Sanitary masks have been keeping us company for almost two years now. Every day we buy them, we wear them to protect us from the virus, and finally we throw them away when they exhaust their function. Often we see them on the ground, abandoned on the sidewalk or on the banks of a river, when they actually should be disposed of among the unsorted waste. In a world that seems to be invaded by masks, Renewable Matter investigated the problems and opportunities of their recycling, reporting on the most virtuous recycling projects and practices in Italy and in the world.
How many masks (and gloves) do we consume in Italy and what happens to them?
Before addressing the issue of recycling, it is necessary to frame at a regulatory level the sanitary or surgical mask as waste and to numerically contextualize the amount of waste we are talking about.
In May 2020, since the survival time of the virus on the waste could hardly be calculated, the president of the Istituto Superiore di Sanità Silvio Brusaferro instructed that the masks and gloves should be disposed of as unsorted waste, but always collected in another closed bag to avoid contact by ecological operators. These directions are still valid today. “It’s a necessary measure to protect the waste management chain,” explains Valeria Frittelloni, head of the National Center for Waste and Circular Economy for Ispra, “that is, to eliminate from the separate collection a potential infectious risk for operators who separate, often through manual procedures, recoverable and recyclable waste. It is a different matter for hospital waste coming from infectious wards; those follow a particular management regulated by a decree of the President of the Republic in 2003”.
In short, since there is no separate collection, the masks are destined to end up in a landfill or, at best, the incinerator. However, analyzing the data on the production of this waste, Frittelloni excludes that there are any alarms or criticalities. According to the most recent Ispra estimates, the daily need for masks is around 35/40 million pieces. The annual waste production, considering the number of masks and gloves per inhabitants, use and average weight of the device, would be around 300 thousand tons in 2020. “Out of the 30 million tons of annual urban waste, they represent a very small percentage,” says Valeria Frittelloni to Renewable Matter, “This waste is not produced in such quantities as to justify the presence of dedicated plants for its management. The environmental alarm is more in the dispersion of masks and other light materials”.
“At the moment the masks are most certainly not the priority,” concludes Frittelloni, “we still have to solve the problem of the 7 million tons of urban waste that still end up in landfills. Plastic, organic fraction, paper: all absolutely recoverable waste”.
Polytechnic of Turin: polypropylene recycling experiments
From the circular economy point of view, for numerical and health reasons, the separate collection and possible recycling of personal protective equipment does not seem to be a priority. However, all over the world several universities and start-ups have been working to find solutions to recycle the polypropylene contained in masks, a plastic material useful for several applications.
To better understand the real possibilities of recycling it is necessary to understand how surgical masks are made. First of all, they are made of three layers of non-woven fabric of a plastic material called polypropylene, which for its characteristics is suited to the required function.
“The masks are generally composed of a filtering part in polypropylene,” explains Daniele Battegazzorre, laboratory technician at the Polytechnic of Turin, “The nose part, on the other hand, is usually composed of a metal wrapped in plastic. Even the elastics are rather heterogeneous. All of this implies a process of separation of materials that complicates recycling”. Dr. Battegazzorre and Professor Alberto Frache of the Department of Applied Sciences and Materials Technology at the Polytechnic University of Turin recently published research in the journal Polymers that demonstrates the real possibilities of recycling masks. “The recycling process used is thermomechanical,” Frache explains, “We thought of four different processes to obtain four thermoplastic materials with somewhat different characteristics from each other, from which plastic objects can be obtained that can be injection molded or extruded”.
By working with polypropylene, you can manufacture PC keyboards, stools, smartphone covers, benches, and lots of other objects. However, with recycled plastic, you can't reproduce other masks for two reasons. “First, because the masks are devices that come into contact with the mouth and by law must be made of virgin plastics,” explains Daniele Battegazzore to Renewable Matter. “The second is the quality of finish of these fibers. They cannot have imperfections that could compromise the filtering capability”.
