City, the water supply sources for the population come mainly from surface waters, but in times of drought and extreme natural phenomena, the need to resort to underground sources is explored. This paper concerns an exploratory investigation with the aim of assessing the quality of groundwater in the southeastern part of the Province of Panama and to determine its possible use as drinking water during extreme natural phenomena. Monthly monitoring over a period of 15 months was carried out. The study included the sampling and analysis of groundwater by different physic-chemical, hydrochemical and biological parameters. The results showed that most of the parameters in the analysed groundwater conformed to the Panamanian drinking water norm and the water potability diagram, this is a convenient source of raw water for purification. As for other uses for this water source, it should be used with caution since it represents a medium risk of soil salinization for irrigation water; and it is a moderately hard water for industrial uses.

The removal of per- and polyfluoroalkyl substances (PFASs) presents a challenge for drinking water providers. Guidelines for PFAS concentrations in final drinking water are regularly updated to ever-decreasing values, and conventional drinking water treatment plants are not designed to remove PFASs. Currently, the most frequently used removal technique, adsorption to granular activated carbon (GAC), is often considered challenging. High-pressure membranes, such as nanofiltration (NF), have been shown to remove PFASs efficiently. However, the creation of a waste stream comprised of at least 10% of the feedwater volume is recognized as a major drawback of this technique. In this study, a NF pilot plant was operated at a drinking water treatment plant in the city of Uppsala, Sweden, for six months. NF removed up to >98% of PFASs and fulfilled other water quality targets, such as the removal of uranium-238, dissolved organic carbon (DOC), and mineral hardness from the raw water. The concentrate from the pilot plant was treated with two different GAC materials and two different anion exchange (AIX) resins in column tests, where the superior performance of AIX over GAC was observed in terms of PFAS removal. PFAS adsorption curves for GAC were found to superimpose each other for the two water types if normalized to the specific throughput of DOC. The application of the freely available PHREEQC model revealed improvement possibilities in terms of resin properties. A cost analysis using the column test results compared GAC filtration to the combination of NF with adsorption materials. Treatment costs were found to be largely dependent on the PFAS drinking water treatment goals and concentrate discharge requirements, which highlight the economic consequences of prevailing guidelines for drinking water and discharge to the environment. The results of this study provide both the scientific community as well as drinking water providers with important insights into the application of NF for PFAS removal during drinking water treatment as well as that mechanistic and economic aspects of NF treatment and the management of the resulting concentrate.

Perfluoroalkyl substances (PFASs) can occur in water sources, pass through drinking water treatment plants (DWTPs), drinking water distribution systems (DWDSs), to the consumer taps. This investigation was carried out to present the transportation behaviors of 17 PFASs, involving seven DWTPs with different water sources, raw water transportation modes, treatment processes, and DWDS structures in eastern and northern China. The results showed that the long-distance raw water transportation pipelines removed a certain extent of PFASs from raw water, probably due to the accumulation of loose deposits. The long-distance, open-channel South-to-North water diversion increased PFAS contamination risk. In the DWTPs, granular activated carbon (GAC) adsorption and ultraviolet radiation removed less than 25% of PFASs, but ozonation-biological activated carbon (O3-BAC) was superior to GAC alone in removing PFASs. Loose deposits couldsignificantly influence PFAS accumulation and release within branch-structured DWDSs. In loop-structured DWDSs, finished water with different PFAS characteristics could mix along the pipeline, with the corresponding DWTP as the center, ultimately forming a relatively uniform distribution in the entire DWDS.

