- 學位論文
厭氧生物固定技術處理實廠都市污水之應用
Anaerobic Immobilization Biotechnology for Domestic Wastewater Treatment
摘要
厭氧生物相較於好氧生物處理污水之優點在於低耗能、低廢棄污泥產量，以及可以生產甲烷作為生質氣體，但其微生物生長緩慢，因此在實際污水處理廠應用上來看，如何在較短水力停留時間(Hydraulic Retention Time, HRT)下避免厭氧微生物的流失成為一項重大的關鍵。薄膜是近年來許多厭氧生物研究使用之方法，但有薄膜積垢、價格較高等問題。故本研究將生物固定化技術(Entrapped Mixed Microbial Cell, EMMC)應用於厭氧生物處理程序，使厭氧污泥以固定平板形式留置於反應槽內，可提升槽內微生物濃度，也大幅提高污泥停留時間，使微生物不容易流失，讓反應所需水力停留時間可以縮短，以期能克服厭氧生物處理低強度都市污水發展上的限制。 單槽連續式厭氧固定生物反應槽(Anaerobic Immobilized Bio-plates Reactor, AnIBPR)在25℃下處理低強度污水，其有效體積為15.6 L，污泥微生物質量為42.4 g/L，在6及8小時水力停留時間下處理化學需氧量(Chemical Oxygen Demand, COD)濃度為200 mg/L的低強度合成及都市污水，探討都市污水對於厭氧固定生物系統的除碳產氣效率以及碳源轉換百分比，並以COD去除率、甲烷產量、甲烷產氣率、甲烷回收率，及溶解甲烷等作為效能評估項目。 結果顯示，AnIBPR反應槽連續操作一年以上沒有顯著污泥流失，整體效能來看，合成污水與都市污水分別可達到86%和70%以上之總化學需氧量(Total COD)去除率以及58%和28%以上之甲烷氣體含量，可產生0.494 kWh/m3及0.128 kWh/m3以上之甲烷產能，轉換為系統單位產電能為0.163 kWh/m3及0.042 kWh/m3以上；而從碳源轉換而言，合成污水之進流碳源有13.8%隨出流流出、21.0%轉換為氣體甲烷、41.9%以過飽和狀態之溶解甲烷形式留在水中，飽和指數為1.49；都市污水之進流碳源有24.9% - 30.6%隨出流流出、6.9% - 10.0%被硫酸鹽所消耗，2% - 3%轉換為氣體甲烷、14.9% - 22.8%以過飽和狀態之溶解甲烷形式留在水中，飽和指數為1.16-1.63。 整體而言，厭氧固定生物與典型厭氧處理系統相比有較佳之處理成效，但產生的甲烷氣卻有大比例以溶解態隨著出流排出，產能減少之餘，也會造成環境衝擊，因此，如何回收或減少溶解甲烷，也是未來應用厭氧生物的重要議題之一。
並列摘要
Compared with aerobic biological processes, anaerobic biological treatment processes (ABTPs) have the advantage of low energy consumption, low waste sludge production, and can produce methane as biogas. However, from the perspective of the application of the actual sewage plant, how to avoid the loss of anaerobic microorganisms under short HRT becomes a significant point because of the slow-growing anaerobic microorganisms. Therefore, this study combined with an immobilization biotechnology of entrapped mixed microbial cell (EMMC) and ABTPs, so that anaerobic sludge in the form of fixed bio-plates in the reactor, can not only enhance biomass concentration, but also greatly improve the sludge residence time (SRT). This way makes the microorganisms not easily to wash out. Thus, the required hydraulic retention time can be shortened in order to overcome the restriction of ABTPs while treating low-strength domestic wastewater. An anaerobic immobilized bio-plates reactor (AnIBPR) was used to treat low-strength synthetic and domestic wastewater at 25℃. The effective volume was 15.6 L, the sludge biomass was 42.4 g/L, and the influent COD concentration was 200 mg/L at a hydraulic retention time (HRT) of 6 and 8 hours. Then we discuss the COD removal rate, methane production rate, methane yield, methane recovery rate and dissolved methane as a performance evaluation project. The results showed that there was no significant sludge loss in the AnIBPR reactor for more than one year. The synthetic and domestic wastewater could each reach 86% and 70% COD removal rate, and 56% and 28% methane content which can produce energy of 0.494 kWh/m3 and 0.128 kWh/m3. The energy also can be converted to the electricity energy of 0.163 kWh/m3 and 0.042 kWh/m3 or more. Considering the carbon source conversion, the synthetic wastewater have 13.8% went out with the outflow, 21.0% converted to gaseous methane, and 41.9% transformed to dissolved methane which stayed in the water as an oversaturated state, and the measured concentration of dissolved methane was 1.49 larger than the concentration of dissolved methane at thermodynamic equilibrium with the measured CH_4 partial pressure. On the other hand, the domestic wastewater have 24.9% - 30.6% went out with the outflow, 2% - 3% converted to gaseous methane, 6.9% - 10.0% was used by sulphate, and 14.9% - 22.8% transformed to dissolved methane which stayed in the water as an oversaturated state, and the measured concentration of dissolved methane was 1.16-1.63 larger than the concentration of dissolved methane at thermodynamic equilibrium with the measured CH_4 partial pressure. In general, anaerobic immobilized organisms have a better treatment effect than a typical anaerobic treatment system, but a large proportion of methane discharged with the effluent in dissolved phase, not only wasted energy, but impacted the environment. Therefore, how to recover or reduce dissolved methane, is also one of the important issues of future application of anaerobic organisms.