含固率和接种比对叶菜类蔬菜垃圾厌氧消化的影响

Influence of total solid content and inoculum-to-substrate ratio on anaerobic digestion of leaf vegetable waste

通过叶菜类蔬菜垃圾中温批式厌氧消化实验,比较了含固率(3%、5%、7%)和接种比(1.5、2.5、3.5)对产甲烷效果的联合影响.结果表明,在研究实验参数范围内,含固率越低、接种比越高,越有利于缩短产甲烷反应迟滞期,平均日产甲烷速率越快.经过52d的培养,在含固率为3%、接种比为3.5的工况中,平均日产甲烷速率最快,达到9.5mL/(gVS·d),日最大产甲烷速率最快,达到49.8mL/(gVS·d),最早进入快速产甲烷期.当接种比为3.5时,随着含固率的升高,产甲烷速率下降,迟滞期延长,但单位底物累计产甲烷量增大,含固率7%时单位底物累计净产甲烷量为481mL/gVS.而当接种比为1.5时,含固率为5%和7%的工况均无法启动甲烷化反应,含固率为3%的工况的产气迟滞期达15d.挥发性有机酸的累积抑制甲烷化反应的启动,迟滞期随着液相中有机酸浓度的增加而延长,当有机酸浓度低于1260mg/L,甲烷化反应没有明显的迟滞期.

Batch experiments were conducted to evaluate mesophilic anaerobic digestion of vegetable waste. The performances of anaerobic digestion were compared at different total solid contents （3%, 5%, and 7%） and inoculum-to- substrate ratios （1.5, 2.5, and 3.5）. Gas and liquid phase analysis showed that the lower total solid content and the higher inoculum-to-substrate ratio shortened the lag phase of methanogenesis, and increased the average daily methane production rate. After 52 days, the treatment at 3% in total solid content and inoculum-to-substrate ratio of 3.5 had the highest average daily methane production rate from VS of 9.5mL/（gVS＇d）, and the highest daily highest methane production rate from VS of 49.8 mL/（gVS＇d）. This treatment was also the first to enter the rapid methanogenic phase. At an inoculum-to-substrate ratio of 3.5, it was observed that as the total solid content increased the lag phase was prolonged and there was an increase in the methane production rate, and an increase in the net cumulative methane production per substrate. The amount of net cumulative methane production per substrate was 481mL/gVS when the total solid content was 7%. At an inoculum-to-substrate ratio of 1.5, the treatment with a total solid content of 5% and 7% was not sufficient to initiate methanogenesis, whereas the treatment with a total solid content of 3% had a relatively long lag phase of 15 days. The observed inhibition is presumably due to the accumulation of volatile fatty acids. Furthermore the extended lag phase can be attributed to the increase in the concentration of volatile fatty acids in the liquid phase. On the other hand, a lag phase was not observed when the volatile fatty acid concentration was less than 1260 mg/L.