Sequential hydrogen and methane production with simultaneous treatment of dairy industry wastewater: Bioenergy profit approach

A sequential study for hydrogen and methane production with pollutants reduction from dairy industry wastewater (DIWW) was conducted using bacterial strain of Enterobacter aerogens and methanogenic bacteria of cow dung. Among the different selected concentrations of DIWW viz: 25%, 50%, 75% and 100%, the 75% concentration depicted the best feasibility for biomass growth rate (0.21 h−1) as well as hydrogen (105 ml H2/g-Chemical Oxygen Demand (COD) and 0.562 L-H2 L−1 DIWW) and methane (190 CH4 ml/g-COD and 0.59 L CH4 L−1-FDIWW) production with the selected substrate. Experimental results were tested with various kinetic models viz. (Monod, Moser, Hanes-woolf and Eadie-Hofestee) to observe substrate utilization and growth pattern of bacteria. Hanes equation (R2 = 0.95) was the best fitted model observed in the present study. Economic Assessment of produced energy (0.22$/m3 DIWW and 0.336$/m3-FDIWW) illustrates the selected pathway has the viability of the system for treatment simultaneous with bioenergy production.