Abstract:

The annual output of rural household waste in China reaches 294 million tons, accounting for about 40% of the organic fraction that needs to be properly treated. Dry anaerobic digestion with high processing efficiency is prone to acidification and ammonia inhibition due to high organic load, which is more obvious in the fermentation of pilot scale and above. A pilot-scale dry anaerobic co-digestion test was conducted on rural organic household waste to solve the problem of ammonia inhibition in dry anaerobic digestion, improve the efficiency of methane production, and provide a basis for the feasibility of harmless treatment of rural organic household waste and biogas project construction. Dry anaerobic co-digestion of rural organic household waste with cattle manure was carried out on a 1m³ scale with a total solids content of 19.94% in a horizontal anaerobic digestion tank, and the inoculum was domesticated using rural organic household waste. Biogas production, methane content, methane production, volatile fatty acid concentration, ammonia nitrogen concentration and microbial community structure were analyzed during the experiment. The results showed that acidification and ammonia suppression did not occur during fermentation. The hydrolysis and acidification phases were adequately carried out and the methanogenic bacteria were provided with sufficient substrate for methane production. At the end of the trial the methane production per unit of volatile solids reached 1.253m³/kg, with methane content fluctuating around 70% and methane production per unit of volatile solids reaching 0.815m³/kg, much higher than that had been reported. The microbial community structure analysis showed that the dry anaerobic digestion pilot system had a good microbial growth environment, with the relative abundance of Methanosarcina greater than 80% and Firmicutes greater than 77% throughout the digestion, which were the absolute dominant groups of archaea and bacteria respectively, and the digestion system had a well microbial environment.

Key words: rural organic household waste, dry anaerobic digestion, co-digestion, pilot scale, methane

摘要：

我国农村生活垃圾年产量达到2.94亿吨，占比约40%的有机部分需妥善处理。处理效率较高的干式厌氧发酵由于高有机负荷，容易出现酸化和氨氮抑制问题，在中试及以上规模的发酵中更加明显。农村有机生活垃圾与牛粪进行1m³规模的干式厌氧共发酵，卧式厌氧发酵罐内总固体含量为19.94%，对其沼气产量、甲烷含量、甲烷产量、挥发性脂肪酸浓度、氨氮浓度和微生物群落结构进行分析。结果表明发酵过程中未出现酸化和氨氮抑制，单位挥发性固体含量沼气产量达到1.253m³/kg，甲烷含量稳定在70%，甲烷产量达到了0.815m³/kg，远高于已有报道。微生物群落结构分析表明此次干式厌氧发酵中试系统的微生物生长环境良好，Methanosarcina相对丰度发酵全程大于80%，Firmicutes全程高于77%，分别为古菌和细菌的绝对优势菌群，发酵系统具有良好的微生物环境。

关键词: 农村有机生活垃圾, 干式厌氧发酵, 共发酵, 中试规模, 甲烷