Free Residual Chlorine Research Articles

Performance evaluation of artificial intelligence with particle swarm optimization (PSO) to predict treatment water plant DBPs (haloacetic acids)

The prevention of water-borne diseases requires the disinfection of water consumed. Disinfection by-products, however, are an increasing concern, and they require advanced knowledge of water treatment plants before their release for human consumption. In this study, multivariate non-linear regression (MNR) and adaptive neuro-fuzzy inference system (ANFIS: Grid partition - GP and Sub-clustering - SC) integrated with particle swarm optimization (PSO) were proposed for the prediction of haloacetic acids (HAAs) in actual distribution systems. PSO-ANFIS-GP and PSO-ANFIS-SC were trained and verified for a total of 64 sets of data with eight parameters (pH, Temperature, UVA254, DOC, Br−; NH4+−N; NO2−−N, residual free chlorine). With MNR, R2 is 0.5184<R2<0.8181 and average absolute error, AAE = 0.172–0.253%). Further, PSO-ANFIS-GP and PSO-ANFIS-SC for HAAs (BCAA, DCAA, TCAA, HAA5, and HAA9) prediction consistently show higher regression coefficients, with lower AAE, (0.8825< R2 < 0.9363 and AAE = 0.1031–0.1499%) and (0.8826< R2 < 0.9322 and AAE = 0.1108–0.1500%) respectively with). With the eight simple parameters, PSO-ANFIS-GP provides an easy way for users to monitor and predict HAAs.

Water quality monitoring in southern Brazil and the assessment of risk factors related to contamination by coliforms and Escherichia coli.

The potability of water, including underground sources, is constantly affected by human activities. To assess water quality and water security in rural and urban areas of southern Brazil, a quantitative, retrospective analysis of water samples collected monthly by the Brazilian health authorities (19,687 samples from 2013 to 2021) was performed. In rural areas, 5,979 water samples (77.54%) were found to be contaminated by coliform bacteria and 3,431 (44.50%) by Escherichia coli. In addition, 1,616 (20.95%) of the contaminated samples were significantly correlated with rainfall amount. In urban areas, 1,268 (10.95%) of the samples contained coliform bacteria and 293 (2.53%) of these samples contained E. coli, with the factor of rainfall associated with 1,081 samples (9.33%) with bacterial contamination. In terms of physicochemical parameters, turbidity exceeded the national standard (5 uT) in 448 (2.32%) samples and fluoride fell below the required level (0.8 mg/L) in 106 samples (0.54%). The presence of free residual chlorine (0.2-2.0 mg/L) was verified in 846 samples (14.38%) in rural areas and in 10,825 samples (56.13%) in urban areas. These results suggest a strong association between rainfall factors and physicochemical alterations, as well as the risk of greater microbial contamination of water for human consumption.

Water safety for human supply in rural communities: a risk-based approach for the Brazilian semiarid region

The existence of water in sufficient quantity and quality is directly linked to the maintenance of public health. In this context, the aim of this study is to assess the quality of water used for human consumption in the rural area of Campina Grande, Paraiba, Brazil. The study also examines the sanitation conditions that could lead to potential health risks for the population residing in these areas, due to water contamination. As a result, alternative collective supply solutions (ACS) and individual supply solutions (AIS) were analyzed, starting from water collection to storage at households. A total of 10 sampling points were used, comprising 5 cisterns and 5 water trucks. The physical and chemical analyses included: free and combined residual chlorine (FRC), turbidity, color, pH, electrical conductivity, and the presence of total coliforms and Escherichia coli. Subsequently, a product and process risk analysis was conducted using the Failure Mode and Effect Analysis (FMEA) method, which enabled the identification and evaluation of key failure risks and their effects. The physicochemical and microbiological results demonstrated that the waters were unsuitable for human consumption at all collection points. Furthermore, the main hazards identified for the product (water), following the classification of risk priority levels, were the presence of E. coli, the presence of total coliforms, low concentration of FRC, high apparent color, and for the process, the absence of rechlorination in the water consumption reservoir. Ultimately, it was possible to diagnose the non-compliance of the waters from alternative supply solutions with Ministry of Health Ordinance No. 888 of 2021. Additionally, the risk analysis proved to be a highly efficient method for this supply method, successfully pinpointing the main vulnerabilities of these waters to contamination.

