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Characteristics of wastewater treatment of sewage mixed with industrial wastewater

공장폐수가 혼합된 하수처리장의 하수처리 특성

  • Ahn, June-Shu (Department of Environmental Engineering, Daejin University) ;
  • Park, Wook-Keun (Department of Environmental Engineering, Daejin University) ;
  • Cho, Jung-Ho (Department of Chemical Engineering, Kongju National University)
  • Received : 2011.05.15
  • Accepted : 2011.07.07
  • Published : 2011.07.31

Abstract

In this study, characteristics of wastewater treatment of sewage intermittently mixed with industrial wastewater is examined by investigating the operational status of each unit operation and measuring water quality. The bioreactor operating condition was measured for MLSS concentration 2,000~3,000 mg/L, HRT 5.3~16.3 hour, SRT 2.8~66.6 day, and SVI frequently showed the value above 200 which was higher than the optimal range of 50~150. It is thought that the sludge is not in suitable condition for sedimentation caused by the incoming industrial wastewater. When industrial wastewater is come into the system, MLDO inside of bioreactor rapidly increased, rate of nitrification is steeply decreased, and Pin floc. is spilled in the secondary clarifier. In the observance of microorganism showed that various bacterial floc. and ciliata were found as well as actinomycetes and filamentous bacteria(Sphaeotilus) which is known to cause bulking. Efficiency of each unit operation was fairly good in average. However, efficiency of the bioreactor treatment showed high fluctuation by unstable operating condition by intermittently incoming industrial wastewater.

본 연구는 간헐적으로 공장폐수가 유입되고 있는 하수처리시설에 대하여 각 단위공정별 운전현황 조사와 수질 측정을 실시하여 운전특성을 파악하고자 하였다. 생물반응조의 운전조건은 MLSS 농도 2,000~3,000 mg/L, HRT 5.3~16.3 시간, SRT 2.8~66.6 일 범위를 나타내었고, SVI는, 최적 범위인 50~150을 상회하여, 200 이상의 측정값이 빈번히 발생하여 슬러지 침강성이 양호하지 않은 것으로 관측되었다. 주요 원인은 공장폐수의 유입에 기인한 것으로 판단되며, 이와 같이 공장폐수 유입 시 생물반응조내의 MLDO가 급격히 상승하고 질산화 효율이 빠르게 감소하며 이차침전지에서는 Pin floc.이 유출되는 현상이 발생하였다. 미생물 관측결과, 다양한 세균 플록과 섬모충류 등이 관측되었으나, Bulking 발생의 원인이 되는 사상균인 Sphaeotilus와 방선균 등도 발견되었다. 단위공정별 처리효율은 평균적으로는 대체로 양호한 처리효율을 나타내고 있었으나 간헐적인 공장폐수 유입의 영향으로 인한 생물반응조의 운전특성의 불안정성으로, 처리효율의 변동성이 크게 나타나고 있었다.

Keywords

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