Bioaugmentation improves batch psychrophilic anaerobic co-digestion of cattle manure and corn straw

Low temperatures result in poor anaerobic digestion (AD). To investigate whether bioaugmentation can improve anaerobic co-digestion of cattle manure and corn straw at 20 degrees C, five different doses of methanogenic propionatedegrading culture (4%, 8%, 12%, 14%, and 16%) were added to batch AD systems to compare bioaugmentation performance. The results showed that the methane production of all the bioaugmented digesters was enhanced compared to the control, increasing 2.80-4.20-fold with digestion times (T-80) shorter by 11-22 d. The recommended dose for biogas production was 14%, and the recommended dose for the highest bioaugmentation efficiency of microbes was 4%. These improvements were due to the addition of methanogenic propionatedegrading culture, which alleviated volatile fatty acids (VFA) accumulation, especially that of acetate and propionate. Metagenomic sequencing analysis indicated that the increased proportion of propionate-oxidizing bacteria, syntrophic butyrate-oxidizing bacteria, and acetoclastic methanogens in bioaugmentation reactors may be responsible for better AD performance.