1. Role of phosphate in microalgal-bacterial symbiosis system treating wastewater containing heavy metals.
- Author
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Tang, Cong-Cong, Hu, Ya-Ru, Zhang, Min, Chen, Sheng-Long, He, Zhang-Wei, Li, Zhi-Hua, Tian, Yu, and Wang, Xiaochang C.
- Subjects
HEAVY metals ,ALGAL communities ,PRECIPITATION (Chemistry) ,PHOSPHATE removal (Sewage purification) ,SYMBIOSIS ,CHEMICAL oxygen demand ,SEWAGE - Abstract
Phosphorus is one of the important factors to successfully establish the microalgal-bacterial symbiosis (MABS) system. The migration and transformation of phosphorus can occur in various ways, and the effects of phosphate on the MABS system facing environmental impacts like heavy metal stress are often ignored. This study investigated the roles of phosphate on the response of the MABS system to zinc ion (Zn
2+ ). The results showed that the pollutant removal effect in the MABS system was significantly reduced, and microbial growth and activity were inhibited with the presence of Zn2+ . When phosphate and Zn2+ coexisted, the inhibition effects of pollutants removal and microbial growth rate were mitigated compared to that of only with the presence of Zn2+ , with the increasing rates of 28.3% for total nitrogen removal, 48.9% for chemical oxygen demand removal, 78.3% for chlorophyll-a concentration, and 13.3% for volatile suspended solids concentration. When phosphate was subsequently supplemented in the MABS system after adding Zn2+ , both pollutants removal efficiency and microbial growth and activity were not recovered. Thus, the inhibition effect of Zn2+ on the MABS system was irreversible. Further analysis showed that Zn2+ preferentially combined with phosphate could form chemical precipitate, which reduced the fixation of MABS system for Zn2+ through extracellular adsorption and intracellular uptake. Under Zn2+ stress, the succession of microbial communities occurred, and Parachlorella was more tolerant to Zn2+ . This study revealed the comprehensive response mechanism of the co-effects of phosphate and Zn2+ on the MABS system, and provided some insights for the MABS system treating wastewater containing heavy metals, as well as migration and transformation of heavy metals in aquatic ecosystems. [Display omitted] • The role of phosphate on MABS system under Zn2+ stress was investigated. • Phosphate alleviated but did not eliminate Zn2+ inhibition on MABS system. • Co-precipitation of phosphate with Zn2+ and biosorption occurred simultaneously. • Zn2+ inhibition was irreversible and induced the growth of tolerant microorganisms. • Both successions of microalgal and bacterial communities were revealed. [ABSTRACT FROM AUTHOR]- Published
- 2024
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