Microbiological Quality Assessment of Drinking Water at Al-Hayy City, Southern Iraq.

The microbial quality of drinking water which distributed form Al-Hayy water treatment plant and number of residential areas fed by these water treatment plant was studied each month over six month during a period extended from the October 2016 to April 2017,through the purification stages up to residential sites at different areas situated with various distances from the supplying source, two samples were taken monthly. This station derived their water from AL-Gharraf River in the southeastern part of Iraq, where the feed areas of the city with drinking water. This study included detection of bacteria, evidence of contamination of water (coliform, faecal coliform, Escherichia coli, faecal streptococcus bacteria and total bacteria count), also some physical and chemical variables ware like (temperature, turbidity, free residual chlorine and pH) . Results of Bacteriological tests showed increasing in TPC, TC, FC, E.coli and FS bacteria in December and January in all study locations as compared to those of the other months for water plant raw and drinking water and the FS values were less than other bacterial types for water plant. The TPC results of drinking water exceed 100 cell/ml, the allowable limit for drinking water, for all samples of water plant. On the other hand the TC, FC and E.coli exceeded zero cell/100ml, the allowable limit for drinking water, in many drinking water samples for water plant with increasing of temperature in summer months. Physiochemical tests showed that air temperature at sampling time was varied between17 and 34°C and between11.5 and 29°C, for water temperature at sampling time also. The results of pH means were within the allowable limit, ranging from 7.2 in October to 7.9 in April.The highest mean value of turbidity recorded for raw water was in December with 89 NTU and the lowest value was in April with 30 NTU, while the highest mean value recorded for Drinking water was 20 NTU again in December and the lowest value was 1 NTU in April. The highest mean value of residual chlorine was recorded in March with 3.8 mg/L, the lowest value was 0 mg/L in some of the farthest points of the plant.

Assessment of Drinking Water Quality in Urban Water Supply Systems: The Case of Hawassa City, Ethiopia.

In many developing countries, such as Ethiopia, water quality and the risk of water-related diseases are serious public health issues. The present study goal was to assess the drinking water quality from source to household tap water. To characterize and analyze drinking water quality parameters, 21 water samples were collected, of which 11 water samples were collected from sources (spring, borehole, and river), 4 from service reservoirs, and 6 from tap water. The mean values of the parameters were as follows: total dissolved solids (TDS) (142.79 mg/L), temperature (22.08°C), turbidity (9.49 NTU), electrical conductivity (EC) (250.14°μS/cm), pH (7.45 mg/L), fluoride (1.15 mg/L), nitrate (NO3-) (2.91 mg/L), total hardness (TH) (57.45 mg/L), calcium (41.7 6 mg/l), magnesium (10.74 mg/L), phosphate (0.44 mg/L), sulfate (3.99 mg/L), residual chlorine (1.53 mg/L), alkalinity (196.39 mg/L), and microbiological (total coliform and coliform/CFU) which were the main physiochemical parameters analyzed for the study. The findings revealed that the majority of the water quality parameters tested were within the WHO and National Drinking Water Quality Standards (NDWQS). However, some of the parameters such as temperature, turbidity, fluoride, and residual chlorine did not meet the standards. The mean temperatures at the source, reservoir, and tap water were 22.01°C 22.5°C,and 21.83°C, respectively. Turbidity levels in source samples ranged from 10 to 45 NTU, with a mean of 24.5 NTU, exceeding the WHO's recommendation of less than 5 NTU. The Boko Alamura well had a high fluoride content (3.9 mg/l), which was above the WHO and NDWQS permissible limits. There was no free residual chlorine in the tap water sample. The results show that the Hawassa drinking water supply did not contain total or fecal coliform in any of the samples tested. The overall WQI for the water source, reservoir, and tap water was also determined to be 89, 71, and 69.7 points, respectively. Therefore, based on the WQI result, Hawassa drinking water quality is good for the source, reservoir, and tap water.

