Biohydrogen: Chapter 6. Biohydrogen Production from Organic Wastes by Dark Fermentation

Hydrogen can be produced sustainably by dark, anaerobic bacterial growth on carbohydrate-rich substrates. This chapter discuses microbiology, biochemistry, molecular biology, and the various other aspects related to dark hydrogen production. Pure cultures, known to produce hydrogen from carbohydrates, include species of Enterobacter and Clostridium. However, for efficient degradation of complex substrates, mixed cultures easily obtainable from natural sources and able to proliferate on nonsterile feedstock are required. Compared to pure substrates, complex substrates, especially different kinds of waste, may offer a sustainable and economical alternative for hydrogen production. However, for maximization of hydrogen production, different physicochemical processes need to be determined. In this regard, the various parameters affecting the dark hydrogen production process, which include pH, temperature, hydraulic retention time, and hydrogen partial pressure, have been discussed in detail. In addition, this chapter discusses the different types of reactors and their suitability to carry out studies on dark fermentative hydrogen production. Overall, the chapter presents a holistic understanding of the dark hydrogen production process and highlights the recent new findings and achievements in the field.