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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.

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.

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.

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.

Iodine is an essential element for humans; however, it can be toxic depending on its chemical form. A variety of toxic and non-toxic iodine species have been identified in environmental water and in the drinking water produced by public water treatment plants. Here, we examined the change of iodine species during the water treatment process at a public water treatment plant in Japan. Samples of raw water and of treated water immediately after each of eight treatment stages comprising the treatment process were collected, and a speciation analysis was conducted by means of ion chromatography– and size-exclusion chromatography–inductively coupled plasma mass spectrometry. In the raw water, iodine was found mainly as iodide or iodinated humic substances that were ultimately oxidized and transformed into iodate, a form non-toxic to humans, by two independent oxidation stages in the water treatment process – ozone treatment and chlorine treatment. No disinfection byproducts were detected at any stage of the treatment process. Fluorescence spectrometry with multivariate analysis revealed that humic substances were markedly decreased by ozone treatment, but not by chlorine treatment. The present results show that, at the plant-scale, ozone treatment is an effective means of removing toxic iodine species from raw water.

The new concentrator of Kipushi (NCK) in Katanga province is located in the southeast of the Democratic Republic of the Congo. This processing plant produces a concentrate of copper and cobalt, and it also generates a large amount of effluents equivalent to 2,500 m3/h. The complex nature of these effluent has become a threat to human lives, vegetation, as well as to freshwater resources in the surrounding areas. During this investigation, it was found that NCK effluents have high turbidity and high levels of sulphates compared with EPA standards. These sulphates originate from acid mine water used as one of the components for the flotation process. Also, high chlorides compared with EPA standards and hardness levels due to high concentrations of calcium and magnesium were recorded. Furthermore, the effluents contain heavy metals such as zinc, copper, cobalt, lead, ion, cadmium, and arsenic. Water used during flotation and downstream processes to produce copper and cobalt concentrates was a mixture of raw water from Kamalenge pond and acid mine water from Kipushi mine in a volume ratio of 70/30 respectively. However, it was found that the mine water is the major contributor to the effluent contamination.

During disinfection, dissolved organic matter (DOM) is the major precursor to form disinfection by-products (DBPs), which may be of potential human health concern. Previous research focused on waters of continental climates and less on subtropical environments. However, water sources in subtropical climates are regularly impacted by major rain events during the summer months. This study evaluated the C- and N-DBP precursor removal capacity of two conventional ion exchange (IEX) resins and one magnetic ion exchange (MIEX) resin with a raw water at normal conditions and impacted by a heavy rain event. The rain event introduced 3 mg C/L total organic carbon (TOC) comprised mainly of low to medium molecular weight organics. All three resins were able to remove TOC and DBP precursors (>66%) but being less efficient in reducing turbidity (3–48%) and colour (9–24%). The resin with the smallest bead size was affected the most by the increased medium MW DOM loading resulting in DOM and C-DBP precursor removal performance losses of 10% and 22%. When applied as a pre-treatment for coagulation, MIEX was more efficient in DBP precursor control than coagulation in addressing the additional organic and DBP precursor loading after a heavy rain event.

This study presents an overview of the changes in humic acids, which are disinfection by-product precursors in a raw water canal, Bangkok, Thailand, during different seasons. Fluorescence excitation–emission matrix (EEM) spectroscopy was employed to characterize and quantify spatial and seasonal variations of dissolved organic matter (DOM) along a raw water canal of the Metropolitan Waterworks Authority (MWA) Bangkok, Thailand. A total of 276 raw water samples were collected from 23 stations during the winter, summer and rainy season. Results indicate that hydrophobic fractions made up the majority of DOM and this water source also had high specific UV absorbance (SUVA). Seasonal variation of DOM was found to be more pronounced than geographical variation along the canal. The presence of humic substances was the highest in the rainy season due to rainfall and surface runoff, while soluble microbial by-product-like substances were found only in summer. The results provide an insight into the prediction of humic acids in source water, which benefits the MWA in being aware of seasonal variation in water quality.

