Effect of light intensity on algal biomass accumulation and biodiesel production for mixotrophic strains Chlorella kessleri and Chlorella protothecoide cultivated in highly concentrated municipal wastewater

In this research, the effect of light intensity on biomass accumulation, wastewater nutrient removal through algae cultivation, and biodiesel productivity was investigated with algae species Chlorella kessleri and Chlorella protothecoide. The light intensities studied were 0, 15, 30, 60, 120, and 200 µmol m−2 s−1. The results showed that light intensity had profound impact on tested responses for both strains, and the dependence of these responses on light intensity varied with different algae strains. For C. kessleri, the optimum light intensity was 120 µmol m−2 S−1 for all responses except for COD removal. For C. protothecoide, the optimum light intensity was 30 µmol m−2 S−1. The major components of the biodiesel produced from algae biomass were 16‐C and 18‐C FAME, and the highest biodiesel contents were 24.19% and 19.48% of dried biomass for C. kessleri and C. protothecoide, respectively. Both species were capable of wastewater nutrients removal under all lighting conditions with high removal efficiencies. Biotechnol. Bioeng. 2012;109: 2222–2229. © 2012 Wiley Periodicals, Inc. Algae cultivation in wastewater streams as feedstock for biofuel production can not only greatly decrease the cost involved in nutrients and water consumption but also serve the dual role of waste reduction and energy production. This paper targeted at optimized light supply to the cultivation system using concentrated municipal wastewater, and the results showed that light intensity had profound effect on biomass accumulation, wastewater nutrients removal through algae cultivation, and biodiesel productivity with mixotrophic strains from the family of Chlorella.