A HOLLOW-FIBER PHOTOBIOREACTOR FOR CONTINUOUS PRODUCTION OF HYDROGEN BY IMMOBILIZED CYANOBACTERIA UNDER PARTIAL VACUUM

Photoproduction of hydrogen by the nitrogen-fixing cyanobacterum Anabaena variabilis was measured in partial vacuum. The rates of hydrogen production under vacuum were compared with those under an argon atmosphere in vials. Hydrogen production was dependent on the residual pressure of gases remaining in the partial vacuum and required light. The adhesion of cyanobacterial cells to hydrophilic and hydrophobic hollow fibres was studied. The degree of immobilization of the cells on the hollow fibres was assessed by examining cell attachment using scanning electron microscopy. A laboratory-scale photobioreactor for production of hydrogen by immobilized cyanobacterium A. variabilis was assembled. The photobioreactor was designed such that the cyanobacterial growth medium passes from the outside of the fibres into the inner lumen space. Photoproduction of hydrogen at rates of 0.02-0.2 ml H-2 per mg dry weight of cyanobacterial biomass per hour was observed for 5 months.