본 연구는 배수지에서 저수조를 포함한 대수용가의 수도꼭지에 이르는 구간에서 탁도와 잔류염소 농도의 시간적⋅공간적 변화를 분석하였다. 모니터링은 배수지, 중블록 유입 지점, 대수용가 유입 지점, 저수조 유출 지점, 수도꼭지 등 5개 지점에서 수행되었으며, 유량, 잔류염소, 탁도, pH, 전기전도도, 온도를 측정하였다. 연구 결과, 수돗물 이동 경로를 따라 잔류염소 농도는 점차 감소하고 탁도는 증가하는 경향을 보였다. 특히, 비업무시간대에는 수돗물 정체로 인한 수질 저하가 확인되었다. 또한, 저수조의 건전성을 평가하기 위해 반응계수를 산출한 결과, 시간에 따른 저수조 내부 건전성 저하와 수질 악화 가능성이 확인되었다. 본 연구는 수돗물의 이동 거리, 사용 시간대, 유량 변화 및 공급 방식에 따라 수질이 달라질 수 있음을 보여주며, 저수조에 의존하는 지역에서는 안전한 수돗물 공급을 위해 지속적인 모니터링과 관리가 필요함을 시사한다.

This study aimed to develop a method to optimize residual chlorine concentrations in the process of providing water supply. To this end, this study developed a model capable of optimizing the chlorine input into the clearwell in the purification plant and the optimal installation location of rechlorination facilities, and chlorine input. This study applied genetic algorithms finding the optimal point with appropriate residual chlorine concentrations and deriving a cost-optimal solution. The developed model was applied to SN purification plant supply area. As a result, it was possible to meet the target residual chlorine concentration with the minimum cost. Also, the optimal operation method in target area according to the water temperature and volume of supply was suggested. On the basis of the results, this study derived the most economical operational method of coping with water pollution in the process of providing water supply and satisfying the service level required by consumers in the aspects of cost effectiveness. It is considered possible to appropriately respond to increasing service level required by consumers in the future and to use the study results to establish an operational management plan in a short-term perspective.

Three water treatment plants(WTPs) in Jeju island whose source water have different characteristics from those of the mainland of Korea were investigated. Coefficients of bulk water decay(kb ) of free chlorine at 5 ଌ for ES, GJ, NW WTPs were -0.003 hr -1, -0.002 hr -1 and −0.001 hr -1 respectively based on bottle tests.To simulate the free chlorine variations in the distribution system using EPANET, ES WTP was chosen. Free chlorine concentrations of several sites were less than the drinking water quality standards(i.e., 0.1 mg/L); E5(0.03 mg/L), E6(0.02 mg/L), W21(0.02 mg/L) and W25(0.03 mg/L). To maintain more than 0.1 mg/L of free chlorine in the distribution system, at least 1.9 mg/L of chlorine was needed at the WTP, which suggested rechlorination was needed to supply palatable tap water to customers.Two sites, one that diverged into E5 and E6 in the east-line and another located before E21 in the west-line were selected for the appropriate rechlorination locations. The recommended rechlorination dosages were 0.42 mg/L for the east and 0.27 mg/L for the west. The simulated results indicated that the free chlorine could be reduced to 0.4 mg/L at the WTP with rechlorination, and taps with excessive free chlorine could be more stabilized(i.e., 0.1 ~0.4 mg/L).

본 연구에서는 모형배수지를 이용하여 유출량의 변동여부와 도류벽의 설치여부에 따른 유출수의 잔류염소농도의 변화를 추적하였다. 모형배수지의 실험결과를 고찰해 보면, 유출량을 변동시킨 경우에 있어서 도류벽이 없을 때와 도류벽이 2개 있을 때, 유출수의 평균 잔류염소농도의 차이가 유출량을 일정하게 유지한 경우에 비하여 줄어 들었다. 이는 유출량 변동의 영향에 의한 것으로 유출량의 변동이 심한 배수지에 있어서는 유출량의 변동이 심하지 않은 정수지에서 보다는 도류