Evaluation of the relationship of wastewater treatment and biodiesel production by microalgae cultivated in the photobioreactor

•Microalgae biodiesel coupled with waste disposal has vast production potential.•It analyzed the carbon fixation effect, economic benefit, and so on of biodiesel.•It evaluated the microalgae biodiesel under different energy supply conditions.•Microalgae biodiesel can be used in transportation to meet low-carbon energy needs. Microalgae has a great preponderance of fast growth rate and high oil contents. Mixed wastewater and industrial waste gas are utilized in this study as the microalgae's growing medium and resource of inorganic carbon. A combined study of waste usage and biomass energy development is conducted based on closed photobioreactor cultivation. With a focus on the cost of microalgal biodiesel, the financial benefits of waste treatment, the CO2 absorption effect, and biodiesel yield, an assessment of the production process is conducted for different algae species under different energy supply situations. The experimental results indicate that Model algal species 3 (M3) are better adapted for the production of biodiesel with the situation of wind power. It has the algae generates 6800 L of algal liquid, 32.3 kg of microalgae, 42.27 kg of CO2 emission reduction, and 12.47 kg of biodiesel in the single production cycle. The production of microalgae biodiesel based on photobioreactors can produce negative carbon emissions in the setting of a wind energy supply, and the total yearly biodiesel production in the same proliferation scale is at least 112.89 times that of open culture ponds. It has realized the sufficient coupling between waste utilization and biomass energy development through the development of microalgae biodiesel based on photobioreactor culture. It reduces the cost of biodiesel development and maintains high economic efficiency of waste disposal while producing negative carbon emissions. New theoretical guidance is provided by the target's advancement of renewable energy, carbon sequestration, and emission reduction, which has substantial effects on reducing pollution and enhancing significant ecological and environmental effects.