What are PFAS?
Per- and polyfluoroalkyl substances (PFAS) are widely used chemicals that break down very slowly over time thanks to the extreme strength of the carbon-fluoride bond. Due to their long lasting nature, they are used in clothing, furniture, heat-resistant non-stick cooking surfaces, food packaging, insulation, and more. This incredible persistence has led to PFAS often being called “forever chemicals”.
Although useful, the presence of PFAS has risen to alarming amounts. PFAS have become pervasive everywhere in the environment from our water systems and our food sources, and even our bodies — PFAS are regularly present in the blood of humans and other animal species. The presence of the widely used synthetic chemical in drinking water is giving rise to a number of problems for living organisms such as an increased chance of immune deficiencies, changes to fertility, and cancer.
Filtration companies make an effort to remove as much PFAS from the water as possible, although, there is no current technology that can feasibly remove the chemical. Plus, even when successfully filtered out the tricky task of safe disposal remains.
Supercritical water oxidation
The good news is that technologies are beginning to emerge that address this problem with good results, and several that were recently highlighted at a congressional hearing, are making industry headlines. Perhaps the most promising is an approach called supercritical water oxidation, invented by the non profit research organization Battelle.
This technology uses 374˚C water at high pressure as an oxidizing agent to break down the strong bonds. A sodium hydroxide salt is added as a neutralizing agent for the acidic after product of the reaction and is later filtered out using a separator. The end result is clean drinking water with undetectable levels of PFAS and after-products that can be safely broken down.
Supercritical water oxidation became the front runner of the solutions put forward, partly due to Battelle’s confidence that the idea will prove to be an “economically viable solution,” based on the tests for scalability of commercial application the company is carrying out.
“This type of scalable technology should give us all comfort that economically feasible, safe, complete, and reliable destruction of PFAS is within our grasp, thus solving the most fundamental issue that comes with using these chemicals,” said Rep. Stephanie Bice, the top Republican on the Subcommittee on Environment.
Obstacles to overcome
There are still obstacles to overcome, involving the energy and monetary hurdles of running the complex reactors. These include the expensive equipment needed to set up the reaction, the high pressures and temperatures required, and extended operating times these facilities will need to be run. In the meantime, Battelle is setting up a demonstration unit this year that can process 1900 L per day or PFAS contaminated liquids to help understand the true costs to develop this solution commercially.
While we wait for the market-scale deployment of PFAS destruction technology, most who take environmental protection and safe living environments seriously argue that we should restrict the use of PFAS to only essential use. Moving away from forever chemicals as much as possible would limit the scale of environmental and health problems, and make any on-going clean up efforts that much easier!