Microalgae cultivation in domestic wastewater for wastewater treatment and high value-added production: Species selection and comparison

Abstract

In this study, six freshwater microalgae, including Scenedesmus sp. LX1, R. subcapitata, T. obliquus, Chlorella sp. HL, Chlorella sp. (A), and Chlorella sp. (B), were appraised for growth, nutrient removal, and high value-added productions in municipal domestic wastewater to select the species with greatest utilization potential. The results showed that after 10 d of cultivation under the sterilized condition, Chlorella grew better than others and Chlorella sp. HL obtained the highest algae density (2.44 × 107 cells/mL). The maximum biomass obtained from Scenedesmus sp. LX1 was 0.55 g/L. The maximum COD removal rate was achieved by R. subcapitata (79.01 %). Scenedesmus sp. LX1 showed excellent NH4+-N and TP remove capacity and achieved the highest removal rate (93.81 % and 87.72 %, respectively) eventually. The harvested biomass was found to accumulate high value-added products, especially protein, with a highest content of 54.64 %, which was observed in T. obliquus. Under the sterilized condition, Scenedesmus sp. LX1 was considered as the optimal candidate for municipal domestic wastewater treatment. Under the non-sterilized condition, Chlorella sp. HL was found to perform better than Scenedesmus sp. LX1 and T. obliquus no matter water purification, algal growth, and high value-added products accumulation.