FLAT-PLATE AND BUBBLE COLUMN PHOTOBIOREACTORS FOR CULTURE OF CHLORELLA PYRENOIDOSA USING SECONDARILY TREATED SEWAGE

摘要

The triple use of microalgae for CO_2 elimination, bioremediation and biomass production forrnsustainable valuable sources like biofuels and fine chemicals is a feasible option with enormous industrial andrneconomic potential. Biodiesel production from microalgae is a promising alternative, because microalgae improverncharacteristics in relation to crops of traditional plant sources. The secondarily treated sewages can containrnammonium, nitrates, phosphates, potassium salts, organic matter, inorganic carbon and other micronutrients. Thesernwastewaters can be used as nutrients to produce an algal biomass with a biochemical composition rich in lipids.rnChlorella pyrenoidosa, Chick 8H Emerson, is a green unicellular algal that can produce a substantial amount ofrnlipids. Experiments in two types of photobioreactors have been carried out, using a flat-plate and a bubble column atrnmini-plant scale and in natural conditions. Culture pH ranged in the range 7.8-9.1, temperature in the interval 287.15-rn309.15 K and an air flow (Q) was supplied to maintain the cells in suspension (Q = 1 v/v/min in the bubble column).rnIn the flat-plate photobioreactor, at intervals, air enriched with CO_2 was supplied, in order to maintain the pH=8.0.rnThis study tries to evaluate the parameter kinetics (maximum specific growth rate, μm, and volumetric biomassrnproductivity, Pb) as well as the formation of lipids in the biomass formed. In the bubble column photobioreactor andrnunder natural conditions, the highest values of μm and Pb were 0.12 d~(-1) and 0.14 10~(-3) g/dm~3h, respectively, while thernflat-plate photobioreactor these parameters were higher, μm=0.50 d~(-1) and Pb=3.15 10~(-3) g/dm~3h. The maximumrnconcentration of total lipids was reached in the bubble column photobioreactor, 20.9% (dry weight).