Residual Chlorine Research Articles

Optimizing the number, locations, and chlorine dosages of booster chlorination stations in water distribution networks

ABSTRACT Safe and reliable drinking water is essential for sustaining life. Chlorination is widely used for disinfection in water distribution networks (WDNs). A higher dose of chlorine is required in an overhead service reservoir to maintain minimum residual chlorine at the farthest end in WDNs. However, delivering high dosages of chlorine from storage tanks can pose public health issues, especially for the residents living near overhead service reservoirs due to the formation of trihalomethanes, haloacetic acids, and chlorophenols. In addition, a higher dosage will lead to increased chlorine consumption and will accelerate pipe corrosion. Booster chlorination (BC) stations with smaller dosages are a solution to this problem. However, identifying the optimal number, locations, and dosage of each BC station in a cost-effective manner is challenging. This study proposes a methodology for determining the optimal number, locations, and chlorine dosages of BC stations in WDNs using a mixed integer linear programming problem. The methodology is illustrated through a simplified WDN in Holeta town, Ethiopia. The results indicate that if one adds two BC stations beyond the three dosage stations at the source, it will lead to a 49% reduction in chlorine use and a 27% decrease in the life cycle cost.

Monitoring microbial safety and evaluation of removal efficiency from drinking water in Ahvaz, Iran

The availability of potable water sources is vital worldwide. Due to the potential for microbial contamination, developing nations focus more research on the existence of microorganisms that are indicators in water than they do on chemical presence. This study was done in order to assess the microbial level of drinking water in Ahvaz city. In this descriptive-cross-sectional study, the measure the microbial tests, two culture mediums, MacConkey broth, and green lactose broth, were used for possible and confirmatory culture respectively. Bioindicators measured in drinking water included fecal coliform and total coliform. Not only the residual chlorine concentration was also measured, but its relationship with bioindicators was also calculated by Spearman's correlation test. Result of this study showed that, the maximum total coliform concentration reported is between 2021 and 2022 (1600 MPN/100 ml). Based on result of this study the average concentration of fecal coliform in 2019, 2020, 2021, and 2022 were 11.88, 10.66, 7.78, and 6.11 MPN/100 ml respectively. The average annual concentration of total coliform and fecal coliform in four years was 28.95 and 9.32 MPN/100 ml, respectively. According result of this study, the Karun River, Ahvaz's main drinking water source, is contaminated by surface water runoff, old facilities, and unfiltered discharge of different wastewater kinds from factories, farms, and communities in Khuzestan.

Intelligent dosing of sodium hypochlorite in municipal wastewater treatment plants: Experimental and modeling studies

Sodium hypochlorite (NaClO), a disinfectant extensively employed in municipal wastewater treatment plants (WWTPs), is frequently overdosed to ensure qualified effluent quality consistently. In light of the escalated disinfectant expenses and detrimental environmental impacts, it is critical to have a precise control model in place to enable intelligent dosing of NaClO. The lack of real-time disinfection evaluation indicators presents difficulties in precisely and swiftly regulating the dosage. Herein, the CT value (the product of residual chlorine concentration and contact time) was initially determined experimentally as a metric for assessing disinfection in municipal WWTPs. Fecal coliform (FC) concentrations become less than 1.0 × 103 MPN/L when the effluent CT value is regulated at 0.20 mg·min/L (calculated as Cl2). In addition, a model employing long short-term memory (LSTM) was developed to predict the dosage, utilizing simplified and suitable parameters such as COD, NH3-N concentration, flow rate, and historical dosage of NaClO as input factors, which demonstrated satisfactory performance (R2 = 0.948). Notably, dosage adjustments were made concurrently in response to CT value feedback. The intelligent dosing model under simultaneous feedforward and feedback control was applied at a full-scale WWTP for nearly two months, considerably reducing disinfectant consumption and meeting the discharge standard of FC.

Relationship between chlorine decay and nanobubble application in secondary treated wastewater.

There has been numerous research on the uses of treated wastewater that needs chlorine disinfection, but none have looked at the impacts of injecting nanobubbles (NBs) on the decomposition of residual chlorine. Gas NB injection in treated wastewater improves its properties. The kinetics of disinfectant decay could be impacted by changes in treated wastewater properties. This paper studies the effect of various NB injections on the residual chlorine decay of secondary treated wastewater (STWW). It also outlines the empirical equations that were developed to represent these impacts. The results show that each type of NBs in treated wastewater had a distinct initial chlorine concentration. The outcomes demonstrated a clear impact on the decrease of the needed chlorine quantity and the reduction of chlorine decay rate when utilizing NB injection for the STWW. As a result, the residual chlorine will remain for a longer time and will resist any microbiological growth under the application of NBs on treated wastewater. Moreover, NBs in secondary treated effluent reduce chlorine usage, lowering wastewater disinfection costs.

