Simulation Of Chlorine Concentrations In Mosul University's Distribution Network Using EPANET Program

1. Introduction Water pipe corrosion corrodes the iron by the oxidation reduction reaction, and the corrosion rate is accelerated by the oxidizing agent used as disinfectant in the tap water. The major oxidizing agent in tap water are ozone and chlorine. pH, alkalinity and residual chlorine concentration are factors of internal corrosion. We are replacing the ductile cast iron pipe with inner coating and stainless steel pipe. However, it is still used in many cases, such as gray cast iron pipes and galvanized steel pipes without internal coatings in Korea. Chlorine is a very strong oxidant for all metals and organics, and the reaction between chlorine and iron is as follows. HOCl + 2Fe2+ + 5H2O → 2Fe(OH)3↓ + Cl- + 5H+ Recently, as the problem with sinkholes has arisen on the a buried road as water pipes, sewage pipes, etc, interest in corrosion has been growing. The purpose of this study is to evaluate the effect of residual chlorine on the corrosion factor by analyzing the water quality and to evaluate the necessity of the proper residual chlorine on in the water purification plant. 2. Experimental Method In order to evaluate the corrosion of residual chlorine concentration of tap water, we were carried out Tafel experiment and water quality analysis. The corrosion rate was measured by a Tafel experiment using an electrochemical corrosion measurement system (PAR VMP-3). For tap water in Seoul, corrosion evaluation was performed according to alkalinity and hardness, residual chlorine concentraion. 3. Summary of results The tap water quality of Seoul was as follows that residual chlorine is 0.4 mg/L, and alkalinity is 50 mg/L as CaCO3, with a pH of 7.3. The results of experiments on the rate of corrosion of Carbon Steel specimens to residual chlorine in seoul tap water, can be seen in Fig. 1. As a result of the Tafel experiment according to the initial residual chlorine concentration under the same conditions (same LI index), The corrosion rate was 0.01 mmpy at 0 mg/L of residual chlorine and 0.074mmpy at 0.8mg/L of residual chlorine, corrosion rate for residual chlorine in carbon steel specimens was more than 7 times. It was confirmed that the higher the concentration of residual chlorine, the faster the corrosion rate was increased. The corrosivity of tap water in Korea is evaluated by the LI index, but residual chlorine has a large effect on corrosion, so it is required to add residual chlorine for the tap water corrosion evaluation. It is reducing the concentration of residual chlorine for reduce the chlorine odor of tap water in the distribution water system in Korea. But, residual chlorine guideline for corrosion reduction is necessary in Korea. Figure 1

Water quality has become a prominent issue in the study of water distribution networks. Variable speed pumps (VSPs) can control and improve the performance of water distribution systems. However, they may have effects on the water quality. The objective of this study was to investigate the impact of VSPs on water quality. The EPANET water quality simulator was applied for modelling water age and chlorine residual in a distribution network. In addition, intrusion of an active contaminant and analysis of leakage effects on residual chlorine concentration were performed through extended period simulations. Results indicate that VSPs may have negative impacts on water quality, including increased water age during low consumption times, and reduced disinfectant residuals at peak hours. In addition, the average rate of chlorine decay for fixed speed pumps (57%) is higher than that for VSPs (54%) when a conservative contaminant (sewage water) is considered.

Chapter 1 - Experimental investigation of leaked potable water quality supplied by the leading water treatment plant in Bangladesh

The residual chlorine concentration is an essential factor to secure reliable water quality in the water distribution systems. The chlorine concentration decays along the pipeline system and the main processes of the reaction can be divided into the bulk decay and the wall decay mechanisms. Using EPANET 2.0, it is possible to predict the chlorine decay through bulk decay and wall decay based on the pipeline geometry and the hydraulic analysis of the water distribution system. In this study, we tried to verify the predictability of EPANET 2.0 using data collected from experimental practices. We performed chlorine concentration measurement according to various Reynolds numbers in a pilot-scale water distribution system. The chlorine concentration was predicted using both bulk decay model and wall decay model. As a result of the comparison between experimental data and simulated data, the performance of the limited 1st-order model was found to the best in the bulk decay model. The wall decay model simulated the initial decay well, but the overall chlorine decay cannot be properly predicted. Simulation also indicated that as the Reynolds number increased, the impact of the wall

