在不同水力停留時間之下利用除氨作用於流體化床反應器處理都市污水之表現

Abstract

由於一般民生污水進流水之 COD、BOD、氨氮等濃度不高，相較於特定來源之污水與污泥硝化後廢水，其性質屬於污染物負荷較低的都市污水，傳統活性污泥程序雖可達到去除有機物的效果，然而對於氨氮的轉化卻相當有限，且為一耗能程序；過去研究結果顯示，厭氧氨氧化程序 (Anaerobic Ammonium Oxidation, Anammox) 可被成功應用於高氨氮濃度廢水之處理。為兼顧放流水質與能源利用率等多方永續經營觀點，本研究採用厭氧程序進行低濃度污水除氮處理，顯然相當具挑戰性。 本研究採用工作體積兩公升之單一流體化床反應器 (Fluidized Bed Reactor, FBR)，處理低濃度都市污水，於不同水力停留時間 (Hydraulic Retention Times, HRT) ，結合部分硝化與厭氧氨氧化及脫硝技術 (Simultaneous partial Nitrification, Anammox and Denitrification, SNAD)，處理水中含氮化合物及有機物質。研究結果顯示在不控溫之下， HRT 24 h 時，NH4+-N 平均去除率可達 99%、TN 平均去除率約81%，將 HRT 縮短至 18 h 並未影響去除率，TN 平均去除率為 86%；然而，若再將 HRT 縮短至 12 h 則因有機氮未能有足夠時間轉化成NH4+-N，有機氮未能轉化成 NH4+-N，就無法供給 Anammox 菌利用，導致 TN 去除率降低至 70%；若再將 HRT 縮短至 6 h 則 TN 去除率降低至 53%；當 HRT 縮短至 3 h 時，TN 平均去除率僅剩 46%，但此時NH4+-N 平均去除率依然維持 98%。 本研究建立之 SNAD 為新穎生物除氮技術，結合流體化床反應器。對於處理低濃度污水而言，具有極高之處理效率，且操作過程並未排泥，因此污泥產量極低。

In this research, low strength real wastewater was treated at different hydraulic retention time (HRTs) by a single fluidized bed reactor (FBR) which includes several chemical processes such as partial nitrification, anaerobic ammonia oxidation (Anammox) and denitrification technology (SNAD). The SNAD process is an innovative biotechnology for the replacement of the traditional nitrification followed by denitrification. One of the major advantage of the SNAD process is energy saving due to the fact that only less than half of influent ammonium is required to be converted into nitrite, thus reducing the operation cost by 60% for aeration purpose compared to the traditional nitrification. In addition, ammonium and nitrite will be converted to nitrogen gas by Anammox. The other merit of the SNAD process is that it could remove nitrogen compounds and organic matter in the same reactor. SNAD technology is a small footprint and can be employed in densely populated cities. Anammox technology was applied to treat high ammonia wastewater in the past. However in this study Anammox was used to treat low strength real wastewater in order to achieve efficient and economic results. In this study, two liters of FBR with carrier supports for biomass attachment, in order to treat nitrogen compounds and organic substances of the wastewater. Studies show that under the condition of 24 hours HRT without temperature controlling, the removal efficiency of NH4+-N and TN were 99% and 81%. When HRT reduce to 12 hours, there is no supply of NH4+-N for Anammox due to the insufficient time for conversion of organic nitrogen to NH4+-N thus decreasing the removal efficiency of TN to 70%. When HRT reduced to 6 hours and 3 hours, the removal efficiency of TN had decreased to 53% and 46%, however the average removal rate of NH4+-N still remain at 98%.