沼液回流时间对厨余垃圾高含固厌氧发酵的影响

研究了高温(55±2)℃下沼液回流时间(1,6,12,24 h/d)对厨余垃圾高含固(15%TS)厌氧发酵产氢的影响,并探讨了不同沼液回流时间下微生物群落的演替规律。结果表明:增加沼液回流时间可提高产氢量,缓解VFAs积累的抑制效应,回流时间为24 h/d时氢气累积产量最大,为111.44 L,VFAs浓度为28.34 g/L,比回流时间1 h/d时降低了15.40%。厨余垃圾厌氧发酵过程中延长回流时间可恢复酸化体系的pH,且未形成氨积累。回流时间较短(12 h/d)的S实验组中,随着发酵的进行,微生物群落结构多样性降低,在门水平上Firmicutes逐渐演替为优势菌(49.2%~89.5%),回流时间较长(24 h/d)的T实验组一直保持较高的微生物多样性,发酵结束时,Firmicutes、Chloroflexi、Proteobacteria、Euryarchaeota相对丰度分别为27.8%、33.6%、13.0%和12.3%;属水平上T实验组(24 h/d)的产氢菌相对丰度高于S实验组(12 h/d),发酵结束时产氢菌Clostridium和Thermoanaerobacterium的相对丰度分别为10.5%和3.2%。延长沼液回流时间可促进VFAs与葡萄糖代谢产氢。冗余分析表明,沼液回流时间和产气量主要与Firmicutes和Chloroflexi中菌属变化较明显相关。

EFFECT OF SLURRY RECIRCULATION TIME ON ANAEROBIC DIGESTION OF KITCHEN WASTE WITH HIGH SOLID CONTENT

The effect of slurry recirculation time(1 h/d, 6 h/d, 12 h/d and 24 h/d) on thermophilic((55±2) ℃) anaerobic digestion of kitchen waste for hydrogen production with high solid content(15%TS) was investigated in this study. The microbial community succession was studied in the condition of different slurry recirculation time. The results indicated that increasing the recirculation time of biogas slurry could improve the hydrogen production and alleviate VFAs accumulation. The maximum hydrogen production was obtained as 111.44 L at the recirculation time of 24 h/d. The concentration of VFAs was 28.34 g/L, 15.40% lower than that in the condition of 1 h/d. Increasing the recirculation time during anaerobic fermentation of kitchen waste could improve the pH of the acidification system, and the ammonia accumulation was not formed. In the experimental group with a shorter recirculation time(12 h/d), microbial community structural diversity decreased during the fermentation. At the phylum level, Firmicutes became the dominant bacteria(with a relative abundance of 49.2% to 89.5%). The experimental group maintained high microbial diversity at the condition of longer recirculation time, with the relative abundance of Firmicutes 27.8%, Chloroflexi 33.6%, Proteobacteria 13.0%, Euryarchaeota 12.3%. At the genus level, the group with longer recirculation time showed higher abundance of hydrogenogens, with the relative abundance of Clostridium 10.5% and Thermoanaerobacterium 3.2%. Extending slurry recirculation time could promote hydrogen production by metabolism of VFAs and glucose, and Proteiniphilum was the key microorganism for VFAs degradation. Redundancy analysis indicated that slurry recirculation time and biogas production were related to Firmicutes and Chloroflexi.