关键词: 餐厨垃圾, 厌氧发酵, 酸化, 恢复, 预警参数

Abstract: Currently, anaerobic digestion for biogas production is the most prevalent treatment technology for food waste, but improper operation can easily lead to acidification.The characteristics of acidification in food waste anaerobic digestion systems caused by increased feeding load, as well as early warning indicators and recovery strategies were studied. The results showed that a 31.3% increase in feeding load within 15 days induced system acidification. Changes in biogas production per unit, total alkalinity (ALK), volatile fatty acids (VFA), and the VFA/ALK ratio were 42, 40, 28, and 28 days earlier than acidification of the system, respectively, and could be used as early warning indicators for acidification, among which biogas production per unit was the most sensitive. During the acidification period, the minimum biogas production per unit, ALK, methane content, and pH decreased by up to 65%, 27%, 19%, and 10.5%, respectively, compared to initial values, while the maximum VFA and VFA/ALK ratio increased by 674% and 953%, respectively. Acidification could be effectively mitigated by reducing the feeding load and adding Na2CO3. The entire process from acidification triggered by increased load to complete recovery took 86 days, with only 4 320 kg of Na2CO3 consumed, demonstrating feasibility and cost-effectiveness. During recovery, indicators normalized in the following sequence, namely methane content, biogas production per unit, pH, VFA, VFA/ALK ratio, and ALK. A decrease in VFA below 2 000 mg/L and VFA/ALK below 0.25 can serve as criteria for determining the resolution of acidification warnings. All indicators showed significant correlations (p<0.01) across stable, acidified, and recovery phases.

Key words: food waste, anaerobic fermentation, acidification, recovery, warning parameters