Bioaugmentation of lyophilised composite hydrolytic and methanogenic inocula in an upscale continuous anaerobic reactor

Lignocellulose- and ammonia-rich feedstocks are abundant but remain underutilised in anaerobic digestion (AD) due to simultaneous inhibition of hydrolysis and methanogenesis. This study used, for the first time, a composite inoculum of hydrolytic bacteria and ammonia-tolerant methanogenic archaea, acclimatised, lyophilised, and stored long-term. When bioaugmented in an upscale continuous stirred-tank reactor, inhibition from high lignocellulose and ammonia levels was counteracted. Methane production increased by 145.05 ± 8.21 % relative to the inhibited phase, accompanied by stable biochemical conditions and restored methanogenic activity. Overall reactor production rate, before the addition of the biomasses and after bioaugmentation, increased by 46.79 ± 2.71 %. These short communication findings provide proof-of-concept that bioaugmentation with stored long-term composite inocula offers a scalable strategy to overcome lignocellulose and ammonia inhibition and enhance biogas production.