結合厭氧氨氧化與厭氧甲烷氧化在填充床反應器

Abstract

在厭氧生物處理下，甲烷的產生往往都會以溶解於液態的形式存在，甲烷是一種非常強的溫室氣體，在100年的期間內，是二氧化碳的25倍，若以氣體的形式，甲烷能較容易被收集並去除，但以溶於水的形式存在，運用物化手法，則需要消耗大量的能源與資源才能達成，因此利用厭氧氧化溶解態甲烷則是一個很好的選擇。硝酸鹽型厭氧甲烷氧化反應能利用硝酸鹽來氧化甲烷，產生亞硝酸鹽與二氧化碳；亞硝酸鹽型厭氧甲烷氧化反應能使用亞硝酸鹽來達到甲烷氧化的目的，並釋放出氮氣與二氧化碳；厭氧氨氧化反應能將銨與亞硝酸鹽作為反應物，產生氮氣與少量的硝酸鹽。這3種反應能相互影響，且此3種反應在連結氮循環與碳循環上，可能扮演著重要的角色。本研究的目的是結合硝酸鹽型厭氧甲烷氧化反應、亞硝酸鹽型和厭氧甲烷氧化反應和厭氧氨氧化反應在填充床反應器，以達到處裡污水中的溶解性甲烷、安氮和硝酸鹽氮。起始進流之氨氮、亞硝酸鹽氮、硝酸鹽氮之初始濃度分別為1 mM、0.5 mM、5 mM。水利停留時間為3天，經過超過5個月的培養，總氮去除比率可達到90 %，在第210天後，氧化還原電為維持在130 mV。在活性測試中，硝酸鹽型厭氧甲烷氧化反應和亞硝酸鹽型和厭氧甲烷氧化反應的甲烷利用效率分別達到1.28x10-3 mmole mg-1-VSS d-1和 1.12x10-3 mmole mg-1-VSS d-1，相較於初始的新豐污泥，利用率達到10倍以上，表示著此反應槽成功的富集化脫硝厭氧甲烷氧化反應(DAMO)。

Anaerobic treatment processes in wastewater treatment industries discharge methane in gaseous as well as in aqueous form. Methane is considered a powerful greenhouse gas that has a global warming potential 25 times greater than carbon dioxide over a 100-year period. While methane in the gaseous phase can be easily collected and purified, dissolved methane is difficult to recover. Therefore, a post-treatment process is needed in anaerobic systems to oxidize dissolved methane, thereby reducing greenhouse gas emissions and making anaerobic wastewater treatment a more eco-friendly technology. Nitrate dependent anaerobic methane oxidation (Nitrate-DAMO) use nitrate as electron acceptor and methane as electron donor to produce nitrite and carbon dioxide. Whereas, nitrite dependent methane anaerobic oxidation (Nitrite-DAMO) use nitrite as electron acceptor and convert nitrite and methane to nitrogen gas and carbon dioxide. Anammox process consume ammonium and nitrite to produce nitrogen gas and nitrate. Nitrate-DAMO can interact with Nitrite-DAMO and Anammox. These three processes might play vital role in connecting nitrogen cycle with carbon cycle. In this study, we try to combine these three processes together to simultaneously remove nitrogen as well as carbon pollutant from the wastewater stream. These three processes occurred in the packed-bed reactor simultaneously with the influent concentration of ammonium, nitrite and nitrate of 1 mM, 0.5 mM and 5 mM, respectively. Hydraulic retention time (HRT) of the reactor is 3 days. The reactor is operated over 5 months. The nitrogen removal rates are over 90 %. The oxidation reduction potential (ORP) in the reactor maintains at 130 mV after the 210th day. In the activity test, the methane consumption rate of the nitrate-DAMO and nitrite-DAMO are 1.28x10-3 mmole mg-1-VSS d-1 and 1.12x10-3 mmole mg-1-VSS d-1, respectively. Those are 10 times higher than initial sludge. It means that it is successful to enrich denitrifying anaerobic methane oxidation (DAMO) in the packed-bed reactor.