Fungal and bacterial evaluation in drinking water distribution network and their association with physicochemical parameters

Preventing the growth of microorganisms in water distribution network (WDN) is an important public health priority. In this study, 98 water samples were collected from the Gorgan City (Iran) water distribution network (WDN) to assess fungal and bacterial contamination in WDN and their association with physicochemical parameters. All microbiological and physicochemical tests were performed as described in the standard method. The results showed that 15.3 %, 12.2 %, and 2 % of the sample had total coliforms, Clostridium perfringens and fecal coliforms, respectively; however, no Escherichia coli and fecal streptococci were found in samples. The average count of heterotrophic bacteria and fungi was 203.45 CFU/mL and 6.83 CFU/100 mL, respectively. Seven genera of fungi were isolated, of which Candida (19.4 %) and Aspergillus (11.2 %) were the most prevalent, followed by Penicillium (5.1 %), Rhodotorula (3.1 %), Cladosporium (2 %), Acremonium (2 %) and Alternaria (1 %). The mean and Standard deviation of free residual chlorine (FRC), pH, turbidity, temperature, total organic carbon and electrical conductivity were 0.22 ± 0.27 mg/l, 7.28 ± 0.22, 0.61 ± 0.68 NTU, 19.27 ± 2.83 °C, 0.45 ± 0.17 mg/l, and 953.49 ± 207.54 (µs/cm), respectively. The presence of pathogens fungus is a major public health concern for people with lowered immunity. The present study indicated that using microorganisms with different features provides a more reliable evaluation to assess the microbial growth in WDN. Amongst physicochemical parameters, FRC above 0.8 mg/l prevented the fungal and bacterial pathogens growth in WDN. However, further research is required to measure the risks of trihalomethane formation.

Analisis Pengaruh Sisa Klor Terhadap Air Distribusi PDAM Surya Sembada IPAM Karang Pilang 3 Kota Surabaya

The provision of drinking water for the community must meet quality standards that include physical, chemical and bacteriological aspects. The use of chlorine gas as a disinfectant can affect the quality of drinking water in an installation. One method to reduce bacteria in the water treatment process is to use disinfectants, among which chlorine is often used. The use of chlorine as a disinfectant in water treatment plays an important role in eliminating bacteria in water. This research aims to evaluate the quality of water treated by PDAM Surya Sembada, with the hope of providing an understanding to the public about the impact of residual chlorine on distributed water

Performance evaluation of the compact water treatment system pilot project at Timah Tasoh Water Treatment Plant, Perlis, Malaysia

Abstract Clean water is crucial to ensuring the well-being of people. The Package Timah Tasoh Water Treatment Plant (WTP) is designed to support the existing conventional plant in coping with the growing demand for clean water. The package plant used the Compact Water Treatment System, classified as a Category B in the Suruhanjaya Perkhidmatan Air Negara (SPAN) guidelines; thus, this performance monitoring research was conducted prior to product registration. The plant consists of aeration, flocculation, clarification, and filtration processes. The performance of this package plant was monitored through comparative and efficiency analysis of removal parameters and carried out over a period of six (6) months. Twelve (12) water quality parameters were selected, including turbidity, pH, total dissolved solids (TDS), colour, ammonia, residual chlorine, aluminium, iron (Fe), manganese (Mn), fluoride, standard total coliform, and E. coli with sampling water of RW, SW, FW, and TW, which was then assessed alongside the drinking water quality standards set by Ministry of Health (MOH). As a result, eight key parameters such as pH, turbidity, colour, TDS, iron, aluminium, manganese, and ammonia were meeting the MOH drinking water quality standards in over 94 % of cases. The remaining parameters are chlorine residual, fluoride, E. coli and standard total coliform were in non-compliance due to the inoperability of disinfection and fluoridisation processes. Most of the significant parameters deduced a better performance in terms of removal efficiency (> 60 %) consistently, except for TDS, throughout the monitoring activity.

