The quantity of man-made nanomaterials (MNMs) being used in consumer products continues to increase. Some consumer products such as sunscreens and cosmetics directly expose humans and the environment to MNMs. However, potential concerns regarding the safety of nanomaterials to humans and the environment, have led to many technology applications actively 'locking away' MNMs during the lifetime of consumer products. Importantly, during or at the end of their life, most consumer products will enter a waste processing facility, e.g. WWTP or solid waste processing plant and MNMs will potentially be released. The NanoWASTE project seeks to fill existing knowledge gaps on MNMs 'end of life' and answer key questions for scientists and regulatory authorities.
The NanoWASTE project will investigate what happens to MNMs when they enter WWTPs. The NanoWASTE project will specifically study titanium dioxide (TiO2) and silver (Ag) MNMs as they are already widely used in a number of consumer products and found to enter waste water streams. In order to be able to follow the TiO2 and Ag MNMs in a complex WWTP system isotopically labelled versions will be synthesised and used in the project. One part of the work will study how the WWTP processes and conditions affect the physical and chemical properties of MNMs (e.g. size, aggregation, surface chemistry) through 'aging'. Importantly, the project will assess MNM removal efficiency during the waste water treatment process. A second focus is to see if there are any negative effects from MNMs which cause a decrease in the operational efficiency of WWTPs. MNMs entering WWTPs will either be removed from the water stream into the sewage sludge or pass directly through the system, exiting with the water effluent. Sewage sludge is often used further as an agricultural fertiliser whilst waste water effluent is typically discharged directly to aquatic systems. The environmental impacts of 'aged' MNMs in both waste water effluent and sewage sludge will be studied, including a comparison with pristine MNMs. In the final stage of the project, models for predicting MNM fate in WWTP processes will be developed
Overall, the project will provide a greater insight into the potential hazards of MNMs to both WWTPs and the environment. The project aims to challenge nanotechnology developers to consider 'end of life' as a key aspect of their design approach. The data generated in this project will be presented to stakeholders together with suggestions for protecting WWTPs from MNM impacts and for reducing MNM release from WWTPs. We hope that the knowledge generated can contribute to the development of future regulations regarding MNMs in consumer products and their disposal at 'end of life'.