Feasibility of growing microalgae on wastewaters collected from a vinegar plant for, concurrently, nutrient removal and biomass production

In this work, feasibility of using winemaking wastewater (WW), vinegar wastewater (VW), and pickle wastewater (PW) to cultivate microalgae was investigated. Results showed that the three wastewaters possessed different nutrient profiles due to their various sources, and VW was much richer in nutrients than WW and PW. The maximum biomass concentrations of 0.73, 2.45, and 0.64 g L⁻¹ were observed when Chlorella vulgaris was cultivated in WW, VW, and PW, respectively, suggesting that VW was a potential algal culture medium. Moreover, four algal strains could grow well on VW, but biomass production and nutrient removal of C. vulgaris were significantly higher than that of the other three strains, indicating that this alga was a promising algal strain for VW treatment. Furtherly, initial cell density was optimized for improving nutrients removal and biomass production. The maximum biomass concentration and productivity of 2.83 g L⁻¹ and 349.8 mg L⁻¹ d⁻¹, and TN, TP, and COD removal efficiencies of 80.02, 64.38, and 77.10 %, respectively, were obtained when initial cell density was 0.4 g L⁻¹. Initial cell density had little impact on the algal chemical composition, but availability and concentration of nutrients and algal species exhibited remarkable influences on the chemical compositions of microalgae cultivated in these wastewaters. These findings not only verified the feasibility of using vinegar production wastewaters to cultivate microalgae, but also paved a way for large-scale microalgae cultivation using the wastewaters.