Purification of Industrial Effluent by Gas Hydrate-based (HyPurif) Process

This study presents a sustainable HyPurif process for managing and recycling industrial water effluent, utilizing gas hydrate-based technology to purify complex effluent. This work purifies two effluents: one from a wastewater treatment plant (WWTP) and the other from a spent caustic treatment plant (SCTP). Various hydrate formers, including propane, HFC134a, and cyclopentane (6 mol %), were selected, as they typically form hydrates closer to ambient conditions. Hydrate formation experiments with effluent water were performed at 278.30 K using pure propane and HFC134a gas. Based on the kinetics of hydrate growth, the study was extended to a mixture (50:50%) of propane and HFC134a, operating at a pressure of 0.6 MPa. The mixture of propane and HFC134a has shown the desired result of forming the hydrate in the gas phase and having high separation efficiency. The results showed that the formation and dissociation of hydrates resulted in a separation efficiency of 80–95%. For instance, in the purified water, the biological oxygen demand (BOD) decreased from 2097 mg/L in the effluent sample to 220 mg/L in purified water (purification efficiency of 90.5%). The chemical oxygen demand (COD) decreased from 3100 mg/L in the effluent sample to 503 mg/L in purified water (purification efficiency of 84%). Total dissolved solids (TDS) were reduced from 89,632 mg/L in the effluent water to 14,698 mg/L in purified water (purification efficiency of 84%). Total suspended solids (TSS) were reduced from 35 mg/L in the effluent water to 3.5 mg/L in purified water (purification efficiency of 90%). However, the purification efficiency for free ammonia and residual chlorine was lower. The concentration of free ammonia decreased from 7 mg/L in the effluent sample to 1.89 mg/L in the purified water (purification efficiency of 73%), and residual chlorine reduced from 0.8 mg/L in the effluent sample to 0.2 mg/L in the purified water (purification efficiency of 75%). Water recovery of ≥40% was achievable per pass, which could be increased, but at the expense of purification efficiency. To the best of our knowledge, this is the first study on the purification of such complex wastewater containing organic and inorganic compounds, heavy metals, and various minerals using the HyPurif process.

Evaluation of Drinking Water Quality and Treatment from Coolers in Public Places in Madinah City, Saudi Arabia

The aim of this work is to prevent the public drinking from water coolers, by using an auto-detection process, if the quality of water is low. Therefore, the proposed water treatment management system for allows the activation of dispensers to provide the best-quality water coolers. The objective is to investigate the quality of the drinking water from coolers in public places in Madinah and to provide clean, safe, and healthy drinking water for the general public. The methodology consisted of performing different analyses, tests, and water treatments, such as physicochemical analyses of the water samples, measurements of the different concentrations of anions, measurements of the concentrations of heavy metals, and bacteriological tests of the water samples. Therefore, 66 water samples were tested, and the experimental values were compared with the reference values given by the World Health Organization (WHO) and Saudi Standards, Metrology, and Quality Organization (SASO) for drinking water. The tests revealed that the physicochemical parameters (pH, EC, TDS, and TH) of different water sources (95.5%) were in accordance with the SASO and WHO values. In addition, all the analyzed water samples (100%) contained permissible levels of nitrates, sulfates, nitrites, and free residual chlorine, as indicated by the results. However, 68.2% of the samples studied had fluoride concentrations below the standard limits. Furthermore, heavy metals such as lead, iron, and others were tested for all water coolers. The measured findings indicated that just one cooler exceeded the permissible limit of 0.3 mg/L for Fe, and the biological contamination testing revealed that 4.5% of the coolers were infected with coliforms. Finally, this research suggests that water coolers should be regularly maintained. Additionally, using the best design for the water desalination process is very important to give the best drinking water quality.

