MBR 단일 반응조에서 용존산소 농도에 따른 동시 질산화-탈질반응(SND)의 영향 = Effects of DO concentration on Simultaneous Nitrification and Denitrification(SND) in a Membrane Bioreactor(MBR)

국문 초록 (Abstract)

MBR(Membrane Bio-reactor) 반응조 내 동시 질산화·탈질(Simultaneous Nitrification and Denitrification, SND)반응을 적용하여 폐수의 유기물 및 질소(N) 제거를 위해 적절한 용존산소(DO) 농도를 도출 및 질산화 및 탈질반응에 미치는 영향을 관찰하기 위해 실험을 수행하였다. 연속 운전실험 결과 반응조 내 pH는 7.5-8.0을 유지하면서 특별한 외부 탄소원의 주입 없이 질소제거가 가능하였다. 용존산소 농도에 따른 유출수의 CODcr 평균 농도는 각각 2.39, 2.95, 12.18 mg/L로 나타났으며, 제거율은 각각 99.3, 99.0, 96.0%로 안정적인 처리 효율을 나타내었다. 운전 조건별(Run 1, 2, 3) 용존산소(DO) 농도에 따른 유출수의 총질소(TN) 농도는 8.62, 7.75, 11.82 mg/L로, 제거효율은 69.88, 72.92, 58.70% 이었고, 용존산소의 농도가 1.3-1.6 mg/L 범위일 때, SND 반응을 적용한 질소제거가 가능한 것으로 나타났다. 회분식 실험 결과 암모니아성 질소(NH4+-N)의 질산화 반응속도의 경우 용존산소 농도에 증가하였으며, 탈질 반응의 경우 반응조 내 적정 C/N비를 유지하였을 때 용존산소 1.0-1.3 mg/L 범위에서 탈질 반응이 일어나는 것을 확인하였다.

다국어 초록 (Multilingual Abstract)

In this study, simultaneous nitrification and denitrification (SND) from synthetic wastewater were performed to evaluate dissolved oxygen(DO) effects on chemical oxygen demand(COD) and nitrogen removal in a single membarne bio-reactor(MBR). DO levels in MBR at Run 1, 2, and 3 were 1.9~2.2, 1.3~1.6, and 0.7~1.0 mg/L, respectively. Experimental results indicated that DO had an important factor to affect COD and total nitrogen(TN) removal. SND were able to be accomplished in the continuous-aeration MBR by controlling ambient DO concentration. It is postulated that, because of the oxygen diffusion limitation, an anoxic micro-zone was formed inside the flocs where the denitrification might occur. From the results of this study, 96% of COD could be removed at DO of 0.7mg/L. At run 2 72.92% of nitrogen was removed by the mechanisms of SND (7.75mg-TN/L in effluent). In this study, SND was successfully occurred in a MBR due to high MLSS that could help to form anoxic zone inside microbial floc at bulk DO concentrations of 1.3~1.6mg/L.

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