Efficient production of biohydrogen from African lignocellulosic residues

Biohydrogen by dark fermentation using organic wastes is a promising technology towards energy transition and green economy. Unfortunately, H₂ production is still limited as several parameters must be finely tuned. This study aims at the development of an efficient process to convert African lignocellulosic residues into H₂. An alkaline H₂O₂ pre-treatment of coffee and pineapple skins, which are hugely produced as waste in many African countries, has been developed. The goal was to get simple sugars, under mild conditions, to foster H₂ production. Once pre-treated, the feedstocks were converted by a heat-treated inoculum into H₂ at two pH values (5.5 and 6.0). The results indicate that coffee and pineapple skins were efficiently transformed into H₂ (up to 47.99 and 91.80 mL/gVS, respectively) at an optimal pH of 6 with a concentration of 1.25 % H₂O₂.

These results proved that H₂O₂ pre-treatment and the fine tuning of pH can be the key drivers to boost H₂ production of lignocellulosic matrices. This combined approach performed successfully and stands for a promising way towards the optimization of the H₂-producing processing from waste streams also in African countries. This will contribute to the United Nation (UN)’s ‘Agenda 2030’ for green energy and sustainable economic growth.