Total Residual Chlorine Research Articles

Evaluation of bio-physical parameters and microbial pollution in water systems

ABSTRACT This study covers the purification and sterilization stations in different regions of the Iraqi city of Baghdad. To systematically conduct this study, several drinking water samples were collected from various sites in Al-Karkh and Al-Rusafa in Baghdad. These samples were tested bacteriologically, such as Bacterial Total Count, Total Coliform Bacteria, fecal bacteria, and Escherichia coli (E. coli). Furthermore, the physical properties of the total hardness (TH), turbidity, residual chlorine, and pH from June 2021 to July 2022 were measured monthly. The seasonal variation of the research parameters is considered by providing a statistical description. The biological tests indicate that the water is seriously contaminated with fecal coliform in one area of the Al-Karkh region during the months of autumn and summer. Also, the biological tests of the Al-Rusafa region elucidate the dangerous concentrations of plate count bacteria in summer and autumn. Furthermore, the Al-Rusafa region reports cases of E. coli and coliform in the summer, which exceed the Iraqi and WHO guidelines. But, the physical tests ascertain the semi-alkalinity of drinking water with the greatest residual chlorine value of 0.9 ppm in the summer.

Quality of Groundwater Distributed by Collective Alternative Solution in Rural Areas Interferes with Weather Variables

Theoretical benchmark: The seasonal and spatial variability of a spring can be monitored by physical, chemical and microbiological parameters, to ensure access to the population of drinking water, managed in a safe manner, since alternative and unsafe sources of water supply, and sometimes without treatment, pose risk to human health. Method: Quantitative, retrospective study of water samples collected monthly by monitoring the quality of water for human consumption in rural and urban areas from collective supply from January 2018 to December 2019. Results and conclusion: Precipitation interfered with all water quality indicators except free residual chlorine; and temperature interfered with turbidity, free residual chlorine, and fluoride. There was a correlation between fluoride and temperature; total coliforms and free residual chlorine, which suggests the possibility of antimicrobial action. Cross-sectoral actions to improve the quality of water supplied in rural areas are therefore proposed, through the adoption of continuous disinfection of all water sources. Research Implications: Presents important indicators on the quality of water consumed by the population, directly influencing the health of consumers. Originality/value: Research carried out in the rural area in Brazil is controversial about the interference of climatic factors in the quality of the distributed water. In view of the need to provide access to the population of drinking water, subject to safe and efficient treatments, without risks to human health, and for this purpose this study assesses the interference of climatic factors in the quality of water.

Machine-learning-assisted prediction and optimized kinetic modelling of residual chlorine decay for enhanced water quality management

The quality of water changes from source to tap, presenting challenges in maintaining consistent water quality across the system. Predicting water quality in distribution systems, including disinfectant residual loss and by-product formation, has been the subject of research since the early 1990s. Although numerous models have been proposed to predict residual chlorine decay, disputes exist among researchers and experts over the superiority of certain models. Accordingly, this study modified the existing process-based bulk decay models by replacing the initial Total Residual Chlorine (TRC) concentration parameter with TRC demand, leading to an improvement in the models' performance. The modification resulted in a 38.03%, 28.02%, 23.11%, and 33.29% average improvement in Mean Squared Error (MSE) values for the First Order Model (FOM), Parallel First Order Model (PFOM), Second Order Model (SOM), and Parallel Second Order Model (PSOM), respectively. The study also introduced an online predictive method based on a Machine Learning (ML) algorithm that predicts the first-order TRC bulk decay rate by using water quality parameters as inputs. A Gaussian Process Regression (GPR) model was used to predict the kinetic parameters in FOM, which accurately predicted the test sets for most of the cases. In addition, a new methodology was proposed in this study for predicting TRC in water distribution systems that incorporates the variability of source natural organic matter, operational actions, and water demands. This method seeks to develop high-fidelity and robust water quality predictions that provide operational decision support for optimized distribution system management. In conclusion, this study emphasizes the importance of understanding water quality changes from source to tap and the challenges of maintaining consistent water quality across the system. The study suggests modifying existing models and introducing a novel methodology for predicting residual chlorine in water distribution systems that can improve water quality management and, ultimately, better public health outcomes.

