The current global pandemic caused by COVID-19 has accelerated the demand for single-use personal protective equipment (PPE). This has led to a resurgence of an already-existing environmental pollution crisis. It is estimated that with the passage of the coronavirus epidemic every month, there is expected use of 200 billion pieces of single-use face masks and gloves. COVID-19 single-use PPE has generated a waste management nightmare often ending up littering the streets, as microplastics in the sea, or in landfills. To deal with the large volumes of waste in the form of discarded PPE requires waste valorisation solutions. Civil engineering applications have been going through a sustainable drive and potentially are an attractive waste management destination for single-use PPE. The civil engineering alternative to recycling COVID-19 single use PPE reduces environmental impact from disposal and incineration. It has become imperative for the research community to develop various recycling solutions that can increase the uptake of this clinical waste material.
In this article, Global Road Technology evaluates recycling COVID-19 single-use PPE from cradle to cradle focusing on civil engineering applications.
What are the parent materials of single-use PPE?
Disposable face masks are produced using polymeric material, which are a voluminous source of microplastics in the environment. Face masks are the most used PPE at the global scale. Disposable face masks are made of different plastics which include:
- mainly polypropylene
- polyethylene
- polyurethane
- polyacrylonitrile
- polystyrene
- polycarbonate
Whereas disposable gloves are made of different materials including:
- PVC
- rubber
- nitrile
- neoprene
What are the challenges with single-use PPE?
There are many challenges associated with single-use PPE and their effects depend on where the single-use PPE ends up being in the linear cycle from single-use to the environment.
Are environmental regulations, health and safety concerns or potential profit loss a concern right now?
These are some of the challenges:
- non-biodegradable takes years to breakdown
- water bodies (river, sea, lakes) pollution
- infiltrates fragile habitats
- end up in food supplies
- easily transported by wind and rainwater
- disintegration into micro and nano plastics
- release of toxic materials
- can harbour the virus if not disinfected
Road construction applications of single-use PPE?
Single-use PPE has been used innovatively to reduce pandemic-generated waste by recycling and reusing the shredded face mask and mixing with recycled concrete aggregate for road construction. The results found that mixtures of shredded face masks and recycled concrete aggregate fitted within the upper and lower bound limits of the standard specifications for Type 1 gradation C materials for road base and subbase. The shredded face mask fibres were found to be very light with a low specific gravity. The results of the tensile tests indicated that the polypropylene layer of the masks contributed to most of the tensile strength. Furthermore, the fibres provided better strength and stiffness.
The inclusion of the shredded face mask into the recycled concrete aggregate provided more ductility and flexibility for the road base and subbase layers because of the higher tensile strength of shredded face mask with more flexibility compared to recycled concrete aggregate. Using shredded face mask with recycled concrete aggregate as an alternative road base/subbase material will not only reduce pandemic-generated waste and the need for virgin materials, but also reduces the construction costs significantly. If 1% of shredded face mask is added to recycled concrete aggregate to make 1km of a two-lane road with a width of 7m and thickness of 0.5m for base and subbase, approximately 93.2 t of shredded face mask would be required, thus preventing 3 million used face masks from ending up in landfills.
Building material applications of single-use PPE?
Single use shredded nitrile gloves have been incorporated in structural concrete at different percentage loadings of the shredded nitrile gloves. There was very good bond formation between the shredded nitrile rubber gloves and the cement concrete with no gap identified in the interfacial transition zone. It was noted that, there was an enhanced bridging effect that allowed for advantageous results in the strength development of the concrete incorporated with nitrile rubber.
The nitrile gloves aid in bond formation, limiting microcracks throughout the concrete compared to the control mix without the shredded nitrile gloves. The presence of single-use nitrile gloves in concrete has the potential to show positive impacts on the mechanical properties of concrete. The compressive strength of the concrete composites containing shredded nitrile gloves increased with an increase in its concentration volume up to a maximum of 0.2%. The elastic modulus can be deemed unaffected showing small variation in the overall properties caused by the low volume of singe-used shredded nitrile gloves in the mix design.
Conclusions
Recycling allows for transformation of waste substances such as single-use PPE into new elements and composite products. The recyclability of single-use PPE in civil engineering applications is broad and its success hinges on its capacity to retain its characteristics that enhance the properties of the composite material. The whole point is to provide a basis for moving towards environmental sustainability by substituting raw materials supply and redirecting waste products in the production of civil engineering materials utilised in various applications such as road and building materials. The optimal solution to a multidimensional problem should consider factors related to governmental regulations, economy, safety, environment, and society, and available facilities and technologies required for multi-criteria decision making.
References
https://www.sciencedirect.com/science/article/pii/S0048969721005957
https://www.sciencedirect.com/science/article/pii/S095965262102970X
https://www.sciencedirect.com/science/article/pii/S0048969721065013
https://www.sciencedirect.com/science/article/pii/S0048969721005957?via%3Dihub
https://www.sciencedirect.com/science/article/pii/S2352186421004454?via%3Dihub
