Recycling of Nutrients from Dairy Wastewater by Extremophilic Microalgae with High Ammonia Tolerance

• DOI: 10.1021/acs.est.0c02833
• Publication Date: 2020-11-15T21:41:26Z
• Authors: Na Pang; Andre David Bergeron; Xiangyu Gu; Xiao Fu; Tao Dong; Yiqing Yao; Shulin Chen
• Keywords: Nitrogen; Phosphorus; Nutrients; Wastewater; 7. Clean energy; 01 natural sciences; 6. Clean water; 12. Responsible consumption; Extremophiles; Ammonia; Microalgae; Biomass; Chlorella vulgaris; 0105 earth and related environmental sciences

This study explored the possibility of incorporating extremophilic algal cultivation into dairy wastewater treatment by characterizing a unique algal strain. Results showed that extremophilic microalgae Chlorella vulgaris CA1 newly isolated from dairy wastewater tolerated a high level of ammonia nitrogen (2.7 g/L), which was over 20 times the ammonia nitrogen that regular Chlorella sp. could tolerate. The isolate was mixotrophically cultured in dairy effluent treated by anaerobic digestion (AD) for recycling nutrients and polishing the wastewater. The highest biomass content of 13.3 g/L and protein content of 43.4% were achieved in the culture in AD effluent. Up to 96% of the total nitrogen and 79% of the total phosphorus were removed from the dairy AD effluent. The ability of the algae to tolerate a high level of ammonia nitrogen suggests the potential for direct nutrient recycling from dairy wastewater while producing algal biomass and high value bioproducts.