A smartfilter for capturing and degrading microfibre

Materials World magazine
29 Oct 2019

A filter for washing machines has been developed in an effort to degrade microfibres released from clothing in a bid to reduce plastic pollution. Idha Valeur reports.

PETexe – a group on 10 students – from Exeter University, UK, have developed a smart filter that can prevent microfibres from entering and polluting water systems. The team said its ultimate goal is to help create a future ‘in which the washing of synthetic clothing is no longer the largest contributor to microplastic pollution’.

The inline filter works in two ways. First, it catches microfibres that are released from clothing during a normal washing cycle, and then it breaks down those plastics using enzymes in a solution, which are released by valves. When degraded, the result is terephthalic acid and ethylene glycol, which can safely be released into the water system as the large volume of water discharged during a wash cycle is enough to dilute the compounds.

PETexe team member and fourth-year mechanical engineering student, Rachael Quintin-Baxendale, told Materials World that, at the moment, the filters are being made using polylactic acid to allow for 3D printing of prototypes during design iterations in the testing phase. ‘Rapid prototyping has been essential as we are constrained by the project’s short timespan due to our entry to the International Genetically Engineered Machine competition, which is completed in early November,’ she said.

‘We currently anticipate an aluminium body for the filter, should the project progress further, although alternative materials have not been heavily researched at this point. The main consideration is simply that it is not a plastic body as this would provide a constraint when it comes to developing more plastic degrading enzymes.’

Minimal microplastics

According to fellow PETexe team member and material engineering student, Jonathan Elliott, research into methods on how to eliminate microplastics is incredibly important as millions of tonnes of them enter the ocean on a yearly basis from washing machines. ‘Microplastics have been detected in marine life around the globe, and while the research into the effects is still limited, any attempt to reduce the amount of microplastics being released is important and could have a significant effect,’ he said.

‘Our work specifically aims to not only prevent microplastic emission from washing machines into the water systems, but also degrade them so they are not removed and added to landfill.’

There’s an app for that

In addition to the filter, the PETexe team has developed an app which will be available for both iOS and Android by the start of November 2019.

‘The smart filter uses an Arduino microcontroller to open and close valves. Among other functionalities, this allows us to release the enzyme solution on demand. This Internet of Things device uses WiFi to connect to the internet. Thanks to Google Firebase sponsoring us, we can use their Cloud technology to support the infrastructure of our app. The biggest advantages of using Firebase are scalability, speed to market and ease with integrating with apps,’ PETexe team member and computer science student, Adriano Matousek, told Materials World.

‘Sensors on the smart filter collect data such as flow-rate which is then stored in the Cloud. In the future, we will analyse this data to feed back into the design and optimise various aspects of the filter, such as minimising the amount of enzyme we release to fully degrade the microplastics,’ he said.

Further, Matousek explained that the app will allow users to monitor their device and provide information if the filter changes status, if the enzyme solutions need to be refilled and how many microfibres have been saved from entering the oceans.

Applications and the future 

According to the team, the main focus is on domestic laundry, but they are also considering the potential to expand to fashion mills, water treatment centres and large-scale laundry services if the biology is proven successful. ‘We have had high interest from various stakeholders from different industrial sectors who have given feedback on how our filter could be implemented and developed further,’ Quintin-Baxendale said.

Although, currently, the filters are operating correctly, the team recognises that more work for further optimisation is required to make sure the filter is viable and effective. ‘However, a significant hurdle for wider adoption is the current lack of legislation or incentives provided by the government to control the microplastic pollution problem, as this means that the cost of the filter will be a burden on consumers,’ Quintin-Baxendale said.

The project is sponsored and supported by Google Firebase, SnapGene and Xeros Technology Group. The students are also working with the support from domestic appliance manufacturer, Miele, to research solutions.