建立同時部分硝化、厭氧氨氧化及脫硝系統

Abstract

以生物方法去除水中氨氮，傳統上都以硝化脫硝兩個步驟來進行。在硝化時需要大量的曝氣動力提供氧氣作為電子接受者，使氨氮轉換為硝酸鹽而進行脫硝步驟。脫硝需要加入大量的有機物作為電子提供者，此方法不僅使得操作費用提升，更有可能導致處理效率低落時，有機物隨著放流水排出，成為另一種污染源。再者，在脫硝不完全時將會產生一氧化二氮此種溫室氣體，而加劇溫室效應。本研究將建立一種新穎脫硝方法，“同時部分硝化、厭氧氨氧化及脫硝技術”，將約莫二分之一的氨氮硝化成亞硝酸鹽後，利用氨氮作為電子提供者，亞硝酸鹽為電子接受者，直接進行脫硝，不需要添加任何有機物，也可節省一半以上的曝氣費用。再者，若污水中含有少量之有機物，亦可進行脫硝，去除有機物。同時部分硝化、厭氧氨氧化及脫硝技術比較傳統方法可節省60％以上的費用。 本文中將找尋適當污泥，並針對所取得之污泥進行16S-rRNA分析，比對基因庫中相關文獻的菌種相似度，以確認取得污泥中有所需要之厭氧氨氧化菌。同時進行質能平衡之計算，探討氮在本系統中的流佈。在實驗室中建立一組穩定操作之反應槽，以垃圾掩埋場滲出水作為進流，探討在不同的氮負荷及有機負荷條件下部分硝化、厭氧氨氧化及脫硝程序之氨氮去除效能。結果發現，氮負荷率的提升會影響處理效率，經處理後亞硝酸鹽氮濃度幾乎趨近於零，而硝酸鹽氮濃度則不超過36 mg/L，氨氮去除效率最高可達94％。經模式計算後，滲出水總氮的去除在此程序中有69-88％是藉由部分硝化及厭氧氨氮氧化所完成，而化學需氧量去除率則只有21-45％。最後分析污泥中菌相的分佈，利用qPCR進行分析，包括好氧氨氧化菌，好氧亞硝酸鹽氧化菌，厭氧氨氧化菌以及與總菌數之間的比例。本研究成功地利用同時部分硝化、厭氧氨氧化及脫硝程序去除污水中含有氮及有機污染物，並證實所馴養的微生物包含厭氧氨氧化菌。

The Simultaneous partial nitrification, anaerobic ammonium oxidation (Anammox) and denitrification (SNAD) process is an innovative biotechnology for the replacement of the traditional nitrification followed by denitrification. The advantage of the SNAD process include less than 60% of operation cost from aeration over the traditional nitrification followed by denitrification, because only half of ammonium stream is required to converting intonitrite and consequently couples the other half of ammonium stream to nitrogen gas. Moreover, the other merit of the SNAD process could remove organic matter by denitrification in the same reactor, which is not able to accomplish by the other autotrophic denitrification processes. The SNAD process was successfully operated in a continuous stirred tank reactor (CSTR) landfill-leachate treatment plant and in a lab-scale sequence batch reactor (SBR). To reveal the SNAD microbial community in the landfill-leachate treatment plant, the 16S rRNA of the sludge from it was analyzed by the molecular tools, which are DNA extraction and Polymerase Chain Reaction (PCR). The result of the 16S rRNA analysis identified that Anammox bacteria were dominant in the SNAD process. On the other hand, we confirm that the Anammox activity contribute most of nitrogen removal by a nitrogen mass balance approach . The result from it indicated the total nitrogen (TN) removal from the combined partial nitrification and Anammox route accounted for 75.5%, while the heterotrophic denitrification contributed to TN removal of 7.7% and COD removal of 23.2%. For the lab-scale study, the lab-scale SBR SNAD process was initially inoculated the biomass from the full-scale landfill-leachate treatment plant. After adaptation of the biomass, four stages (I to IV) with varying nitrogen loading rate (NLR)was examined for the process performance. The increase of the NLR reduced the ammonium removal proportionately. The nitrite concentration was close to zero and the nitrate concentration was less than 36 mg/L in all the stages during the operation period. The total nitrogen removal in the SBR resulted mainly from partial nitrification and Anammox (69-88%) that was evaluated by a stoichiometric model. Overall, the SNAD process offers validated performance on simultaneous nitrogen and chemical oxygen demand (COD) removal economic-friendly.