Environmental, social, and WASH factors affecting the recurrence of cholera outbreaks in displacement camps in Northeast Nigeria: a rapid appraisal

Abstract In 2021, Nigeria witnessed a severe cholera outbreak that affected Borno state, in which more than 1,600,000 internally displaced persons (IDPs) resided at the time. This rapid appraisal explored factors that facilitate the recurrence of cholera outbreaks in sites hosting IDPs in Northeast Nigeria. Semi-structured interviews were conducted with water, sanitation, and hygiene (WASH), management, and healthcare personnel working in ten displacement camps in Borno state. The interviews were complemented by transect walks and field observations, measurements of free residual chlorine levels, and publicly available data published by the International Organization for Migration Displacement Tracking Matrix. The recurrence of cholera outbreaks appears to be facilitated by substantial interactions between IDPs and host communities, and suboptimal WASH services in camps. Of particular concern, IDP camps are exposed to extreme weather-related events that damage facilities and subsequently affect WASH practices. WASH services in camps may likewise be severely hindered by an influx of new arrivals. In conclusion, we emphasize the importance of expanding WASH activities to host communities and developing site-specific WASH interventions and chlorination targets. Practical recommendations are needed for the prevention and control of outbreaks following extreme weather-related events and population influxes.

Analysis of Groundwater Quality in Bauchi Metropolis (Nigeria) and interpretation using GIS

Fresh water resources include groundwater as a crucial component. It is essential to meeting the water needs of the country's diverse users and sectors. If the water quality is not evaluated, the usage and sustainability of the natural resources cannot be ensured. This study deals with the analysis of ground water quality in Bauchi metropolis and interpretation using ArcGIS according to the inverse distance weighting (IDW) technique. Water samples were taken from 18 hand dug wells randomly selected from six districts to assess for both bacteriological and physiochemical parameters. The bacteriological parameter tested for was Total Coliform Count, while the physiochemical parameters were: pH, Electrical Conductivity, Total Dissolves Solids, Free residual chlorine Cl-, Lead Pb, Total Hardness, Calcium Ca2+ and Magnesium Mg2+ using standard procedures prescribed by American Public Health Association, APHA. The results showed that all samples tested positive to Total Bacteria Count in the laboratory when compared to WHO Standard. whereas samples S3, S4, S5, S6, S7, S8, S12, S13, S14, S16, S17 tested negative to Total Bacteria Count under NSDWQ Standard while the remaining samples tested positive. Sample S10 was the highest at 134 cfu/100ml while S17 was the least at 1 cfu/100ml. Samples S1and S2 were not within the standard recommended pH range. Only sample S7 at 0.60 mg/L tested positive to free chlorine when compared with the NSDWQ guideline value. Sample S6 had the least TDS value of 90 mg/L while the highest value of 710 mg/L was recorded for S7. For lead content, Maximum value was recorded as 0.26 mg/L in samples S14 and S15. Sample S2 had the highest calcium value of 1.45 mg/L while S14 had the least value of 0.00 mg/L. Maximum value of magnesium was recorded in sample S14 having 3.58 mg/L while the lowest value was recorded in S11 having 0.52 mg/L. All Water samples were within the allowable limits for total hardness and are considered to be soft. It was concluded that samples S6 and S16 conformed to most of the standards while sample S7 did not conform to most of the standards when compared to WHO and NSDWQ.

Persistence kinetics of a novel disinfectant peracetic acid for swimming pool disinfection

Disinfection is essential to swimming pool water (SPW) quality. Peracetic acid (PAA) has attracted attention for water disinfection for advantages such as less formation of regulated DBPs. Persistence kinetics of disinfectants is difficult to elucidate in pools because of the complex water matrix stemming from body fluid loadings from swimmers and long residence times. In this research, the persistence kinetics of PAA was investigated in SPW benchmarked against free chlorine, use bench-scale experiments and model simulation. Kinetics models were developed to simulate the persistence of PAA and chlorine. The stability of PAA was less sensitive to swimmer loadings than chlorine. An average swimmer loading event reduced the apparent decay rate constant of PAA by 66 %, a phenomenon that diminished with increasing temperatures. L-histidine and citric acid from swimmers were identified as main retardation contributors. By contrast, a swimmer loading event instantaneously consumed 70–75 % of the residual free chlorine. The required total dose of PAA was 97 % less than chlorine under the 3-days cumulative disinfection mode. Temperature was positively correlated with disinfectant decay rate, with PAA being more sensitive than chlorine. These results shed light on the persistence kinetics of PAA and its influential factors in swimming pool settings.

