以生物處理降解半導體廠廢水氨氮之研究

Abstract

因應行政院環境保護署(簡稱環保署)於101年10月12日發佈訂定「科學工業園區污水下水道系統放流水標準」，新竹科學園區管理局擬將氨氮等項目列入納管標準及污水費計價中，本研究透過分析半導體實廠廢水處理的水質特性及每日氨氮排入及排出量，探討該廠生物處理系統中各單元對氨氮的處理效能，進一步依理論基礎及文獻資料推估該廠生物處理系統對氨氮的最大處理能力及提出改善建議。 本研究計採實廠3股(7點)廢水各12次，頻率為每個月兩次，依進流水水量及水質特性顯示，該廠氨氮廢水經生物脫氮槽、曝氣槽及薄膜生物反應槽 (MBR) 反應後，TOC、 COD、 sCOD平均效率分別為95%、97%、97%；TN、TKN、NH4+-N、NO3--N平均轉換率分別為22%、86%、96%、0%，顯示生物處理系統對有機物及氨氮具有一定的降解及處理能力，但因脫氮槽的脫氮效果不佳，脫氮槽對NO3--N平均去除率僅為28%，造成總氮的去除效率僅為22%。 生物系統進流水NH4+-N最大體積負荷率為 0.08-0.26 kg/m3/d(Ave 0.17 kg /m3/d) ， 顯示進入生物系統的最大NH4+-N體積負荷率與文獻中的可處理體積負荷率 (0.176-0.4 kg/m3/d ) 差異不大。 依分析結果顯示迴流水中sBOD/TKN = 0-1.72 (Ave 0.016 )，與理論值每克NO3--N全部轉化為N2所需之 BODL 理論值約為 4 g明顯不足，建議調整脫氮槽的C/N比，應可改善脫氮槽的脫氮效率。

Due to the new effluent standards for optoelectronic material and element manufacturing industry on 12 Oct. 2012, NH4+-N and many other items is going to be included in Science Park Sewage Effluent Standards and charging fee. This study analyzed the basic water characteristics and the daily ammonia nitrogen discharge volume, and estimated the efficiency of each treatment unit in a real semiconductor wastwater plant. Based on the basic theory and reference data, the study also estimated the maximum treatment capacity of ammonia nitrogen in the plant, and suggested further improvement strategies. This study sampled 7 sampling points from 3 source waters twice a month for 6 months. After the denitrification, nitrification and MBR reaction process, the treatment efficiency of TOC, COD, and sCOD were about 95%, 97%, and 97%, based on the average influent volume and water quality. And the TN, TKN, NH4+-N, NO3--N degradeation rate were about 22%, 86%, 96%, 0%. It showed the basic ability of the biological treatment system to degrade and treat organic compounds and ammonia nitrogen. However, the poor dinitrification efficiency, 28% in the denitrification tank, resulted in a low removal efficiency of total nitrogen (22%). The result also showed the maximum loading rate of NH4+-N was near the same with the reference data, which was 0.08-0.26 kg/m3/d (Ave 0.17kg/m3/d) and 0.176-0.4 kg/m3/d, respectively. The difference between sBOD/TKN (Ave 0.016) and theoretical demand of BODL (4g) showed the C/N ratio was abviously inadequate. In conclusion, adjusting the C/N ratio is expected to improve the denitrification efficiency.