Recent developments in biohydrogen production through dark fermentation of biomass waste: feedstocks, microbial population dynamics, and system integration

Abstract

Dark fermentation is the conversion of various biomass wastes into biohydrogen. It occurs in the absence of light. The purpose of this review is to provide the latest advances in biohydrogen production via dark fermentation, focusing on feedstock characteristics, microbial community dynamics, and approaches to system integration. Carbohydrate-based substrates are ideal for the production of biohydrogen due to their high fermentative potential. In contrast, lignocellulosic biomass requires pretreatment to enhance its susceptibility to microbial degradation. Hydrogen-producing microorganisms such as Clostridium spp were considered, focusing on metabolic processes, changes in the microbial communities involved, and process stability at different process parameters. The hydrogen partial pressure, byproducts, and inhibition due to competition between methanogens, lactic acid bacteria, and hydrogen-utilizing organisms were reviewed along with control mechanisms. The use of fermentation by-products, volatile fatty acids, and acidified slurry has been considered within biorefinery concepts. This approach addresses the economic challenges associated with the biohydrogen production technology. Although some success has been achieved, several issues remain. These include scalability and feedstock variation. These factors present important bottlenecks for future commercial applications of this technology.