Combined application of EPANET and empirical model for possible formation of trihalomethanes in water distribution network of Chattogram city to identify potential carcinogenic health risk zone

The study identifies potential carcinogenic health risk-zone of Chattogram city for the occurrence of trihalomethanes (THMs) at its water distribution network. The EPANET-THMs simulation model along with an empirical model have been adopted in the study to predict THMs content of supply water of the distribution network of the city’s Karnaphuli service area. The empirical model has estimated THMs level of supply water based on influential water quality parameters, and few of these have been used as pre-set values for subsequent EPANET simulation. The simulation (R2= 0.7) shows that THMs’ concentrations throughout the network vary from 33 to 486 μg/L. Around 60% of total junctions showed THMs concentrations above 150 μg/L, while that is above 50 μg/L for most (99%) of the junctions. Residual Free chlorine, one of the precursors for the THMs formation in distribution line, has also been simulated by EPANET considering varying applied chlorine dose at the water purification unit and wall (Kw) and bulk (Kb) decay constants. The simulated free residual chlorine peaks are found to be closer to the actual values with chlorine dose of 2 mg/L, and decay constants, Kw = 1 d−1 and Kb = 1 d−1. A mean lifetime total risk of cancer due to the presence of THMs has been found to be very high. Spatial distribution of carcinogenic risk shows that the central zone of the service area is the most vulnerable zone, followed by the western and northern zone. The first ever zone wise risk identification could be used as baseline data for operational and regulatory purposes and may raise awareness among the city’s inhabitants. Furthermore, the application of EPANET in combination with an empirical model could be an effective tool for predicting THMs’ concentration in water distribution networks in developing countries like Bangladesh to minimize the expenses of measuring THMs.

Hand hygiene and water quality assessment in schools of Muthanna province, Southern Iraq.

The severe drought and prolonged heat waves in Iraq have adversely affected the water quality supplied to public facilities. Schools are among the most affected facilities by water scarcity. This work aims to evaluate the level of students' hand hygiene, and the quality of municipal (MW) and drinking water (DW) in some schools of Al-Muthanna Province, Iraq. Between October 2021 and June 2022, a total of 324 water samples from 162 schools and 2,430 hand swabs (HSs) from 1,620 students (1,080 males and 540 females) were collected. Some physicochemical standards of water were assessed besides investigating faecal contamination in water and students' hands using Escherichia coli as an indicator. All MW samples were faecally contaminated with poor standards of pH, turbidity, total dissolved solids, color, and chlorine. Despite the good physicochemical standards of all DW samples, E. coli was observed in 12% of samples. Hand hygiene levels dropped by 2.5-fold within a few hours after school entry compared to early-morning levels (before school entry). Male students were 1.5- and 1.7-fold more prone to hand contamination than female students either inside or outside school, respectively. An increasing chlorine tolerance by E. coli was observed in water samples with turbidity > 5 NTU and pH > 8. The students' hand hygiene level decreases within a few hours of entering school, particularly among male students. Residual-free chlorine < 0.5 mg/L with high turbidity and alkalinity in water is insufficient for 100% prevention of E. coli contamination.

Insight into mixed chlorine/chloramines conversion and associated water quality variability in drinking water distribution systems

Mixed chlorine/chloramines are common in drinking water distribution systems (DWDSs); however, their transformation and impact on chemical and microbial characteristics are not well understood. We systematically investigated water quality parameters associated with mixed chlorine/chloramine species conversion in 192 samples (including raw, finished, and tap water) collected throughout the year in a city in East China. Various chlorine/chloramine species (free chlorine, monochloramine [NH2Cl], dichloramine [NHCl2], and organic chloramines [OC]) were detected in both chlorinated and chloraminated DWDSs. NHCl2 + OC increased with transport distance along the pipeline network. The maximum proportion of NHCl2 + OC in over total chlorine in tap water reached 66 % and 38 % from chlorinated and chloraminated DWDSs, respectively. Both free chlorine and NH2Cl showed a rapid decay in the water pipe systems, but NHCl2 and OC were more persistent. Correlations between chlorine/chloramine species and physicochemical parameters were established. Models for predicting the sum of chloroform/TCM, bromodichloromethane/BDCM, chlorodibromomethane/CBDM, and bromoform/TBM (THM4) (R2 = 0.56) and haloacetic acids (HAAs) (R2 = 0.65) exhibited greater accuracy based on machine learning tuned with chlorine/chloramine species, particularly NHCl2 + OC. The predominant bacterial communities in mixed chlorine/chloramine systems were those resistant to chlorine or chloramine such as proteobacteria. NH2Cl was the most significant explanatory factor (28.1 %) for the variation in microbial community assemblage in chloraminated DWDSs. Although residual free chlorine and NHCl2 + OC, accounted for a smaller proportion of chlorine species in chloraminated DWDSs, they played an essential role (12.4 % and 9.1 %, respectively) in the microbial community structure.

