Recent focus on wastewater treatment includes energy-saving and renewable energy generation for energy-independence of water infrastructures. Aeration and pumping in biological wastewater removal processes account for nearly 30-60% of the total electricity cost in real wastewater treatment plants. In this study, the performance and microbial characteristics were investigated in sequencing batch reactor under typical oxygen and oxygen limited condition. Under typical DO (7.55±0.99 mg/L) and low DO (0.23±0.08 mg/L) conditions, COD removal was stable over 91 % during SBR operation. Ammonia removal efficiency was reduced from 95.6 % to 89.2 % when DO concentration was dropped sharply. Phosphorus removal efficiency also reached 77% at oxygen-limited condition. The results indicated that removal efficiency both ammonia and phosphorus was influenced by DO condition. Microbial analysis revealed that Proteobacteria and Bacteroidetes at phylum level was dominant in typical DO and low DO conditions and DO concentration did not much affect phylum distribution. Population decrease of genera of nitrifying bacteria(Dokdonella) and Dechloromonas spp. affect removal efficiency of nitrogen and phosphorus at low DO condition.

ABSTRACT
 1. 서 론
 2. 재료 및 방법
  2.1 반응조 구성 및 운전
  2.2 Batch cycle 모니터링
  2.3 수질분석
  2.4 미생물 분석
 3. 결과 및 고찰
  3.1 유기물질 분해
  3.2 영양물질 제거: 질소 및 인
  3.3 반응조 one cycle 모니터링: 정상 DO농도와 낮은 DO농도 운전 비교
  3.4 반응조 내 미생물 분석: 정상 DO농도 운전과 낮은 DO농도 운전 비교
 4. 결 론
 References

• 황국선(국립한국교통대학교 환경공학과/KG엔지니어링 종합건축사사무소 환경평가부) | Kuksun Hwang (1Department of Environmental Engineering, Korea National University of Transportation/Department of Environmental Assessment , KG ENGINEERING&ARCHITECTURE CO., LTD.)
• 신동혁(국립한국교통대학교 환경공학과) | Donghyeok Shin (Department of Environmental Engineering, Korea National University of Transportation)
• 정인교(국립한국교통대학교 환경공학과) | Ingyo Jeong (Department of Environmental Engineering, Korea National University of Transportation)
• 박성제(국립한국교통대학교 환경공학과) | Sungje Park (Department of Environmental Engineering, Korea National University of Transportation)
• 장인수(국립한국교통대학교 환경공학과) | Insoo Chang (Department of Environmental Engineering, Korea National University of Transportation)
• 김정배(계명대학교 환경학부 지구환경학) | Jeongbae Kim (Department of Environment, Keumyung University)
• 최정동(국립한국교통대학교 환경공학과) | Jeongdong Choi (Department of Environmental Engineering, Korea National University of Transportation) Corresponding author