| Title |
A Study on Formation Characteristics of THMs and TOXs as a Function of Cl2/NH3-N in Raw Water of Water Treatment Plants Located on Keum River |
| Authors |
윤제용(Je Yong Yoon), 변석종(Seok Jong Byun), 이상덕(Sang Duk Lee) |
| Abstract |
Chlorine is currently being used for the disinfection process in nearly all domestic water treatment plants. Trihalomethanes(THMs) and a lot of chlorinated disinfection byproducts(DBPs) are inevitably produced as a result of chlorine use. The chlorinated DBPs other than THMs are hard to measure and regulate individually. Total organic halides(TOXs) which indicate the sum of chlorinated DBPs may be used as a process control variable for the control of DBPs. In this study, the formation characteristics of THMs and TOXs as a function of the ratio of Cl₂ to NH₃-N in two types of raw water which have the different characteristics of ammonia concentration were investigated. The breakpoint chlorination of the drinking water treatment plants was simulated to represent the characteristics of DBPs formation. Breakpoint chlorination curves with naturally occurring ammonia were not significantly different, when compared to those with chemical ammonia. The breakpoint was observed at Cl₂/NH₃-N ratio of 7.0∼7.7. When Cl₂/NH₃-N ratio was below 5, where chloraminations were practiced, THMs & TOXs formation were low, becoming up to 8㎍/L and 78㎍/L respectively. Below Cl₂/NH₃-N ratio of 5, THMs formation was almost identical regardless of water quality presumed and the source of ammonia, while TOXs formation slightly reflected water quality. On the other hand, when the ratio of Cl₂to NH₃-N was above 7.5, the level of THMs & TOXs formation increased significantly, becoming up to 36㎍/L and 259㎍/L respectively. It was found that the overall level of THMs and TOXs formation was not high, considering the organic content and the high chlorine dose applied. The implication of this DBPs formation characteristics could be enormous for the regulation policy of DBPs. THMs that is only the regulated DBPs explained about 8∼14% of TOXs. |