| 摘要: | 固定生物膜法處理程序，可以有效去除污水之營養物質，相較懸浮性處理程序，生物膜法具有其優點，但仍有許多生物膜代謝原理及程序控制策略，亟待研究與突破。本研究乃針對生物膜法中之浸水式生物濾床之程序及原理，設計一系列之生物濾床模廠加以研究，研究分成兩部份：除氮生物濾床系統、除磷生物濾床系統，分別探討生物濾床除氮及除磷之特性。 研究結果顯示，除氮生物濾床之程序限制步驟為硝化作用，而硝化是否完全取決於COD濃度及水力停留時間。據生物濾床各位置之有機負荷，可解釋各菌種相對應之濾床位置，故向上流濾床COD去除之濾床位置在0-20公分處（即反應初期段）；氨氮之硝化作用在濾床位置40-80公分處（即反應之中、後段）。顯示氧化有機物之異營菌分佈在濾床較底部；而硝化自營菌分佈在濾床之中、後段。而向下流之硝化菌分佈，濾床高度效應影響較小，硝化菌呈現平均分佈於濾床各區域。批次實驗亦驗證此菌相分佈之結果。 雙管柱除氮生物系統，缺氧生物濾床對COD吸附之主要區域在100-80公分處，以行脫硝反應，且缺氧濾床之ORP所對應缺氧環境之脫硝作用，符合COD利用趨勢。總氮去除率隨HRT增加而增加，而HRT主要仍影響硝化作用之進行，若硝化不完全，好氧出流液以氨氮為主；硝化完全之HRT試程，出流液以NO3--N為主。而比生物降解速率是取決於生物活性及有效生物質量而決定。迴流比增加，硝酸氮脫硝量增加，總氮去除率亦隨之增加，但因好氧循環停留時間不足，導致硝化漸漸不完全，造成亞硝酸氮及氨氮之累積，使總氮去除率下降。單管柱除氮系統之效率展現與雙管柱系統無顯著差異，但易受反沖洗影響好氧生物相之分佈。 批次進流除磷生物膜系統在交替厭氧、好氧環境下，可有效達到超量蓄磷之功能。而批次循環時間決定處理容量及總磷去除效率，不足或過長之時間均會降低去除效率。此外，適當的厭氧好氧時間比亦是除磷系統中重要參數，就批次實驗之SPRR及PHAs之蓄積容量測試中，顯示批次循環時間在6-8小時、厭氧好氧時間在1：2時，具最佳之除磷活性。 除磷生物膜系統之程序限制步驟在厭氧釋磷反應，簡易基質能在厭氧時，迅速被利用，且得到較高之PHB?PHAs之比值。而釋磷量與PHAs的累積程度與起始COD濃度均成正相關，生物膜內層擴散的延遲效應，導致0-30分鐘SPRR與起始COD無相關性、30-60分鐘之SPRR與起始COD成正相關。 生物膜中的磷蓄積菌好氧釋磷評估中，因生物膜胞內聚磷酸鹽蓄積容量是未飽和，使外在的磷酸鹽濃度高於之前厭氧所釋放磷酸鹽的程度，仍可完全攝磷，故在生物膜除磷系統中，與厭氧釋磷相較，好氧釋磷並不構成限制之程序。 The nutrient could be effective controlled using attached biofilm system. The fundamental approach of removing nutrient in the biofilter process is similar to activated sludge process. Although several researches have investigated factors of nutrient removal in biofilter, little information is available in terms of the metabolism and process arrangement. Therefore, this study of setting up a series of submerged biofilters were investigated the feature of biofilter on TN removal and TP removal. Whether nitrification is complete or not is the limited process in TN removal. Nitrification is dependent on HRT and residual COD. COD rapidly decreased to lower level in the 0-20cm height. However, nitrification occurred until 40-80cm height. That resulted from distribution of different microorganisms. Heterotrophs distributed in the initial zone of the biofilter and nitrifying bacteria in the middle to upper zone. The growth of nitrifying bacteria has a tendency towards higher zones of the downflow biofilter especially at the longer HRT. In the dual column system, the recycling NO3-N could be completely eliminated in the anoxic biofilter. TN removal and nitrogen type of the effluent would be dependent on HRT and recycle ratio. The specific rates decomposed pollutant depends to the biological activity and the effective biological VSS. The operation in low recycled ratio would result in worse total nitrogen removal, but the NH3-N of effluent would be lower. The operation in higher recycled ratio would be opposite to low recycled ratio. Compared with the dual column, the single column system was not feature different in TN removal. Sequential Batch Biofilm Reactor system (SBBR) is effective in removing phosphorus. The storage and release of intracellular inclusions, especially PHAs and poly-P, would be an important factor for phosphorus removal. Under different operating conditions, total phosphorus removal was always determined by accumulation of PHAs and phosphorus release under the anaerobic phase. The PHAs accumulation under the anaerobic phase was always in proportion to the biofilm phosphorus content under the aerobic condition. The result shows PAOs activity was closely related to PHAs accumulation. However, the PHAs accumulation under the anaerobic phase would be dependent on the hydrolysis of the complex carbon source into short chain fatty acids. The effect of the An/Ox time ratio on TP removal was significant. Shorter anaerobic time would result in insufficient phosphorus release and greater time would result in inactive PAOs. The appropriate An/Ox time ratio was suggested as 1/2 and appropriate duration time was suggested as 6-8 hours. In the anaerobic phase, the main activity of COD uptake occurs in initial 30 minutes. However, activity of phosphorus release occurs in 30-60 minutes and this phenomenon is more significant for initial substrate with higher concentrations due to the delay effect of mass transfer of adsorbed COD. The PHAs accumulation and phosphorus release share a similar trend. Since PHAs' demand per released phosphorus is independent of the initial COD, the enhancement of PHAs' accumulation would benefit phosphorus release. In the biofilm's system, the only requirement is to have sufficient and simple initial substrate and it would result in sufficient PHAs' accumulation for phosphorus release. In the aerobic phase, because poly-P storage's capability is always not saturated, PAOs could uptake excess PO43-. In other words, the limitation of TP removal is always caused by anaerobic phase, not the aerobic phase. |
