Mitigating excessive ammonia nitrogen in chicken farm flushing wastewater by mixing strategy for nutrient removal and lipid accumulation in the green alga Chlorella sorokiniana

Abstract

This study aimed to evaluate algal growth, lipid production, and nutrient removal in chicken farm flushing wastewater (CFFW). The excessive ammonia nitrogen (EAN) content in the CFFW wastewater represented a major factor limiting the algal growth. A strategy of mixing CFFW with municipal wastewater (MW) that contained less ammonia nitrogen was adopted. The results showed that the mixed wastewaters reduced ammonia nitrogen content, balanced nutrient profile, and promoted biomass production. The residual nutrients in mixed wastewaters were significantly reduced due to the algal absorption. Furthermore, alga grown on mixed wastewaters accumulated a higher level of total lipids and monounsaturated fatty acids that can be used for biodiesel production. The key issue of low biomass yield of algal grown on CFFW due to the inhibition of EAN was efficiently resolved by mitigating limiting factor to algal growth basing on mixing strategy, and accordingly the nutrients in the wastewater were significantly removed.

Keywords: Biomass production; Chicken farm flushing wastewater; Chlorella sorokiniana; Mixed strategy; Nutrient removal.