How to catch the invisible enemy
05 March 2021
PFASs are the holy grail of chemistry, but a bane for environmentalists. PhD Matthias Van der Bergh has a way to remove these imperishable chemicals from water.
Perfluorinated alkylated substances (PFASs) repel water and fats. Even at high temperatures. That's what keeps you dry beneath your rain-proof jacket, or why the food on your Teflon pan won't stick.
Despite these manmade chemicals’ A+ performance, troubles start once PFASs end up in waste water. Unless humans remove them from the environment, nature can take millenniums to decompose them as they’re incredibly persistent.
"They combine many desirable properties in one chemical," says PhD Matthias Van der Bergh, a fresh trainee at Renewi Belgium. "Problems arise if they end up in rivers or the sea as they're difficult to extract once mixed with other organic substances from decomposed branches, leaves or dead animals."
Cleaning dark waters
PFASs have, sadly, become headline generators in the past years. The US has seen many multi-million dollar lawsuits against chemical companies that polluted local communities' drinking water. Chronic exposure to small doses of PFASs can cause cancer or other severe diseases, prompting American regulations on PFASs to take stricter measures for their disposal.
The situation is similar, yet less bleak, in Europe. Tap water can contain tiny doses of PFAS, while only waste waters near factories producing them can contain alarming levels. The EU has regulated PFASs disposal since the 70s. Still, it waited till 2017 to introduce strict limits on the maximum concentration allowed in waters or waste waters.
A spongy adsorbent
The go-to adsorbent to remove PFASs from water is activated carbon. These filters do their job in clean water, like the one from your tap, and absorb water-repellent substances like PFASs. They become an expensive and ineffective solution in dirtier waters as they soak substances in order of concentration, making them fail to mop up low-concentrated and elusive PFASs.
During a 5-years project at KU Leuven, Van Den Bergh designed the prototype of an adsorbent specific for PFASs. The absorbent acts like a magnet: it attracts all water-repellent substances in a liquid, but only retains PFASs molecules. Thanks to its sponge-like design, non-PFASs molecules will pass through or not fit in the custom-made pores.
"The research I've handed in September 2020 is not market-ready," says Van Den Bergh. "But it's a necessary step forward, and I hope it'll contribute to achieving the targeted EU environmental quality standards for 2027."
After handing-in his PhD, Van Den Bergh decided to bring his bio-engineering expertise to Renewi and start a traineeship.
"I've always liked nature, and I wanted a job within the environmental sector," says Van Den Bergh. "That's why the traineeship at Renewi is a great fit. It's a sector which will change tremendously in the next decades, and I'd like to help to advance the circular economy."
Would you like to know more about his PhD?
Matthias Van den Bergh
Trainee Materials Recycling & Hazardous Waste