Photosynthetic performance of a helical tubular photobioreactor incorporating the cyanobacterium spirulina platensis

The photosynthetic performance of a helical tubular photobioreactor (“Biocoil”), incorporating the filamentous cyanobacterium Spirulina platensis, was investigated. The photobioreactor was constructed in a cylindrical shape (0.9 m high) with a 0.25‐m2basal area and a photostage comprising 60 m of transparent PVC tubing of 1.6‐cm inner diameter (volume = 12.1 L). The inner surface of the cylinder (area = 1.32 m2) was illuminated with cool white fluorescent lamps; the energy input of photosynthetically active radiation(PAR, 400 to 700 nm) into the photobioreactor was 2920 kJ per day. An air‐lift system ncorporating 4%CO2 was used to circulate the growth medium in the tubing. The maximum productivity achieved in batch culture was 7.18 g dry biomass per day [0.51 g · d biomass/L · day, or 5.44 g · d biomass/m2(inner surface of cylindrical shape)/day] which corresponded to a photosynthetic (PAR) efficiency of 5.45%. The CO2 was efficiently removed from the gaseous stream; monitoring the CO2 the outlet and inlet gas streams showed a 70% removal of CO2 from the inlet gas over an 8‐h period with almost maximum growth rate. © 1995 John Wiley & Sons, Inc.