Evaluation of a vertical flat-plate photobioreactor for outdoor biomass production and carbon dioxide bio-fixation: effects of reactor dimensions, irradiation and cell concentration on the biomass productivity and irradiation utilization efficiency

Outdoor culture of the thermophilic cyanobacterium Synechocystis aquatilis SI-2 with a vertical flat-plate photobioreactor (VFPP) was studied during t he period of January to August of 1999 in the northern region of Japan (Kam aishi, Iwate, 39 degreesN, 142 degreesE). The aim of this study was to inve stigate the CO2 fixation ability of the VFPP device under various irradiati on conditions. An average biomass productivity of over 30 g m(-2) day(-1) w hich corresponds to a CO2 fixation rate of 50 g mday(-1), was achieved duri ng this period with a 192-1 scale culture. The effects on biomass productiv ity of the light path, height of the reactor, cell concentration and irradi ation were also investigated. Variation of the optimal cell concentration t o achieve the highest productivity for outdoor operation is discussed. A ce ll concentration of 1-2 g l(-1) was found to be most suitable for the irrad iation range of 1-12 MJ m(-2) day(-1) under the experimental conditions use d.