Effect of feeding mode and dilution on the performance and microbial community population in anaerobic digestion of food waste

The effect of feeding mode and dilution was studied in anaerobic digestion of food waste. An upflow anaerobic digester with a settler was fed at six different organic loading rates (OLRs) from 4.6 to 8.6 kg COD/m3/d for 200 days. The highest methane productivity of 2.78 L CH4/L/d was achieved at 8.6 kg COD/m3/d during continuous feeding of diluted FW. Continuous feeding of diluted food waste showed more stable and efficient performance than stepwise feeding of undiluted food waste. Sharp increase in propionate concentration attributed towards deterioration of the digester performances in stepwise feeding of undiluted food waste. Microbial communities at various OLRs divulged that the microbial distribution in the continuous feeding of diluted food waste was not significantly perturbed despite the increase of OLR up to 8.6 kg COD/m3/d, which was contrast to the unstable distribution in stepwise feeding of undiluted food waste at 6.1 kg COD/m3/d.