Production of Spirulina biomass in closed photobioreactors

The results of a six year investigation on the outdoor mass culture ofSpirulina platensis and S. maxima in closed tubular photobioreactors arereported. On average, under the climatic conditions of central Italy, theannual yield of biomass obtained from the closed culture units wasequivalent to 33 t dry weight ha -1 year-k In the same climatic conditionsthe yield of the same organisms grown in open ponds was about 18 t ha -Iyear -1. This considerable difference is due primarily to better temperatureconditions in the closed culture system. The main problems encounteredrelate to the control of temperature and oxygen concentration in theculture suspension. This will require an appropriate design and managementof the photobioreactor as well as the selection of strains specificallyadapted to grow at high temperature and high oxygen concentration.Key words: Spirulina, outdoor mass culture, tubular reactor, photobioreactor