Chapter 9 - Bioaugmentation strategies via acclimatized microbial consortia for bioenergy production

Abstract

In this chapter, the potential of bioaugmentation with microbial consortia in anaerobic digestion (AD) processes of biomass wastes to remediate several forms of stress for more sustainable production of biofuels is discussed. The key findings in bioaugmentation strategies in recent years, specifically targeted at various limitations in AD, including (1) ammonia inhibition from nitrogen-rich organic wastes, (2) inefficient degradation of recalcitrant lignocellulosic biomass, (3) accumulation of volatile fatty acids (VFA) in heavily loaded AD digesters, (4) subpar production efficiency of biohydrogen, and (5) recalcitrant emerging pollutants (e.g. plastics) in AD bioreactors are summarized. The theoretical basis and operational procedures of the bioaugmentation are also assessed. Repeated inoculation method and pretreatments-aided bioaugmentation were identified as promising approaches as these mitigate technical bottlenecks related to ineffective bioaugmentation, especially for recalcitrant substrates. Furthermore, bioaugmentation strategies could also be applied to hybrid fermentation systems for enhanced hydrogen production, while VFA–tolerant Methanosarcina and plastic-degrading microbes deserve further studies for the recovery of failing heavily loaded digesters and degrading plastics, respectively. Exploration of more functional genes and enzymes associated with both acetoclastic and hydrogenotrophic methanogenic pathways are recommended for future research. Technical limitations and prospects of bioaugmentation strategies for enhanced AD are also highlighted. Based on the overview on bioaugmentation technologies, more pilot-scale and larger scale tests are essential for future implementation of bioaugmentation strategies in full-scale biogas plants. Critical analyses of bioaugmentation strategies would facilitate the establishment of more sustainable AD systems for better waste management and greater renewable biofuels production.