Revealing mechanisms of triclosan on the removal and distribution of nitrogen and phosphorus in microalgal-bacterial symbiosis system

• Published in: Environmental pollution (1987) 2023-11, Vol.337, p.122539-122539, Article 122539
• Main Authors: Chen, Sheng-Long, Wang, Tian-Yang, Tang, Cong-Cong, Wang, Rong, He, Zhang-Wei, Li, Zhi-Hua, Tian, Yu, Wang, Xiaochang C.
• Format: Article
• Language: English
• Subjects: Bio-accumulation; Extracellular polymeric substance; Microbial community structure; Microbial growth; Nutrient removal
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2023.122539

Microalgal-bacterial symbiosis (MABS) system performs synergistic effect on the reduction of nutrients and carbon emissions in the water treatment process. However, antimicrobial agents are frequently detected in water, which influence the performance of MABS system. In this study, triclosan (TCS) was selected to reveal the effects and mechanisms of antimicrobial agents on MABS system. Results showed that the removal efficiencies of chemical oxygen demand, NH4+-N and total phosphorus decreased by 3.0%, 24.0% and 14.3% under TCS stress. In contrast, there were no significant decrease on the removal effect of total nitrogen. Mechanism analysis showed that both the growth rate of microorganisms and the nutrients retention capacity of extracellular polymeric substances were decreased. The intracellular accumulation for nitrogen and phosphorus was promoted due to the increased cytomembrane permeability caused by lipid peroxidation. Moreover, microalgae were dominant in MABS system with ratio between microalgae and bacteria of more than 5.49. The main genus was Parachlorella, with abundance of more than 90%. Parachlorella was highly tolerant to TCS, which might be conductive to maintain its survival. This study revealed the nutrients pathways of MABS system under TCS stress, and helped to optimize the operation of MABS system. [Display omitted] •The MABS system with or without EPS exfoliation were used to reveal TCS’ effects.•The removal of COD, NH4+-N and TP decreased while TN removal was not affected.•Microbial assimilation, EPS adsorption and bio-accumulation were affected by TCS.•The dominant microalgal and bacterial species were Parachlorella and Rhodococcus.•Microalgae played leading roles on assimilation and bio-accumulation.