The current study presents the effect of process chemistry as well as climate conditions on the water balance of a heap leach operation for black-schist ore. The research is based on the actual water balance at the Terrafame (former Talvivaara) mine site in Finland during the years 2017 and 2018 (base case). In addition, scenarios with a deviation in climatic conditions (Antofagasta case), chemistry (non-heat generation case) and effects of climate change (RCP4.5 (representative concentration pathway) case and RCP8.5 case) were investigated. In the first case, the annual precipitation and evaporation were simulated for a highly arid climate such as in the Antofagasta Mountains, whereas in the second case, an assumption was made of no excess heat generation (exothermic reactions) in the heap reactions. The base case predicted a requirement of 9,000,000 m3 annual discharge of water from the site with the heaviest annual rainfall. The discharge requirement and therefore the water footprint of the plant was shown to be highly dependent on the climatic conditions, as the Antofagasta case predicted a discharge of water from the site as low as zero. Heat generation, typical of the reactions dominating in a boreal black-schist heap leach operation, was shown to be vital for water management operations and therefore discharge management in Nordic climatic conditions (the non-heat generation case), where the discharge requirement was shown to be nearly threefold compared to the base case (2018). If the black-schist ore body resided in Antofagasta, the freshwater consumption would be over eight times the current consumption in the base case in Finland. Climate change scenarios show that the changing climate would increase the range of variation but only increase the need for water discharge from the site by 5% in the wettest years, while raw water utilization would increase by 46 to 83% during the driest years. In general, the results highlight the issues related to the mass and energy balance of a heap leach nickel process, and therefore feasibility—showing that although the heat generation is ore- and process-specific, the water consumption as well as discharge to the surrounding environment is highly dependent on the climatic conditions (precipitation, temperature) in the geographical location.

Traces of Molybdenum (Mo) in drinking water pose potent dangers owing to its harmful effects on the health of humans. This study used nanoscale zero-valent iron (Fe0) supported by activated carbon (NZVI/AC) for removing Mo(VI) from raw water. In an attempt to gain an understanding of the various factors that affect the process, we designed the study to look into the impact of various experimental parameters including pH, adsorption kinetics, and coexisting ions on the Mo(VI) removal using fixed-bed column runs and a batch-adsorption method and for Mo(VI) removal using NZVI/AC. The optimum conditions were found to be pH 4.5 and an equilibrium time of 9 h and 72 h for simulation water (SW) and raw water (RW), respectively. The removal of Mo(VI) was remarkably inhibited by the presence of silicate (SiO42&minus, ) and phosphate (PO43&minus, ), while the impact of humic acid and some other anions was insignificant. Metal cations such as Fe3+, Al3+, Zn2+, and Ni2+ enhanced the adsorption of Mo(VI). The influent contaminant concentration Mo(VI) in raw water was found to be 0.1603 mg/L, the empty-bed contact time (EBCT) was 3 and 6 min, whereas the breakthrough empty-bed volumes were 800 and 1100 and at the value of 70 &mu, g/L provided by WHO provisional guidelines, respectively.

Microplastics are omnipresent in the atmosphere, terrestrial and aquatic ecosystems, food and beverages. They may cause risks to biodiversity and the human population. The present study aims to assess the concentrations of microplastics in raw and drinking water of the Sinos River in Southern Brazil. The water was collected at eight locations along the Sinos River and in eight residences supplied with treated river water. The samples were processed by dying plastic particles with Nile Red and counting by fluorescence microscopy. River water showed an average of 330.2 particles L&minus, 1 and treated water 105.8 particles L&minus, 1. Fibers were the most abundant particles shapes in the samples. Particle abundance in the raw water did not follow the urbanization gradient in the Sinos River basin. The exact pathways of microplastic particles remain unidentified, but the predominance of fibers suggests that untreated sewage from washing machines may be a principal source of contamination, particularly in the headwaters. The microplastic in the drinking water is an additional factor to be considered in conservation efforts aiming at improving water quality in the Sinos River basin.

