Investigation of Hydrogen Production by Dark Co-fermentation of Water Hyacinth and Banana Peels

Abstract

Climate change and fast-growing energy demand have triggered research for alternative sources of energy that are environmentally-friendly. Various clean energy sources have been extensively researched among which hydrogen as an energy carrier is found to be producible from biomass and waste resources. Water hyacinth, regarded as the worst aquatic plant due to its exponential invasiveness of aquatic environments, causes damage both to the environment and populations. In Lomé, water hyacinth invades lakes hindering economic and navigation activities. Its removal from the lakes generates heavy expenses and the harvested water hyacinth plants are landfilled. In an attempt to propose a sustainable solution to this situation, this study aimed to investigate hydrogen production by dark co-fermentation of water hyacinth and banana peels. Water hyacinth leaves, stems, roots, and banana peels were dried and ground. The ground samples were characterized to determine their elemental composition, proximate analysis, and fiber content. The data from the characterization were used to simulate the dark cofermentation process as well as the economic analysis of biohydrogen production by this process using SuperPro Designer®. Then, tests of biogas production from banana peels, water hyacinth leaves and stems were carried out. Results showed that water hyacinth leaves, stems and banana peels had a suitable elemental composition for biohydrogen production. The volatile solid and cellulose contents of water hyacinth and banana peels revealed that these substrates had the necessary nutrients for biohydrogen production. The simulated co-fermentation produced 124,64, 110,52, 99,85, and 67,36 mL g-1 volatile solid for water hyacinth to banana peels mixing ratios of 100:0, 70:30, 50:50, and 0:100 respectively. The tests of biogas production from banana peels, water hyacinth stems, and leaves generated respectively 334.82, 324.79, and 280.15 mL g-1 volatile solid. It was therefore concluded that the production of hydrogen coupled with biogas generation and composting would be a promising option to valorize water hyacinth and banana peels wastes into energy in the city of Lomé.