4.2.4. Biohydrogen

Wastewater may be used through dark fermentation for the production of hydrogen. A microbial consortium contains a wide variety of bacteria, and some of them inhibit hydrogen production (i.e., hydrogenophilic-methanogenesis) by their consumption (homo-acetogens and methanogens) [54]. So, for optimum hydrogen production, the activity of inhibitory microbes gets suppressed or they are killed, either by heat pretreatment of inoculum or by increasing dilution rate and by decreasing the pH of reactors. Another reliable and finely honed process is catalytic methane to hydrogen conversion [72]. Di fferent wastewater and e ffluent have been used for hydrogen production, these are TxW, PWW, rejected water and seed sludge, MW, OMW, BW, etc. [54,71,73–75].
