Variable Chlorine Decay Rate Modeling of the Matsapha Town Water Network Using EPANET Program

Ababu T Tiruneh,L Zwane,Tesfamariam Y Debessai,Stanley J Nkambule,Gabriel C Bwembya

doi:10.4236/jwarp.2019.111003

Abstract

A variable chlorine decay rate modeling of the Matsapha town water network was developed based on initial chlorine dosages. The model was adequately described by a second order rate function of the chlorine decay rate with respect to the initial chlorine dose applied. Simulations of chlorine residuals within the Matsapha water distribution network were run using the EPANET 2.0 program at different initial chlorine dosages and using the variable decay rate as described by the second order model. The measurement results indicated that the use of constant decay rate tended to underestimate chlorine residuals leading to potentially excess dosages with the associated chemical cost and side effects. The error between the two rate models varied between 0% and 15%. It is suggested that the use of water quality simulation programs such as EPANET be enhanced through the extension programs that accommodate variable rate modeling of chlorine residuals within distribution systems.

Highlights

Disinfection of water is an important step in water treatment and is commonly employed as the last barrier in conventional water treatment processes for rendering water a potable quality [1]
It is suggested that the use of water quality simulation programs such as EPANET be enhanced through the extension programs that accommodate variable rate modeling of chlorine residuals within distribution systems
A second order model fit to the data shown in Figure 3 adequately describes the variation of the bulk decay rate with the initial chlorine

Summary

Introduction

Disinfection of water is an important step in water treatment and is commonly employed as the last barrier in conventional water treatment processes for rendering water a potable quality [1]. Chlorination started to be used for water supply disinfection at the beginning of the 20th century, gradually spreading worldwide as evidence on statistics of reduction of waterborne epidemics from chlo-. The use of gas chlorine emerged in the 1920s making the transportation and operation simpler [2]. In the 1930s and 1940s increase of knowledge of the different chlorine species, pH dependence of chlorination, chloramination and laboratory methods of chlorine determination became available. By the 1970s concern about the risk of formation of trihalomethanes (THMs) was raised prompting the use of chloramination and ozone as alternative disinfection methods [3]

Methods

Results

Conclusion