Effect of varying feeding rates on N2O emission in the SNAD system
|關鍵字:||結合部分硝化與厭氧氨氧化系統;氧化亞氮;同時硝化厭氧氨氧化與脫硝系統;進料速率;CANON system;nitrous oxide;SNAD system;feeding rates|
|摘要:||生物處理含氮廢水過程中，副產物氧化亞氮之產生備受矚目。氧化亞氮是破壞臭氧層的主要氣體，其造成全球暖化能力是二氧化碳的310倍且停留在大氣的時間可高達120年。因此有很多學者致力於研究結合不同處理工藝其所產生的氧化亞氮情況及削減處理方式，但其中對於同時硝化、厭氧氨氧化和脫硝系統下產生氧化亞氮情行至今尚未探討。本研究為使用新穎的生物處理技術方式探討氧化亞氮之產生量，主要探討不同的進料速率對於氧化亞氮逸散的影響。實驗之初為結合部分硝化及厭氧氨氧化於一個反應槽裡之方式 (即為CANON系統) 處理含氮廢水，氧化亞氮的轉換率高達9~12%，氨氮的平均去除率約95%。當CANON系統穩定時便轉成能同時處理含氮及碳之廢水之SNAD系統，氧化亞氮之轉換則率減至3%，但氨氮平均去除率因為硝化菌與異營菌競爭之關係而受到影響降低至87%。在不同進料速率 (0.125、0.75、<0.45 L/h) 下，氧化亞氮的轉換率則有呈現上升的趨勢 (3%～6%)。實驗結果說明SNAD系統與CANON系統相比之下約削減63%的氧化亞氮逸散量並SNAD有減少氧化亞氮排放之潛能，而進料速率越低有助於減低氧化亞氮的排放。|
Nitrous oxide (N2O) emission from biological wastewater treatment plant as a byproduct has been receiving more attention in recent years. N2O is considered as the dominant ozone-depleting substance. The global warming potential of N2O is about 310 times more than CO2 with a life time of 120 years. Consequently, many researchers have stated investigating N2O emission problems, combining different treatment processes and mitigation methods. However, not a single research has been done regarding nitrous oxide emission in a novel biological nitrogen removal technology i.e. the SNAD (Simultaneous partial Nitrification, Anammox and Denitrification) system. Thus, the aim of this study was to investigate the N2O emission from SNAD system under varying feeding rate. A combination of the partial nitrification and the Anammox processes in a single reactor (e.g. CANON) was carried out in the beginning (day 1 to 95) remove nitrogen from synthetic wastewater and study the emission. The N2O conversion rate was approximately 9~ 12% if influent nitrogen and the nitrogen removal efficiency reached to 95% in the CANON system. When the system turned from CANON into SNAD, which can deal with organic carbon and nitrogen compounds simultaneously, the N2O conversion rate decreased to 3% of the influent nitrogen. Due to competition between the autotrophic bacteria and the heterotrophic bacteria, the nitrogen removal efficiency decreased to 87% in the SNAD system.N2O emission increased from 3% to 6% under different feeding rates (0.125, 0.75, 0.45 L/h ). From the results we observed that there was a reduction of about 63% in nitrous oxide emission when the CANON system turned into the SNAD system. It was concluded that the SNAD system had a potential to mitigate N2O under a lower feeding rate.