Riboflavin-induced microbial succession for enhanced tellurite reduction in wastewater treatment

Abstract

Tellurite is a common component of industrial wastewater; thus, its efficient removal is crucial for environmental protection and wastewater treatment. Although the efficiency is low, the activated sludge process (ASP) is frequently used to treat wastewater by reducing tellurite (Te(Ⅳ)) to harmless elemental tellurium (Te(0)). Riboflavin is a biostimulant that when added to ASP can significantly shape the structure of microbial communities and improve the efficiency of treating telluride-containing wastewater. However, the underlying biological mechanism remains unclear. Herein, two groups—control and biostimulation—of sequencing batch reactors (SBRs) were constructed and run under the same conditions. In the control group (CG), only tellurite was added, whereas biostimulation group (BS) was treated with tellurite and riboflavin. After adding riboflavin, chemical oxygen demand, tellurite removal rates, and extracellular polymeric substance generation increased. The 16 S rRNA high-throughput sequencing results revealed that the succession of microbial communities was effectively promoted in the ASP by riboflavin treatments and that telluride-reducing bacteria—such as Sphingopyxis, Shinella, Brevundimonas, and Brucella—were significantly increased. Key topological properties suggested that riboflavin treatments changed the co-occurrence patterns of SBR microbial communities and strengthened microbial interactions, considerably improving the stability and efficiency of the tellurium-containing wastewater treatment system. In summary, we explored the effect of adding riboflavin to the ASP to stimulate the succession of sludge microbial communities for improved tellurite reduction. The findings of this research contribute to our understanding of the mechanism of riboflavin in optimizing wastewater treatment for removing recalcitrant pollutants.