Bioaugmentation with well-constructed consortia can effectively alleviate ammonia inhibition of practical manure anaerobic digestion

Bioaugmentation is an attractive method to improve methane production (MP) in the anaerobic digestion (AD) process. In this study, to tackle the ammonia inhibition problem, a long-term (operating over 6 months) accli-matized consortia and a well-constructed consortia were selected as the bioaugmentation consortia for sequencing batch AD reactors fed with dairy manure and pig manure under mesophilic condition. Similar re-sponses, in terms of the reactor performance and microorganisms structure to the different consortia, were observed with both manure kinds indicating that the effectiveness of bioaugmentation was mainly decided by the composition of the added consortia, not the feedstock. 39 - 49% increment in MP was obtained in the reactors bioaugmented with well-constructed consortia, which was higher than the acclimatized consortia (about 25% increment in MP). Both acetogenesis and methanogenesis (advantageous) steps were stimulated with well-constructed consortia bioaugmentation. According to key functional enzyme analysis, the increment of glycine hydroxymethyltransferase and phosphoglycerate mutase might be the critical point in the bioaugmented AD system. Based on the higher functional contribution rate of the well-constructed consortia bioaugmentation reactors, Methanosarcina could have expressed more comprehensive functions or performed stronger activities in different functions than Methanosaeta.

Automated summary

Bioaugmentation using well-constructed consortia can significantly improve methane production in anaerobic digestion. The effectiveness of bioaugmentation mainly depends on the composition of the added consortia. Well-constructed consortia can stimulate acetogenesis and methanogenesis steps, leading to a higher methane production increment. Key functional enzymes such as glycine hydroxymethyltransferase and phosphoglycerate mutase may play a critical role in the bioaugmented anaerobic digestion system.