Evaluation of the physical, chemical and microbiological parameters of the drinking water at the city of Caraz during the period August 2017-January 2018 [Evaluación de los parámetros físicos, químicos y microbiológicos del agua potable de la ciudad de Caraz durante el período agosto 2017-enero 2018

The objective of the present investigation was to evaluate the main physicochemical and microbiological parameters of drinking water in the city of Caraz, located in the province of Huaylas, department of Ancash, during the period between August 2017 and January 2018. For this purpose, samples were taken at four points in the city, from the supply reservoir to the home distribution network. Twenty-three physical, chemical and microbiological parameters were analyzed: color, conductivity, total dissolved solids, total suspended solids, temperature, turbidity, residual chlorine, chlorides, total hardness, fluorides, nitrates, dissolved oxygen, pH, sulfates, arsenic, cadmium, copper, iron, manganese, mercury, lead, total coliforms and fecal coliforms. In determining the indicated parameters, standardized chemical analysis methods were used for each of them. Some analyzes were carried out in the same place (in situ) and others in the chemistry laboratory as well as in the environmental quality laboratory of UNASAM. The results obtained were contrasted with the maximum permissible limits (MPL) of the Regulation of Water Quality for Human Consumption (MINSA, 2010). Of the 23 parameters evaluated, 20 were below the MPL (maximum permissible limit), with the exception of mercury and total and fecal coliforms, whose certainty given by the method used did not allow us to affirm that the values ​​obtained are within the MPL.

Water as Source of Salmonella Species Contamination in Jordanian Broiler Farms

Broiler chickens are a major meat product worldwide. Maintaining the health of flocks is essential for poultry farming and it is critical to minimize exposure to waterborne pathogens. This study determined the extent of Salmonella spp. infections and identified sources of waterborne disease transmission at representative Jordanian broiler farms. We investigated 10 broiler farms located in five Jordanian Governorates; Amman, Irbid, Karak, Zarqa, and Madaba. Cloacal swabs were collected from chickens and water samples were collected from farm tanks, broiler house tanks, and drinking apparatus (drinkers) over three rearing cycles. Water was tested for pH and residual free chlorine. Salmonella spp. was isolated from the cloacal and water samples using biochemical methods and confirmed as Salmonella enterica serovar Enteritidis by PCR. Salmonella enterica serovar Enteritidis was detected at sampled farms at different percentages and the pathogen was found in 16.6% (15/90) of drinkers and 20% (30/150) of cloacal samples. The total and free residual chlorine concentrations in the water were lower than the recommended levels. The average pH was within the recommended values. This study concluded that S. Enteritidis is prevalent in broiler farms in Jordan. Thus, improved hygienic practices at broiler farms and the establishment of national water quality guidelines are necessary to decrease S. Enteritidis transmission in boiler farmers and thus enhance food safety in Jordan.

Pollution Characteristics and Risk Assessment of DBPs in Typical Drinking Water Sources in Wuhan Under the COVID-19 Pandemic

In order to reveal the pollution characteristics and risk levels of DBPs in typical drinking water sources in Wuhan under the COVID-19 pandemic, 26 sampling sites were selected in typical drinking water sources in Wuhan. N,N-diethyl-1,4-phenylenediamine spectrophotometry and gas chromatograph-micro-cell electron capture detector (GC-μECD) methods were used to detect residual chlorine disinfectants and DBPs in water, respectively, and their health and ecology risks were assessed. The results showed that free chlorine or total residual chlorine were detected in 16 of the 26 water samples, and the maximum concentration was 0.04 mg·L-1, which exceeded the limit of the surface water standard in China. The concentration of residual chlorine was higher in sampling sites near the outfall of a municipal sewage plant. There were 34 types of DBPs measured in 10 sampling sites, and 24 types of substances were detected with the detection rate of 10.00%-100.00%. The ρ (total DBPs) was in the range of 0.11-104.73 μg·L-1, with an average value of 7.26 μg·L-1. The concentration of chloroform was the highest among all the DBPs, ranging from 9.98 μg·L-1 to 11.15 μg·L-1, with an average value of 10.47 μg·L-1. The concentration of 2-bromo-2-iodoacetamide was the lowest, ranging from ND-0.11 μg·L-1, with an average value of 0.01 μg·L-1. The overall detection level of the DBPs area was low in this study area, and the result of the health risk assessment showed that the DBPs had no carcinogenic or non-carcinogenic health risks to human body. However, the results of the ecological risk assessment showed that chloroform presented a high ecological risk to aquatic organisms.

