Hydrogen production by dark fermentation using a new low-cost culture medium composed of corn steep liquor and cassava processing water: Process optimization and scale-up

Abstract

The use of effluents for hydrogen production through dark fermentation is promising because it results in the generation of value-added products and reduction of the effluent's organic load. A low-cost medium using agroindustrial effluents, corn steep liquor (CSL) and cassava processing wastewater (CPW) was evaluated for hydrogen production with microbial consortia (Vir and Gal). Four variables were evaluated for their impact on biohydrogen production through a Plackett Burman design. Subsequently, the significant variables were optimized using a central composite design, resulting in two mathematical models with regression coefficients R² > 0.92. The maximum yields were validated and resulted in 107 and 83.1 mL of biohydrogen/g _{COD removed} for Vir and Gal, respectively. The lower medium cost for biohydrogen production was 81.5 USD/m³, approximately 80% more economical than some supplemented media. Finally, the scale-up of the biohydrogen production by consortia to 5L resulted in an increase of more than 40%.

Keywords: Biohydrogen; Cassava-processing wastewater; Corn steep liquor; Microbial consortia.