It is important to predict chlorine decay with different water purification processes and distribution pipeline materials, especially because chlorine decay is in direct relationship with the stability of water quality. The degree of chlorine decay may affect the water quality at the end of the pipeline: it may produce disinfection by-products or cause unpleasant odor and taste. Sand filtrate and dual media filtrate were used as influents in this study, and cast iron (CI), polyvinyl chloride (PVC), and stainless steel (SS) were used as pipeline materials. The results were analyzed via chlorine decay models by comparing the experimental and model parameters. The models were then used to estimate rechlorination time and chlorine decay time. The results indicated that water quality (e.g. organic matter and alkalinity) and pipeline materials were important factors influencing bulk decay and sand filtrate exhibited greater chlorine decay than dual media filtrate. The two-component second-order model was more applicable than the first decay model, and it enabled the estimation of chlorine decay time. These results are expected to provide the basis for modeling chlorine decay of different water purification processes and pipeline materials.

Water availability and quality are still challenges around the world, but access to safe drinking water is essential for human development. This study analyzed the chemical parameters of drinking water quality in the Santa Cruz de la Sierra region of Bolivia. Residual chlorine, pH and concentration of dissolved solids were measured in water supplied by drinking water and basic sanitation service providers (EPSA). The water quality results indicated that the water supplied met the requirements established by the Bolivian Standard NB 512 in terms of residual chlorine, pH and concentration of dissolved solids. However, a decrease in residual chlorine concentration was observed as the water moved away from the disinfection point. Microbiological testing is recommended to ensure the absence of viable organisms in the distributed water. In conclusion, this study highlights the importance of chlorination, as the only treatment performed in the study area, the pH and the concentration of dissolved solids as indicators of drinking water quality. Automation of chlorination processes and continuous monitoring of these parameters is suggested to ensure a safe and high-quality water supply in the study area.

Limited data are available on the effects of water quality and contaminant conditions on Atlantic menhaden, but data measuring the effects of temperature, salinity, temperature‐salinity interactions and dissolved oxygen are available forvarious life stages. Temperatures below5 °C and above 33 °C are lethal to larvae and juveniles but juvenile Atlantic menhaden demonstrate the ability to avoid high, potentially lethal temperatures in laboratory studies. Adult Atlantic menhaden prefer higher temperatures than juveniles. Juveniles demonstrate the ability to survive large shifts in salinity (i.e., changes of 31.5 ppt). Lethal dissolved oxygen (D.O.) concentrations of 1.1 mg/L are also reported for juvenile Atlantic menhaden. These hypoxic D.O. conditions can be found in the bottom waters of mainstem areas of Chesapeake Bay. Fortunately, this species usually inhabits the surface waters where D.O. conditions are higher. Toxicity data are available for Atlantic menhaden exposed to six single chemicals. Most of these studies were designed to evaluate the effects of biocides (primarily chlorine) and/or other interacting conditions such as increased temperature on the survival at various life stages of Atlantic menhaden. The toxicity of only one chemical (chlorine) has been evaluated with Atlantic menhaden larvae. Free residual chlorine (FRC) concentrations of 0.5 mg/L or more are toxic to larvae; a 10 °C thermal increase added simultaneously with this chlorine concentration is also lethal. Chlorine toxicity data with juvenile Atlantic menhaden are more numerous. Ninety‐six hour LC50's of 0.18 and 0.15 mg/L were reported at test temperatures of 15 and 25 °C respectively. Both of these toxic concentrations were much higher than the U.S. Environmental Protection Agency's (U.S. EPA's) acute and chronic water quality criteria for chlorine. Therefore, it appears that the chlorine criteria would be protective of this life stage. Moreover, juveniles were reported to avoid approximately half of the acute LC50's for chlorine. This strongly schooling species was reported to have better avoidance capabilities when tested in groups than when tested individually. Dechlorination practices are important for reducing potentially toxic effects of chlorine on juvenile Atlantic menhaden. Environmentally realistic concentrations of excess sulfite often associated with dechlorination would likely be either nontoxic or avoided if potentially toxic conditions existed. Also, juveniles generally avoided lower sulfite concentrations at higher temperatures. The toxicity of tributyltin (TBT) to juvenile Atlantic menhaden was evaluated in three studies: an acute toxicity study, an avoidance study, and a subchronic toxicity study. A TBT concentration of 4.5 μg/L was acutely toxic; concentrations approximately three times this value were avoided by menhaden at this life stage. Concentrations of TBT realistic in marina areas of Chesapeake Bay (for example, 0.093 and 0.490 μg/L) were reported to have no adverse effects on juveniles in 28 day sub‐chronic studies. Populations of Atlantic menhaden have remained stable in Chesapeake Bay in recent years. Despite the success of this fish, information on adverse water quality and contaminant effects may be useful. These data may be very important for managing the species or establishing protective water quality or contaminant regulations or standards. The following research is proposed with Atlantic menhaden: micro‐layer toxicity studies with eggs; standard acute and chronic single chemical or multiple chemical toxicity studies with early life stages; behavioral toxicity studies with juveniles using schooling behavior as an endpoint and in situ and on‐site ambient toxicity studies designed to determine not only survival, but histopathological, histochemical, behavioral and physiological effects.

