Enhancement of ammonium removal from landfill leachate using microalgae by an integrated strategy of nutrient balance and trophic mode conversion

• Published in: Algal research (Amsterdam) 2022-01, Vol.61, p.102572, Article 102572
• Main Authors: Li, Jingjing, Qian, Jun, Tang, Junhang, Jin, Zeyu, Lu, Qian, Cheng, Jiali, Zhou, Xiangqin, Zhang, Xiru, Fu, Siyi, Wan, Ting, Li, Hugang, Chen, Qin, Zhou, Wenguang
• Format: Article
• Language: English
• Subjects: Ammonium removal; Landfill leachate; Nitrogen deprivation; Nutrient balance; Protein; Trophic mode conversion
• ISSN: 2211-9264; 2211-9264
• DOI: 10.1016/j.algal.2021.102572

Landfill leachate is heavily-polluted wastewater generated from municipal solid wastes, which generally includes amounts of ammonium that are highly toxic to living organisms and the environment. The locally isolated microalgae have great potential in removing ammonium and producing value-added biomass from leachate. In this study, we determined the most robust algal strain, which was isolated and screened from a local landfill, and identified using the 18 s RNA gene sequences analysis. Subsequently, the integrated strategy of nutrient balance and trophic mode conversion was employed to make the leachate suitable for ammonium removal and algal growth. The results showed that a most robust, locally isolated strain NCU-9 (Nanchang University-9), was a promising strain and was selected out of four candidates and identified as Chlorella pyrenoidosa. This strain had a high tolerance to ammonium and leachate-borne bacteria when grown in unsterilized leachate. An optimal strategy was used, which included the nutrient balancing of nitrogen (N) to phosphorus (P) ratio (N/P) at 30:1 along with trophic mode conversion of N deprivation, to enhance the ammonium removal rate to as high as 95% in leachate remediation. The protein analysis of the cell composition was used to confirm this optimum strategy for ammonium removal, while the potential of NCU-9 was also considered as a value-added feedstock for animal feed in the downstream industry. Based on these results, we can conclude that microalgae-based leachate remediation has practical potential for nutrient recovery and biomass utilization. [Display omitted] •One promising isolated algal strain NCU-9 was identified as Chlorella pyrenoidosa.•95% removal of NH4+-N was achieved by nutrient balance and trophic mode conversion.•High protein content of NCU-9 was achieved by trophic mode conversion in leachate.