• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.916-927
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• 2010

In general water treatment process, the disinfection process by chlorine is used to prevent water borne disease and microbial regrowth in water distribution system. Because chlorines were reacted with organic matter, carcinogens such as disinfection by-products (DBPs) were produced in drinking water. Therefore, a suitable injection of chlorine is need to decrease DBPs. Rechlorination in water pipelines or reservoirs are recently increased to secure the residual chlorine in the end of water pipelines. EPANET 2.0 developed by the U.S. Environmental Protection Agency (EPA) is used to compute the optimal chlorine injection in water treatment plant and to predict the dosage of rechlorination into water distribution system. The bulk decay constant ($k_{bulk}$) was drawn by bottle test and the wall decay constant ($k_{wall}$) was derived from using systermatic analysis method for water quality modeling in target region. In order to predict water quality based on hydraulic analysis model, residual chlorine concentration was forecasted in water distribution system. The formation of DBPs such as trihalomethanes (THMs) was verified with chlorine dosage in lab-scale test. The bulk decay constant ($k_{bulk}$) was rapidly decreased with increasing temperature in the early time. In the case of 25 degrees celsius, the bulk decay constant ($k_{bulk}$) decreased over half after 25 hours later. In this study, there were able to calculate about optimal rechlorine dosage and select on profitable sites in the network map.

• Analytical Science and Technology
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• v.10 no.4
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• pp.264-273
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• 1997

Anodic oxidation reaction was applied to remove trihalomethanes in an aqueous solution. Each component was determined by using solid phase microextraction(SPME) fiber and GC-ECD. Anodic and cathodic compartments were separated in order to protect contaminants and connected by $KNO_3$-agar bridge. The calibration graphs of the 6 THM components were shown good linearlity from a few ppb up to a few hundreds ppb concentration level. Anodes such as platinum(Pt), titanium(Ti). zircornium(Zr), titanium metal coated with iridium(Ti-Ir), and glassy carbon coated with mixed valence ruthenium(mv Ru) were tried to remove the THMs at different potentials. The best result was obtained on the Ti-Ir anode applied 9 volts DC. The electrode could effectively remove almost all the THM components from the stirring solution within about 1.5 hours. The glassy carbon electrode coated with mixed valence ruthenium showed excellent removing effect at the begining, but the maximum removing level was remained at 60% probably due to the destruction of the electrode surface. The concentration of chloroform, however, tends to be increased due to the electrode reaction producing the component at the condition.