| Summary: | Investigating the behaviour, fate and transport of Silver nanoparticles (Ag-NPs) in wastewater treatment plants (WWTPs) is of great importance due to their presence in many consumer products and its potential to be toxic to environmental organisms. In this study, the transformation and fate of Ag-NPs was assessed using a multi-method characterisation approach, prior-to, during and post-aeration in the pilot sequencing batch reactor (SBR) and over a 21 day period in SBR. Synthesized 10 nm citrate and polyvinylpyrrolidone (PVP) coated Ag-NPs were spiked into OECD synthetic sewage (OECDss) media and it constituents and in the (OECDss) + activated sludge (AS) media. Ag-NPs show agglomeration, dissolution and changes in surface chemistry at all measured time points i.e., at 0 hrs, at 24 hrs, at 45 hrs (during aeration) and at 48 hrs (during settling) and indicated that 80% of the citrate and PVP Ag-NPs could be removed in the form of Ag2S, AgCl and Silver Phosphate-NPs. More than 50% of Ag-NPs accumulated within the sludge over a 21 day period (with no addition of fresh AS), and this occurred via physical adsorption on the surface of the AS flocs. This work demonstrates that Ag-NPs in wastewater can undergo a range of transformation processes, which include oxidation, dissolution, agglomeration, precipitation in an SBR pilot plant.
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