Formation Characteristics and Control of Disinfection Byproducts in a Drinking Water Treatment Plant Using Lake Water

This study investigated the influence of characteristics of natural organic matter (NOM) on the formation of disinfection by-products (DBPs), and proposed the control strategies of DBPs formation in a drinking water treatment plant using lake water in Gyeongsangbuk-do.The fluorescence excitation-emission matrix analysis results revealed that the origins of NOM in raw waters to the plant were a mixture of terrestrial and microbial sources.Molecular size distributions and removals of NOM fractions were evaluated with a liquid chromatography-organic carbon detector (LC-OCD) analysis.Humic substances and low molecular weight organics were dominant fractions of NOM in the raw water.High molecular weight organics were relatively easier to remove through coagulation/precipitation than low molecular weight organics.The concentrations of DBPs formed by pre-chlorination increased through the treatment processes in regular sequence due to longer reaction time.Chloroform (74%) accounts for the largest part of trihalomethanes, followed by bromodichloromethane (22%) and dibromochloromethane (4%).Dichloroacetic acid (50%) and trichloroacetic acid (48%) were dominant species of haloacetic acids, and brominated species such as dibromoacetic acid (2%) were minimal or none.Dichloroacetonitrile (60%) accounts for the largest part of haloacetonitriles, followed by bromochloroacetonitrile (30%) and dibromoacetonitrile (10%).The formation of DBPs were reduced by 16~44% as dosages of pre-chlorine decreased.Dosages of pre-chlorine was more contributing to DBPs formation than variations of dissolved organic contents or water temperature.