“Initially we tested only new masks. Then, thanks to the collaboration with the municipality of Mondovì (Cuneo) and the cultural association Circolo delle Idee, which in June collected a large number of disposable masks from the Vasco-Beccaria-Govone High School, we took them to a center for sanitization and tested the recycling of heterogeneous masks, of different colors and types of elastic bands”.
According to Alberto Frache, the steps to make recycling possible are two: “First, disposable masks should be separated at least in those contexts where it is easier to collect the waste, such as schools or factories. Sanitization would be the next step, but since we are not virologists we cannot express ourselves with absolute certainty on the sterilization and killing of the virus”.
New roads in Australia
In Australia, researcher Mohammad Saberian Boroujeni of the Royal Melbourne Institute of Technology has investigated a system for turning masks into asphalt. “First, the masks need to be collected and extracted from other waste streams,” Boroujen explains to Renewable Matter. “They can be pulled from the rest of the waste stream using jets and air barriers. Next, the masks must be disinfected and shredded into fibers with a length of 2 cm and a width of 0.5 cm. Finally, these fibers are ready to be mixed with processed construction rubble or recycled cement aggregate.” The University of Melbourne is planning to build a road with this material and there are some local companies interested in collaborating on the project.
“Face masks have some amazing properties, including high tensile strength and ductility,” Boroujeni continues, “Using them could provide greater strength and flexibility to the base and subbase of roads”. For this application, it is not necessary to separate the propylene layers as it would be a labor-intensive process. “All the layers of the masks can be recycled and reused for road construction,” the researcher assures us.
German Chemical Recycling
In Germany, the focus is on chemical recycling in a project involving Fraunhofer Institute UMSICHT, SABIC and Procter & Gamble. The company P&G has begun collecting used surgical masks from employees at its production sites. The waste is then taken to an experimental pyrolysis facility. “A single-use healthcare product like a surgical mask has high hygiene requirements, both in terms of disposal and manufacturing. Mechanical recycling would not have worked,” explains Alexander Hofmann, head of the Recycling Management department at Fraunhofer UMSICHT. “Therefore, in our solution, we first automatically shredded the masks, then thermochemically converted them into pyrolysis oil”. According to Hofmann, pyrolysis breaks down the plastic into molecular fragments under pressure and heat, which will also destroy any residual pollutants or pathogens, including coronavirus. This would make it possible to produce raw materials that can also meet the requirements of health care products.
In France and in Canada
Plaxtil, a small start-up company from Châtellerault, a municipality in French New Aquitaine, is collecting used masks in strategic locations such as shopping malls or pharmacies; after which they are quarantined for four days. After the hand removal of the underwire for the nasal closure, they are crushed in a special machine and sterilized by passing them through a UV tunnel. The next step is mixing them with a special resin to harden the material to the right consistency. In this way, various objects can be produced, including anti-Covid items, such as transparent protective visors.
The company Vitacore, based in a small suburb of Vancouver, Canada, has devised a way to derive building materials by recycling masks. First, the devices are sanitized over high heat. Then the plastic material is shredded and prepared for melting. Once melted, polypropylene pellets are obtained and reused in building materials and as concrete reinforcement.
Can biodegradable masks be a solution?
“There are several factors that make the use of biodegradable materials complicated,” explains Alberto Frache. “Polyester materials are much more sensitive to humidity and I don't think it's easy to create a fabric like the one used for masks. At the moment, biodegradable materials cost twice as much and are difficult to find. From the point of view of recyclability, I don't see any problem, but the masks thrown on the ground remain, even if they are biodegradable”.
The Lausanne Institute of Technology in Switzerland is experimenting with HelloMask, a plastic made from 99% biomass. It is transparent, it filters at the right point and is, of course, biodegradable, but it costs too much.
Finally, there is talk of financial unsustainability for large-scale production for another idea born in Australia. The Queensland University of Technology is testing a fabric made from sugar cane waste: the cellulose fibers would make it capable of filtering nano particles the size of viruses, leaving a good ability to breathe.
Image: ph Daniel Tafjord, art Pobel (Unsplash)