The objectives of this research are to evaluate and compare the oxygen transfer coefficients(KLa) in both a general bubbles reactor and a micro-nano bubbles reactor for effective operation in sewage treatment plants, and to understand the effect on microbial kinetic parameters of biomass growth for optimal biological treatment in sewage treatment plants when the micro-nano bubbles reactor is applied. Oxygen transfer coefficients(KLa) of tap water and effluent of primary clarifier were determined. The oxygen transfer coefficients of the tap water for the general bubbles reactor and micro-nano bubbles reactor were found to be 0.28 hr -1 and 2.50 hr -1 , respectively. The oxygen transfer coefficients of the effluent of the primary clarifier for the general bubbles reactor and micro-nano bubbles reactor were found be to 0.15 hr -1 and 0.91 hr -1 , respectively. In order to figure out kinetic parameters of biomass growth for the general bubbles reactor and micro-nano bubbles reactor, oxygen uptake rates(OURs) in the saturated effluent of the primary clarifier were measured with the general bubbles reactor and micro-nano bubbles reactor. The OURs of in the saturated effluent of the primary clarifier with the general bubbles reactor and micro-nano bubbles reactor were 0.0294 mg O2/L․hr and 0.0465 mg O2/L․hr, respectively. The higher micro-nano bubbles reactor's oxygen transfer coefficient increases the OURs. In addition, the maximum readily biodegradable substrate utilization rates(Kms) for the general bubbles reactor and micro-nano bubbles reactor were 3.41 mg COD utilized/mg active VSS․day and 7.07 mg COD utilized/mg active VSS․day, respectively. The maximum specific biomass growth rates for heterotrophic biomass(μmax) were calculated by both values of yield for heterotrophic biomass(YH) and the maximum readily biodegradable substrate utilization rates(Kms). The values of μmax for the general bubbles reactor and micro-nano bubbles reactor were 1.62 day -1 and 3.36 day -1 , respectively. The reported results show that the micro-nano bubbles reactor increased air-liquid contact area. This method could remove dissolved organic matters and nutrients efficiently and effectively.

Abstract
 1. 서 론
 2. 재료 및 방법
  2.1. 산소전달특성평가
  2.2. 실험장치 및 방법
 3. 결과 및 고찰
  3.1. 산소전달특성평가
  3.2. 동력학 계수 측정
 4. 결 론
 참 고 문 헌

• 한영립(동아대학교 환경공학과) | Young-Rip Han (Department of Environmental Engineering, Dong-A University)
• 정병길(동의대학교 환경공학과) | Byung-Gil Jung (Department of Environmental Engineering, Dong-Eui University) Corresponding Author
• 정유진(국립환경과학원) | Yoo-Jin Jung (National Institute of Environmental Research)
• 조도현((주)네가트론) | Do-Hyun Cho (Negatron Co., Ltd)
• 성낙창(동아대학교 환경공학과) | Nak-Chang Sung (Department of Environmental Engineering, Dong-A University)