scholarly journals Estimating fast and slow reacting components in surface water and groundwater using a two-reactant model

2016 ◽  
Vol 9 (1) ◽  
pp. 19-25
Author(s):  
Priyanka Jamwal ◽  
M. N. Naveen ◽  
Yusuf Javeed
Keyword(s):  
Surface Water ◽  
Water Distribution ◽  
Distribution Networks ◽  
Bulk Water ◽  
Data Sets ◽  
Decay Data ◽  
First Order ◽  
Surface Water And Groundwater ◽  
Inorganic Matter ◽  
Chlorine Decay

Abstract. Maintaining residual chlorine levels in a water distribution network is a challenging task, especially in the context of developing countries where water is usually supplied intermittently. To model chlorine decay in water distribution networks, it is very important to understand chlorine kinetics in bulk water. Recent studies have suggested that chlorine decay rate depends on initial chlorine levels and the type of organic and inorganic matter present in water, indicating that a first-order decay model is unable to accurately predict chlorine decay in bulk water. In this study, we employed the two-reactant (2R) model to estimate the fast and slow reacting components in surface water and groundwater. We carried out a bench-scale test for surface water and groundwater at initial chlorine levels of 1, 2, and 5 mg L−1. We used decay data sets to estimate optimal parameter values for both surface water and groundwater. After calibration, the 2R model was validated with two decay data sets with varying initial chlorine concentrations (ICCs). This study arrived at three important findings. (a) We found that the ratio of slow to fast reacting components in groundwater was 30 times greater than that of the surface water. This observation supports the existing literature which indicates the presence of high levels of slow reacting fractions (manganese and aromatic hydrocarbons) in groundwater. (b) Both for surface water and groundwater, we obtained good model prediction, explaining 97 % of the variance in data for all cases. The mean square error obtained for the decay data sets was close to the instrument error, indicating the feasibility of the 2R model for chlorine prediction in both types of water. (c) In the case of deep groundwater, for high ICC levels (> 2 mg L−1), the first-order model can accurately predict chlorine decay in bulk water.

scholarly journals Estimating fast and slow reacting component in surface and groundwater using 2R model

2015 ◽  
Vol 8 (2) ◽  
pp. 197-217 ◽  
Author(s):  
P. Jamwal ◽  
M. N. Naveen ◽  
Y. Javeed
Keyword(s):  
Surface Water ◽  
Water Distribution ◽  
Distribution Networks ◽  
Bulk Water ◽  
Water Distribution Networks ◽  
Reactant Ratio ◽  
Surface Water And Groundwater ◽  
Decay Test ◽  
Chlorine Decay ◽  
Surface And Groundwater

Abstract. Maintaining residual chlorine levels in a water distribution networks is a challenging task; especially in the context of developing countries where water is usually supplied intermittently. To model chlorine decay in water distribution networks, it is very important to understand chlorine kinetics in bulk water. Recent studies suggested that chlorine decay rate depends on initial chlorine levels and type of organic and inorganic matter present in water, indicating that first order decay model is unable to accurately predict chlorine decay in bulk water. In this study, we employed two reactant model (2R) to estimate the fast and slow reacting components in surface water and groundwater. We carried out bench scale test for surface and groundwater at initial chlorine level of 1, 2 and 5 mg L−1. We used decay datasets to estimate optimal parameter values for both surface water and groundwater. After calibration, the 2R model was validated with two decay dataset with varying initial chlorine concentration (ICC). This study came up with three important findings (a) the ratio of slow to fast reacting components in groundwater was thirty times greater than that of the surface water, (b) 2R model can accurately predict chlorine decay in surface water, 98 % of the variance in the chlorine decay test was explained by the model and (c) in case groundwater, 2R model prediction accuracy reduced with the decrease in ICC levels, only 87 % variance in data was explained by the model. This could be attributed to high slow to fast reactant ratio in groundwater.

scholarly journals Residual Chlorine Decay in Juja Water Distribution Network using EPANET Model

2019 ◽  
Vol 9 (1) ◽  
pp. 332-334 ◽  
Keyword(s):  
Water Distribution ◽  
Distribution Network ◽  
Treatment Plant ◽  
Water Distribution Network ◽  
Residual Chlorine ◽  
Simulation Tool ◽  
First Order ◽  
Water Company ◽  
Field Samples ◽  
Chlorine Decay