The concentration of chlorine in water declines as it reacts with various substances, causing decay of the residual free chlorine until its total consumption. In light of the typical characteristics of the water from protected dug wells and tube wells, this study aimed to evaluate the decay kinetics of free chlorine in the water of alternative individual supply (AIS) solutions used in the city of Porto Velho in the Brazilian Amazon region. The free chlorine decay constant in the water was evaluated by “bottle tests,” applying a first-order model. According to the results, the type of well and initial chlorine concentration significantly influences the free chlorine decay speed. The water samples from the tubular wells had lower chlorine demand levels, attributed to their better water quality. The simulation of the residual chlorine decay in the different supply sources is an important tool to support safe disinfection processes.

One of the parameters responsible for decreased water quality in a distribution system is temperature changes. This study was conducted to examine the effect of temperature on pH, turbidity, and residual chlorine in Sanandaj, Iran, Water Distribution System. The required water samples were taken from 85 stations during April to October 2014. Sampling was carried out over 6 months and twice per month. The average amount of residual chlorine measured at these stations was 0.58 and 0.52 mg/l, and turbidity was 0.86 and 0.98 nephelometric turbidity unit (NTU) in winter and spring, respectively. The temperature did not have any effect on pH, the amount of pH in winter and spring were 7.56 and 7.57, respectively. The results showed significant differences in the concentration of residual chlorine and turbidity of Sanandaj Water Distribution Network between winter and spring (P ≤ 0.01). Thus, the concentration of residual chlorine and turbidity varies in warm and cold seasons. However, no significant difference was observed in pH (P ≥ 0.01). The research results indicated that temperature does not have any effect on the qualitative parameters measured in the study area.

In this work, flow entropy (FE), flow path entropy (FPE), water quality entropy (WQE) and water quality path entropy (WQPE) of a water distribution system (WDS) were proposed and applied to four cases – a single-source branched network, a single-source looped network, a multi-source branched network and a multi-source looped network. The maximum FE, FPE, WQE, and WQPE for four cases were obtained and compared by solving optimisation models. For single-source branched network the maximum FE, FPE, WQE, and WQPE are the same. For multi-source branched network, the maximum FE is equal to the maximum FPE, and the maximum WQE is equal to the maximum WQPE. However, the maximum FE/FPE is not equal to the maximum WQE/WQPE. For single-source looped network and multi-source looped network, the maximum FE is also equal to the maximum FPE, while the maximum WQE is not equal to the maximum WQPE. The WQE and WQPE decreased with an increase in pipe length, pipe diameter and chlorine decay coefficient. The proposed concepts of FE, FPE, WQE and WQPE can help analyse the WDS from the viewpoints of water quantity as well as water quality.

