Background: CO₂ emission, water pollution and petroleum shortage are the issues coming with the development of industry. A cost effective system was constructed to fix the CO₂ in flue gas (15% CO₂), remove nitrogen and phosphorus from manure wastewater and produce biofuels at the same time. The significant cultivation conditions were selected by Plackett-Burman design, and then optimized with central composite design.

Results: Optimum culture condition was predicted at light intensity of 238 μmoL·m^-2·s^-1, TN of 152 mg·L^-1, inoculum density of 0.3 g·L^-1, under which the measured CO₂ fixation rate, total nitrogen and phosphorus removing rate, and lipid content were 638.13 mg·L^-1·d^-1, 88.16%, 73.98% and 11.9%, respectively. The lipid content was then enhanced to 24.2% by a nitrogen starvation strategy.