Operation of conventional drinking water treatment plants (DWTPs) is limited by seasonal variations in the characteristics of raw water, such as algae levels and turbidity. In this study, an integrated flotation and sedimentation unit (IFSU) with side flow-inclined plate settlers (SFIPS) was applied to enhance the removal ratio of algae and turbidity in a full-scale field experiment. To accomplish this, the performance of two IFSU reactors (with and without SFIPS) treating algal-rich water, low-turbidity water and high-turbidity water was compared. Extensive experiments were conducted based on a central composite face-centered design, and the results were analyzed using response surface methodology. Polyaluminium chloride dose, NaOH dose, influent turbidity level and influent chlorophyll level were selected as the operating variables to analyze, optimize and model the process. The results showed that SFIPS functioned as a counterflow inducer to enhance the effects of stratified flow patterns and decrease the clarification loading rate in the separation zone during the dissolved air flotation process, leading to considerable increases in algae and turbidity removal in the IFSU reactor. The results of this study will facilitate upgrades of conventional DWTPs to improve their potential.

In order to reduce the number of operations for the assessment of potable water treatment, principal component analysis and hierarchical clustering are applied to large databases of raw and treated water of three treatment plants with various processes. It appears that the measurements can be divided into three clear groups, with a correlation higher than 0.8. The first contains salinity, conductivity, water hardness, calcium, magnesium and chlorides. The second includes turbidity and organic matter. The third includes pH and alkalinity. Despite the disparities in water quality and in all the cases, three parameters were sufficient to represent all the routine measurements: conductivity, turbidity and pH, which can represent the three principal components of the data. It can reduce by two-thirds of the measurement and analysis, dropping from 6,960 to 2,088 analysis annually. The analysis on the principal axes of the individuals, represented by raw and treated water from the three treatment plants, reveals that the quality of the raw water seems more important than the type of treatment process, in the resulting quality of treated water. These results could be generalized and easily adopted by other treatment plants whatever the process. They could offer substantial savings of time, chemicals, electricity and longevity of the devices.

This study was to assess the effect of powdered activated carbon (PAC) pre-adsorption time on ultrafiltration performance for surface water treatment. Experimental results demonstrated that membrane fouling could be mitigated by extending the pre-adsorption time. The molecular weight (MW) distribution of water samples was determined by liquid chromatography – organic carbon detector (LC-OCD) and results showed that the mechanism of PAC controlling fouling was attributed to a decrease in the low molecular weight (LMW) fraction of raw water via extending the pre-adsorption time. Fouling indexes (FIs) were used to evaluate membrane fouling potential and the results showed that polysaccharides (PS) and proteins (PN) were greatly responsible for membrane fouling. Therefore, prolonging the PAC pre-adsorption time and decreasing the PS and PN content in raw water are the main measurement for the alleviation of membrane fouling when PAC is used as the pretreatment in waterworks.

Huge amounts of water treatment sludge are wasted annually in Egypt. One common practice of sludge handling is to discharge into waterways or by disposal after drying into landfills. Currently, there is a critical need for sustainable solutions that provide environmental protection as well as benefits for water producers. Coagulant recovery is not new but is still a good solution for sludge handling and reduction of operational costs. This work aims at completing the picture on coagulant recovery from alum sludge in El-Sheikh Zayed water treatment plant (ESZ-WTP) by acidification using hydrochloric acid. This study also investigates the effect of sequential recovery on the efficiency of the coagulant and treated water quality. Sludge characterization was done through determination of metals9 concentration and composition, water content and organic matter concentration. The influence of acid concentration, sludge mass, acid/sludge mass ratio, mixing speed, temperature, and mixing time on aluminum leaching was studied. At optimum values of these parameters, 82.4% aluminum recovery was obtained. In addition, repeated recoveries were carried out at lab scale using raw water from ESZ-WTP. Our research revealed that recovered coagulant can be used for three times9 recoveries as the trihalomethanes remain within acceptable limits.

The Mudgeeraba drinking water treatment plant, in Southeast Queensland, Australia, can withdraw raw water from two different reservoirs: the smaller Little Nerang dam (LND) by gravity, and the larger Advancetown Lake, through the use of pumps. Selecting the optimal intake is based on water quality and operators' experience; however, there is potential to optimise this process. In this study, a comprehensive hybrid (data-driven, chemical, and mathematical) intake optimisation model was developed, which firstly predicts the chemicals dosages, and then the total (chemicals and pumping) costs based on the water quality at different depths of the two reservoirs, thus identifying the cheapest option. A second data-driven, probabilistic model then forecasts the volume of the smaller LND 6 weeks ahead in order to minimise the depletion and spill risks. This is important in case the first model identifies this reservoir as the optimal intake solution, but this could lead in the long term to depletion and full reliance on the electricity-dependent Advancetown Lake. Both models were validated and proved to be accurate, and with the potential for substantial monetary savings for the water utility.

