利用生物濾床去除苯、甲苯、乙苯及鄰二甲苯之研究

Abstract

揮發性有機氣體(VOCs)會對環境及人體造成毒害，其中BTEX (苯，benzene；甲苯，toluene；乙苯，ethylbenzene；二甲苯，xylene) 則是因結構問題造成其生物降解不易。本研究以生物法降解BTEX之參數最佳化為目的進行實驗，調整生物床體滯留時間、氮源濃度及酸鹼度藉以達到去除效率之提升，以及利用弱鹼處理減少反應器堵塞問題探討其去除效率。結果發現以X1與ZB2兩株菌固定化之反應器滯留時間於60秒及2g/L (NH4)2SO4氮源濃度下，平均去除效率可達88%以上，進流負荷445.44 g m-3 h-1下其最大去除負荷量為369.59g m-3 h-1，其中乙苯去除效率超過95%。在pH 7的反應器中生物質量上升速率較高，pH 5時維持平均去除效率90%以上。以0.4% NaOH處理濾床生物質量增生問題，生物膜去除可達83%，且處理後不影響系統去除效率。本系統於滯留時間60秒、氮源濃度2g/L及pH 7下，具有最佳去除能力，且菌株可適應酸性環境及不影響BTEX去除效率下可使用鹼液清洗載體生物質量。

Volatile organic compounds (VOCs) discharged into the environment can cause the ecological and health hazards. Benzene, Toluene, Ethylbenzene and xylene (BTEX) are common industrial solvents. They are difficult to biodegrade due to the aromatic structures. In this study, we estimate optimal parameters of BTEX removal by biofiltration. Operational parameters of gas retention time, inlet concentration of BTEX, nitrogen, removal capacity, pH and clogging in the biofilter were investigated. Results indicated that the BTEX removal efficiency of bioreactors immobilized with X1 and ZB2 was over 88% when the influent loadings were 445.44 g m-3 h-1. Moreover, removal efficiency of ethylbenzene was over 95%. The biomass accumulation rate of bioreactor at pH 7 was faster than that at pH 5 and pH 9. The removal efficiency was stable and up to 90% when pH was decreased to 5. To decrease the clogging in the biofilter, 0.4% NaOH was used to eliminate the biomass and biofilm reduction efficiency could achieve 83%. However, the performance of removal BTEX was not affected by the treatment with NaOH. In this study, the maximum of BTEX eliminating capability was obtained in 2g/L ammonium sulfate, pH 7 and EBRT 60 s. The bioreactor immobilized strains X1 and ZB2 is feasible for the remove of BTEX gas.