The current study was carried out to analyze the residual chlorine decay analysis within the existing Juja water distribution network. The study used EPANET as a simulation tool. From the field samples, the first-order bulk decay coefficient Kb was found equal to - 0.04 . The wall coefficient Kw was assumed to - 4.0 mg/ /day as guided by literature. The analysis shows that the entire supply area of the existing distribution network faces higher residual chlorine concentration (0.70 to 0.8 mg/l) from 9 am. The study recommended the reducing of the initial chlorine added at the treatment plant and the optimization of the network, which will provide a proper residual chlorine dosage to reduce Juja consumers exposure to health risk and also to be economically reasonable for the water company in charge

Causes of waterborne outbreaks in community water systems in Finland: 1980-1992

1995 ◽  
Vol 31 (5-6) ◽  
pp. 33-36 ◽  
Author(s):  
K. Lahti ◽  
L. Hiisvirta
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
Water Distribution ◽  
Water Source ◽  
Distribution Networks ◽  
Etiologic Agent ◽  
Chlorinated Organic Compounds ◽  
Water Supplies ◽  
Community Water Systems ◽  
Etiologic Agents

Finland is known as a country with thousands of unpolluted lakes and pristine groundwaters. For this reason treatment processes applied in the drinking-water industry are quite simple. These kinds of water supplies, as well as private wells, are vulnerable for accidental pollution, leading to twenty-four reported waterborne epidemics outbreaks in Finland in 1980-1992. About 40 per cent of these outbreaks were due to contaminated water from community drinking-water supplies. The number of people affected in these outbreaks was around 7 700. Contaminated groundwater was a more common cause than surface water. The majority of Finnish groundwater supplies distribute water without any treatment or only with alkalization. In most outbreaks leakage and blockage of a sewage pipe in the vicinity of a groundwater well resulted in the contamination of drinking-water. The largest of these outbreaks affected some 5 000 people. The etiologic agents in these epidemics were most probably viruses; faecal indicator bacteria and enteric viruses were detected in water samples during the epidemics. Contamination of water distribution networks due to cross-connection caused two restricted epidemics. Inadequate disinfection of surface water was the reason for three outbreaks. Two of these were caused by the same water supply in subsequent years. The raw water source for this supply was of quite a high quality, for which reason the treatment consisted only of rapid sand filtration and chlorination. For fear of the chlorinated organic compounds formed during disinfection the amount of chlorine in water treatment was reduced to a level where disinfection was inadequate, and some hundred people became ill. The etiologic agent in these outbreaks remained unknown.

scholarly journals Modeling chlorine distribution in water supply system utilizing empirically determined chlorine decay rate

2019 ◽  
Vol 100 ◽  
pp. 00054
Author(s):  
Anna Musz-Pomorska ◽  
Marcin K. Widomski ◽  
Agnieszka Matczuk ◽  
Konrad Sadura
Keyword(s):  
Water Supply ◽  
Decay Rate ◽  
Water Distribution ◽  
Supply System ◽  
Water Supply System ◽  
Free Chlorine ◽  
Time Duration ◽  
First Order ◽  
Numerical Studies ◽  
Chlorine Decay

Analysis of free chlorine propagation in water supply network has a significant meaning for the process of water distribution. Results of numerical studies allow the proper selection of disinfectant or suitable monitoring of pipelines endangered by stagnation of water. The first-order reaction of chlorine decay in pipe boundary layer and inside the waterbody is commonly successfully assumed in numerical modeling. The aim of this studies was to analyze transport of chlorine inside the rural water supply system. The calculations were performed with application of Epanet 2.0 with assumed the first-order re action of chlorine decay and empirically determined chlorine decay rate in the mass of waterbody. The periodical disinfection of water in the network with the constant chlorine concentration 0.3 mg·dm-3 introduced during the whole time duration of simulation was assumed to calculations. The obtained results of chlorine distribution showed that even after 4 days there were available pipelines in which concentration of free chlorine was lower than 0.2 mg·dm-3. Thus, the microbiological protection of water quality is unavailable in these pipelines.

scholarly journals Application of DVC-FISH method in trackingEscherichia coliin drinking water distribution networks

2012 ◽  
Vol 5 (1) ◽  
pp. 515-532
Author(s):  
L. Mezule ◽  
S. Larsson ◽  
T. Juhna
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Surface Water ◽  
Water Samples ◽  
Water Distribution ◽  
Large City ◽  
Distribution Networks ◽  
Water Distribution Networks ◽  
E Coli ◽  
Drinking Water Distribution