Pilot plant testing is invaluable for ascertaining the robustness of water treatment processes against raw water quality events such as turbidity and colour spikes, whether it be for stress testing of an existing process or designing of a new process. Unfortunately, the natural occurrence of such events (particularly colour) can be difficult to predict and commercial humic materials generally fail to closely match the indigenous natural organic matter (NOM) present in the raw water. Therefore, it is highly desirable to be able to simulate NOM event conditions. This paper describes a simple brewing method that we developed and used in our recent pilot plant evaluation of a proposed DAF/Ozone/BAC process for drinking water treatment. Using this method we successfully prepared, by using fallen leaves etc. collected from the local catchment area, large quantities of a concentrated NOM stock solution with its specific ultraviolet absorbance (SUVA), when diluted, very close to the median SUVA of historical NOM events. The brewed solution showed broadly similar NOM characteristics to those of the raw water encountered during the pilot investigation period in terms of molecular weight distribution and fractionation. The coagulation behaviour was also examined for the spiked and non-spiked raw water.

Water resources in Egypt have become stressed due to changes in climate patterns. Egypt is characterized by two seasons, a mild, wet winter and a hot, dry summer. In recent years, many areas have become vulnerable to the impact of extreme climate events. The impact of these events on water supplies has become more pronounced. This study states that there is a tangible impact of extreme climate events upon both water resources quality and water supplies. The Nile river water turbidity was investigated as an operational indicator for the water treatment plants (WTPs). The results illustrated that an unprecedented increase in average turbidity of raw water in Upper Egypt (from 4 up to 110 NTU) led to a cut in water supplies for up to 100 hours in some areas. While in Alexandria the turbidity did affect WTP operation efficiency, safe water could still be produced. Cuts in water supply would have an impact on hygiene and make people prone to use unsafe water sources. These consequences stimulate water supply bodies to develop action plans to mitigate and/or avoid such potential impacts on public health. This study suggests proposed steps to develop an appropriate plan to face such extreme events.

The required coagulant dosage is strongly related to the quality of raw water or wastewater. Online sensors for most quality parameters are now readily available to treatment facilities, yet remain rarely used in treatment process control. This paper presents the evaluation of an advanced coagulant dosing control system based on online measurements in full-scale processes. The popular multivariate analytical method, partial least square regression, was used to build up the relationship between the coagulant dose and wastewater quality. The system was tested in two wastewater treatment plants (WWTPs) in Norway. Coagulant savings up to 30% in Norwegian plants were observed with feed forward calibrations. The considerable savings reduce sludge production, leading to further cost saving on sludge treatment. This paper presents the method, function and experiences of the full-scale implementation of the system in different WWTPs.

The removal efficiency of particulate matter from a sedimentation basin with an inclined plate settler in drinking water treatment facilities is sometimes reduced by density flow caused by temperature increases in the raw water. In this study, the structure of the density flow and its prevention are investigated by means of three-dimensional computational fluid dynamics (CFD). The results of CFD show that upward velocity is uniform and normal operations are performed before the increase in inlet water temperatures. After the onset of a temperature increase in the raw water, the upward flow velocity on the inclined plate settler increases, especially in the upstream zone of the plate. This velocity increment has a strong correlation with increase in turbidity as a result of the overflow of particulate matter. The effects of the installation of baffle plates on the inclined plate settler to reduce turbidity were explored. The CFD results using baffle plates show a significant decrease in upward velocity on the inclined plate settler. This suggests that baffle plates are effective in suppressing the overflow of particulate matter. To verify the prediction by CFD, baffle plates were installed in a drinking water treatment facility. The results show that the turbidity of treated water was reduced by the proposed procedure.

Predicting the coagulant dosage is especially crucial to the purification process in water treatment plants, directly affecting the quality of the purified water. Nowadays, several mathematical methods have been adopted for the purification process, but their predictive precision and speed still need to be improved. This study applies a novel neural network called the extreme learning machine (ELM) to predict the coagulant dosage based on certain signification factors of the raw water. Performances are compared between ELM and back-propagation neural networks in this paper. The results show that both neural network algorithms perform well in this application and ELM can realize online prediction due to its short time consumption.

