Efficient production of biohydrogen from African lignocellulosic residues

• Coffee and pineapple residues are promising for H 2 production. • H 2 O 2 pre-treatment and pH optimization improve H 2 production. • 1.25 vol% H 2 O 2 pre-treatment supports the highest H 2 yield. • Higher H 2 was released at pH 6 for both feedstocks. Biohydrogen by dark fermentation using organic wastes is a promising technology towards energy transition and green economy. Unfortunately, H 2 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 H 2 . An alkaline H 2 O 2 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 H 2 production. Once pre-treated, the feedstocks were converted by a heat-treated inoculum into H 2 at two pH values (5.5 and 6.0). The results indicate that coffee and pineapple skins were efficiently transformed into H 2 (up to 47.99 and 91.80 mL/gVS, respectively) at an optimal pH of 6 with a concentration of 1.25 % H 2 O 2 . These results proved that H 2 O 2 pre-treatment and the fine tuning of pH can be the key drivers to boost H 2 production of lignocellulosic matrices. This combined approach performed successfully and stands for a promising way towards the optimization of the H 2 -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.