本研究採54公尺長之生物擔體渠道進行連續流試驗，探討對生物旋轉盤（RBC）及活性汙泥法（ASP）處理後之二級放流水水中氮化物，經生物擔體渠道轉化之機制及重用為灌溉用水之可行性。另以模擬二級生物處理後之放流水，針對均採3.5 cm 直徑之三孔洞A 磁球及無孔洞B磁球擔體鋪設之6.35公尺渠道，各採十不同流速進行對於氮化物之去除速率比較之批次試驗。 研究發現渠道內之硝化及脫硝速率深受流速之影響，於起始亂流之流況，可得較佳之總凱氏氮及總氮之去除速率，氮化物轉化速率與基質濃度呈零階反應，生物擔體渠道可同時進行硝化及脫硝反應，於氮化物轉化路徑中，發現吸附於生物膜上及底泥之懸浮固體物，於生物膜厚度上產生溶氧梯度及其水解提供碳源，可能是進行脫硝之主因。經本渠道淨化之RBC 放流水，經淨化後可滿足台灣省灌溉用水短期使用之總氮建議限值規定，使其運用於灌溉用水為可行。本研究就平板渠道實驗所得之COD及氮化物轉化速率，以動態調配法運用於不同之管網配置及流況下，對於COD及氮化物最低濃度推求之嘗試，經演算後認為可行。 A channel of 54-m was set up to investigate the nitrogen removal for effluents of both Rotary Biological Contactor (RBC) and Activated Sludge Process (ASP) treated wastewater in a continuous flow basis. Also, a batch type system was run with different kinds of balls of the same diameter as the biofilm carrier, ball A with three hollow holes and ball B without any holes on to compare the nitrogen removal rates at various velocities. The objectives of this study are to realize the pathways of nitrogenous compounds and reuse possibility for irrigation purposes for purification the biological treated wastewater by biofilm channel. The results found that nitrification and denitrification rates were highly influenced by the velocity, at the range of turbulent flow achieved the better Total Kjeldahl nitrogen (TKN) and total nitrogen (TN) removal rates. Nitrification and denitrification processes occurred simultaneously in the natural biofilm channel. The trapped suspended solid on the biofilm formed an anoxic environment and its hydrolysis offered carbon source might be the main reason for denitrification at low COD and high dissolved oxygen concentrations in the bulk solution. The treated RBC effluent purified by biofilm channel to fit the TN-N or TKN concentrations to be 10 mg/l below for irrigation usage was possible. The types of biofilm carriers and velocity should be considered in developing purification model in biofilm channel. Dynamic Programming was proved to be useful for predicting the optimal COD and nitrogen concentrations at the outlets of various sewer alignments.