Residual dissolved aluminum (Al) in drinking water is becoming a serious concern due to its high potential risks to human health. However, the mechanism by which residual dissolved Al forms is yet to be elucidated in detail. In this study, the effects of pre-oxidation by ozonation and chlorination on the properties of dissolved organic matter (DOM) and residual Al concentrations remaining in solution after coagulation were explored in a pilot-scale test. Changes in the DOM properties caused by the water treatment process were characterized by ultraviolet-visible absorbance spectroscopy. Theprotonation-active sites, carboxylic- and phenolic-type groupsof DOM were quantified by spectral parameter DlnA400 (differential log-transformed spectra at wavelength 400 nm) in combination with the revised non-ideal competitive adsorption model. The results show that ozonation and chlorination significantly affect the properties of DOM and the amount of residual dissolved Al in coagulated drinking water. This effect was associated with the changes in the carboxylic- and phenolic-type groups in DOM. Results of the study show that residual dissolved Al in coagulated water can be controlled by affecting theAl binding sites in DOM by pre-oxidation before coagulation. The nature of pre-oxidation agent and its dosage should be selected depending on the quality of the raw water to be treated. Ozonation was concluded to be preferable pre-oxidation agent for the water in examined this study.

The water of Langat River is not suitable for drinking without treatment because of chemical pollution from both the point and non-point pollution sources, although it is one of the primary sources of drinking water in Selangor state, Malaysia. There is no significant study in Malaysia that has investigated the efficiency of treatment plants to remove metals from treated water. Therefore, Chelex 100 resin-ion exchanged method was applied to investigate the raw water samples and treated water samples of eight treatment plants. Samples were analyzed by Inductive Coupled Plasma-Mass Spectrometry for the dissolved concentrations of aluminium, arsenic, cadmium, chromium, and lead, which have complied with the drinking water quality standard of Ministry of Health Malaysia and World Health Organization. However, the average metal removal efficiency is about 52.48 ± 8.89% from treated water by the treatment plants based on a single sampling and this could be considered a preliminary indication to upgrade the treatment technology in Malaysia, because the efficiency in removing trace metals by the plants may vary in hourly samplings.

In recent years, the concentration of aluminium in the Iskar River occasionally exceeds the environmental quality standard (EQS). The river and the Iskar Dam, build on the river, are the main drinking water source of Sofia city (Bulgaria), with population exceeding 1.2 million. The average concentrations of aluminium in the raw water entering the drinking water treatment plants of Sofia city—Bistritza and Pancharevo—in 2018 were 0.148 mg/L and 0.199 mg/L, respectively, which are very close to the limits set in Directive 98/83/ EC. This study uses multifactorial analysis, taking into account the influence of the mineral and chemical composition of sediments of the Iskar Dam, the geological conditions at the dam’s catchment area, the relationship between the aluminium concentrations and precipitation in the region and also the relationship between the aluminium concentration and the turbidity at the inlet of the two treatment plants, to determine the origin of aluminium in the raw drinking water of Sofia city. The obtained linear regression models for the aluminium concentration and the turbidity at the inlet are significant (p ≤ 0.001) with coefficients of determination (R2) for DWTP–Bistritza and DWTP–Pancharevo of 0.54 and 0.51, respectively.

The number of people living without access to clean water can be reduced by the implementation of point-of-use (POU) water treatment. Among POU treatment systems, the domestic biosand filter (BSF) stands out as a viable technology. However, the performance of the BSF varies with the inflow water quality characteristics, especially turbidity. In some locations, people have no choice but to treat raw water that has turbidity above recommended levels for the technology. This study aimed to measure the efficiency with which the BSF removes microorganisms from well water and from fecal-contaminated water with turbidity levels of 3, 25, and 50 NTU. Turbidity was controlled by the addition of kaolin to water. Turbidity removal varied from 88% to 99%. Reductions in total coliform (TC) and Escherichia coli ranged from 0.54&ndash, 2.01 and 1.2&ndash, 2.2 log removal values (LRV), respectively. The BSF that received water with a higher level of turbidity showed the greatest reduction in the concentration of microorganisms. Additional testing with water contaminated with four bacterial pure cultures showed reductions between 2.7 and 3.6 LRV. A higher reduction in microorganisms was achieved after 30&ndash, 35 days in operation. Despite the filter&rsquo, s high efficiency, the filtrates still had some microorganisms, and a disinfection POU treatment could be added to increase water safety.