PHOTOPRODUCTION OF HYDROGEN BY CYANOBACTERIA UNDER PARTIAL VACUUM IN BATCH CULTURE OR IN A PHOTOBIOREACTOR

Optimal conditions for H-2 photoproduction by the cyanobacterium Anaba ena variabilis were investigated in batch experiments. Increasing ligh t intensities during the incubation of cyanobacterial cells led to inc reased H-2 production which was accompanied by suppression of O-2 evol ution. The batch experimental results were subsequently applied to the use of cyanobacteria in a computer-controlled photobioreactor for H-2 production. Some devices associated with the photobioreactor such as the pH electrode, CO2 cylinder and air line via proportional control g as flow valves and the vacuum and peristaltic pumps were connected via an interface card to an IBM computer. BBCBASIC (86) plus was the chos en language to write a program to control the photobioreactor. A two-p hase H-2 production system is suggested as being feasible for practica l demonstration. In the first phase the cyanobacterial cells photosynt hesize under light intensities of 45-55 mu mol . s(-1) . m(-2) and est ablish conditions for subsequent H-2 production. In the second phase t he cells produce H-2 under light intensities of 170-180 mu mol . s(-1) . m(-2) Photoproduction of H-2 at rates of about 12.5 ml H-2 . gcdw(- 1) . h(-1) was observed. (C) 1997 International Association for Hydrog en Energy. All rights reserved.