Bioaugmentation with propionate-degrading methanogenic cultures to boost start-up phase of food waste anaerobic digestion at high organic loading rate

This study investigated whether bioaugmentation can boost the start-up of anaerobic digestion (AD) of food waste at high organic loading rate (OLR), and the effects of addition dosage and frequency on bioaugmentation performance. The results showed that the start-up efficiency of all bioaugmented reactors was better than that of non-bioaugmentation control at the high OLR of 3.0 g VS L-1 d-1. Besides, relatively high dosages or frequencies promoted methane production. Adding 0.675 g VS L-1 of bioaugmentation seed each 5 days during the first hydraulic retention time (HRT), the digester performed the best among the three bioaugmented systems, which remained relatively stable for next 3 HRTs without bioaugmentation introduction. 16S rRNA gene sequencing analysis indicated that bioaugmentation maintained aceticlastic Methanothrix at a high abundance and avoided volatile fatty acids accumulation, particularly acetate and propionate, which contributed to a successful start-up of anaerobic digestion at high OLR.