Advances in responses of microalgal-bacterial symbiosis to emerging pollutants in wastewater.

Nowadays, emerging pollutants are widely used and exist in wastewater, such as antibiotics, heavy metals, nanoparticle and microplastic. As a green alternative for wastewater treatment, microalgal-bacterial symbiosis has been aware of owning multiple merits of low energy consumption and little greenhouse gas emission. Thus, the responses of microalgal-bacterial symbiosis to emerging pollutants in wastewater treatment have become a hotspot in recent years. In this review paper, the removal performance of microalgal-bacterial symbiosis on organics, nitrogen and phosphorus in wastewater containing emerging pollutants has been summarized. The adaptation mechanisms of microalgal-bacterial symbiosis to emerging pollutants have been analyzed. It is found that antibiotics usually have hormesis effects on microalgal-bacterial symbiosis, and that microalgal-bacterial symbiosis appears to show more capacity to remove tetracycline and sulfamethoxazole, rather than oxytetracycline and enrofloxacin. Generally, microalgal-bacterial symbiosis can adapt to heavy metals at a concentration of less than 1 mg/L, but its capabilities to remove contaminants can be significantly affected at 10 mg/L heavy metals. Further research should focus on the influence of mixed emerging pollutants on microalgal-bacterial symbiosis, and the feasibility of using selected emerging pollutants (e.g., antibiotics) as a carbon source for microalgal-bacterial symbiosis should also be explored. This review is expected to deepen our understandings on emerging pollutants removal from wastewater by microalgal-bacterial symbiosis.