축산폐수를 처리하기 위한 2상 혐기성소화(TPAD)공정을 생물학적 질소제거공정(BNR)과 결합하여 운전하였다. 질산화된 유출수를 TPAD 공정의 산생성 반응조로 반송할 경우 탈질반응이 산생성 반응에 미치는 영향과 효율을 관찰하였다. 질산화된 유출수의 반송은 유입된 COD의 VFA로의 전환율을 향상시켰다. 질산화된 유출수에 적응된 산생성 슬러지의 산생성 속도는 적응되지 않은 슬러지보다 6배 빠른 것으로 관찰되었다. 탈질반응은 생성된 VFA를 탄소기질로써 사용하였지만 산생성 활성도를 향상시킬 수 있었다. 탈질속도는 COD/N비에 영향을 받았지만, 질산성 질소에 대한 산생성 슬러지의 적응여부에 더욱 지배적인 영향을 받는 것으로 나타났다. 산생성 슬러지에 의한 탈질반응은 0차 반응을 보였으며 탈질속도는 1.31$sim$1.90 mg/L$cdot$h이었다. 반면, 질산화된 유출수에 적응된 산생성 슬러지의 탈질속도는 3.30 mg/L$cdot$h로 거의 2배가 빠른 것으로 나타났다. COD/N비 10에서 1g의 질산성 질소를 탈질반응에 의해 제거하는데 소비된 COD의 양론비는 5.1$sim$6.4 범위이었다.
Anaerobic denitrification in a two phase anaerobic digestion(TPAD) process combined with biological nutrients removal (BNR) system was studied for a piggery wastewater treatment. Denitrification efficiency and the effects of the nitrified effluent on acidification was investigated by recycling the nitrified effluent to the acidogenic reactor. Recycle of the nitrified effluent to the acidogenic reactor enhanced the conversion efficiency of the influent COD into volatile fatty acids(VFAs) in the TPAD-BNR system treating the piggery wastewater. Acidification rate of the acidogenic sludge acclimated with the nitrified effluent showed 6 times higher than that acclimated without it. VFA could be used for denitrification as carbon sources, however, nitrate could enhance acidification activity in the acidogenic reactor. VFA production rate was affected on the COD/Nitrate(COD/N) ratio, however, it depended much more whether the acidogenic sludge acclimated with nitrate or not. Denitrification with the acidogenic sludge acclimated without nitrified effluent followed zero-order reaction and the reaction rate constants were in the range of 1.31$sim$1.90 mg/L$cdot$h. Denitrification reaction rate constants of the acidogenic sludge acclimated with nitrified effluent were 3.30 mg/L$cdot$h that showed almost twice of them evaluated from the previous tests. The stoichiometric ratios of utilized COD to removed nitrate showed similar in both tests which were in the range of 5.1$sim$6.4 at COD/N ratio of 10.
