Development and cost-benefit analysis of a novel process for biofuel production from microalgae using pre-treated high-strength fresh cheese whey wastewater

In this study, a novel two-step integrated process is proposed to facilitate the microalgae biofuel production as well as fresh cheese whey wastewater (FCWW) treatment simultaneously. The pre- and post-treatment of high-strength FCWW were performed by means of coagulation and algal cultivation, respectively. The pre-treatment of FCWW for maximum removal of chemical oxygen demand (COD), turbidity (TUR) and total solids (TS) as responses was obtained by statistical optimization of coagulation parameters. The maximum removal of COD, TUR and TS at the optimum level of variables was obtained as 68.09%, 47.80% and 73.63%, respectively. The pre-treated FCWW was further treated by Chlorella pyrenoidosa and observed a significant reduction in the above-mentioned responses (87–94%). The maximum algal biomass yield and lipid productivity were observed as 2.44 g L⁻¹ and 77.41 mg L⁻¹ day⁻¹, respectively. Based on promising results of FCWW treatment and its use as a third-generation biodiesel feedstock, a cost-benefit analysis of the developed process was assessed for microalgal oil production. The total profit earned by the integrated process model was $9.59 million year⁻¹. Accordingly, the estimated production cost of algal oil (TAG) from the developed system was estimated to be $79.03 per barrel.