Prechlorination of water upstream of an ultraviolet (UV) disinfection process may possibly influence the effectiveness of UV inactivation through the absorbance of UV radiation. Alternatively, UV may act to destroy chlorine, reducing the residual in water. Monochromatic UV light was more effective in degrading monochloramine whereas polychromatic UV light was more effective in degrading free chlorine. The extent of degradation varied with the type of chlorine species, water quality and type of UV irradiation (mono- or polychromatic). However, decay of chlorine and monochloramine at typical UV disinfection doses (<100 mJ/cm2) was negligible. The transmission of UV irradiation was affected slightly by the presence of chlorine and monochloramine, and these effects on inactivation of MS2 coliphage were modeled for LP− and MP-UV reactors. The presence of 1 mg/L free chlorine or monochloramine decreased the inactivation of MS2 coliphage by less than 0.1 log for a LP-UV reactor. For the MP-UV reactor, MS2 inactivation decreased by between 0.1 and 0.3 log.

The distribution network is the last component of a water supply system in which potable water must be provided to the consumer.The presence of chlorine in drinking water is a necessity and a guarantee that water is microbiologically compliant.The study was carried out by means of the Epanet 2.0 program on a future distribution network in the hilly area, in which a simulation period of 4 days was considered.The water quality analysis was performed using the flow rates resulting from the hydraulic simulation.To track the propagation of the contaminant through network pipelines, a maximum permissible value of 0.5 mg/L, entered during the entire simulation period, was considered.The reactions that occur in the bulk flow, were modeled by means of a 1st and 2nd order a decomposition law.The obtained values of the free residual chlorine concentration showed that during the 96 h of simulation, there were certain pipelines in which the chlorine concentration did not meet the minimum allowable limit of 0.1 mg/L.Modeling water quality offers the opportunity to view the decreasing of chlorine concentration, so that the free residual chlorine dosage can be optimized.

Evaluation of water quality and potential scaling of corrosion in the water supply using water quality and stability indices: A case study of Juja water distribution network, Kenya

Free chlorination is a widely employed disinfection method in humanitarian water provision due to its many advantages. However, its effective application is hindered by the challenge in determining adequate initial doses to achieve free chlorine residuals that satisfy both health and aesthetic requirements. Current guidelines show varying recommended dosing strategies, and many do not adequately consider chlorine decay mechanisms that occur during water storage. Even though turbidity is commonly used as a criterion for deciding chlorine dose, it may not be an adequate proxy for the water quality in many cases. This paper addresses the fundamental relationships between chlorine decay kinetics and selected key water parameters (i.e., natural organic matter, water temperature, chlorine demand) by conducting chlorine decay tests in controlled conditions and in jerrycans (i.e., simulating humanitarian water treatment conditions). Chlorine decay constant from the Feben and Taras’s empirical model and first order model formed linear and exponential relationships with two water parameters (UVA254 and 30-min chlorine demand). With these relationships, the two chlorine decay models can be calibrated quickly and frequently in the field, allowing effective determination of initial chlorine dose. These two models calibrated based on the suggested water parameters from the study could predict chlorine decay in water having a main chlorine demand-inducing constituents as natural organic matter. However, they underpredicted chlorine decay in surface water with additional chlorine reactants. Further research on additional chlorine decay mechanisms is needed to expand the applicability of the models.

Long duration forecasting and its performance capability for seasonal variation modelling of residual chlorine concentrations: A comparative evaluation of two small-scale water distribution systems in Japan