Effect of mine wastewater on nutrient removal and lipid production by a green microalga Micratinium reisseri from concentrated municipal wastewater

• A dual strategy for wastewater treatment and biofuel feedstock production.
• Mine wastewater increased the nutrient removal efficiency of M. reisseri.
• Mine wastewater improved the growth and lipid productivity of M. reisseri.
• Concentrated municipal wastewater supported the algal autoflocculation.

Effect of mine wastewater on the nutrient removal efficiency of a green microalga Micratinium reisseri from concentrated municipal wastewater (CMW) with simultaneous lipid production was investigated. Different dilution ratios (1–10%) of CMW either with mine wastewater (MWF) or mine wastewater without Fe (MWOF) were used. M. reisseri showed the highest growth (0.8 g L−1) and nutrient uptake (35.9 mg TN L−1 and 5.4 mg TP L−1) at 3% MWF ([Fe]tot = 6.7 mg L−1), and the highest lipid productivity (10.4 mg L−1 day−1) at 5% MWF ([Fe]tot = 11.2 mg L−1) after 15 days. CMW supported the algal autoflocculation due to formation of phosphate, calcium and magnesium precipitates at a high suspension pH. Fatty acid methyl ester analysis revealed that the microalgal lipids possessed 79–82% of C16/C18 fatty acids. Application of mine wastewater improved the nutrient removal efficiency, growth and lipid productivity of M. reisseri cultivated in CMW.