PHOTOSYNTHETIC PRODUCTION OF THE FILAMENTOUS CYANOBACTERIUM SPIRULINA-PLATENSIS IN A CONE-SHAPED HELICAL TUBULAR PHOTOBIOREACTOR

The photosynthetic productivity of the filamentous cyanobacterium Spir ulina platensis was investigated in a cone-shaped helical tubular phot obioreactor. A laboratory-scale photobioreactor was constructed with a 0.255-m(2) basal area and a conical shape (0.64 m high x 0.57 m top d iameter). The photostage comprised transparent reinforced polyvinyl ch loride (PVC) tubing with spirally wound, metal-wire reinforcing in the tubing wall (31 m in length and 1.6 cm internal diameter with 0.25 cm wall thickness; total volume = 6.231). The inner surface of the photo stage (0.651 m(2)) was illuminated with compact fluorescent cool white lamps; the photosynthetically active radiation (400-700 nm) energy in put into the photobioreactor was 1249 KJ day(-1) (12 h day/12 h night) . The operation of an air-lift photobioreactor with CO2-enriched air ( 4%) at a flow rate of 0.31 min(-1) showed a maximum daily photosynthet ic efficiency of 6.83% under batch-culture conditions. This correspond ed to a production rate of 15.9 g dry biomass m(-2)(basal area) day-l or 0.51 g dry biomass 1 medium(-1) day(-1).