Exploration of Microalgal Species for Nutrient Removal from Anaerobically Digested Swine Wastewater and Potential Lipids Production

Bio-treatment of anaerobically treated swine wastewater (ADSW) mediated by microalgae has been deemed as a promising strategy. In the present study, six microalgal strains were used to conduct batch experiments in 0~100% ADSW in order to evaluate their potentials for nutrient removal and biodiesel production. Two strains, Chlorella vulgaris FACHB-8 and Chlorella sp. FACHB-31, were selected based on their better growth performances, higher tolerance to wastewater (up to 100%), and better nutrient removal abilities. The capacity of each strain to remove TN, TP, NH4+-N, as well as lipid production and biomass composition in 100% ADSW were further examined. After 15 days of culture, 87.68~89.85%, 92.61~93.68%, and 97.02~97.86% of the nitrogen, phosphorus, and ammonia nitrogen were removed by Chlorella sp. FACHB-31 and C. vulgaris FACHB-8. Their lipid content and lipid productivities were 29.63~33.33% and 18.91~23.10 mg L-1 d(-1), respectively. Proteins were both the major biomass fraction followed by lipids and then carbohydrates. Their fatty acid profiles both mainly consisted of C-16:0, C-18:1, C-18:0, and C-18:2. Taken together, our results suggest that C. vulgaris FACHB-8 and Chlorella sp. FACHB-31 are potential candidates for biodiesel production by using ADSW as a good feedstock.

Automated summary

In this study, six microalgal strains were evaluated for their nutrient removal and biodiesel production potential in anaerobically treated swine wastewater. Two selected strains, Chlorella vulgaris FACHB-8 and Chlorella sp. FACHB-31, showed good performance in removing nitrogen, phosphorus, and ammonia nitrogen, as well as producing significant amounts of lipids. The fatty acid profiles of these strains mainly consisted of C-16:0, C-18:1, C-18:0, and C-18:2.