Responses of aquatic organisms downstream from WWTPs to disinfectants and their by-products during the COVID-19 pandemic, Wuhan

The outbreak of COVID-19 has led to the large-scale usage of chlorinated disinfectants in cities. Disinfectants and disinfection by-products (DBPs) enter rivers through urban drainage and surface runoff. We investigated the variations in residual chlorine, DBPs, and different aquatic organisms in the Hanjiang, Fuhe, and Qinglinghe Rivers in Wuhan during the COVID-19 pandemic. The sampling sites were from the wastewater treatment plant outlets to the downstream drinking water treatment plant intakes. Total residual chlorine and DBPs (dichloromethane and trichloromethane) detected in the river water ranged from 0 to 0.84 mg/L and 0 to 0.034 mg/L, respectively. The residual chlorine and DBPs showed a gradual reduction pattern related to water flow, and the concentration at intakes did not exceed the Chinese drinking water source quality standards. Phytoplankton and zooplankton densities were not significantly correlated with residual chlorine and DBPs. The fluctuations in phytoplankton resource use efficiency (RUE) and zooplankton RUE in the Fuhe River, with the highest residual chlorine, and the Qinglinghe River with the highest DBPs, were higher than those in the Hanjiang River. For benthic macroinvertebrates, the number of functional feeding groups in the Hanjiang River was higher than that in the Fuhe and Qinglinghe Rivers. The water and sediment bacterial communities in the Hanjiang River differed significantly from those in the Fuhe and Qingling Rivers. The denitrification function involved in N metabolism was stronger in the Fuhe and Qinglinghe Rivers. Structural equation modelling revealed that residual chlorine and DBPs impacted the diversity of benthos through direct and indirect effects on plankton. Although large-scale chlorine-containing disinfectants use occurred during the investigation, it did not harm the density of the detected aquatic organisms in water sources. With the regular use of chlorinated disinfectants for indoor and outdoor environments in response to the SARS-CoV-2 globally, it is still necessary to study the long-term and accumulated responses of water ecosystems exposed to chlorine-containing disinfectants.

Disinfection by-products in drinking water distribution system of Bucharest City

Chlorine is widely used in Romania and all over the world as a disinfectant of drinking water. During the chlorination process, the natural organic matter and inorganic ions react with chlorine forming disinfection by-products (DBPs). The predominant organic disinfection by-products are trihalomethanes (THMs) while the main inorganic disinfection by-products are chlorate and chlorite ions. THMs were detected in all investigated drinking water samples from Bucharest distribution system with values from 27.8 µg/L up to 75.1 µg/L, which are below the maximum concentration value admitted by Romanian drinking water legislation of 100 µg/L. Chloroform constitutes the major component in total THMs concentration found in all tested drinking water. Chlorate and chlorite anions were not detected in any of the investigated drinking water samples. THMs concentration was correlated with total organic carbon (TOC), residual chlorine and chloride.

Impact of UV irradiation on disinfection by-product formation and speciation from post-chlorination of dissolved organic matter

Abstract The objective of this study was to investigate the effects of combined low-pressure ultraviolet (UV)irradiation and chlorination on the formation of disinfection by-products (DBPs) from different dissolved organic matter (DOM) as DBP precursors. Commercially available humic acid (HA), extracellular organic matter (EOM) from green algae, cyanobacteria, and diatom, namely Scenedesmus quadricauda (SQ), Merismopedia sp. (Msp), and Phaedactylum tricornutum (PT), were used as the sources of DOM. The DBP formation increased with increasing total residual chlorine; EOM from PT presented the highest formation potential followed by HA, Msp, and SQ. The low dosage of 40 mJ/cm2 UV irradiation is insignificant to change the DBP formation from HA and SQ; however, it decreased the DBP formation from bromide-containing EOM of PT and promoted the DBP formation from EOM of Msp at various total residual chlorines. The DBP formation of each DOM correlated well with total residual chlorine. The maximum DBP formation potential (DBPFP) reduction of 42.25 and 13.75% for haloacetic acid formation potential (HAAFP) and trihalomethane formation potential (THMFP) was obtained at the UV irradiation dosage of 300 mJ/cm2 for EOM of PT. However, for the EOM derived from Msp, a maximum increase of 58.1 and 51.1% for HAAFP and THMFP was observed after UV-chlorination.