Abstract. Sporadic detection of live (viable) Escherichia coli in drinking water with molecular methods but not with standard plate counts has raised concerns about the reliability of this indicator in the surveillance of drinking water safety. Previous studies have shown that in low numbers metabolically active E. coli can be found in the biofilm of drinking water. The aim of this study was to analyse the distribution of non-cultivable E. coli in the drinking water distribution system meeting microbiological quality standards and evaluate the importance of the biofilm as its harbour. In total 24 biofilm samplings and 40 at least 100 times pre-concentrated water samples were taken over a period of two years from two water treatment plants (surface water and groundwater) and four locations in water distribution network of a large city. Cultivable, total and able to divide (viable) E. coli concentration was measured in all samples. The results showed that none of the network biofilm samples contained cultivable E. coli and less than two cells per 10 l were detected in the pre-concentrated water samples. However, almost all of the samples contained viable E. coli in the range of 1–50 cells per litre or cm2 which represented approximately 53% of all E. coli detected. The amount of viable E. coli was higher in the biofilm after surface water treatment when compared to the outlet from the groundwater plant and the number tended to increase from both treatment plants further into the network irrespective of the season. In conclusion, E. coli in the water supply is not necessarily directly linked to recent faecal contamination and tends to accumulate in the networks where it is less exposed to disinfectants. Thus it can be accepted that biofilm formation in the drinking water distribution networks increases the risk of accumulation of viable but not cultivable E. coli in the system.

Experience in controlling Asellus aquaticus in water distribution systems

2001 ◽  
Vol 1 (2) ◽  
pp. 217-223
Author(s):  
A. Oleszkiewicz ◽  
M. Geringer d'Oedenberg ◽  
J. Chapman
Keyword(s):  
Surface Water ◽  
Peracetic Acid ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Water Reservoir ◽  
Distribution Networks ◽  
Average Dose ◽  
Asellus Aquaticus

Asellus aquaticus is one of the nuisance organisms found in water distribution systems. Case studies of operations aimed at control of this crustacean and its disinfestation, carried out in two water distribution networks: in Pevensey Bay (Eastbourne, UK) and in Gdansk (Poland), are presented. Raw water reservoir receiving surface water was the source of infestation in Pevensey Bay. In Gdansk A. aquaticus probably penetrated the water distribution system with surface water getting into a leaky collecting well receiving groundwater from a chalk aquifer. The presence of organic matter in water entering the systems seemed to favour the infestation. Chemical treatment with pyrethrins (Pevensey Bay) and peracetic acid/hydrogen peroxide preparation (Gdansk) was used. The concentration of pyrethrins was 10 (g/dm3 and the average dose of peracetic acid was 4 mg/dm3. Both chemical treatments were found quite effective, however, some sections of the (much larger than Pevensey Bay) distribution network in Gdansk were not completely cleaned of the infestation.

Modelling the chlorine decay process in a distribution network using a pilot system

2014 ◽  
Vol 9 (4) ◽  
pp. 534-550
Author(s):  
R. Buamah ◽  
K. Akodwaa-Boadi ◽  
M. Paintsil ◽  
E. K. Baah-Ennumh ◽  
A. A. Adjaottor
Keyword(s):  
Cast Iron ◽  
Distribution System ◽  
Water Distribution ◽  
Batch Reactor ◽  
Distribution Network ◽  
Bulk Water ◽  
Residual Chlorine ◽  
Pipe Material ◽  
Bulk Fluid ◽  
Chlorine Decay

Chlorine is one of the many disinfectants used to ensure bacteriological safety of drinking water. Usually residual chlorine is maintained within the distribution network to combat any probable re-contamination of the distributed water. This residual free chlorine, however, decays in water due to its reaction with the bulk water and the pipe material or deposits on the pipe walls. This study aimed at determining and modelling chlorine decay in the Kumasi water distribution network (KWDN) and determined locations where residual chlorine boosting is necessary. A double-jacketed batch reactor and a constructed pilot distribution system (PDS) were used to determine the bulk and wall decay coefficients. The PDS was run using aged PVC pipes (15–20 years), asbestos concrete pipes (40–50 years) and cast iron pipes (84 years) that have been in use in the KWDN. The SynerGEE® hydraulic model was used to identify the ‘zero chlorine’ points and predict top-up quantities. The bulk decay coefficient was found to be 0.053 h−1 within 8 hours at 26 °C and the residual chlorine decayed within the bulk fluid by 32–34% of its initial dose. Under the conditions tested, the cast iron pipes had the highest overall decay coefficients (K). Five locations within the network were identified as probable chlorine boosting points).

