Green Biorefinery

This paper aims to examine the potential of waste biorefineries in developing countries as a solution to current waste disposal problems and as facilities to produce fuels, power, heat, and value-added products. The waste in developing countries represents a significant source of biomass, recycled materials, chemicals, energy, and revenue if wisely managed and used as a potential feedstock in various biorefinery technologies such as fermentation, anaerobic digestion (AD), pyrolysis, incineration, and gasification. However, the selection or integration of biorefinery technologies in any developing country should be based on its waste characterization. Waste biorefineries if developed in developing countries could provide energy generation, land savings, new businesses and consequent job creation, savings of landfills costs, GHG emissions reduction, and savings of natural resources of land, soil, and groundwater. The challenges in route to successful implementation of biorefinery concept in the developing countries are also presented using life cycle assessment (LCA) studies.

Lignocellulosic biomass is an abundant resource with untapped potential for biofuel, enzymes, and chemical production.
Its complex recalcitrant structure obstructs its bioconversion into biofuels and other value-added products. For
improving its bioconversion efficiency, it is important to deconstruct its complex structure. In natural systems like
rumen, diverse microbial communities carry out hydrolysis, acidogenesis, acetogenesis, and methanogenesis of lignocellulosic
biomass through physical penetration, synergistic and enzymatic actions enhancing lignocellulose degradation
activity. This review article aims to discuss comprehensively the rumen microbial ecosystem, their interactions,
enzyme production, and applications for efficient bioconversion of lignocellulosic waste to biofuels. Furthermore,
meta ‘omics’ approaches to elucidate the structure and functions of rumen microorganisms, fermentation mechanisms,
microbe-microbe interactions, and host-microbe interactions have been discussed thoroughly. Additionally, feed additives'
role in improving ruminal fermentation efficiency and reducing environmental nitrogen losses has been discussed.
Finally, the current status of rumen microbiota applications and future perspectives for the development of
rumen mimic bioreactors for efficient bioconversion of lignocellulosic wastes to biofuels and chemicals have been
highlighted.