Continuous biohydrogen production in immobilized biofilm system versus suspended cell culture

► Biohydrogen production by immobilized and suspended bioreactors were compared. ► Ceramic balls (450 m2/L) were used as support matrix for the first time. ► Stable biohydrogen production was achieved even at low HRTs in immobilized reactors. ► 5 folds more hydrogen production was achieved in 8 times smaller bioreactor.