生物脫氮系統是由數個主要的反應所組成，包括有機物之消化、有機氮之硝化與硝酸鹽之脫硝。在硝化反應中，硝化菌之活性不易維持，且易受溫度所影響。進流基質之碳氮比對於脫硝效果之好壞則有顯著的影響。由於複雜之操作程序與菌相，造成硝化、脫硝系統不易穩定的特性。對此許多學者指出利用氧化還原電位(ORP)、氫離子濃度(pH)與溶氧(DO)等指標，能有效指出硝化與脫硝終點，進而增進生物脫氮之效能。但也有些學者指出這些指標在過高或過低的負荷下，不易顯示出其效果。因此本研究一改過去學者利用定性折點來控制生物脫氮的方法，改以Nernst equation進行硝化脫硝反應程序中氨氮與硝酸鹽之定量預測，以去除基質負荷之干擾。 本研究利用硝化及脫硝通式推導出相關的Nernst equation並分別利用以發表之文獻數據與批次硝化及脫硝試驗探討研究模式之特性與驗證修正模式之適用性。由研究結果發現，硝化Nernst equation中的Log ([NH4-N]/[NO3-N])變數之係數，不受進流基質濃度所影響，因此利用硝化Nernst equation可免除折點控制的的缺失。由批次脫硝試驗中發現，利用pH及Log(COD)之對pε之變化率，可判定脫硝Nernst equation之型態。當進流碳氮比小於2時，利用乙醇作為碳源之脫硝反應可利用Eq. (1) 做得模式架構，來模擬反應中氧化還原電位之變化。 E=a"+b"pH+c"log([NO3-N]) (1) 由批次硝化與脫硝試驗所獲得之結果可歸納出相關反應之控制策略，並利用此操作策略進一步控制厭氧、好氧、缺氧及好氧之循序批分式生物反應槽。由結果發現，其COD、氨氮及硝酸鹽平均之出流濃度分別為25、0及4mg/L，且水質穩定，因此證明利用修正之Nernst equation可有效控制生物硝化脫硝反應的進行。 In this study, Nernst equation was used for simulation the ORP variety during nitrification and denitrification and the results could be further applied to automatic control nitrification and denitrification reaction quantitatively. The nitrification and denitrification Nernst equation was modified according to several hypothesis and three kinds of nitrification and denitrification were obtained. Subsequently, Corresponding literatures was cited for verifying the hypothesis. The result showed the Nernst equation could be used to describe the variety of ORP during nitrification and denitrification. The respective investigation of nitrification and denitrification Nernst equation was carried out by batch trials. The algorithm for automatic control was decided by the results. For evaluating the results of real-time control, (AO)2 SBR systems was also operated by fix-time control. The optimum period for the system was decided by ASM No. 3. In real time control study, the average effluent of COD, ammonium and nitrate was 25, 0 and 4 mg/L, respectively. The results showed (AO)2 SBR system could obtain good effluence quality with real-time control by Nernst equation.