Modeling iron release from cast iron pipes in an urban water distribution system caused by source water switch

Significant iron release from cast iron pipes in water distribution systems (WDSs), which usually occurs during the source water switch period, is a great concern of water utilities because of the potential occurrence of “red water” and customer complaints. This study developed a new method which combined in-situ water stagnation experiments with mathematical models and numerical simulations to predict the iron release caused by source water switch. In-situ water stagnation experiments were conducted to determine the total iron accumulation in nine cast iron pipes in-service in Beijing when switching the local water to treated Danjiangkou Reservior water. Results showed that the difference in the concentration increment of total iron in 24 hr (ΔCITI,24), i.e. short-term iron release, caused by source water switch was mainly dependent on the difference in the key quality parameters (pH, hardness, nitrate, Larson Ratio and dissolved oxygen (DO)) between the two source waters. The iron release rate (RFe) after switch, i.e. long-term iron release, was closely related to the pipe properties as well as the DO and total residual chlorine (TRC) concentrations. Mathematical models of ΔCITI,24 and RFe were developed to quantitatively reveal the relationship between iron release and the key quality parameters. The RFe model could successfully combine with EPANET-MSX, a numerical simulator of water quality for WDSs to extend the iron release modeling from pipe level to network level. The new method is applicable to predicting iron release during source water switch, thus facilitating water utilities to take preventive actions to avoid “red water”.

Distribution and Public Health Significance of Vibrio Pathogens Recovered from Selected Treated Effluents in the Eastern Cape Province, South Africa

Treated sewage harbours pathogenic microbes, such as enteric bacteria and protozoa, are capable of causing several diseases. Some of these are emerging pathogens sometimes recovered in the absence of common water quality indicator organisms. The possibility of selected treatments plants serving as momentary reservoirs of Vibrio pathogens during a non-outbreak period was assessed. The occurrence and diversity of Vibrio pathogens were monitored for one year (December 2016 to November 2017) in the treated effluents and upstream and downstream areas of the receiving water bodies of two wastewater treatment plants (WWTPs), designated AL and TS. Physicochemical parameters of TS and AL WWTPs’ water samples were analysed using a multi-parameter meter (Hanna, model HI 9828, Padova, Italy) and a turbidimeter (HACH, model 2100P, Johannesburg, South Africa). Water samples were augmented with alkaline peptone water and cultured on thiosulfate citrate bile salts sucrose agar at 37 °C for 24 h. The recovered probable pathogens were confirmed via PCR amplification, using primers specific for Vibrio species of public health significance. The distribution of Vibrio species positively and significantly (p < 0.01) correlated with turbidity (r = 0.630), temperature (r = 0.615), dissolved oxygen (r = 0.615), pH (r = 0.607), biological oxygen demand (r = 0.573), total dissolved solid (r = 0.543), total suspended solid (r = 0.511), electrical conductivity (r = 0.499), residual chlorine (r = 0.463) and salinity (r = 0.459). The densities of Vibrio species were found to be significantly higher (p < 0.05) in effluents from both AL and TS WWTPs than upstream and downstream of the receiving rivers across the sampling regime. Furthermore, the maximum Vibrio species density across the sampling regime were observed during the warmer Summer and Spring season. Moreover, six medically important Vibrio species were detected in the water samples, indicating that the methods employed were efficient in revealing that WWTPs are potential reservoirs of Vibrio pathogens, which could pose a substantial public health risk if the receiving water is used for domestic purposes. Our findings further strengthen existing calls for the inclusion of emerging bacterial pathogens, including Vibrio species, as water quality indicators by the South African Department of Water Affairs. Hence, we recommend regular monitoring of treated effluents and receiving water bodies to ensure early control of potential outbreaks of vibriosis and cholera.

