光電業污水廠批次式活性污泥池最適操作之研究

Abstract

半導體及光電等高科技產業因製程過程中排放含高濃度氨氮廢水，可採物理、化學或生物等除氮方法與技術處理含氮廢水，然而生物除氮硝化過程中，因消耗鹼度導致pH值降低之現象，為維持良好處理效能，以及符合放流水標準，操作過程中需額外添加鹼劑以維持pH中性，增加了藥品用量及操作成本。 本研究以光電業為主之污水廠SBR生物池為試驗對象，探討經調整操作循環週期，以及改變操作步驟為間歇性曝氣及縮短曝氣時間等方式，對處理效能及操作成本之影響，尋求處理成本最適化操作之參考。 在操作參數方面，調整操作循環週期會影響SBR生物池之處理水量及容積、HRT、F/M與BOD容積負荷。改變操作步驟調整曝氣方式及縮短曝氣時間後SBR生物池之DO會降低，造成DO不足以進行完整的硝化作用。 在處理效能方面，BOD5平均去除率均達62%以上，並不受調整操作循環週期及改變操作步驟而受影響。氨氮及硝酸鹽氮平均去除率並不受調整操作循環週期及改變操作步驟，而有大幅度的改變。此外，在DO不足的環境下進行硝化作用時，氨氧化菌較亞硝酸氧化菌對DO更具競爭優勢。 在操作成本方面，調整系統HRT及縮短曝氣時間，使反應過程中達半硝化作用之操作條件。因此，減少了鹼度的消耗，使反應過程中pH下降的變化幅度趨緩，可減少NaOH加藥量。此外，調整操作循環週期造成SBR生物池處理水量增加，調整表曝機間歇性曝氣及縮短曝氣時間，會降低單位用電量，提升節電效益。因此，調整操作循環週期及改變操作步驟可降低整體操作成本。

Semiconductor and optoeletronics high-tech industries often release high concentration of nitrogen and ammonia containing wastewater in manufacturing process. When removing nitrification in biotreatment process simultaneously, the consuming alkali lowers the pH value. To comply with effluent standards, the increase of additional alkaline agent when operating causes chemical and operational cost enhanced. This study mainly focused on the sequence batch reactor (SBR) pools in optoelectronics wastewater treatment plant as subject to find the optimal methods to operate efficiently and to reduce operating cost by adjusting operational cycle or alternating operation steps which as intermittent aeration mode, shortening aeration duration mode and etc. The operating parameter has shown when adjusting operation cycle, it will affect treatment volume, HRT, F/M and BOD volume loaded in SBR pools. After changing the operation steps to cause low DO level in SBR pools by adjusting aeration mode and shortening aeration duration mode, the way will reduce DO level to complete the nitrification. In terms of efficient operation, BOD5 would be removed at least 62% averagely, and not be affected by the adjustment of operation cycle and steps. Ammonia and nitrate nitrogen removal rates, however, have not been influented by these adjustments. In addition, under low DO level when nitrification, ammonia-oxidation bacteria (AOB) would be more competitive with nitrite-oxidation bacteria (NOB). In terms of operating cost deduction, the ways of adjusting HRT and shortening aeration duration cause the partial nitrification condition in reacting process. Therefore, the deduction of the consuming alkalinity will slow down the descended pH variation and reduce NaOH dosage. In addition, the adjustment of operational cycle has increased the volume treatment of SBR pools. The adjustment of aerator on intermittent aeration mode and shortening aeration duration mode could save power cost. Thus, the methods of adjustment in operating cycle and operating steps could entirely deduct operating cost.