Household drinking water quality and its predictors in flood-prone settings of Northwest Ethiopia: A cross-sectional community-based study

Globally, the deterioration of drinking water quality is a major public health problem that contributes to the spread of disease and causes death. Therefore, it is important to have regular quality control monitoring. This study aimed to assess the level of physicochemical and bacteriological quality of household drinking water and its contributing factors in flood-prone settlements of South Gondar Zone, Ethiopia. A community-based cross-sectional study was conducted in flood-prone settings of Northwest Ethiopia from January 17 to March 30, 2021. Structured questionnaires were used to gather the sociodemographic, environmental, and behavioral data. A total of 675 drinking water samples were collected from water storage containers of selected households. Logistic regression models were used for both univariate and multivariable studies. The survey included a total of 675 households. The mean values of pH (5.9 ± 1.03), turbidity (6.7 ± 2.21 NTU), and free residual chlorine (0.02 ± 0.01 mg/l) did not meet the WHO recommended limits for drinking water. The prevalence of fecal contamination of drinking water in the study area was 62.2% with [95% CI (53–60%)]. Family size [AOR = 2.205, 95% CI (1.375–3.536), absence of latrine [AOR = 3.449, 95% CI (1.349–8.823)], and lack of a separate container to draw water from its storage [AOR = 0.454, 95% CI (0.249–0.827)] were significant predictors for fecal contamination of household drinking water. In conclusion, the water quality in terms of pH, turbidity, residual chlorine, and bacteriological parameters was poor and not suitable for consumption. High prevalence of fecal contamination of water was found, and it was significantly associated with family size, the absence of a latrine, and the lack of a separate cap to take water from the storage. Therefore, continuous chlorination and monitoring its concentration, educating the community on how to use stored water, educating the advantage of having a latrine, and promoting point-of-use treatments such as filtration and boiling are needed.

Evaluation of Chemical Compounds and their Relationship to the Breaking Point after adding Chlorine to Water

Evaluation of the chemical compounds formed during the process of sterilizing water with chlorine is a very important point. During sterilization the water goes through three stages each stage resulting different chemical compounds. In the first stage, chlorine reacts with iron, magnesium and nitrates. In the second stage it reacts with ammonia and in the third stage it reacts with the organic compounds in the water. Chlorine in these three stages is called combined chlorine. Then it reaches the breaking point, after this point the water must be free from side chemical compounds, and chlorine after this point is called the residual free Chlorine. Drinking water samples were taken from 3 city in Kirkuk governorate, and the concentrations of magnesium, nitrate, sulfate, acetic acid derivatives, as well as the halomethane group in addition to some physical determinants were evaluated.&#x0D; There were deviations in some chemical concentrations when comparing the results with the last Iraqi specification NO. 417. The deviations that appeared in some concentrations were treated by using two chemical methods, the first using activated carbon and the second using aluminum chloride polymer. The importance of the study is to ensure the effectiveness of chlorine by eliminating chemical compounds dangerous in the water.