Estimation of the variability of the chemical composition of drinking water transported by water distribution networks

2020 ◽  
Author(s):  
М.Ю. Вождаева ◽  
А.Р. Холова ◽  
И.А. Мельницкий ◽  
И.И. Белолипцев ◽  
Н.В. Труханова ◽  
...  
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
Water Distribution ◽  
Distribution Networks ◽  
Water Distribution Networks ◽  
Sampling Point ◽  
Factors Affecting ◽  
Dead End ◽  
General Chemical ◽  
Range Of Variation

При оценке надежности и эффективности работы предприятий водопроводно-канализационного хозяйства повышенного внимания требует транспортировка питьевой воды до потребителя из-за возможного ухудшения ее качества при длительном времени транспортирования, а также в тупиковых и локальных застойных зонах распределительных сетей. Выявлено, что значения общехимических показателей в питьевой воде при ее транспортировке достаточно стабильны. Исключение составляют мутность питьевой воды поверхностного водозабора и жесткость питьевой воды инфильтрационного водозабора. Статистические критерии, полученные при обработке многолетних данных (диапазон варьирования концентраций металлов, стандартное отклонение и форма графиков плотности распределения их концентраций), свидетельствуют о большей стабильности состава питьевой воды в сетях по сравнению с водой в резервуаре чистой воды на водозаборах. Близкое к нормальному распределение значений концентраций выбранных показателей говорит об отсутствии значимых случайных факторов, влияющих на качество воды в сетях. Тупиковые и локальные застойные зоны сетей являются уязвимыми для коррозионных процессов, происходящих внутри труб, что подтверждается более высокими значениями индекса Ланжелье для воды, отобранной в этих зонах. В целом питьевая вода поверхностного водозабора характеризуется большим разбросом концентраций компонентов и является более коррозионно-активной по сравнению с водой инфильтрационного водозабора. В воде застойных и тупиковых зон водораспределительных сетей наблюдается увеличение содержания железа, цинка, мутности. Относительно действующих на сегодняшний день нормативов качества воды значения концентраций находятся на стабильном приемлемом уровне во всех точках отбора, что подтверждается диапазоном варьирования концентраций, охватывающим весь период наблюдения (2006–2016 годы). While estimating the reliability and efficiency of water supply and sanitation utilities, transporting drinking water to the consumer requires closer attention due to possible quality deterioration during long transportation time, as well as in dead-end and local stagnant zones of distribution networks. It was revealed that the values ​​of the general chemical indicators in drinking water during its transportation are quite sound. An exception is the turbidity of drinking water from surface water intakes and the hardness of drinking water from infiltration water intakes. Statistical criteria obtained during long-term data processing (the range of variation in metal concentrations, standard deviation and the shape of the density distribution graphs of their concentrations) evidence greater stability in the composition of drinking water in networks compared to water in clean water tanks at water intakes. A close to normal distribution of the concentration values of the selected indicators suggests the absence of significant random factors affecting the quality of water in the networks. Dead ends and local stagnant zones of networks are exposed to corrosion processes occurring inside pipes, which is confirmed by higher values of the Langelier index in water samples from these zones. In general, drinking water from surface water intakes is characterized by a wide scatter in the concentrations of the components and is more corrosive compared to the water from infiltration water intakes. Water in stagnant and dead-end zones of water distribution networks has raised turbidity and contains increased concentrations of iron and zinc. Relative to the current water quality standards, the concentration values were at a stable acceptable level in any sampling point, which is confirmed by the range of variation in concentrations during the whole observation period (2006–2016).

Kinetics of Free Chlorine Decay in Water Distribution Networks

2010 ◽  
Author(s):  
Venkat Devarakonda ◽  
N. Albert Moussa ◽  
Vicki VanBlaricum ◽  
Mark Ginsberg ◽  
Vincent Hock
Keyword(s):  
Water Distribution ◽  
Distribution Networks ◽  
Free Chlorine ◽  
Water Distribution Networks ◽  
Chlorine Decay ◽  
Kinetics Of
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