Published 2018-05-24This post is also available in Swedish
Better cleaning with smart renewable materials
Purification filters that not only remove environmentally hazardous substances but also inform the operators that it is time to change filter material — this is one line being pursued in Mistra TerraClean, a research programme intended to develop sustainable and smart purification systems.
‘At the moment, there’s a flurry of activity in our partner labs. Doctoral students are working all over the place to produce and test new materials,’ says Ulrica Edlund, Professor of Polymer Technology at KTH Royal Institute of Technology and Programme Director of Mistra TerraClean.
The research programme Mistra TerraClean, which started in earnest in the autumn, is setting out to develop new methods of purifying air and water. Heavy metals, toxic organic compounds and nitrogen oxides are some of the environmentally hazardous substances for which scientists want to find more effective separation methods. But the programme is about not just developing new materials with increased removal efficiency, but also adding new, ‘smart’ features to the materials.
‘We’re going to modify our materials to make them smarter — either by putting on new chemical groups that can selectively attract a specific contaminant, or by applying tiny electronic sensors that can add new functions in various ways.’
Today’s filters require a great deal of manual monitoring. A smart filter equipped with sensors could, for example, send data to the operators when it is time for maintenance — when the material is saturated and the time has come to change it. But it can also adjust its function to maintain the cleaning capacity, even if the composition of the wastewater or combustion gases changes.
‘The programme’s basic idea is to develop new filter materials that do a better job, and can be regulated more, than current passive filters.’
Nanocellulose is one of four types of materials studied. This material is relatively new, and there are hopes that many applications will be found in the long term, in areas ranging from food packaging to flexible electronics. Mistra TerraClean researchers hope to use nanocellulose for water purification.
‘We’ve previously carried out projects with nanocellulose to purify industrial process water. We want to continue developing the material in Mistra TerraClean,’ says Aji Mathew, Professor at Stockholm University.
In a previous EU project, Mathew and her colleagues developed new filter materials based on nanocellulose. In trials in the paper industry, the material proved to have good properties compared with traditional industrial filters. With the mining industry, Mistra TerraClean researchers will continue to develop the material.
‘Their process water contains impurities, mainly metals, which are difficult to remove with ordinary filters. We’ll try to increase the functionality of the nanocellulose, both to increase the amount of metal we can remove from the process water and to prolong the life of the filter.’
In addition to nanocellulose, three other types of materials will be studied: zeolites, activated carbon and Upsalite. Activated carbon and zeolites are already used for industrial purification. Upsalite, a type of magnesium carbonate, is a promising substance first produced in a laboratory at Uppsala University a few years ago.
‘These are four materials where we in Sweden are at the cutting edge of research. What´s more, it’s possible to produce all the materials from renewable raw materials,’ Edlund says.
Research in Mistra TerraClean is organised into five subareas — ‘work packages’. In the first two, potential filter materials will be developed in labs. This means producing, characterising and testing new materials, but also determining what smart features can be added.
Mistra TerraClean cooperates with a number of companies in the mining industry, and also with, for example, energy companies and manufacturers of chemicals and filters. Municipal wastewater treatment plants are also participating through their trade association, the Swedish Water & Wastewater Association (SWWA).
‘The companies are our problem owners, so they’re important right from this early development phase. We have a dialogue with our industry partners so that we know what needs there are and what purification requirements we have to meet,’ Edlund says.
Once the materials have been manufactured and tested in the laboratory, it is time to test their functioning on a larger scale. Edlund hopes that the first case studies at partner companies can start in 2018.
One of the major challenges of the programme will be to go from promising trials on a lab scale to a working product at industrial level. The volumes of contaminated air or wastewater to be purified are considerably larger, and the controlled conditions prevailing in the lab are never equivalent to those in industry.
Edlund agrees that there will be a challenge.
‘However, our goal is that by the end of the programme period, there will be a number of functional materials that work on a large industrial scale.’
Text: Henrik Lundström
Facts — Mistra TerraClean is developing sustainable purification systems
Mistra TerraClean, with a total budget of SEK 60 million, began in 2017 and will continue until 2021. The programme is led from KTH Royal Institute of Technology, and there are several universities and research organisations in the consortium: Stockholm University, Uppsala University, Swetox — Academic Research Centre for Chemicals, Health and Environment, IVL Swedish Environmental Institute, RISE Research Institutes of Sweden and the trade association SwedNanoTech. Among the companies participating are Vattenfall, Boliden, Camfil and AkzoNobel.