Impact of water content on the hydrogen production from lignocellulosic residues by dark fermentation

Abstract : Biohydrogen production from lignocellulosic residues is restricted by several factors that limit industrial application of this process. Among them, the reactor size reduces the economical feasibility of the process. Dry ananerobic processes operates with low water quantity and could allow treating more waste. This study investigates the hydrogen production from wheat straw under several dryness conditions (sixtotal solid (TS) content). The results showed a hydrogen production of 14 NmlH2.gVS-1 in semi dry consitions (9.5-14.2 %TS). For dry medium (18.8 to 28.1 %TS), the hydrogen production decreases to lower value of 6-7 NmlH2.gVS-1. Finally, in highly dry conditions (28.1 to 33.2%) the hydrogen production is reduced to 3-4 NmlH2.gVS-1. The study reveals that hydrogen can be produced in semi-dry conditions in similar proportion than saturated conditions. However, dry and particularly highlydry conditions are not favourable to hydrogen production.