Metagenomic characterization of the enhanced performance of multicomponent synergistic thermophilic anaerobic co-digestion of food waste utilizing kitchen waste or garden waste as co-substrate.

Food waste (FW) single-substrate anaerobic digestion usually suffers from rapid acidification and inhibition of oil and salt. To overcome these problems and improve the process efficiency, supplementing other substrates has been used in FW anaerobic digestion. This study investigated the biogas production potential through co-digestion of FW with kitchen waste (KW) or garden waste (GW) in different ratios under thermophilic conditions. The results showed that the optimal ratios were FW:KW=60:40 and FW:GW=80:20 which biogas production improved 73.33% and 68.45% compared with single FW digestion, respectively. The organic matter removal rate of co-digestion was 84.46% for FW+KW group (RFK) and 65.64% for FW+GW group (RFG). Co-digestion increased the abundance of the dominant hydrolytic bacteria Defluviitoga and Hydrogenispora and hydrogenotrophic methanogen Methanoculleus. Furthermore, glycoside hydrolases (GHs), vital carbohydrate-active enzymes (CAZymes), were improved by co-digestion. Co-digestion could also effectively promote the function of cellulase and hemicellulose. This strategy for utilizing different organic wastes together as co-substrate provides a new avenue for bioenergy production.

Multivariate insights into enhanced biogas production in thermophilic dry anaerobic co-digestion of food waste with kitchen waste or garden waste: Process properties, microbial communities and metagenomic analyses.

Multisubstrate synergetic anaerobic co-digestion can effectively overcome low efficiency of food waste (FW) mono-digestion. This study investigated the effect of supplementing FW with kitchen waste (KW) or garden waste (GW) on thermophilic dry anaerobic co-digestion. FW-KW and FW-GW co-digestion enhanced biogas production by 24.69 % and 44.96 % at organic loading rate (OLR) of 3 g VS L-1 d-1, and increased OLR tolerance from 3 to 4 g VS L-1 d-1 through mitigating ammonia nitrogen inhibition and volatile fatty acids accumulation. Co-digestion enriched the dominant hydrolytic bacteria Defluviitoga, resulting in an acceleration of substrate hydrolysis. FW-KW co-digestion improved biogas production by increasing gene abundance related to key enzymes in methanogenesis pathways and promoting the conversion of intermediate products into methane. FW-GW co-digestion enhanced biogas production by enriching ABC transporters-associated genes, leading to efficient substrate utilization. This study provides a promising approach for FW treatment with multivariate insights into thermophilic dry anaerobic co-digestion.

Enhanced sludge reduction during swine wastewater treatment by the dominant sludge-degrading strains Chryseobacterium sp. B4 and Serratia sp. H1.

Sludge reduction is considered a main target for sludge treatment and an urgent issue for wastewater treatment. In this study, two dominant sludge-degrading strains, identified as Chryseobacterium sp. B4 and Serratia sp. H1, were used for inoculation in swine wastewater treatment to investigate the enhancement of sludge reduction. The results showed the volatile suspended solid (VSS) removal rate in experimental groups inoculated with Chryseobacterium sp. B4, Serratia sp. H1, and a combination of the two strains improved by 49.4%, 11.0%, and 30.5%, compared with the control with no inoculation. Furthermore, microbial community structure and functional prediction analyses indicated Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria could play an essential role in sludge reduction, and the dominant sludge-degrading strains B4 and H1 enhanced sludge reduction by strengthening carbohydrate, nucleotide, amino acid, and lipid metabolism and membrane transport functions. This study provides new insights into sludge reduction during wastewater treatment with dominant sludge-degrading strains.