| Title |
Importance of Prechlorination Practices and Structures of Clearwell in Estimating Disinfection Capabilities in Water Treatment Plants |
| Authors |
윤제용(Je Yong Yoon),변석종(Seok Jong Byun),최유식(Yu Sik Choi) |
| Abstract |
Disinfection is one of the most important processes in water treatment plants since it protects consumers from waterborne diseases. In Korea, chlorine which is most frequently used as a disinfectant is generally applied in two ways: prechlorination and postchlorination. Postchlorination is to supply chlorine to the influent of a clearwell. While, prechlorination is to add chlorine to rapid mixing chamber or water intake in plants. Major disinfection reaction occurs in the step of post chlorination. Therefore, frequently, prechlorination is not counted on in evaluating disinfection credit. This study was conducted to evaluate the importance of prechlorination and the existence of baffling wall in clearwell with the United States disinfection requirement(Surface Water Treatment Rule). Eight water plants were considered. Yoon`s classification(1997) was selected in classifying the prechlorination practice in water treatment plant. It was found that most of the prechlorination practices performed in water plants(three out of four types) were not important in gaining any significant disinfection credit. One prechlorination practice conducted to remove ammonia in raw water became significant in meeting the disinfection requirement. Despite the existence of baffling walls of clearwell, T_(10)/T varied considerably in the range of 0.3-0.6, indicating that the existence of baffling wall itself does not guarantee the goodness of plug flow characteristics. For some plants, T_(10)/T were lower than that of US-EPA conservative recommendation which is considered when tracer test could not be performed. |