Behavioural science for nanoparticles

Scientists from the Centre for Ecology & Hydrology (CEH) and the Science and Technology Facilities Council’s ISIS Neutron Source, along with colleagues from King’s College London and Oxford University, have been studying nanoparticle behaviour in sewage treatment plants and have identified a way to potentially help remove them during primary sewage treatment.

Nanoparticles are used in foods, cosmetics, medicines and cleaners. However, once discarded into the water supply, very little is known about their impact on the environment. The scientists examined silica nanoparticles commonly found in consumer products and routinely discharged to wastewater. They simulated primary sewage treatment and used the ISIS Neutron Source to view the sewage at the nanometre scale.

The neutrons penetrate the sewage and scatter from the nanoparticles, allowing the aggregation behaviour of the nanoparticles to be measured.

By doing this, the scientists could measure behaviour of the nanoparticles through time. They found that coating silica nanoparticles with a detergent-like material or surfactant made the nanoparticles interact with components of the sewage to form a solid sludge, which could then be separated from the wastewater.

‘Routine environmental checks do not pick up on the particles,’ said Dr Helen Jarvie of CEH. ‘If they reach the secondary stage of treatment they may also have an impact on the sustainability of the microbial communities used there. By adding coatings to them we may be able to direct their fate and make sure they are removed from