Short-Term Guideline Values for Chlorine in Freshwaters.

The current Australian and New Zealand default guideline value of 3 µg Cl/L for total residual chlorine in freshwaters is largely based on acute data converted to chronic data using a default acute to chronic ratio of 10, without consideration of chlorine decomposition. Given the rapid decomposition of chlorine, initially as hypochlorite and then as chloramine, it is appropriate to consider a guideline value based on short-term (acute) toxicity rather than one based on longer-term chronic data, as has been recommended for chlorine in marine waters. The literature on the fate of chlorine in drinking water discharged to freshwaters and on the ecotoxicity of total residual chlorine has been reviewed, and on the basis of this, revised default guideline values were derived for both hypochlorite and chloramine in freshwater using a species sensitivity distribution of toxicity data. The values for 95% species protection were 7 and 9 µg Cl/L as total residual chlorine, respectively. The former would apply to any total residual chlorine-containing effluent, but in the case of drinking water where dechlorination has been undertaken, the chloramine-based default guideline value is likely to be more appropriate. Both are likely to be conservative because they were largely based on toxicity testing under continuous flow-through conditions. They will apply at the edge of the mixing zone, and the variable receiving water concentration at this point might best be determined from a time-weighted average total residual chlorine concentration. Environ Toxicol Chem 2021;40:1341-1352. © 2021 SETAC.

Correlation of various water quality parameters and water quality index of districts of Uttarakhand

This study is based on hydrogeochemical and biological parameters and calculation of Water Quality Index (WQI) to assess water quality of a rural tract in five districts of Garhwal and Kumaon district of Uttarakhand, India. The drinking water quality parameters are pH, Total Hardness, Alkalinity, Turbidity, Iron (Fe), Chloride (Cl), Fluoride (F), Dissolved Solids (TDS), Sulphate (SO4), Nitrate (NO3), Calcium (Ca), Magnesium (Mg), Arsenic (As), conductivity, Total Coliform, Fecal Coliform and Total Residual Chlorine. It was observed that the physicochemical properties were as per BIS standards and found suitable for drinking purposes. However Bacteriological parameters i.e. Total coliform and Fecal coliform of some sampling sites ranged from 20 to 300 ​CFU/100 ​ml, which were higher than permissible limit (0 ​CFU/100 ​ml) as per BIS standards. Statistical analysis had been used to calculate the correlation coefficient of different parameters with WQI and the study showed significant linear relationship and the high correlation coefficient between different pairs of water quality parameters. The correlation matrix shows that total iron concentration, total coliform, and faecal coliform have a significant effect on Water quality index. Among these parameters, TDS has the highest correlation with conductivity, sulphate, and chloride ion concentration whereas turbidity significantly correlates with the presence of nitrate in drinking water.

Application of sodium hypochlorite (NaOCl) for ammonia removal in wastewater effluent of PT. HS

<table width="508" border="1" cellspacing="0" cellpadding="0"><tbody><tr><td valign="top" width="380"><p><strong>Abstract.</strong> PT HS is a world’s leading toy manufacturing company with more than 6,000 workers. Due to the high number of workers in PT. HS, it will impact to domestic activities (toilet discharge). Based on the annual report for wastewater effluent, noted that parameter ammonia from PT HS’s wastewater effluent was exceeding the industrial estate limit which the average of ammonia concentration is 50 mg/L. Whereas, In the industrial estate regulation contain of several standard parameters that must be comply by the company such as ammonia standard which has maximum 10 mg/L for the wastewater effluent. <strong>Objectives:</strong> The objectives of this experiment are to know the optimum dose of NaOCl 9% on ammonia removal and to know the concentration of residual chlorine after the treatment process. <strong>Method and results</strong>: This research use the experimental method to get the primary data. After the experiment in the laboratory, the results proved that the sodium hypochlorite exposure reduces ammonia concentration in water samples with 82,2% removal efficiency from 50 mg/L to 8,9 mg/L ammonia concentration reduced with 110 mg/L of NaOCl 9% solution within 30 minutes contact time and it resulted the residual chlorine 0.72 mg/L. <strong>Conclusion:</strong> The chlorination process was effective to reduce the ammonia concentration. Also, the residual chlorine was still in the standard limit which not exceeds from 1 mg/L. The result also shows that the dose variations of sodium hypochlorite influence ammonia removal efficiencies. Also, mostly the total residual chlorine forecast will increase with the increasing sodium chlorine dose.</p></td></tr></tbody></table>

