Innovative CO2 pretreatment for enhancing biohydrogen production from the organic fraction of municipal solid waste (OFMSW)

► CO2 sparging pretreatment for fermentative H2 production from waste was studied. ► H2 yield was either increased or decreased depending on the level of CO2 flowrate. ► H2 yield was increased by more than 20% for some operating conditions. ► Improvement of bio-H2 production was linked to positive bacterial interactions.