多级逆流工艺促进城市污泥厌氧发酵生产挥发性脂肪酸

采用一种新型的厌氧发酵工艺——多级逆流发酵工艺对城市污泥进行厌氧发酵, 实现高效产挥发性脂肪酸的目的。结果表明, 实验条件下应用多级逆流发酵工艺, 挥发性脂肪酸浓度与产率分别达到(10.5±0.5) g/L和0.20 gVFAs/ gVS, 与普通厌氧发酵工艺相比, 分别提高了31%和54%。此外, 在多级逆流工艺中, 底物有机质去除率可达50%, 较普通厌氧发酵提高了37%。进一步分析多级逆流工艺产酸的机制, 发现产酸效率的提高在于降低了发酵产物对厌氧产酸细菌的抑制效应, 并且工艺的VFAs产率以及有机质去除率分别取决于第一级和第三级厌氧发酵过程。因此, 城市污泥采用多级逆流工艺厌氧发酵不仅能够有效促进挥发性脂肪酸的生成, 而且能够较大程度上提高污泥中有机质的去除率。

Bioproduction of Volatile Fatty Acids from Excess Municipal Sludge by Multistage Countercurrent Fermentation

A novel anaerobic fermentation process--multistage countercurrent fermentation was applied to improve the bioproduction of volatile fatty acids (VFAs) from excess municipal sludge. Results showed that the total VFAs concentration and the total VFAs yield reached (10.5 +/- 0.5) g/L and 0.20 gVFAs/gVS (Volatile solid) using this novel process. Comparing with the conventional anaerobic fermentation, the concentration and yield of total VFAs increased by 31% and by 54%, respectively. Moreover, removal ratio of organic solids also increased by 37% and it was 50% at the end of multistage countercurrent fermentation. We further investigated the mechanism of VFAs production. Results revealed that this novel process could reduce the inhibitory effect of VFAs on the acid-forming microorganisms, and the total VFAs yield and the removal ratio of organic solids respectively depended on the first stage and the third stage of this novel process. Therefore, the multistage countercurrent fermentation can efficiently improve the bioproduction of VFAs from excess municipal sludge, and relatively enhance the removal ratio of organic solids.