Integrating electrochemical pretreatment with microalgae treatment for nitrogen and phosphorus removal and resource recovery from swine wastewater

This study integrates electrochemical pretreatment with microalgae (Scenedesmus obliquus) treatment to enhance nitrogen and phosphorus removal and resource recovery from swine wastewater. By optimizing electrochemical and microalgae treatment conditions, the dilution factor and the hydraulic retention time for microalgae treatment were reduced to 5 times and 7 days, respectively. Under the optimized operational conditions, removal efficiencies of total nitrogen and ammonia could reach over 89 % and 96 %, respectively, and the removal efficiency of total phosphorus was over 99 %. The study also found that aluminum was more suitable than iron for anode as it produced fewer residues. Additionally, the electrochemical pretreatment reduced Cu²⁺ and Zn2⁺ concentrations, mitigating negative impacts on microalgal growth. The microalgae biomass harvested from developed processes was rich in saturated fatty acids, which was desirable for biodiesel production. This approach addresses the challenges of nutrient removal for swine wastewater treatment with high quality biomass recovery.