Real-time determination of appropriate coagulant dosage under wide fluctuation of raw water quality in a water treatment plant (WTP) is a challenging task due to nonlinearity relation between coagulant dosage and raw water characteristics. In this research, three techniques, multilayer perceptron (MLP), adaptive neuro fuzzy inference system (ANFIS), and generalized regression neural network (GRNN), are applied to determine the coagulant dosage at Bansong drinking WTP. Each model is developed based on 8,760 historical data sets with hourly resolution for a whole year. Several statistical properties are determined to obtain the best-fit model from each method. The top performing models of each method are evaluated by external validation indices and absolute relative error according to nine turbidity zones. From the result, MLP and ANFIS models meet all conditions of validation indices, but GRNN cannot. The MLP shows the best result for high turbidity zones over 20 NTU as well as for overall performance. Meanwhile, ANFIS provides consistent results and better performance than MLP for low turbidity zones which have higher disorder of coagulant dosage data. The GRNN shows high accuracy for the highest turbidity zone which occurs during the rainy season. It is concluded that MLP, ANFIS, and GRNN can support operators effectively for real-time determination of coagulant dosage.

Disinfection by-products are compounds occurring in drinking water as a result of reactions between disinfectants and impurities in raw water, and their occurrence has been a public health concern for the last four decades. Haloacetic acids (HAAs) are one of the major by-products of chlorination. The concentration and variation of HAAs was monitored in 540 samples taken from tap water in six water and wastewater districts of Tehran, Iran. Seasonal variation indicated that natural organic matter and HAA levels were much higher in the spring and fall seasons. The concentrations of HAAs in drinking water samples varied with water sources. They were higher in drinking water obtained from surface water. In this study, the analysis method of human health risk assessment with regard to exposure to HAAs by drinking water in Tehran was based on the United States Environmental Protection Agency (USEPA) guideline. It was found from these studies that the risk to human health appears to be negligible. © 2017 IWA Publishing.

Detailed source water monitoring showed large variations in the total concentrations of aluminium and iron in the Vaal Dam, South Africa, which were highlighted as a specific concern for one of the largest drinking water treatment plants in South Africa. This study aimed to better understand the presence of these metals in the source water, removal of these metals through the conventional treatment process, and final water quality trends, for the period 2008 to 2014. Aluminium and iron concentrations were highly variable and showed significant influence on colour and turbidity in source water. Sedimentation performed well, and removed over 70% of the metal concentration from the raw water. Filtration removed 15% of the remaining aluminium and iron concentrations. The pH and turbidity of the final water had minor effects on the metal concentration in the final water. The conventional treatment process was shown to be capable of removing aluminium and iron from the source water as both were within water quality limits in the final water. This study highlighted the importance of source water quality monitoring and treatment plant efficacy in evaluating whether the current treatment technology is appropriate for current and future challenges.

The overall purpose was to assess the feasibilities of recycling filter backwash water (FBWW) and combined filter backwash water (CFBWW) in a drinking water treatment plant in south China. The variations of regular water-quality indexes, metal indexes (Al, Mn and Cd), polyacrylamide and disinfection by-product indexes (trihalomethanes and their formation potentials) along with the treatment and the recycling processes were monitored. Results showed the recycling procedure caused increases of turbidity, total solids, ammonia nitrogen (NH3-N), permanganate index (CODMn), and dissolved organic carbon, Al, Mn and Cd concentrations in a mixture of raw water and FBWW or CFBWW compared to those in raw water. However, the recycling procedure had negligible impacts on the qualities of settled water and filtered water because most of the contaminants could be effectively removed by the conventional water treatment process. Although recycling did cause slight increases of NH3-N and CODMn levels in settled water and filtered water, the quality of finished water always conformed to Chinese standards for drinking water quality according to the surveyed indexes in the present study. Thus, it is appropriate to recycle waste streams in water-stressed areas if the source water is well managed and the water treatment processes are carefully conducted.

The relative accuracy of static and dynamic water treatment works (WTWs) models was examined. Case study data from an operational works were used to calibrate and verify these models. It was found that dynamic clarification, filtration and disinfection models were more accurate than static models at predicting the final water quality of an operational site but that the root mean square errors of the models were within 5% of each other for key performance criteria. A range of abstraction rates at which the WTWs was predicted to operate adequately were identified using both types of models for varying raw water qualities. Static clarification, filtration and disinfection models were identified as being more suitable for whole works optimisation than dynamic models based on their relative accuracy, simplicity and computational demands.