Unexpected weakened formation of disinfection byproducts and enhanced production of halates by cupric oxide during chlorination of peptide-bound aspartic acid

Under the condition that the residual chlorine is guaranteed, the biofilm still thrives in drinking water distribution systems through secreting a large number of extracellular polymeric substances (EPS), in which protein components are the primary precursor of disinfection byproducts (DBPs), mostly in the form of combined amino acids. The aim of this study is to investigate the action of CuO on the formation of halates (XO3−, ClO3− and BrO3−) and DBPs (trihalomethanes, THMs; haloacetonitriles, HANs) with aspartic acid tetrapeptide (TAsp) as protein surrogate. The presence of CuO promoted the self-decay rather than TAsp-induced decay of oxidants, resulting in an increase in XO3− yield and a decrease in DBPs yield. It was CuO-induced weaker production of cyanoacetic acid and 3-oxopropanoic acid that induced the decreased yields of HANs and THMs, respectively. The FTIR and Raman spectra indicate a weak complexation between CuO and TAsp. Given this, the CuO-HOX/OX− complexes were inferred to be reactive to HOX/OX− but less reactive to TAsp. The study helps to better understand the formation of XO3− and DBPs during the chlorination of EPS, and propose precise control strategies when biofilm boosts in water pipes.

Point-of-use chlorine residuals and disinfection byproduct occurrences in rural households served by public water utilities in Appalachian Virginia

ABSTRACT We characterized concentrations of trihalomethanes (THMs), a measure of disinfection byproducts (DBPs), in tap water samples collected from households with utility-supplied water in two rural counties in Appalachian Virginia, and assessed associations with pH, free chlorine, and metal ions which can impact THM formation. Free chlorine concentrations in all samples (n = 27 homes) complied with EPA drinking water guidelines, though 7% (n = 2) of first draw samples and 11% (n = 3) of 5-min flushed-tap water samples exceeded the US Safe Drinking Water Act (SDWA) maximum contaminant level (MCL) for THM (80 ppb). Regression analyses showed that free chlorine and pH were positively associated with the formation of THM levels above SDWA MCLs (OR = 1.04, p = 0.97 and OR = 1.74, p = 0.79, respectively), while temperature was negatively associated (OR = 0.78, p = 0.38). Of the eight utilities serving study households, samples from water served by three different utilities exceeded the EPA MCL for THM. Overall, these findings do not indicate substantial exposures to DBPs for rural households with utility-supplied water in this region of southwest Virginia. However, given the observed variability in THM concentrations between and across utilities, and established adverse health impacts associated with chronic and acute DBP exposure, more research on DBPs in rural Central Appalachia is warranted.

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.

Removal of Residual Chlorine from Stormwater Using Low-Cost Adsorbents and Phytoremediation

In recent decades, the pollution of water with micropollutants has become an increasing environmental concern. Since 2019, increased stormwater pollution from chlorine-based disinfectants has been recorded due to the COVID-19 pandemic. Runoff from disinfected areas and the residual chlorine present in stormwater are transported to surface water bodies, posing a risk to aquatic flora and fauna. The objectives of this study were (1) to evaluate the efficiency of different low-cost and recyclable filter materials in removing residual chlorine, and (2) to test plants’ ability to reduce residual chlorine concentrations through phytoremediation. Experiments were conducted in the laboratory (column and batch) and in the field (raised garden bed) to assess the efficiency of various filter materials (peat, wood chips, sawdust and the lightweight aggregates) in retaining residual chlorine to be implemented in green infrastructure. The best retainers of chlorine were sawdust (96%) and the LWA Leca (76%). No harmful effects of residual chlorine (changes in growth, color, leaf size, etc.) on plants (Tagetes patula or Pisum savitum) were observed and the residual chlorine in the leachate samples was below the equipment’s detection limit. Our research results will contribute to future studies aiming to remove various micropollutants from stormwater using remediation technologies.

The ideal model for determination the formation potential of priority DBPs during chlorination of free amino acids

