Hydrogen Production from Wastewater by Biochemical Methods

Abstract

The environmental impacts associated with fossil fuels and depletion of their resources motivated the development of alternate fuels. Hydrogen is an attractive alternate fuel with high heating value and no environmental impact. Although hydrogen is majorly produced by steam reforming, biochemical production especially from carbohydrate rich wastes is of great interest. Hydrogen production from these wastes is carried out by indirect/direct biophotolysis, dark fermentation, two‐stage fermentation and photofermentation. The major constraints of these processes are low hydrogen evolution rate and less yield at large scale. However, effective pretreatment of substrates and inoculum maximize the yield of hydrogen. The factors influence the hydrogen production include nature of microorganism, biochemical process/reactor, temperature, pH, ionic strength, hydraulic retention time, hydrogen and carbon dioxide partial pressure, organic acid concentration, and C/N ratio. The commercial exploitation of biohydrogen production is hindered by lack of high potential microorganism and bioreactor. Hence, it demands multidisciplinary research to understand the fundamental underlying principles besides the development of microbial strains for industrial applications.