There are debates about whether rainwater is suitable as drinking water. A serious shortcoming of the debate is that there are differences in the design and management of rainwater harvesting (RWH) systems. This study is based on the performance of two RWH systems that are used for drinking purposes at a kindergarten and a primary school in Cu Khe, Vietnam. Each system comprised a painted galvanized iron roof, a first-flush diverter, two stainless steel tanks connected in series, a calmed inlet, mosquito screens on open holes, PVC pipelines, filter cartridges, and a UV sterilizer. During 18 months, stored rainwater was sampled five times, and treated rainwater was sampled four times. Twenty-three water quality parameters were analyzed, including pH, total dissolved solids, turbidity, nitrate, nitrite, ammonia, hardness, arsenic, iron, cadmium, nickel, chromium, manganese, mercury, selenium, lead, zinc, Escherichia coli , and total coliform. It was found that all the physicochemical qualities of the stored rainwater, prior to treatment, satisfied the World Health Organization (WHO) drinking water guidelines. After physical filtration and UV sterilization, all parameters, including microbiological indicators, satisfied the WHO drinking water guidelines. Further management strategies to stabilize water quality were discussed.

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

Coagulation and flocculation are two main processes used to integrate colloidal particles into larger particles and are two main stages of primary water treatment. Coagulation and flocculation processes are only needed when colloidal particles are a significant part of the total suspended solid fraction. Our objective was to predict turbidity of water after the coagulation and flocculation process while other parameters such as types and concentrations of coagulants, pH, and influent turbidity of raw water were known. We used a multilayer perceptron (MLP), a radial basis function (RBF) of artificial neural networks (ANNs) and various kinds of fuzzy regression analysis to predict turbidity after the coagulation and flocculation processes. The coagulant used in the pilot plant, which was located in water treatment plant, was poly aluminum chloride. We used existing data, including the type and concentrations of coagulant, pH and influent turbidity, of the raw water because these types of data were available from the pilot plant for simulation and data was collected by the Tehran water authority. The results indicated that ANNs had more ability in simulating the coagulation and flocculation process and predicting turbidity removal with different experimental data than did the fuzzy regression analysis, and may have the ability to reduce the number of jar tests, which are time-consuming and expensive. The MLP neural network proved to be the best network compared to the RBF neural network and fuzzy regression analysis in this study. The MLP neural network can predict the effluent turbidity of the coagulation and the flocculation process with a coefficient of determination (R2) of 0.96 and root mean square error of 0.0106.

The potential of powdered activated carbon (PAC) adsorption for odor removal in low turbidity drinking water was investigated. The batch experiments were conducted under various conditions including PAC species, dosage, contact time and dosing point. The effects of pre-chlorination and PAC dosage on turbidity were also studied. Results showed that adsorption was quite vulnerable to initial threshold odor number (TON), and higher influent TON required a larger dosage. Both PAC species (derived from coal and wood) presented excellent adsorption capacity for odorants. The adsorption process versus time had three steps and the adsorption kinetics were well fitted by the second order model. Pre-chlorination had an adverse effect on both raw water TON and odor removal. PAC adsorption was enhanced by dosing during coagulation and could, in turn, save coagulant dosage.

To ascertain the quality of drinking water, surveillance of drinking water quality was conducted in Bhopal. The water supply to water treatment plants (WTPs) is from Kolar dam and Upper Lake. There was no significant change in water quality at the Kolar WTP on a day-to-day basis except in summer, when the manganese content of raw water was 0.3–0.4 mg/L, which was removed during treatment. The treated water quality from Birla Mandir WTP was within desirable limits during all the seasons. Filtered water from Idgah WTP showed significant coliform counts, indicating malfunctioning of filter beds. However, after chlorination coliforms were absent. For Phulphukta WTP, residual chlorine at the sump was 0.8–2.0 mg/L; therefore finished water was free from bacterial contamination. The finished water quality of all the WTPs met Central Public Health and Environmental Engineering Organisation guidelines. Although the sump water was free from bacterial contamination, it was contaminated with coliforms at the consumer end, which may be attributed to improper maintenance of service reservoirs and contamination en route. The proper maintenance of the distribution network, awareness of hygienic and sanitary conditions around public taps and proper storage of water are prerequisites for maintaining a safe water supply in the city.

