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Eliminating "forever chemicals" from our water

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For decades, manufacturers found a wide range of uses for per- and polyfluoroalkyl substances (PFAS). The properties of these synthetic chemicals made them ideal for many products, from frying pans to firefighting foam. In the last decade, however, governments in Europe have learnt more about their health risks. They are now imposing limits on PFAS concentrations in water, and many organisations are looking for ways to remove PFAS from their water altogether.

PFAS is a term used to denote more than 4,500 different compounds found in many industrial and commercial products. They are also commonly known as “forever chemicals” due to their strong carbon-fluorine bonds, which make them highly resistant to degradation. As a result, they remain in the natural environment for years, if not centuries, without breaking down.

Published in SWM Bimonthly 18 - June 2023
SWM Bimonthly 18

These substances are now ubiquitous because they have been used in a wide range of everyday products and processes ever since the 1940s, valued for their surface-active properties and ability to repel both water and fats. Their high chemical and thermal stability make them useful in food processing equipment, food packaging, firefighting foams, stain-resistant coatings, paints, varnishes, cleaning products, and cosmetics like shampoo, dental floss, nail polish, and eye makeup. Workers encounter them in various industries, including construction, electronics, automotive, aerospace, and chemicals.

Associated health problems

PFAS aren’t just in our products and our industrial processes; they are also in our soil, in our food, in our water, and in our blood. They have been detected in virtually every region of the world and, according to the European Environment Agency, most of the global population is exposed to them. Recent studies have found PFAS have contaminated the drinking water of millions of Europeans.

PFAS aren’t just in our products and our industrial processes; they are also in our soil, in our food, in our water, and in our blood

What concerns the public about these chemicals isn’t just their spread as pollutants; it’s that some PFAS have been linked with cancer, liver damage, thyroid disease, immune system dysfunction, increased cholesterol levels and various other health problems. In an assessment in 2020, the European Food Safety Authority (EFSA) found that part of the European population exceeds the tolerable weekly intake for some PFAS: perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorohexane sulfonate (PFHxS).

As the risks become clearer, European governments are acting to limit exposure to PFAS and protect their citizens’ health

Increasingly stringent regulations

Many governmental and private organisations are working with ECT2, a Montrose Environmental Group company, to remove PFAS from water

As the risks become clearer, European governments are acting to limit exposure to PFAS and protect their citizens’ health. They are achieving this through restrictions on the use of PFAS, as well as focusing on their detection and remediation. In accordance with the Stockholm Convention, the European Union (EU) imposed restrictions on PFOS many years ago, banned PFOA in 2020, and looks likely to ban PFHxS too.

More recently, the European Commission has published a regulation setting maximum levels for certain PFAS in food, and in January this year, the EU’s Drinking Water Directive passed into law, imposing new limits for all PFAS in drinking water. Member States have two years from this date in which to comply with this directive. In addition, five EU Member States – Denmark, Germany, the Netherlands, Norway and Sweden – have submitted a proposal to the European Chemicals Agency (ECHA) to restrict PFAS under the EU’s Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation.

Removing PFAS from water

In response to new and incoming regulations, many governmental and private organisations are working with ECT2, a Montrose Environmental Group company, to remove PFAS from water. Some have acted quickly, before new standards are in place, to avoid potential liability.

ECT2 has been dealing with PFAS since 2013. Its customisable treatment systems are suitable for removing these chemicals from groundwater, process water, wastewater, landfill leachate, and drinking water. More than 350 of these systems are deployed or under construction worldwide. Collectively, they have treated more than 10 billion litres of water to date.

One of several solutions the company offers is called SORBIX™ PURE, which uses a 5-micron filter to remove organic material and two columns in which specialised resin media reduce PFAS concentrations to below detection levels. The synthetic resins, composed of a neutral, hydrophobic backbone, divinylbenzene cross links, and positively charged exchange sites, are essentially adsorbents with ion exchange functionality. The hydrophobic carbon-fluorine tail of a typical PFAS molecule adsorbs to the resin’s hydrophobic backbone and cross links, and the negatively charged head of the PFAS molecule is attracted to the resin’s positively charged ion exchange site. Having used the ion exchange technology to attract and trap the PFAS molecules, the system then allows clean water to flow through. This technology, using a combination of adsorption and ion exchange, produces a PFAS removal capacity that is 13x more effective in comparison to other technologies such as granular activated carbon (GAC). SORBIX™ PURE is the most efficient technology on the market for removing PFAS compounds, including short-chain molecules.

