[Effect of inorganic carbon supplement on the growth and lipid accumulation properties of Scenedesmus sp. LX1].

With secondary effluent as growth medium, the growth and lipid accumulation properties of Scenedesmus sp. LX1 in the control and carbon supplement (Na2CO3, NaHCO3 and CO2) groups were compared. After 14 days of cultivation, there was no significant difference in growth and lipid accumulation of Scenedesmus sp. LX1 among the 4 groups. The algal biomass, lipid and triacylglycerols production were 0.70-0.77 g x L(-1), 0.27-0.34 g x L(-1) and 0.029-0.033 g x L(-1), respectively, and the lipid content per algal biomass was 35% - 45%. The microalgal photosynthesis would increase the water's pH to about 9.2, which could induce CO2 transferring into secondary effluent. In control group, the amount of CO2 transferring from atmosphere into secondary effluent was 1.0 g x L(-1), occupying 97% of total fixed CO2 by microalga. Calculation shows that, the CO2 transferring from atmosphere into secondary effluent is enough to support microalgal growth and lipid accumulation. Therefore, to cultivate Scenedesmus sp. LX1 in secondary effluent, there is no need of carbon supplement.