| The reaction of disinfectant (eg. chlorine) with natural organic matter (NOM) in water leads to the formation of disinfection by-products (DBPs). DBPs have potential risks to human health. Among different DBPs, thrihalomethanes (THMs), which consist of CHCl3, CHBrCl2, CHBr2Cl and CHBr3,is one of the most common groups of DBPs.This thesis focused on the East River in China, as it is the major drinking water source supplying for Hong Kong. The main objective is to investigate possible factors influencing THMs production, both in the field and in the laboratory. This study aims to provide data for disinfection treatment in drinking water and the quality management of drinking water source.Water samples were collected along the East River from up-river to low-river during time of sampling. The result showed that there was an obvious trend that THMs were increased with the levels of TOC, TN, TP, TS1 in middle - low river water of East River. These data indicated that THMs formation was related with eutrophication of source water and chemical contamination of watershed.The effect of chlorination conditions (temperature, chlorine dose, bromide ion concentration, reaction time) on THMs production was simulated in the laboratory. The result showed THMs production increased with the increase of temperature, chlorine dose, reaction time, while there appears to be more complicated relationships between individual THM and bromide ion concentration. We generated an optimum chlorination condition by the orthogonal design.Three dominant algal species in the Shenzhen Reservoir: Osicillatoria sp. (a blue green algae), Chlamydonomas sp. (a green algae), Synedra sp. (a diatom), were used for chlorination experiments. Chloroform production in algal cells and the extracellular products at different growth phases was investigated. The results showed that Synedra sp. had the highest production of chloroform among the three species and the chloroform production increased with the algal growth for the three algal species. Further, algal cells had a higher production than algal extracellular products,whereas chloroform production from extracellular products was similar as that of algal cells at log and death phases.As NOM consisting of humic substances (humic acids and fulvic acids) and non-humic substances (protein, amino acids, carbonhydron) were generally regarded as the precursors of DBPs, in this paper, six model compounds (protein, humic acid, starch, maltose, glucose, Asp) was selected to be chlorinated. The results showed that protein showed the highest chloroform production, while hydrocarbon had the lowest.
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