Challenges with plastic waste management

A recent publication by Prof. George Huber and colleagues from UW Madison’s Department of Chemical and Biological Engineering describes  challenges with the management of plastic waste. The article describes new technologies that have the potential to improve the low rate of plastics recycling, which currently stands somewhere near 10% globally. The rest ends up in landfills, burned for energy, or elsewhere in the environment (i.e. dumped into bodies of water).

It takes an estimate of 2 kg of oil to make 1 kg of plastic, which is lost if the material is landfilled. If plastic waste is burned, some energy is recovered, but this process creates CO2 emissions.

The paper, “Expanding Plastics Recycling Technologies: Chemical Aspects, Technology Status and Challenges” gives a deep dive into current plastics manufacturing and life cycle, including end of life.

Current plastics recycling is mostly “mechanical,” meaning that plastic waste is sorted, cleaned, then ground up and reprocessed. The washing and sorting steps can be quite expensive, as high purity is required. Also, each time plastic is reground and remelted it is slightly degraded, limiting the number of times that this process can be performed. Certain resin types respond better to this process, so most recycling is limited to poly(ethylene terephthalate) (PET) and polyethylene (PE). This plastic waste slowly breaks down into microplastics (particles 5 mm or less in size), which are able to more easily circulate throughout the environment. Microplastics have been found almost everywhere they have been looked for, from mountain tops to farmlands to urban settings, and are known to accumulate organic pollutants.

Chemical recycling promises the creation of circularity. Instead of the slight degradation during each mechanical recycling process, completely new polymer can be synthesized during the chemical recycling process, with properties as good as virgin plastic. Further development of this technology may lead us to the circular economy of the future.