Assessing the effects of silver nanoparticles on biological nutrient removal in bench-scale activated sludge sequencing batch reactors
Consumer products are increasingly integrating Ag and Ag nanoparticles (AgNPs) because of their antimicrobial properties. As AgNPs wash off these products, they may enter into wastewater streams and could possibly impact microorganisms essential to biological nutrient removal. In this study, Gum Arabic and Citrate coated AgNPs were spiked into sequencing batch reactors (SBRs) inoculated with nitrifying sludge from a local wastewater treatment plant. Treatment efficiency (COD and ammonia removal), Ag dissolution measurements, and microbial community analyses were performed to evaluate the response of the SBRs to Ag addition. Results suggest that nitrifying and heterotrophic functions were disrupted initially following pulse additions, but stabilized rapidly. Ammonia removal was more strongly affected than COD by both Ag as AgNO3 and AgNPs. The results indicate that Ag and AgNPs could impact wastewater treatment in the short term but the amount of treatment disruption will depend on the magnitude of influent Ag.