Amino acids (AAs) account for about 15–35% of dissolved organic nitrogen (DON), and are known as the important precursors of nitrogenous disinfection by-products (N-DBPs). Determining the formation potential (FP) of AAs to DBPs is used to reveal the key precursors of DBPs for further control, while the ideal method for N-DBPs FP of AAs during chlorination is not revealed. In this study, the ideal FP test models for five classes of priority DBPs during chlorination of four representative AAs (accounted for about 35% of total AAs) were analyzed. For haloaldehydes (HALs), haloketones (HKs), haloacetonitriles (HANs), haloacetamides (HAMs), and halonitromethanes (HNMs), their FPs during chlorination of four AAs were 0.1–13.0, 0.01–1.1, 0.1–104, not detectable (nd)-173, and nd-0.4 μg/mg, respectively. The FPs of priority DBPs had significant deviations between different FP test models and different tested AAs. For HALs, the model, whose chlorine dosage was determined by 15 × molar concentration of AAs [Cl (mM) = 15 × M](named: model II), was the ideal model. For HKs, model II was also the ideal FP test model for AAs with ≤3 carbons, while for AAs with 4 carbons, the model, whose chlorine dosage was determined by keeping the residual chlorine at 1 ± 0.2 mg/L after 24 h of reaction (named: model 4), was the ideal model. For HANs and HNMs, model 4 was the ideal FP test model for most of the studied AAs. The performance of HAMs during chlorination of amino acids was totally different from other P-DBPs, and model 3 was recommended to be the ideal model, in which chlorine dosage was determined by 3 × mass concentration of AAs [Cl (mg/L) = X × DOC]. This study is a reference that helps researchers select an ideal model for N-DBPs FP study of AAs.

Effects of Chlorinated Water on Neurite Length of Cultured Dorsal Root Ganglion Neurons and Semaphorin 3A Content of Cultured Epidermal Keratinocytes

The tap water that we normally use contains certain concentrations of free residual chlorine to kill microorganisms and viruses and make it safe for use. Water containing free residual chlorine not only dries out our hair and skin but can also cause irritation and itching in some people—especially those with sensitive skin or reduced skin barrier function. We investigated the effects of free residual chlorine on cultured dorsal root ganglion neurons and cultured epidermal keratinocytes. First, we measured neurite length in cultured rat dorsal root ganglion neurons. Next, to evaluate the effects of chlorine on semaphorin 3A (Sema3A) and nerve growth factor (NGF) levels in cultured human epidermal keratinocytes, we used an enzyme-linked immunosorbent assay to measure NGF in the supernatant and polymerase chain reaction and Western blot to determine Sema3A and NGF levels. Chlorine elongated the neurite length and increased the number of projections in cultured rat dorsal root ganglion neurons. Although there were no changes in NGF mRNA or protein levels in the supernatant of cultured human epidermal keratinocytes in the presence of chlorine, Sema3A mRNA and protein levels decreased, and the ratio of Sema3A to NGF was also reduced.

Influence of physical and water quality parameters on residual chlorine decay in water distribution network

Chlorine is the most common disinfectant in drinking water distribution practice. World Health Organization recommends 0.2–5.0 mg/l of residual chlorine in drinking water. This paper analyzed influence of physical and water quality parameters on chlorine decay in drinking water distribution. Principal component analysis, directed tree and regression were used to investigate influence of these parameters on chlorine from water treatment plant to water consumption points. Results show that initial chlorine, electrical conductivity and distance explain 62 % of chlorine decay with estimated error of 0.045 mg/l. The decision-tree feature importance scores of initial chlorine and electrical conductivity were 0.47 and 0.23 respectively. The combined feature importance scores of physical parameters of distance (0.09), pipe diameter (0.06), flow velocity (0.03), pressure (0.02) and travel time (0.046) were less than that for initial chlorine concentration (0.47) alone. These results show that conventional chlorination at water treatment plants removes largely fast inorganic reactants leaving traces of slow organic reactants as the dominant secondary contaminants in water distribution system. The key policy recommendation is to use water quality parameters more than physical parameters in order to enable water utility managers maintain residual chlorine within safe public health standards.

Analysis of Residual Chlorine Content in Swimming Pool Water on Eye Irritation Complaints

Analysis of Residual Chlorine Content in Swimming Pool Water on Eye Irritation Complaints

Analysis of Residual Chlorine Content in Swimming Pool Water on Eye Irritation Complaints

Analysis of Residual Chlorine Content in Swimming Pool Water on Eye Irritation Complaints

Recovery of phosphate from incineration ash of sewage sludge by chlorination and carbo-chlorination

In this study, the volatilization behavior of the constituent elements of sewage sludge incineration ash (SSA) with and without carbon during the chlorination was investigated for recovering P. For chlorination of SSA, Fe and K volatilized from 700 to 800 °C, no volatilization of P was observed. For chlorination of SSA with carbon, Fe, P, and Si volatilized from low temperatures, reaching volatility rates of 80, 55, and 35 %, respectively, at 1000 °C. When chlorinated SSA/C (sample with carbon added to chlorination residue prepared at 1000 °C for 30 min holding), P volatilized from 800 °C (10 %), reaching a volatilization rate of 75 % at 1000 °C. P volatilization increased from 10 to 55 % until 60 min holding at 800 °C without volatilization of Si, Mg, and K. Although P volatilization progressed at 900–1000 °C holding, Al, Mg, and Si also volatilized. These results indicate that combination of chlorination/carbo-chlorination is suitable for selective volatilization of P.

