好氧与厌氧交替加速2,4,6-三氯酚的生物降解

ACCELERATION OF 2,4,6-TRICHLOROPHENOL BIODEGRADATION THROUGH AEROBIC AND ANAEROBIC CONDITION ALTERNATION

2,4,6-trichlorophenol(TCP)是一种较难生物降解的有机化合物,而TCP还原脱氯是其生物降解的关键,该过程通常在厌氧条件下进行。TCP对位的氯离子比邻位难脱除,所形成的中间产物4-氯酚(4-CP)在厌氧条件下很难得到进一步降解。然而,此时将反应体系切换成好氧条件时4-CP则可得到有效降解。基于好氧和厌氧交替可共存的特点,采用垂直折流板式生物反应器降解TCP。相比单纯厌氧降解,厌氧和好氧交替模式可明显加速TCP的生物降解。对于初始浓度为50μmol/L的TCP,完全去除的时间可从34 h缩短至12 h。该运行模式可缓解中间产物对TCP降解的抑制,4-CP的代谢产物苯酚在好氧条件下可得到迅速降解,缓解了其抑制作用,加速TCP在厌氧条件下的生物降解。

2,4,6-trichlorophenol(TCP)is a recalcitrant organic compound,and reductive dechlorination is the key step for biodegradation of TCP,which is usually carried out in anaerobic conditions.Chloride ion in the para-position of TCP is harder to remove compared to Cl in the ortho-position,which means that 4-chlorophenol(4-CP),an intermediate of TCP reductive dechlorination,is difficult to further biodegrade in anaerobic conditions.However,the 4-CP was effectively biodegraded when the anaerobic mode was switched into an aerobic mode.Based on this advantage of alternating between anaerobic and aerobic modes,a vertical baffled bioreactor(VBBR)was employed for TCP biodegradation.Compared with anaerobic biodegradation alone,alternating between anaerobic and aerobic modes significantly enhanced TCP biodegradation.For an initial TCP concentration of 50μmol/L,the time for complete removal of TCP was shortened from 34 h to less than 12 h.The mechanism was the relief of inhibitions by TCP-biodegradation intermediates.For example,phenol,an intermediate of 4-CP reductive dechlorination,got more rapid biodegradation in the aerobic mode,which relieved its inhibition and enhanced the biodegradation of TCP in the anaerobic mode.