污泥厌氧消化产酸发酵过程中乙酸累积机制

目的]研究污泥厌氧消化产挥发性脂肪酸(VFA)过程中的有机物碳流的转化机制,阐明乙酸累积机理。方法]研究溴乙烷磺酸盐(BES)和氯仿(CHCl3)抑制模型下中间代谢产物和气体的累积,检测各产乙酸功能菌群数量,推断污泥产酸发酵过程中的有机物碳流方向和乙酸累积机理。结果]BES模型乙酸浓度达27 mmol/L,fhs基因拷贝数比对照组高2-3倍,产氢产乙酸菌略有下降。CHCl3模型乙酸浓度达22 mmol/L,fhs基因拷贝数比BES组低一个数量级,产氢产乙酸菌下降明显。结论]BES特异性较高,除产甲烷菌外对其他厌氧产酸细菌没有影响,乙酸浓度增加并且其主要来源于水解发酵产酸以及同型产乙酸过程。氯仿除抑制产甲烷菌外,对同型乙酸菌和产氢产乙酸菌也有强烈的抑制作用。

Mechanism of acetate accumulation during sludge anaerobic digestion

Abstract: Objective] To investigate the organic carbon metabolism during sludge anaerobic digestion and to clarify the mechanism of acetate accumulation. Methods] We Used inhibitors 2-bromoethanesulfonate (BES) and chloroform (CHCl3) to block the methanogesis to investigate the accumulation of various fermentation intermediates. We determined the bacterial number of homoacetogen and syntrophic acetogen and calculated the thermodynamics of the acetogenesis reaction to identify the directions of organic carbon metabolism and acetate accumulation during sludge anaerobic digestion. Results] With the addition of BES, the acetate concentration was 27 mmol/L, the gene copy number of fhs was 2-3 folds of the control group and the number of sytroph acetogen was slightly decreased. In the group of chloroform addition, the acetate was 22 mmol/L, while the copy number of fhs gene was one order of magnitude lower than that in the BES model. Conclusion] The two inhibitors lead to acetate accumulation from the anaerobic digestion of sludge. BES inhibited the methanogen and had no effect on other anaerobic acetogens. The accumulation of the acetate came from the hydrolysis acidogenesis, homoacetogenesis and syntrophic acetogenesis. Chloroform inhibited not only methanogen but also the homoacetogen and syntrophic acetogen severely. The acetate accumulation mainly came from the hydrolysis acidogenesis fermentation.