Plastic recycling is injecting huge amounts of microplastics in our environment, study finds

“It seems a bit backward, almost, that we do plastic recycling in order to protect the environment, and then end up increasing a different and potentially more harmful problem,” said Erina Brown, lead researcher of the study, in an interview with Wired.

The team visited a state-of-the-art plastic recycling facility in the U.K., which the researchers chose not to name to maintain anonymity. They sampled the wash water, a mixed homogeneous discharge, from four different flow paths at four different points along the production line in the facility. Wash water is used throughout the process and is discharged at each of the four sample sites. The filtration measures undertaken by the facility involve 50µm particle filters, which are mesh sieves forming part of a liquid/solid separator at three of the four outlet locations.

The results were perplexing. They found that the filtration process is effective for larger microplastics but allowed smaller (<10µm) to be discharged into the receiving waterway.

The team concluded that the current process of recycling is a potential source of plastic pollution to the environment that it is designed to help prevent. 

The researchers calculated that without the filtration process, the facility would be emitting up to 6.5 million pounds of microplastic per year, which currently stands at an estimated 3 million pounds. “So it definitely was making a big impact when they installed the filtration,” says Brown. “We found particularly high removal efficiency of particles over 40 microns.”

Study abstract:

With current plastic production and the growing problem of global plastic pollution, an increase and improvement in plastic recycling is needed. There is limited knowledge or assessment of microplastic pollution from point sources such as plastic recycling facilities globally. This pilot study investigates microplastic pollution from a mixed plastics recycling facility in the UK to advance current quantitative understanding of microplastic (MP) pollution release from a plastic recycling facility to receiving waters. Raw recycling wash water were estimate to contain microplastic counts between 5.97 106 – 1.12 × 108MP m−3 (following fluorescence microscopy analysis). The microplastic pollution mitigation (filtration installed) was found to remove the majority of microplastics >5µm, with high removal efficiencies for microplastics >40µm. Microplastics <5µm were generally not removed by the filtration and subsequently discharged, with 59-1184 tonnes potentially discharged annually. It is recommended that additional filtration to remove the smaller microplastics prior to wash discharge is incorporated in the wash water management. Evidence of microplastic wash water pollution suggest it may be important to integrate microplastics into water quality regulations. Further studies should be conducted to increase knowledge of microplastic pollution from plastic recycling processes.