Review
SHEN RuMeng, CAI FanFan, SONG Chao, JIN Yan, ZHANG Si, CHEN Chang, LIU GuangQing
Anaerobic digestion (AD) is an established technology to realize treatment and recycling of organic waste, which has great social, environmental and economic benefits. However, the excessive accumulation of volatile fatty acids and ammonia nitrogen during the AD process results in inhibition of microbial activity, which leads to problems such as incomplete substrate digestion, unstable system operation and low biogas production efficiency. Biochar is a low-cost and renewable carbon material with high specific surface area, varied elemental composition, abundant surface functional groups and good conductivity which has the capability to effectively enhance AD. However, the mechanism of biochar-enhanced AD processes—especially the relationship between the mechanism and the physicochemical properties of the biochar—is not well understood and this limits the application of biochar in practical engineering. This review summarizes the effects of biochar on AD, the strengthening pathways and the influence of different preparation conditions on its physicochemical properties. This not only provides theoretical guidelines for future mechanistic studies of biochar, but should also promote the large-scale engineering application of biochar-enhanced AD technology.