97 / 2021-06-30 21:20:38

Study on performance of single-phase anaerobic digestion process for food wastes

food wastes, anaerobic digestion, start-up, biochemical methane potential, stability

Aiming at the technological difficulties in hard start-up of single-phase anaerobic digestion process for food waste, which is liable to acidification and imbalance under high organic volumetric loading, the performance of start-up, continuous operation and influence on shock loading of anaerobic digestion for food waste were carried out in the self-designed single-phase anaerobic reactor under mesophilic conditions. The results showed that high inoculation ratio (80%), smaller initial organic volumetric loading (≤1.0kgVS·m^-3·d^-1) and gradually increasing organic volumetric loading with small amplitude of 0.5 kgVS·m^-3·d^-1 per step were a proper way to start up the single-phase anaerobic digestion process for food waste. Under stable operation of 33 days, single-phase anaerobic digestion process for food waste had been started up successfully. During the process, maximum biogas production rate of 5.73L·L^-1·d^-1 was obtained, and the content of methane fluctuated in the range of 59.4%~79.8% with average biogas yield of 0.91L·gVS^-1 which was equal to 117.90 m³·t wet food wastes^-1. Alkalinity was not less than 6500mgCaCO₃·L^-1 and pH value kept in the suitable range of 7.41~7.79. Above all, the process was in better performance and stable operation with good buffer capacity. At the same time, coefficient variation of each stability indexes for anaerobic digestion process was analysised, such as total alkalinity (TALK), bicarbonate alkalinity (BA), the ratio of bicarbonate alkalinity to total alkalinity (BA/TALK), the ratio of total concentration for volatile fatty acid to bicarbonate alkalinity (VFA/BA), pH value and biogas production rate. Minimum coefficient of variation of each characteristic index and stable operation of single-phase anaerobic digestion process for food waste was obtained at organic volumetric loading of 3.0~4.0 kgVS·m^-3·d^-1. And Maximum organic volumetric loading rate which single-phase anaerobic digestion process for food waste could bear was 4.0 kgVS·m^-3·d^-1.