Optimization of culture conditions for Chlorella sorokiniana using swine manure wastewater

Abstract

Algae, an ideal feedstock for biodiesel, can assimilate organic and inorganic pollutants of animal wastewater and convert them into cellular constituents such as lipids and carbohydrates. In the study, the impacts of Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorus (TP) of swine manure wastewater and inoculation concentration of algae seeds on biomass production of algae Chlorella sorokiniana were studied. Our results demonstrated that concentration of TN in wastewater would scarcely affect the algae growth, and inhibition of ammonia nitrogen (NH3-N) on the growth of C. sorokiniana was not so obvious, although NH3-N occupied the overwhelming proportion of nitrogen source. Three factors (COD, TP, and inoculation size) which had significant impact on biomass production of C. sorokiniana using swine manure wastewater were optimized using response surface methodology. The optimal biomass production (128 mg l−1 d−1) was obtained when C. sorokiniana was cultivated in swine manure wastewater containing 345 mg l−1 COD and 45 mg l−1 TP, with the initial inoculation concentration of 136 mg l−1 algae seeds (dry weight). Then the strain was cultivated in 30 l photobioreactor with the optimized condition, a biomass yield (160 mg l−1 d−1) was achieved, accompanied with removal rates of TN (72%), TP (86%), and COD (38%). The study could provide guidance for large-scale cultivation of algae in wastewater.