Fast Startup of Semi-Pilot-Scale Anaerobic Digestion of Food Waste Acid Hydrolysate for Biogas Production

In this study, a fast startup of semi-pilot-scale anaerobic digestion of food waste acid hydrolysate for biogas production was carried out for the first time. During the period of fast startup, more than 85% of chemical oxygen demand (COD) can be degraded, and even more than 90% of COD can be degraded during the later stage of anaerobic digestion. During this anaerobic digestion process, the biogas yield, the methane yield, and the CH 4 content in biogas were 0.542 ± 0.056 m 3 /kg COD consumption, 0.442 ± 0.053 m 3 /kg COD consumption, and 81.52 ± 3.05%, respectively, and these values were high and stable. Besides, the fermentation pH was very stable, in which no acidification was observed during the anaerobic digestion process (outlet pH was 7.26 ± 0.05 for the whole anaerobic digestion). Overall, the startup of this anaerobic digestion can be completed in a short period (the system can be stable 2 days after the substrate was pumped into the bioreactor), and anaerobic digestion of food waste acid hydrolysate is feasible and attractive for industrial treatment of food waste and biogas production.