Demonstrating the application of batch anaerobic digestion recirculating slurry inoculation of food waste engineering from a microbiological perspective

Abstract

In this study, the food waste recycled slurry was mixed inoculated with the discharge of the biogas station, and the effect of inoculation ratio and circulating batch on the performance of the system was studied for 2 t/d food waste anaerobic digestion to demonstrate engineering applications. The results showed that a proper proportion of the digestion slurry cycle can promote dehydrogenase activity in the system, and the activity of methanogens and the content of coenzyme F420 gradually increase with the increase of the cycle batch. Under the optimal mixing ratio (50% slurry volume ratio, R50), the time for anaerobic digestion of food waste to reach 90% of the total cumulative methane output can be shortened to 13 days, and the cumulative biogas output is as high as 16.96 L. The value of the kinetic constant k increases with the number of refluxes, and finally reaches 0.114 d−1. The microbial community gradually succeeds in an appropriate direction. The VFA and alkalinity content in the system together affects the composition of Firmicutes, Bacteroides, and Chloroflexus in the system. These results will help increase the utilization rate of biogas slurry, reduce its external discharge, and improve the performance of batch anaerobic digestion engineering applications.