Potential of Chlorella sorokiniana Cultivated in Dairy Wastewater for Bioenergy and Biodiesel Production
2022
Hamidian, Najmeh | Zamani, Hajar
Microalgae can serve as a sustainable and economic feedstock in biofuel production. This study addressed the cultivation of freshwater microalgae Chlorella sorokiniana EAKI in untreated dairy wastewater (DWW) as a low-cost nutrient source for qualified biofuel production. To this end, biomass production, lipid accumulation, and fatty acids (FAs) profile, as well as biodiesel production of C. sorokiniana grown in undiluted and diluted DWW, were examined. According to the findings, the highest microalgae biomass production (1.5 ± 0.131 DW g L⁻¹) can be obtained using undiluted DDW with the largest biomass productivity of 63.136 ± 1.040 mg L⁻¹ day⁻¹ and a specific growth rate of 0.094 ± 0.006 day⁻¹. It was found that lipid content reached the highest level (1.644 mg mL⁻¹) in undiluted DWW at the end of the exponential growth phase. Additionally, lipid productivity of C. sorokiniana grown in synthetic and undiluted DWW media was 57.870 and 79.962 mg L⁻¹ day⁻¹, respectively. Based on the FA profile, wastewater-grown microalgae produced lipids with 40% saturated FAs and 33% unsaturated FAs. According to physico-chemical characteristics, biodiesel produced from wastewater-grown C. sorokiniana is useful for high-quality biodiesel production. The NMR and FTIR spectra confirmed that biodiesel produced from C. sorokiniana was composed of FA methyl esters. Based on empirical formulas, the theoretical biomethane productivity of microalgae ranged from 0.353 to 0.644 L CH₄ g⁻¹ VS. Thus, the low-cost nutrient media of DWW can be used to culture C. sorokiniana as an efficient strain for sustainable and cost-effective biofuel generation.
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