Assessment of Physico-chemical and Bacteriological Quality of Drinking Water Sources in Kakamega County, Kenya

Water-borne diseases still present a major health burden in Africa. Large segments of the rural population here have no access to potable water. This study has been designed to assess the physico-chemical and bacteriological quality of drinking water sources in the study area. The study was conducted in Kakamega county covering the twelve sub-counties of Likuyani, Lugari, Malava, Navakholo, Lurambi, Ikolomani, Shinyalu, Mumias East, Mumias West, Matungu, Butere and Khwisero. Socio-demographic characteristics of the study populations were captured using a structured pre-tested questionnaire. The Most Probable Number (MPN) method was used to determine the abundance of Total coliforms and Escherichia coli (E. coli) in the water samples collected. Physico-chemical analyses (Temperature, pH, Electrical conductivity, Total dissolved solids and Dissolved oxygen) were carried out. Free residual chlorine was determined by colorimetric method with DPD chlorine tablets. The analyses were conducted following guidelines of American Public Health Association and WHO. Only 17% (68/400) of the study population had access to piped water in the study area. Waste management practices of the localities was found poor as more than 62 % (248/400) of the respondents dispose waste materials in open fields. All drinking water sources investigated were contaminated with Total coliforms. There was a wide variation in Total coliforms and E. coli. Total coliform counts ranged from 0.0 - 3652.5 cfu/100 ml whereas E. coli ranged from 0.0 - 33.0 cfu/100 ml. Both Rivers/streams and unprotected dug wells recorded the highest number of Total coliforms and E. coli. Piped water, Rainwater collection and Boreholes recorded the lowest number of Total coliforms and E. coli. E. coli counts in most drinking water sources investigated exceeded the maximum permissible limits set by WHO/KEBS, implying that they are not safe for household applications without prior treatment. The results indicate that protected drinking water sources (piped water, boreholes, protected dug wells and protected springs) are subjected to a high level of fecal contamination in the study area. Construction flaws on casing, concrete covers, fences, diversion ditches, and protection of springs' eyes and other plumbing accessories could be one of the causes. Protected water sources may become contaminated for other reasons, such as a lack of frequent surveillance, disinfection, and correct maintenance. Poor sanitation practices, a lack of hygiene education, poor supervision and maintenance, and inconsistent water point disinfection can all be blamed for the high levels of E. coli. The recorded temperature and pH ranged between 19.9–27.2°C and 4.8 - 9.1, respectively. Turbidity and Electric conductivity of the water samples ranged, respectively, between 0.43–467.02 NTU and 18.7–510.7 μS/cm. Residual chlorine in piped water showed a range of 0.06-1.2 ppm. In addition, Total dissolved solids were found to be between 20.1 and 639.2 mg/l; whereas Dissolved oxygen ranged from 2.2- 15.4 mg/l. The results of the current investigation showed that some bacteriological and physico-chemical parameters of the various water sources had values above the maximum permissible limits advised by WHO/KEBS. The Water sector stakeholders in the area should put in place proper intervention measures which include raising public awareness on the water quality of drinking water sources and enhancing the current infrastructure in order to reduce any potential health hazards.

Assessment of the Performance of a Water Treatment Plant in Ecuador: Hydraulic Resizing of the Treatment Units

Granting access to drinking water has been a challenge because 47% of the worldwide population is not connected to a drinking water distribution network in rural settlements. This study aimed to evaluate the contaminant removal efficiency in a conventional water treatment facility in the Austro region of Ecuador, Paute, to identify the treatment units requiring hydraulic resizing. Water samples were collected from each treatment unit to characterize the physical-chemical and microbiological parameters, and the dimensions of the treatment ponds for hydraulic evaluation purposes. Water hardness, electrical conductivity, SO42−, and Fe2+ were the main issues found in the water, which failed to comply with Ecuadorian technical guidelines. The treatment units, such as the flocculator, rapid sand filter, and storage tank, were resized to meet the demand of the future population. In addition, the residual free chlorine was measured as insufficient in the community’s tap water, showing an unprotected water distribution system to microbiological contamination. No disinfection by-products were found despite the existence of biodegradable organic matter. The findings of this research propose improvements in the deployed treatment practices to provide the community with drinking water in accordance with the Sustainable Development Objectives (SDG 3 and SDG 6).