Raw water quality variation has a great effect on drinking water treatment. To improve the adaptivity of drinking water treatment and stabilize the quality of treated water, a raw water quality assessment method, which is based upon the support vector machine (SVM), is developed in this study. Compared to existing raw water quality assessment methods, the assessment method studied herein is oriented to drinking water treatment and can directly be used for the control of the chemical (alum and ozone) dosing process. To this end, based upon the productive experiences and the analysis of the operating data of water supply, a raw water quality assessment standard oriented to drinking water treatment is proposed. A raw water quality model is set up to assess the raw water quality based upon the SVM technique. Based upon the raw water quality assessment results, a feedforward–feedback control scheme has been designed for the chemical dosing process control of drinking water treatment. Thus, the chemical dosage can be adjusted in time to cope with raw water quality variations and hence, the quality of the treated water is stabilized. Experimental results demonstrate the improved effectiveness of the proposed method of raw water quality assessment and the feedforward–feedback control scheme.

Industrial-scale ultrafiltration (UF) membrane systems have gained wide acceptance for producing safe drinking water. Laboratory and pilot plant studies are often carried out prior to the design of full-scale water treatment plants. Emphases are laid on how accurately these laboratory and pilot plant studies represent actual industrial-scale systems and the limitations. A case study which encompasses laboratory experiments, pilot plant and industrial-scale UF systems has been carried out in Malaysia using the same type of modified polyethersulfone hollow fiber UF membrane and surface raw water source. This research elaborates on the practical utilization of laboratory experiments and pilot plant results on the design and scale-up for industrial-scale water treatment plants. The results obtained in filtrate quality, transmembrane pressure and specific electricity requirements elucidate that both laboratory- and pilot-scale studies are essential to determine the detailed design criteria of an industrial-scale UF membrane water treatment plant with limitations that require attention. Design engineers are able to reduce the safety factor allowance and minimize cost by utilizing laboratory- and pilot-scale results for the scale-up of UF membrane water treatment plants.

In this study, iron oxide modified sands with nano-pores (IOMSNP) were enveloped in biofilm (B-IOMSNP) in order to treat the ammonium-nitrogen (NH4+-N) in micro-polluted raw water. The biomass, optimum backwashing conditions, treatment efficiency, and surface morphological properties of the B-IOMSNP were investigated via bio-filtration experiments. The raw quartz sands (RQS) and IOMSNP exhibited biomass levels of 24.32 nmol-P/(g-sand) and 83.71 nmol-P/(g-sand), respectively. The B-IOMSNP filter exhibited a lower swelling ratio, smaller initial head loss, and longer filtration period when water and air were used alternately for backwashing rather than water alone. In addition, the B-IOMSNP was most effective when air alone (at a strength of qair,I = 7 L/(s·m2) for tair,I = 6 min), a combination of air and water (at strengths of qair,II = 7 L/(s·m2) and qwater,II = 5 L/(s·m2) for tair-water,II = 6 min, respectively), and water alone (at a strength of qwater,III = 7 L/(s·m2) for twater,III = 4 min) were used alternately for flushing. The results indicated that the proposed B-IOMSNP could efficiently resist the shock induced by high NH4+-N concentrations (4 mg/L). The ripening period of the B-IOMSNP column was equal to 30 minutes. Furthermore, the B-IOMSNP reduced the turbidity of the water to values of less than 0.2 NTU for 72 hours and exhibited an NH4+-N removal rate of up to 96% and a head loss of 132 cm. In contrast, the biofilm-coated RQS exhibited an NH4+-N removal rate varying from 60% to 82%, a filtration period of 16 hours, and a terminal head loss of 58 cm. Due to its nano-pores and rough surface, the IOMSNP exhibited a specific surface area 39 times greater than that of the RQS, resulting in a higher filtration performance and absorption capacity.

The water crisis in the state of Selangor has prompted the state water authority to use water from abandoned mining pools as an alternative resource of raw water supply. In this study, the potential use of the mining pool water has been assessed to evaluate its safe use for potable water consumption, which is the source of raw water to be supplied to water treatment plants. Assessments were made between sampling sites that include abandoned mining pools, active sand mining pools, and the receiving streams (two tributaries and the main river, Selangor River) within Bestari Jaya catchment, Selangor River Basin. As anticipated, some concentrations of metals were found in the active mining pool and in its discharge, such as iron, manganese, lead, copper and zinc. However, the trace elements were found at very low concentrations or below detection limits in the abandoned mining pools and in the rivers. It was found that generally the quality of the water in the rivers (upstream of water intake of the water treatment plants) was well below the recommended guideline limits set out by the Malaysia Ministry of Health for untreated raw water, and therefore is safe for potable water use.