Ecotoxicological response of Spirulina platensis to coexisted copper and zinc in anaerobic digestion effluent

• Published in: The Science of the total environment 2022-09, Vol.837, p.155874-155874, Article 155874
• Main Authors: Zhou, Ting, Li, Xuan, Zhang, Qi, Dong, Shiman, Liu, Huan, Liu, Yuhuan, Chaves, Alex V., Ralph, Peter J., Ruan, Roger, Wang, Qilin
• Format: Article
• Language: English
• Subjects: Ecotoxicological response; Heavy metal; Risk assessment; S. platensis; Sterilized anaerobic digestion effluent
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.155874

Copper ion (Cu2+) and zinc ion (Zn2+) are widely co-existent in anaerobic digestion effluent as typical contaminants. This work aims to explore how Cu2+-Zn2+ association affects physiological properties of S. platensis using Schlösser medium (SM) and sterilized anaerobic digestion effluent (SADE). Microalgae cells viability, biochemical properties, uptake of Cu2+ and Zn2+, and risk assessment associated with the biomass reuse as additives to pigs were comprehensively assessed. Biomass production ranged from 0.03 to 0.28 g/L in SM and 0.63 to 0.79 g/L in SADE due to the presence of Cu2+ and Zn2+. Peak value of chlorophyll-a and carotenoid content during the experiment decreased by 70–100% and 40–100% in SM, and by 70–77% and 30–55% in SADE. Crude protein level reduced by 4–41% in SM and by 65–75% in SADE. The reduction ratio of these compounds was positively related to the Cu2+ and Zn2+ concentrations. Maximum value of saturated and unsaturated fatty acids was both obtained at 0.3 Cu + 2.0 Zn (50.8% and 22.8%, respectively) and 25% SADE reactors (33.8% and 27.7%, respectively). Uptake of Cu in biomass was facilitated by Zn2+ concentration (> 4.0 mg/L). Risk of S. platensis biomass associated with Cu2+ was higher than Zn2+. S. platensis from SM (Cu2+ ≤ 0.3 mg/L and Zn2+ ≤ 4.0 mg/L) and diluted SADE (25% and 50% SADE) reactors could be used as feed additives without any risk (hazard index 4.0 mg/L) in medium promotes the uptake of Cu2+ by S. platensis cells.•S. platensis sufficiently recovered nutrient from anaerobic digestion effluent.•Heavy metals in anaerobic digestion effluent were removed by S. platensis.•C18:3 proportion increased by 97.04% at 0.3 mg/L Cu2++2.0 mg/L Zn2+.•Biomass from 25% and 50% anaerobic digestion effluent can be used as animal feeds.