| 摘要: | 固定生物膜系統之技術日益精進，對於碳、氮、磷之併同去除，在活性污泥法除氮、除磷代謝機制之基礎上，研究其可行性，將對未來實廠應用上應有發展之潛力。本研究係針對生物膜法中生物濾床之程序及原理，建立三段串聯式生物濾床系統，研究探討併同去除碳、氮、磷之可行性與濾床特性。 在交替曝氣循環的培養下，進流端會有很高的COD殘留至好氧狀態，容易造成好氧異營菌的大量生長，使得PAO與脫（亞）硝異營菌較無法發揮其活性，隨著在中後端COD負荷低，好氧異營菌比例較低，PAO與脫（亞）硝菌等異營菌才會佔一定的比例，待COD負荷更低時，硝化自營菌等生長速率更慢的微生物才會生長。 本研究分反應循環時間為1、3、6、12、18 hrs共五個試程，循環時間＝1、18 hrs試程釋磷、攝磷活性不佳，且循環時間＝18 hrs之亞硝化作用亦較不顯著，因此可知併同將氮、磷去除的效率偏低。在循環時間＝12 hrs試程下，雖然有顯著的亞硝酸氮累積，但硝化作用受限制，且脫亞硝作用不足以將所有氮去除，對於將氮更有效去除仍不可行，且PAO活性偏低，對於除磷亦無顯著的效率。而循環時間＝6 hrs試程，具有較佳的釋磷與攝磷活性，但並無顯著的亞硝化作用，針對併同去除氮、磷而言，存在衝突性，只能將磷較有效之去除，而除氮效率卻不佳。循環時間＝3 hrs試程， 相對於其他循環時間試程，有最佳之釋磷與攝磷活性，且更有將亞硝酸氮進一步氧化成硝酸氮的硝化作用存在，故此試程對氮、磷併同去除，在實廠工程應用上將較為可行。 隨著循環時間之增加，硝化速率有遞減之趨勢，顯示循環時間增加，高COD負荷殘留至好氧狀態，促使硝化自營菌所佔比例愈低。且硝化速率集中在濾床中後端，在濾床中後端COD負荷較低有較高之活性。脫亞硝速率或脫硝速率在濾床中後端明顯較高，顯示進流端好氧異營菌為優勢菌種，脫亞硝菌、脫硝菌則偏重在濾床中後端生長。 除磷效率之高低取決於釋磷活性之大小。循環時間＝3、6 hrs試程於濾床中後端明顯釋磷速率較高，反應出攝磷速率亦較高。循環時間＝1 hr試程厭氧時間不足以PAO釋出聚磷酸鹽，而循環時間＝12、18 hrs試程有過高殘留COD促使好氧異營菌增殖，促使PAO所佔比例較低，而釋磷作用並不顯著，造成除磷效率偏低。 SPRR、SPRM、SPUR隨著循環時間變化有相似之趨勢，顯示厭氧批次實驗下有較佳之SPRR與SPRM，將反映在好氧批次實驗之SPUR亦明顯較高，更驗證厭氧環境釋磷活性較高，好氧環境攝磷活性亦較高之生物除磷原理。 The attached biofilm systems on simultaneously removing organic carbons, total nitrogen, total phosphates are based on activated sludge process, with investigation in progress of decades, that are available to apply in pilot-plant scale. This study of setting up a three-stage submerged biofilter is investigated the feature of removing nutrients. Because of residual COD in the initial zone of the biofilter, aerobic heterotrophs tend to overgrow in the zone. With the height of the biofilter being higher, the COD loading lower, PAOs and denitrifying bacteria would bring into the better activity. This study involves five cycle duration (CD) runs — 1,3,6,12,18 hours. The run of CD = 1 hr alternative aeration is frequent, then resulting in poor activity of phosphorus release. CD = 12,18 hrs, COD loading lasts accumulating in all zones of the biofilter and causes inactive PAOs. CD = 3,6 hrs, sufficient anaerobic time and lower COD loading would result in increasing phosphorus release and accumulation of PHAs. Hence, TP removal efficiency is dependent on anaerobic phosphorus release. In TN removal, nitritation is specific reaction in the biofilter, but complete nitrification isn’t predominant. Denitritation is then forced to play an important role on TN removal. In general, TN removal efficiency is poorer in this study. The run of CD = 3 hrs has more complete nitrification than other ones, and that would be more practicable on simultaneous TN & TP removal. With CD increasing, nitrification rate has a tendency to decrease. Nitrifying bacteria distributed in the middle to upper zones that are lower COD loading, these microorganisms would have better performance. Denitrification rate is also higher in the zones. TP removal efficiency depends on activity of phosphorus release. The better activity of phosphorus release is in anaerobic phase, the more excess uptake of phosphorus is in aerobic phase. Hence, TP removal efficiency is increasing. The runs of CD = 3,6 hrs are better performing examples of this study. SPRR, SPRM, SPUR have the similar trend accompanied with time. Batch experiment revealed that the better are SPRR and SPRM, the better is SPUR. |
