하수배제방식이 하수처리 효율에 미치는 영향 = Effect of Sewage Collection System on the Treatment Efficiency of Wastewater Treatment Plants

국문 초록 (Abstract)

본 연구는 하수배제방식이 하수처리장의 효율에 미치는 영향을 조사하였다 이를 위하여 표준활성 슬러지공법을 이용하여 하수를 처리하는 두 모델처리장을 대상으로 , BOD, COD, SS, T-N, 그리고 T-P의 제거율을 비교하였다. 모델처리장 K1은 합류식 관거로 이송한 하수를 분뇨와 연계하여 처리하고 있으며, K2 처리장은 분류식 관거를 통하여 이송된 하수만을 처리하고 있다. 하수처리장 유입유량은 하절기에 증가하는 경향을 보였고, 유기물과 SS 농도는 봄철에 증가하는 경향을 보였다. K1 처리장의 유입유량과 농도가 K2 처리장에 비해 변화가 심하였는데, 이는 하수배제방식의 차이 때문인 것으로 판단된다. K1 처리장은 설계유량보다 처리량이 더 많았음에도 불구하고 방류수 수질기준을 만족하였는데, 이는 활성슬러지공법이 충분한 안전율로 설계되기 때문인 것으로 판단된다. K2 처리장의 유입유량의 설계유량보다 적어 두 모델처리장의 효율을 정확하게 비교하기 어려웠지만, 분류식 하수관거가 활성슬러지공법의 효율을 향상시키는데 더 유리한 것으로 보인다.

다국어 초록 (Multilingual Abstract)

The activated sludge process has been the most popular for the treatment of domestic wastewater. In this study, the effect of sewage collection system on the treatment efficiency of wastewater treatment plant (WTP) was investigated. For this purpose, two WTPs operated using the activated sludge process were selected as model plants and the removal efficiency of each contaminant, such as BOD, COD, SS, T-N, and T-P, was compared. Plant K1 treats the domestic wastewater transported through the combined collection system and the nightsoil which is intermittently added into aeration tank. On the other hand. Plant K1 treats only the domestic wastewater transported through the separated collection system. Influent flowrate increased during summer season, but organic content and SS concentration increased during spring. Plant K1 showed higher range of fluctuation with respect to both wastewater quantity and quality compared to plant K2 due to the difference in sewage collection system. Even though Plant K1 treated much more wastewater than the designed capacity, the concentration of effluent from Plant K1 was less than the discharge limit. This is due probably to the safety factor which was taken into consideration when the activated sludge process was designed capacity, it was impossible to compare exactly the efficiencies of two model plants. But, it seems that the separated collection system is more beneficial in improving the efficiency of activated sludge process.