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標題: | 厭氧固定生物處理低強度污水之研究 Treatment of Low Strength Wastewater Using Immobilized Anaerobic Biomass |
作者: | Pei-Hsun Wu 吳佩勳 |
指導教授: | 林正芳 |
關鍵字: | 低強度污水處理,厭氧固定生物反應槽,溫度,甲烷轉換率,溶解性甲烷, Low-strength wastewater treatment,anaerobic immobilized bioreactor,temperature,methane yield,dissolved methane, |
出版年 : | 2017 |
學位: | 博士 |
摘要: | 以厭氧生物處理都市污水為未來所需,因其可減少能量使用和污泥體積,然而必須在短水力停留間(hydraulic retention time, HRT)有效處理低強度污水並同時面臨保留緩慢生長微生物的挑戰,故在低強度污水處理中使用厭氧生物處理方法,反應槽生物流失仍然是一個關鍵問題,而薄膜系統含有高生物質量濃度亦存在促進薄膜積垢問題,根據上述觀點,在本研究使用厭氧固定生物平板及隔板反應槽,以固定生物技術將懸浮式厭氧污泥固定化,使厭氧污泥以固定平板型式而非懸浮分散型態留置於反應槽內,以提高反應槽厭氧生物質量濃度及降低懸浮污泥量,使其具長污泥停留時間(sludge retention time, SRT)以處理低強度污水,並以中溫和低溫條件(15、25、35℃)探討厭氧固定生物系統的處理效能,並探究系統溶解性甲烷(methane, CH4)和揮發性脂肪酸(volatile fatty acid, VFA)的生成,以更加深入了解新型厭氧固定生物反應槽(anaerobic immobilized bio-plates reactor, AnIBPR)之處理表現及成果效益。
AnIBPR之有效體積和固定生物填充率分別為14.5 L及27.5%,在16小時HRT下,處理COD濃度為400 mg/L的低強度合成污水,探究其在不同溫度之處理效能,結果顯示,AnIBPR反應槽在中溫(35℃和25℃)和低溫(15℃)條件下,可達86%至92%的COD去除,其反應槽之溶解性CH4為過飽和(飽和指數為1.03-1.21),隨著溫度的降低而增加,在15℃下,溶解性CH4濃度增加,此歸因於在低溫下較低的質量傳輸系數(KLa),且伴隨系統CH4產量減少,而有顯著傳質限制,導致系統有過飽和溶解性CH4,將處理溫度提高至中溫條件可提高系統反應速率和產率,在溫度15℃、25℃、35℃穩定狀態下,氣相CH4含量為75%-83%,整體甲烷轉化率為0.22-0.26 L/g CODremoved (63-74%理論甲烷轉化率),而在穩定狀態所測得出流水之VFAs為3.3-12 mg COD/L,其濃度低推測無阻礙系統處理效能。 整體而言,AnIBPR系統使用固定生物平板有較高的生物質量濃度,對於溫度變化所造成的衝擊具有其耐受性及迅速回復的穩定處理效能,表現出其固定厭氧反應槽的獨特性,不致因為較短的水力反應時間而流失厭氧微生物,顯示在短的接觸時間(水力停留時間)及環境溫度(15-35℃)下反應槽具有穩定處理低強度污水效能之可行性,且其利用隔板使污水上下繞流之流體形式,不需薄膜操作或反應槽載體、顆粒流體化的能源,其最大的效益將是不僅可以節省傳統活性污泥法處理都市污水之龐大耗能亦可於處理污水同時產能,惟仍需進一步以實際廢水進行試驗評估其效能及建立設計參數。 Anaerobic treatment of domestic wastewaters is desirable because it reduces energy use and sludge volume, but it must meet the challenges of effectively treating low-strength wastewaters in a short contact time while retaining the slow-growing microorganisms. Using anaerobic process in low strength wastewater treatment, washing out of biomass from reactors remains a critical issue, where a concomitant high biomass content contributes significantly to membrane fouling in the membrane system. In light of these issues, we deployed in this study immobilized anaerobic biomass in the form of bio-plates as readily installed baffles to provide high anaerobic biomass content but low suspended biomass content in the reactor and to achieve long sludge retention time (SRT) for treatment of low-strength wastewaters. Treatment performance of the immobilized anaerobic system according to mesophilic and psychrophilic conditions (15、25、35℃) were investigated. The production of dissolved methane (CH4) and volatile fatty acid (VFA) were investigated in order to better understand the new anaerobic immobilized bio-plates reactor (AnIBPR). An AnIBPR of effective volume of 14.5 L and bio-plate packing ratio of 27.5% was used to treat low-strength synthetic wastewater (COD of 400 mg/L) at a hydraulic retention time (HRT) of 16 h. Treatment performance was investigated at different temperatures. The results showed that the reactor AnIBPR achieved COD removal of 86% to 92% at mesophilic (35℃ and 25℃) and psychrophilic (15°C) conditions. Dissolved CH4 was found to be oversaturated in the reactor (saturation factor of 1.03-1.21), increasing with decreasing temperature. Increased dissolved CH4 content at 15℃, albeit at decreased production, was attributed to significant mass transfer limitation due to lower KLa at low temperature, resulting in oversaturation of dissolved CH4. Increasing treatment temperature to mesophilic conditions led to increased reaction rates and yields. At steady state, gas-phase CH4 content was 75%-83% and the overall yield was 0.22-0.26 L/g CODremoved (63%-74% of theoretical conversion rate). Steady-state volatile fatty acids (VFAs) were measured at 3.3-12 mg COD/L, small amounts that were unlikely to hamper treatment performance. AnIBPR enabled very high biomass in the bio-plates that increased its tolerance to temperature shock or speed up its subsequent recovery, presenting unique among contemporary anaerobic reactors and indicating stable treatment performance of the reactor that promised viable treatment of low-strength wastewaters at a short contact time (HRT) and ambient temperature (15-35℃). In addition, the AnIBPR reactor used baffles to force wastewater up and down and required no energy uses in fluidization and membrane processes for the reactor contents. It appeared that immobilized bio-plates reactor provides huge energy saving in comparison to tradition activated sludge method in treating domestic wastewaters and has energy generation potential for treatment of wastewaters. However, additional work is needed to evaluate its performance on treating actual municipal wastewater and establish appropriate design parameters. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/59704 |
DOI: | 10.6342/NTU201700553 |
全文授權: | 有償授權 |
顯示於系所單位: | 環境工程學研究所 |
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