Marine ecological impact analysis of residual chlorine emission from LNG transfer station

During the operation of LNG terminals, sodium hypochlorite was used to prevent Marine organisms from attaching to the equipment, resulting in aquatic life problems caused by residual chlorine discharge. The free residual chlorine in seawater is more toxic to aquatic organisms, and the maximum inhibitory effect on Chlorella growth is shown when the concentration of residual chlorine is 0.20mg/ L. Meanwhile, Chlorella growth is greatly affected by residual chlorine, and the recovery time is longer. The concentrations of zooplankton affected by continuous exposure to chlorine were lower than those affected by intermittent exposure. The effect of residual chlorine on shellfish is relatively small. When the residual chlorine concentration is lower than 1mg/L, shellfish can still open their shells to feed, but the feeding speed decreases.

Microbiological and Physico-chemical Assessment of Drinking Water in Bharatpur Metropolis

Objectives: To understand microbiological and physico-chemical quality of drinking water in Bharatpur metropolis. Methods: In a cross-sectional study, a total of 500 water samples (200 Municipal-supplied tap water, 200 hand-pump water and 100 open-well water) were collected from Bharatpur and processed for the investigation of physico-chemical and microbiological parameters. Physico-chemical parameters were analyzed by using an ENPHO water kit. The pH, arsenic and free residual chlorine (FRC) values of all the samples were within Nepal Drinking Water Quality Standard (NDWQS) 2062, whereas the concentrations of total hardness, ammonia, iron and nitrite didn’t meet the recommended limit in some of the samples. For bacteriological testing, membrane filtration (MF) technique was employed. Results: Out of the total 500 samples, 42.8% (214/500) were coliform positive. Open well water (57%) showed the highest prevalence of coliforms followed by hand-pump water (43.0%) and municipal tap water (35.5%). The occurrence of coliform in water was found to be associated with the proximity of latrines/cowsheds from the source of water (p&lt;0.05). On antibiotic sensitivity testing (AST) of the coliforms, Gentamicin was the most effective antibiotic whilst Ampicillin was the least effective. A higher incidence of multi-drug resistant (MDR) isolates was observed with Citrobacter spp. 46.5% (60/129) followed by E. coli 11.4 % (7/61). Conclusion: None of the Klebsiella spp. isolates were MDR. Regular monitoring of water quality parameters should be done by the concerned authorities and stakeholders of the Metropolis to ensure the quality of drinking water to the city-dwellers.

An overview of water quality within the Colombo Municipal Council area; A retrospective report analysis

Access to safe and quality drinking water is a fundamental requirement and a basic human right. Water quality is determined by its biological, physical, and chemical properties. Colombo Municipal Council (CMC) area consists of the largest population who utilize pipe-borne water supplied by the National Water Supply and Drainage Board (NWS&amp;DB) Sri Lanka. The objective of the study was to assess the water quality of the drinking water under selected parameters within the Colombo Municipal Council area. In this quantitative, retrospective, cross-sectional study, 268 water analysis reports from 1st July to 30th November 2021 were considered with the permission of the Ethics Review Committee of KIU (KIU_ERC_21_194A) and relevant authorities of NWS&amp;DB. Data on selected parameters such as color, turbidity, pH, Total Dissolved Solids (TDS), Free Residual Chlorine (FRC), the total number of coliform bacteria, and the total number of Escheretia-Coli (E-Coli) were extracted. Data analysis was done using SPSS (Version 25). All values were considered based on reference ranges of Sri Lanka Standards (SLS) guidelines. The study indicated that, among nine water schemes and four water reservoirs, the highest contributions for purification were from the Maligakanda water scheme (15.9% n =56) and Maligakanda water reservoir (51.6%, n=139). All the samples were fully treated water and the mean of the color was 4.03 Hazen Units which was within the permissible level, though ( 3.7 % n=10) of samples exceeded the range. The mean value of the turbidity was 0.49 Nephelometric Turbidity Unit (NTU) which was within the permissible level and only one sample had deviated from the maximum permissible level. The mean pH value was 7.33 and except for one, all other samples were within the permissible level. The mean value of the TDS was 24.51mg/L and the majority (95.8 %, n= 257) of FRC values varied between 0.6-0.8mg/L which was within the permissible level, while 3.39% (n=10) of samples had 0 mg/L. All samples were free from coliform and E-Coli. Most of the samples were within the permissible range of color, pH, turbidity, TDS, FRC, and free from Coliform and E-Coli which can be recommended for use.