生物炭缓解餐厨垃圾厌氧消化酸化的效果及机制

EFFECT AND MECHANISM OF BIOCHAR IN MITIGATING ACIDIFICATION OF ANAEROBIC DIGESTION PROCESS FOR FOOD WASTE

研究了在高有机负荷(30 g VS/L,VS为挥发性固体含量)下生物炭缓解餐厨垃圾厌氧消化酸化,促进产甲烷的效应及机制。结果表明:碱性多孔生物炭在最优添加量下(1 g/g VS),反应20 d时,累积产甲烷量达到312.40 mL/(g·VS),与对照组相比提升了101.7%,同时产甲烷停滞期缩短62%。并在酸化最严重时挥发性脂肪酸(VFA)含量降低1151.28 mg/L。研究结果表明:生物炭的多孔结构是促进挥发性脂肪酸分解的关键因素,碱度和营养物质可以起到促进作用。高通量测序结果表明:最佳添加量下甲烷丝菌属(Methanothrix)、拟杆菌(Bacteroidales)、梭菌(Clostridiales)的相对丰度分别由26.12%、43.08%和9.95%提高到46.05%、56.25%和12.20%。生物炭缓解餐厨垃圾消化酸化的机制是为微生物提供反应场所,增强了微生物间的电子传递,提高了厌氧微生物的呼吸速率。

A stimulated experiment was carried out to investigate the promotion of anaerobic digestion of kitchen waste by biochar at high organic loads(30 g VS/L). The results indicated that the cumulative methane production was increased by 101.7% to 312.40 mL CH;/g VS after 20 d at the optimum addition of alkaline porous biochar(1 g/g VS), while the lag phase for methane production was reduced by 62% as compared to the control group. Besides, the addition of biochar reduced the volatile fatty acid(VFA) content by 1151.28 mg/L at the most severe acidifying stage. Mechanism exploration disclosed that the porous structure of biochar exerted vital influence on the decomposition of VFA, and alkalinity and nutrients also played an important role in the VFA degradation. The results of high-throughput sequencing showed that the relative abundance of Methanothrix, Bacteroidales and Clostridiales were increased from 26.12%, 43.08% and 9.95% to 46.05%, 56.25% and 12.20%, respectively. The underlying mechanism for biochar affecting the digestion were providing reaction sites for microorganisms, enhancing electron transfer among microorganisms, and accelerating the respiration rate of the microorganisms.