有机负荷调控对餐厨垃圾高温固态发酵全过程影响

为提高餐厨垃圾沼气工程能源利用效率.本试验采用全混合式连续发酵，通过调控餐厨垃圾高温厌氧发酵过程中OLR变化，探究OLR为0.7、1.2、4.4 kg·m^-3·d^-1下产气性能、pH、SCOD和VFAs等参数变化.结果表明，反应器能在0.7 kg·m^-3·d^-1下低负荷启动，此阶段产气性能较差，VFAs浓度受正丁酸含量增长缓慢上升，但仍处于低浓度范围.OLR提升至1.2 kg·m^-3·d^-1，正丁酸分解成乙酸速率加快，乙酸浓度比0.7 kg·m^-3·d^-1阶段增长17.36%，发酵液中VFAs积累导致系统酸化抑制产甲烷菌产气性能，外加碱溶液无法调控酸碱平衡.OLR为4.4 kg·m^-3·d^-1时，VFAs浓度增长趋于平稳，调节pH至6.7以上反应器稳定运行.随着产甲烷菌活性恢复，沼气产量维持在25 L·d^-1左右，VFAs浓度快速下降并稳定在19.68~21.30 g·L^-1之间.实际沼气工程可控制OLR在0.7 kg·m^-3·d^-1下启动，待发酵系统稳定运行后增加OLR至4.4 kg·m^-3·d^-1同时调节pH到6.7以上，可以达到最佳产沼气工艺.而维持OLR在1.2 kg·m^-3·d^-1更适合获得高浓度VFAs.

Effect of organic load regulation on the whole process of high temperature solid state fermentation of food waste

In order to improve the energy efficiency of food waste in biogas projects. The objective of this study was to evaluate the performance (methane yield, production of volatile fatty acid, pH, SCOD) of completely stirred tank reactor which was fed with food waste continuously at different OLR (0.7, 1.2, 4.4 kg·m^-3·d^-1). The results showed that the reactor can be operated at organic load rate of 0.7 kg·m^-3·d^-1, which has the low methane yield and the VFAs concentration increases slowly due to the increase in n-butyric acid concentration, but the VFAs are still in the low concentration range. When the organic load increased from 0.7 kg·m^-3·d^-1 to 1.2 kg·m^-3·d^-1, the content of acetic acid increased 17.36% due to the rapid conversion of n-butyric acid, and VFAs accumulation was observed that caused a decrease in the activity of methanogens and the addition of alkaline solution could not adjust the acid-base balance. When OLR was 4.4 kg·m^-3·d^-1, the concentration of VFAs tended to be stable and the reactor can be operated stably by adjusting the pH to above 6.7. At this stage, the biogas production was maintained at around 25 L·d^-1, and the VFAs were widely used and stabilized between 19.68 g·L^-1 and 21.30 g·L^-1. For a biogas plant running, it seemed to be an energy input saving way if started with OLR 0.7 kg·m^-3·d^-1 and adjusted to 4.4 kg·m^-3·d^-1 and kept the pH stable above 6.7. However, maintaining OLR at 1.2 kg·m^-3·d^-1 is more suitable for obtaining high concentrations of VFAs.