| Title |
A Study on Characteristics of Chlorine Dosage and Distribution of Residual Chlorine in Domestic Water Treatment Plants |
| Authors |
윤제용 ; 변석종 ; 이상덕 ( Je Yong Yoon ; Seok Jong Byun ; Sang Duck Lee ) |
| Abstract |
Chlorine is currently being used to control microorganism, odor, color and inorganics such as Fe, Mn in nearly all domestic water treatment plants. However, an overdose of chlorine can cause the formation of unexpectedly high disinfection byproducts(DBPs) such as trihalomethanes, besides being econonomically not sound. On the other hand, under dosage of chlorine may increase public health risk resulting from waterborne disease. Therefore, it is necessary to investigate the characteristics of chlorine dosage in water treatment plants to provide the proper guideline of chlorine practice. In this study, five water treatment plants were selected for investigating for characteristics of chlorine dosage and distribution of residual chlorine. Three major characteristics of chlorine dosage were found. First, for raw water with high ammonia concentration(3∼5㎎/L), a large quantity of chlorine was added to get rid of ammonia through breakpoint chlorination. Post-chlorination practice in this case becomes unnecessary because the chlorine residual prior to clear well is sufficiently high in maintaining chlorine residual in distribution system. Second, for the same type of raw water with first case in terms of ammonia content, only small amount of chlorine was added to the water two sites (as pre-chlorine & post -chlorine) to form the combined chlorine as residual chlorine. This type of chlorine practice is called as $quot;chloramination$quot;. Chloramination in Korea is unique in two ways. 1) naturally occurring ammonia was used far ammonia source 2) this was chosen due to the shortage of chlorine capacity not for the control of chlorinated byproducts. Third, for the water which does not contain high ammonia content, dual chlorine addition practice was selected. Pre-chlorination is performed to meet the chlorine demand of raw water. Post-chlorination is performed to maintain the proper residual chlorine in distribution system. |