An Experimental Study on the Treatment of Organic Wastewater by Soil Microbes Using Three-phase Fluidized Bed

삼상유동층 반응기에서 토양미생물에 의한 유기성 폐수처리에 관한 연구

In this study, isolated and cultured nitrogen fixed microbes were seeded in the three-phase fluidized bed in which gas, solid and liquid were contacted directly. Input velocity was varied from 8.12 cm/hr to 16.32 cm/hr. And upflow gas pressure was fixed to 80 psi. Return ratios were from 0.2 to 0.6 with the each experimental condition. According to these condition, movement of media, growth of biofilm and removal efficiency were measured. As the results, in case of briquette ash, biofilm was developed to $170{\mu}m$ when velocity was 8.12 cm/hr and return ratio was 0.6. In this condition, COD removal efficiency was 97% and $NH_4$-N removal efficiency was 83%. At the same condition, biofilm thickness of glass bead was $17.59{\mu}m$ and its COD and $NH_4$-N removal efficiency was 83% and 72%. Nitrogen fixed microbes have following characters: it formed dark-brownish sludge, excellent adhesive force, easy solid-liquid separation and low oxygen uptake ratio, but sensitive to DO concentration. Not only it endured shock loading, but required short time to steady state.

본 연구에서는 기체 액체 고체의 직접접촉이 일어나는 3상 유동층 반응기를 이용하여 유입상승 유속에 의한 공극률의 변화와 생물막의 두께 및 밀도를 관측하였다. COD의 용적부하율은 반송비(r=0.2, 0.4, 0.6)로 조절하여 $201.12-1150.8g/m^3{\cdot}d$로 하였으며, 고체 매질로는 연탄재입자(평균유효입경 : 1.34 mm)와 유리비드(3 mm)를 사용하여, 매질의 차이에 따른 반응기의 효율에 대하여 비교하였다. 그 결과 반송비를 일정하게 고정시킨 경우, 연탄재 매질에 의한 생물막의 두께가 유리비드를 사용한 것보다 약 4.8배 두꺼우며, COD 제거 효율은 두 매질사이에는 변화가 거의 없으나, 암모니아성 질소의 제거에는 연탄재의 경우가 약간 높았다. 반응조내의 식종균으로는 합성폐수와 유사한 배지에서 동정 분리하여낸 토양미생물을 이용하였다 이 토양미생물은 기존의 활성슬러지균 보다 점착력과 침강성이 뛰어났다.