الفهرس 
ABSTRACT
OBJECTIVES OF STUDYOnly 14 pages are availabe for public view
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Abstract
Disinfectants such as chlorine are used in drinking water treatment to protect the public health from pathogenic microorganisms. However, disinfectants react with humic materials present in raw water sources and produce by-products, such as trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and haloketones (HKs). THMs include four compounds; chloroform, bromodichloromethane, dibromochloromethane and bromoform. THMs are suspected carcinogenic, mutagenic and have found to cause adverse pregnancy outcomes. This research simulates water age in Assiut drinking water system using Water CAD software and THMs production is investigated. Pre-chlorinated water samples for the experimental work were collected from Nazlet Abdellah water filtration plant and post-disinfected with chloramines with different chlorine to nitrogen ratios (Cl2/N). Experiments have examined varying residence times, ratios of Cl2/N, pH conditions and storage containers’ type on the formation of THMs. It was found that as the residence time increased the THMs concentrations increased Water age in some areas in Assiut drinking water distribution network (DWDN) reaches more than 10 hours which may increase THMs concentrations. Using chloramines instead of free chlorine as a secondary disinfectant resulted in lowering THMs concentrations to a ratio of 58.9% after 48 hours of disinfection. Ratios of Cl2/N ranged from 2/1 to 6/1 were to be comparable and effective on lowering THMs formation and the most effective ratio was 4/1. Also, it was found that as the pH increased the produced THMs concentrations increased. The measured THMs concentrations in chloraminated water which has been stored in glass and plastic bottles were found to be approximately the same.