Silver nanoparticles (AgNPs) released from different consumer products will be transported to wastewater treatment plants. We will investigate the behaviour of AgNPs during the wastewater treatment, focusing on the physical and the chemical changes of the AgNPs which significantly affect the toxicity of the AgNPs as well as their transmission through the wastewater treatment plants.
Background
AgNPs are increasingly used as biocides in a wide range of products. The release of AgNPs from the respective goods is of concern due to the potential impact on the environment and thus needs to be investigated. AgNPs, or nanomaterials in general, released from domestic and industrial sources are mostly collected in sewer systems and transported to wastewater treatment plants (WWTPs) from where they may enter the aquatic environment (or soils via sewage sludge). WWTPs thus play a key role in controlling the release of AgNPs into the environment.
Aim
The fate of the AgNPs including their transmission through the WWTP and their sequestration into sewage sludge strongly depends on their physico-chemical properties. We will investigate the physical (agglomeration) and chemical (speciation of Ag) changes of the AgNPs during different stages of the wastewater treatment including aerobic and anaerobic conditions. For that purpose we will use electronmicroscopic and spectroscopic methods. Specifically, we will evaluate the effect of the size and of the surface coatings (functionalisation) of the AgNPs on their transmission through the WWTP.
Significance
An improved mechanistic understanding of the physical and chemical processes controlling the retention / transmission of AgNPs in WWTPs will to some extent also be transferable to assessing the retention of other types of NPs in WWTPs. Furthermore, the results of this study will enable us to evaluate the importance of other pathways of nanomaterials into the environment such as the direct discharge via stormwater overflows relative to the WWTPs.
The results of this study will therefore contribute to a more accurate exposure modelling of AgNPs and in addition will help to develop new nanomaterials with a reduced impact on the environment.
Original title: Behavior of silver nanoparticles in a wastewater treatment plant
Grant: CHF 221'648.-
Duration: 36 months
Project leader
- Dr. Ralf Kägi