Plastic recycling should not be an end in itself

Figure 1. Recycling rate and secondary material volume for the 2017 recycled product subsegment (Klotz and Haupt, 2021). AC: Air Conditioning, B & C: Building and Construction, C & I: Commercial and Industrial, CE: Home Appliances, EEE: Electrical and Electronic Equipment, HH: Home, ICT: Information and Communication Technology, NC: Non-Consumer, PTT: Pots, Tray and Tab .. Credit: DOI: 10.1016 / j.wasman.2022.01.002

The desire to keep plastics in circulation is now prevalent. However, according to Magdalena Klotz, high collection rates are of little use if the recycled material replaces unused material only to a limited extent.

Plastic recycling is currently a trend. The collection sites for pilot projects in the Zurichchenk and Schwamendingen municipalities were literally flooded with plastic packages, and people from other regions came to dispose of plastic waste. This desire for recycling is often based on the belief that recycled materials can compensate for the environmental impact of our consumption. However, to achieve this goal, recycled materials need to significantly replace primary resources.

But we are far from it with plastics and most other materials. Currently, only about 7 percent of the more than 1 million tonnes of plastic used in Switzerland are made from recycled waste. Without making changes to the system, I think secondary plastics can only be replaced with unused materials in the future.

status quo

One obvious way to increase plastic recycling Collecting more waste individually. Currently, there are several initiatives that have set this goal at the local and regional level in Switzerland. Many are targeted at household mixed plastics, which means that there is no national recycling system yet, most of which are currently used for energy recovery. That is, it will be incinerated. Migros also wants to introduce a mixed collection system for plastic packaging. In contrast, we have been collecting PET beverage bottles and other PET bottles for a long time.

However, plastics are not only found in the prominent packaging sector. Plastic is also used in window frames, vacuum cleaners, cars, silo packaging films, and T-shirts. Waste from these products is also recycled — in some cases even significant amounts are recycled. Nonetheless, only 9 percent of the total 790,000 metric tonnes of plastic waste generated in Switzerland in 2017 was recycled.

Recovery improves recycling rate

There is a reason for the low recycling rate. Some plastic waste is very difficult to collect individually. Also, about 20% of the separately collected waste is lost in the sorting and recycling process. This also applies to mixed plastic packaging from home.

As a scientist, I wanted to know how much the recycling rate could be increased in the future. I recently investigated this question using Material Flow Analysis. To that end, we raised the collection rate of plastic fractions collected in 2017 to 80%. This is the rate already achieved with PET bottles, paper, or aluminum. As a result, the recovery rate was improved and the process was not changed, resulting in an overall recycling rate of 23%. Still modest, this is more than double the current recycling rate.

Limited importance to the environment

But what does the 23% recycling rate ultimately bring to us?From an ecology point of view, plastic recycling is primarily environmentally beneficial when secondary materials are replaced by unused materials, thereby preventing CO.2 Emissions of plastic production. According to our analysis, this will probably only be partially possible with an enhanced collection system, without any additional changes to the system. The reason for this becomes clear when we take a closer look at plastic as a material.

Various types of plastics are composed of polymer chains and additives that can be combined in almost unlimited ways. Since it is not possible to recycle hundreds of thousands of wastes separately, many are recycled together. However, when mixed, they become a secondary plastic with different properties than the original plastic. This means that recycled products can usually only be used with certain products in a particular share. Therefore, the total amount of recycled material that can replace the primary material is limited.

Taking into account the limited potential of secondary materials, our model has shown that only about 75 percent of recycled products can replace primary plastics. This reduces the theoretically possible recycling rate of 23% to a practically achievable recycling rate of 17%. In 2017, the amount of secondary material was so small that we were able to completely reuse the amount of secondary material and return it to production. But with more plastic recycling, that changes.

You also need to think about how to use recycled plastic.

In my work, I repeatedly find that most research and policy goals on recycling are unaware of the problem of how to use secondary plastics.Even the EU’s goal of recycling half of the whole Plastic packaging By 2025, we will unilaterally focus on the production of recycled products. This can lead to an overestimation of achievable environmental benefits. In reality, excess recycling can simply flow into additional products and increase consumption.

We expect it to be beneficial to the environment in the future. plastic If you just collect more, recycling will be lower waste Do not change the recycling route or product design.

I’m not saying that Plastic recycling Not worth it.Ideally saves energy and CO2 Avoid emissions, harmful alternative disposal routes and save resources. However, simply filling the Migros collection box with water or dismantling the vehicle at the end of its life cycle cannot guarantee these environmental benefits. To actually achieve these ecological goals, Plastic waste Collect more accurately and design the product more evenly if possible to avoid mixing during recycling. This will pave the way for recycling to increasingly replace primary plastics in the production process.

According to a Spanish study, each anesthetized patient produces over 1 kg of plastic waste.

For more information:
Magdalena Klotz et al, Limited availability options for secondary plastics may limit their roundness, Waste management (2022). DOI: 10.1016 / j.wasman.2022.01.002

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Plastic recycling should not be an end in itself

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