Co-fermentation of water hyacinth and beverage wastewater in powder and pellet form for hydrogen production

Hydrogen (H2) production potential of water hyacinth (WH) and beverage wastewater (BW) mixture in powder and pellet form at various combination ratios were evaluated. Batch co-fermentation results showed peak biogas production of 105.5 mL and H2 production of 55.6 mL at the combination ratio of 1.6 g WH and 2.4 g BW in pellet form. With the same ratio in pellet form, the maximum H2 production rate 542 mL H2/L-d, maximum specific H2 production rate 869 mL H2/g VSS-d and H2 yield 13.65 mL/g feedstock were obtained, and were 88, 88 and 34% higher than its powder form. The predominant soluble metabolite was acetate in the concentration of 1059–2639 mg COD/L (40–79% of total metabolites) in most runs during co-fermentation of mixed feedstock. Carbon-to-nitrogen ratio and the physical form of the combined feedstock are essential criteria for optimum H2 production. Co-fermentation also alleviates the waste disposal problem of the industries.