An assessment of the persistence of putative pathogenic bacteria in chloraminated water distribution systems

This study investigated how a chloramine loss and nitrifying conditions influenced putative pathogenic bacterial diversity in bulk water and biofilm of a laboratory- and a full-scale chloraminated water distribution systems. Fifty-four reference databases containing full-length 16S rRNA gene sequences obtained from the National Centre for Biotechnology Information database were prepared to represent fifty-four pathogenic bacterial species listed in the World Health Organisation and Australian Drinking Water Quality Guidelines. When 16S rRNA gene sequences of all samples were screened against the fifty-four reference pathogenic databases, a total of thirty-one putative pathogenic bacteria were detected in both laboratory- and full-scale systems where total chlorine residuals ranged between 0.03 - 2.2 mg/L. Pathogenic bacterial species Mycolicibacterium fortuitum and Pseudomonas aeruginosa were noted in all laboratory (i.e. in bulk water and biofilm) and in bulk water of full-scale samples and Mycolicibacterium fortuitum dominated when chloramine residuals were high. Other different pathogenic bacterial species were observed dominant with decaying chloramine residuals. This study for the first time reports the diverse abundance of putative pathogenic bacteria resilient towards chloramine and highlights that metagenomics surveillance of drinking water can serve as a rapid assessment and an early warning of outbreaks of a large number of putative pathogenic bacteria.

Bacterial community including opportunistic pathogens dynamics in a chlorine tablet-dosed chloraminated service reservoir and reticulation pipes

This study reports even minimal changes of chloramine (measured as total chlorine) residual by chlorine tablets dosing in a service reservoir modify the bacterial community composition. The study was carried out by characterising the bacterial community composition in bulk water samples collected from the inlet, outlet, and downstream of a service reservoir. A regular dose of chlorine tablets to increase the chloramine by about 0.15 mg/L in the service reservoir increases total chlorine to ammonia nitrogen ratio and induces locally breakpoint chlorination within the proximity of the chlorine tablets. This, in turn, selects the specific bacterial groups despite smaller changes in the chloramine concentration. The dominated bacterial genera (87.1–93.8%) in the service reservoir were Methylobacterium and unclassified Rhizobiales whereas Methylobacterium, unclassified Rhizobiales, and Hyphomicrobium dominated (71.8–93.4%) downstream distribution pipelines of the service reservoir. E.Coli was not detected during the study period. Total chlorine residuals, nitrification, and temperature did not influence the presence/absence including the relative abundances of the majority of the opportunistic pathogens (characterized using the MiSeq Illumina platform). However, the presence of Burkholderia and Legionella increased at low total chlorine residuals and high temperatures in a small number of samples. Although this might indicate the importance of higher total chlorine residuals, more studies are needed to confirm if it is a valid strategy/or if there is health significance.

Occurrence and diversity of waterborne fungi and associated mycotoxins in treated drinking water distribution system in South Africa: implications on water quality and public health.

Despite increased public health concerns on the occurrences of potentially pathogenic/mycotoxigenic fungi in public drinking water system, dissemination of hygienically relevant fungi and their associated mycotoxins via distribution system under the dual burden of ageing infrastructure and ancillary distribution network lacking infrastructure for high-pressure water delivery systems is unknown. In this study, the diversity of fungi and occurrence of mycotoxins at 30 different points along treated piped water supply and ancillary distribution networks in Johannesburg, South Africa, were monitored for 12months. Mycological analysis using cultural and molecular methods yielded 282 fungi belonging to phylum Ascomycota, having Aspergillus (91%), Penicillium (65%) and Trichoderma (31%) as dominant genera, with Aspergillus fumigatus, Penicillium citrinum, Purpureocillium lilacinum and Aspergillus flavus as the most prevalent species. Communal standpipe and reservoir outlets had significantly higher prevalence than other water samples. There was no strong correlation between total coliforms (r = 0.4266) and residual chlorine (r = - 0.1937), and fungal prevalence at p < 0.05. LC-MS/MS analysis detected aflatoxins B1, M1, G1 and G2 in 50, 9, 9 and 46% of water samples analysed, respectively, ranging between 0 and 3.18ng/l. Deoxynivalenol (DON), 3-acetyl DON and 15-acetyl DON levels were between 8.4-96.1, 18.7-145.7 and 15.2-71.6ng/l, respectively. However, the estimated average daily dose (ADD) for detected mycotoxins was below the tolerable daily intake (TDI), suggesting no toxicological risk. Presence of potentially mycotoxigenic fungi, despite the low toxicological risk, demonstrates a need for appropriate monitoring for fungi and mycotoxins in treated drinking water distribution systems for improved water quality and long-term public health assurance.