Virulence Genes and Biofilm Formation Among Legionella pneumophila Isolates Collected from Hospital Water Sources.

Legionella pneumophila can be transmitted to people, especially immunocompromised patients, via hospital water pipe systems and cause severe pneumonia. The aim of our study was to investigate the presence of major virulence factor genes, ability of biofilms formation, and correlation between presence of Legionella isolates and temperature, pH, and residual chlorine of water. Hundred water samples were collected from nine hospitals in Tehran, Iran. Temperature, pH, and residual chlorine were determined during sampling. Different virulence genes and the ability to form biofilms were subsequently analyzed among the L. pneumophila isolates. Results showed that 12 (12%) samples were positive in culture method and all of the isolates were positive as L. pneumophila species (mip). A correlation was found between Legionella culture positivity and temperature and pH of water, but there was no significant correlation between residual chlorine of water samples and the presence of Legionella. The isolation of Legionella rate in summer and spring was higher than winter and autumn. Twelve (100%) isolates were positive for mip genes, 9 (75%) for dot genes, 8 (66.66%) for hsp, 6 (50%) for lvh, and 4 (33.33%) for rtx. All of the isolates displayed strong ability for biofilm production every three days. Two of these isolates (16.6%) displayed weak ability to form biofilm on the first day of incubation. This study revealed that water sources in hospitals were colonized by virulent Legionella and should be continuously monitored to avoid elevated concentrations of Legionella with visible biofilm formation.

Modeling the decay of free residual chlorine in water distribution networks in Brazilian rural communities using artificial neural network

Disinfecting water with chlorine is crucial for maintaining sanitation and preventing waterborne diseases. However, managing Free Residual Chlorine (FRC) concentrations becomes challenging in water supply systems, as its levels can decrease throughout the distribution network, impacting water quality and public health. By leveraging water quality data from the Water Quality Surveillance Information System for Human Consumption (Sisagua) and employing the variable selection method t-Distributed Stochastic Neighbor Embedding, we crafted a Multilayer Perceptron (MLP) neural network. This MLP, fine-tuned with weighted mean square error (WMSE), was designed to evaluate the decline of free residual chlorine in water distribution networks within rural Brazilian communities. Training the model with the weighted mean squared error (WMSE) increased the average hit rate from 3.6 % to 5.0 %. In contrast to the traditional colorimetric method for predicting free residual chlorine, the proposed methodology showed superior performance, with accuracy rates of 85.45 %, 95.58 % and 99.84 % for equipment accuracies of 0.5 mg. /L, 1.0 mg/L and 2.0 mg/L, respectively. The MLP approach not only anticipates nonconformities related to FRC but also aids in adjusting chlorine dosage proactively.

Mycological Assessment of Selected Swimming Pools of Recreational Centers around the University of Port Harcourt, Nigeria

Aims: This study was carried out to determine the physicochemical properties and mycological safety of four swimming pools within and around the University of Port Harcourt, Rivers State, Nigeria. Study Design: Random sampling design was employed. Place and Duration of Study: Department of Microbiology Laboratory, University of Port Harcourt, between August and October, 2023. Methodology: A total of 8 samples were collected before and after patronage by patrons from 4 swimming pool. Standard methods were employed for the physicochemical parameters such as pH, turbidity and residual chlorine as well as the enumeration for fungi using potato dextrose agar. Results: The pH values ranged from 4.50 to 10.00. The Nephelometric Turbidity Unit ranged from 0.45 to 0.90 NTU while the residual chlorine ranged from 0.36 to 355.00 mg/l. The fungal counts ranged from 1 to 9 cfu/ml, while the isolated species on the basis of cultural morphology and microscopic characteristics were identified as species of Fusarium, Penicillium, Aspergillus, Histoplasma, Rhodotorula, Microsporium and Trichophyton. Conclusion: This study has revealed a potential health risk associated with the use of water of the examined recreational facilities due to none compliance with the WHO standard of < 1 cfu/100ml for fungal and the other parameters, suggesting a public health concern and need for effective interventions.