Where Have Billions Of Masks Been Discarded?

In the prevention and control of pneumonia caused by new coronavirus infection, masks are the last "line of defense" for many citizens. Without masks, they can't get out of the door, pick up their children and go to work. Although the domestic epidemic situation has been well controlled, we still need to pay attention to protection, after all, the epidemic situation abroad is still wanton.

Light mask has become a mobile phone, key general necessities of life. However, how to deal with the hundreds of millions of discarded masks? How to reduce their pollution to the environment?

Just as people are getting used to wearing masks, some environmentalists have raised a variety of concerns: plastic substances contained in disposable masks will pollute water sources; discarded masks will entangle wild animals; wild animals who eat disposable masks by mistake will be in danger. Environmental groups have found that thousands of disposable masks have been discarded outdoors, causing damage to towns and villages.

British photographers photograph Peregrine hunting masks in the wild (source: bbc.com)

So, where will disposable masks that protect people's lives go after they are discarded? Will they cause new pollution problems? How to deal with discarded disposable masks scientifically? How can we balance public health with sustainable development?

How dirty are the discarded masks?

First of all, let's take a look at the yellow particles on the velvet surface of the used mask under the microscope. When it is magnified to 2000 times, we can see the moving bacteria.

Therefore, the mask must be handled in time! The masks worn by the general population have no risk of virus transmission, and can be treated according to the requirements of domestic waste classification, while the masks discarded by patients, suspected patients and nursing staff need to be collected and treated separately according to the medical waste.

How to deal with discarded masks?

China is the world's largest producer and exporter of masks, and the annual output of masks accounts for about 50% of the world. In 2018, China's production of masks was about 4.54 billion, and exceeded 5 billion in 2019. Under the influence of the epidemic situation, the total production of masks in 2020 is expected to double compared with that in 2019.

After the outbreak of the epidemic, the relevant enterprises quickly tackled key problems in the production of special materials and built melt blown cloth production lines (source: Sinopec)

How many discarded masks were produced during the outbreak? Wang dujin made a simple calculation for the reporter: according to the fact that each person discards one mask every day (weighing about 5g), 3500-4000 tons of discarded masks will be produced every day in China.

Disposable medical mask is mainly composed of waterproof layer (spunbonded non-woven fabric), filter layer (melt blown non-woven fabric), ear strap, nose bar and other components. The main body of the material is polyurethaneand polyethylene (PU) which is used as the core material of the medical mask, such as polyethylene (PU) and polyethylene (polyethylene), which are used as the core materials of the medical mask, such as polyethylene, polyethylene, polyethylene, etc., which are used as the core materials of the mask, such as polypropylene and polyethylene, which are used as the core materials of the mask.

The common filter layer of mask is prepared by melt blown process. The diameter of polypropylene Microfiber is about 2 μ M. when the droplet with bacteria or virus is close to the microfiber, it will be firmly adsorbed by the static charge on its surface, so as to achieve the purpose of blocking bacteria or viruses. However, the absorbed pathogens were not killed, which brought special inconvenience to the recovery of discarded masks.

So, what harm will be brought by improper disposal of disposable masks?

Liu Yijie told reporters that masks are easy to move with the wind. If discarded randomly in the environment, on the one hand, it will affect the landscape environment and increase the transmission path of bacteria and viruses; on the other hand, after the mask enters the soil or water body, it will be broken in the light, rainstorm or strong wind, resulting in long-term micro plastic pollution.

Environmentalists found a large number of discarded masks washed up on the beach (source: oceansasia. ORG)

However, although plastic (polypropylene) is the main component of disposable masks, masks are not the main use direction of plastic materials. Therefore, a large number of disposable masks will not lead to a significant increase in plastic waste.

Wang dujin said that at present, the centralized Incineration scheme is mainly adopted for the treatment of disposable masks. The advantage of this method is that it can solve the problem of garbage disposal such as waste masks at one time, and can use the heat generated by collection to generate electricity. Its disadvantage is that it will produce some toxic by-products, which will pollute the environment to a certain extent.

In addition to incineration, possible treatment options for disposable respirators include landfill degradation, mechanical processing and chemical recovery. Wang dujin said that from the perspective of circular economy, at present, these methods are not ideal, unable to make full use of the processing process to realize value-added, nor can they bring more energy and economic benefits.

Optimize the selection and design of mask

In view of the environmental challenges brought about by discarded masks, in addition to efforts in sorting collection and treatment, value-added technologies should also be developed to realize "turning waste into treasure" and sustainable development.

The reason why it is difficult to realize high-efficiency recycling of waste polymer masks is that it is difficult to recycle the original polymer into a closed-loop. Therefore, if the future disposable medical masks are designed as integrated materials, the recycling and recycling problems of discarded masks can be alleviated from the perspective of basic materials.

Common disposable mask material is mainly made of polypropylene non-woven fabric

He suggested that in the selection and design of masks, the types of materials should be reduced, polypropylene materials should be used as much as possible, other polymer materials should be used less, and metal should be avoided to achieve the simplification of material types and functional diversification, and provide maximum convenience for subsequent value-added recycling.

The mask made of single material is more simple and convenient in value-added utilization. After recycling, it can be directly processed to realize low-value utilization (melting processing to produce daily necessities such as garbage cans or flowerpots), chemical conversion (pyrolysis to monomer or small molecular compounds) and upgrading and reconstruction (melting process to realize functionalization and high performance).

In addition, Wang dujin suggested that on the basis of the integration of mask materials, new polymer functional materials should be developed as soon as possible, so that the masks can not only block bacteria and viruses, but also kill bacteria and viruses, and prolong the service life.