Impact of variability in decay coefficients on simulating monochloramine dissipation in storm sewers

Concerns about total residual chlorine effects on the aquatic environment have led to a lowering of allowable effluent discharge concentrations. Many municipalities use monochloramine as a water disinfectant, which makes its way into drainage systems through outdoor and industrial water uses, and ultimately into surface waters. Monochloramine is known to dissipate with variable temporal and spatial decay coefficients; however, no existing stormwater models simulate these aspects. Thus, this study describes a novel Variable Decay Coefficient Simulator (VDCS) that predicts levels of degradable pollutants in sewer systems. The importance of spatially- and temporally-varying monochloramine decay coefficients on pollutant concentrations was assessed through three scenarios using, (1) a constant decay coefficient, (2) spatially-varying decay coefficients per land-use, and (3) spatially- and temporally-varying decay coefficients. At the system outfall, the spatially- and temporally-varying decay coefficients generated 67% and 100% higher concentrations, respectively, than the constant decay coefficient. These differences have important implications for the modeling of degradable pollutants in stormwater systems, and for the application of environmental regulations.

Evaluation of Zona Air Minum Prima (ZAMP) Program in Ngagel Tirto Surabaya

Zona Air Minum Prima (ZAMP) is a special area where the water distributed to customers has met the quality standard to be directly consumed without needing to be boiled first. PDAM Surya Sembada Surabaya implemented the Zona Air Minum Prima (ZAMP) program starting on May 2018 in Ngagel Tirto by serving 152 house connections. However, to implement the ZAMP program in Surabaya, there are various challenges and constraints both from technical and community factors. Therefore, to find out the condition of the implementation of ZAMP program, an analysis of the operational aspects and utilization aspects of potable water by customers of ZAMP program is needed. The method that we used in this research was by taking water quality samples for measurement of total coliform and residual chlorine parameters as well as the pressure at customers’ house connections, water quality analysis in laboratory, distribution network analysis with WaterCAD v8i, questionnaires and literature studies. In operational aspect, the distribution system is almost continuous for 24 hours with an average production capacity that has been able to fulfill the customer water usage during peak hours. The pressure at the farthest point of distribution network has met the minimum criteria. About 70% of water samples have met the quality standard of potable water for total coliform parameters. In utilization aspect of potable water by the customer, the percentage of customers who directly consume potable water from the tap is 0%. However, about 73% of respondents are interested to consume potable water if PDAM can guarantee that the water quality has met the quality standard of potable water until the water reaches the tap of customers’ house.

Characters of chloramine decay in large looped water distribution system – the case of Tianjin, China

Abstract In the water distribution system of a large city, chloramine could experience rapid decay as residence time extends, which may further threaten drinking water safety. A correlation analysis was conducted between the total chlorine residual of four sites on the distribution system and the water quality of the corresponding water treatment plant with data from 2016 to 2018 for the city of Tianjin. The results showed that the total chlorine residuals of all sites were negatively correlated with the temperature of the treated water, while the total chlorine residual of pipeline water did not uniformly correlate with that of the treated water. Further, a chloramine decay calculation study showed that pipe wall-induced decay contributes a lot of chloramine losses by conducting Total Chloramine Decay Model (TCDM) calibration with the monitored data. Hence, increasing the total chlorine residual of treated water, especially in the hot season, may not effectively maintain the disinfectant concentration at an ideal level.