ECT2 plant in Williamtown, Australia

Minimising waste in PFAS removal

A key problem for organisations filtering out PFAS from contaminated water is the sheer volume of material that many of them use for the job. Some companies using GAC to remove PFAS find they have to swap out this carbon several times a week. For their systems to remain effective, they need to do this on a continuous basis, resulting in thousands of tonnes of PFAS-laden carbon that they need to take away to be incinerated. An advantage of using ion exchange resin, instead of carbon, is that it uses just a fraction of the volume of material needed to remove the same amount of PFAS.

SORBIX™ PURE uses a combination of adsorption and ion exchange, producing a PFAS removal capacity that is 13x more effective 

To reduce their waste and costs even further, some organisations make use of a patented system from ECT2 called SORBIX™ RePURE, which allows PFAS-saturated resin to be regenerated on-site and reused many times. This is the only regenerable ion exchange system available on the market. Instead of requiring users to remove and dispose of their resin, this system uses a special solution to remove the PFAS from the resin so that it is ready to be used again. The system then distils this solution, so that, like the resin, it can also be reused.

Remediating water

ECT2’s full-scale installations of remediable ion exchange technology have proven effective in eliminating PFAS for many years, and in different parts of the world. An early example is from 2014, when environmental investigations at a Royal Australian Air Force base in Williamtown, Australia, found the chemicals in ground and surface water. The Australian government’s Department of Defence sought to treat it, to prevent its further spread. To meet this challenge, ECT2 set up a water treatment process that first removed solids and other organic matter from the water, and then used ion exchange resin to remove the PFAS. The system was successful, and the authorities requested an upgrade to manage higher flow rates. The system has purified over 427 million litres of surface water with no exceedances since April 2019.

Another ion exchange system from ECT2 is in use at the former Pease Air Force Base in Portsmouth, USA, where PFOA and PFOS used for fire-training activities had found their way into the regional aquifer. The GAC solution used at first to remove PFAS at the site had been creating a large amount of spent waste, each vessel lasting only 2-3 weeks before needing a change-out, so the United States Air Force Civil Engineering Center moved quickly to find a more sustainable alternative. After a side-by-side pilot study comparing SORBIX™ RePURE and bituminous GAC, the former went into full-scale operation in 2018, and has treated more than 130 million litres of PFAS-impacted water to date, with an average influent PFAS concentration of 48 µg/l. Current estimates indicate that the system is operating at an approximate concentration factor of one million to one: i.e., about one gallon of solid waste is generated for every million gallons of water treated. This is due in part to SuperLoading™, a patented process developed by ECT2 that further concentrates the PFAS recovered during the regeneration and distillation processes.

  • SORBIX™ PURE is the most efficient technology on the market for removing PFAS compounds, including short-chain molecules

To reduce their waste and costs even further, some organisations make use of a patented system from ECT2 called SORBIX™ RePURE

A more recent example of ion exchange technology in action is the work ECT2 is doing to help a pilot customer in Halmstad, Sweden, to remediate drinking water. Responsible for the local public water supply, Laholmsbuktens VA wants to tackle the issue of PFAS that has polluted the groundwater over time. The team also wants to ensure that its drinking water complies with the Swedish Food Agency’s regulations, which specify maximum PFAS4 levels of 4 ng/l. They were not sure, however, which technology would provide the most cost-effective way to achieve this. For the pilot project, ECT2 suggested testing two systems side by side: (1) a traditional system using granular activated carbon, and (2) ECT2’s ion exchange system SORBIX™ PURE. The two systems tested the same water. The test showed that SORBIX™ PURE had a dramatically longer lifespan than activated carbon. Using this system will result in lower waste generation and lower lifecycle costs for Laholmsbuktens VA.

ECT2’s SORBIX™ PURE and SORBIX™ RePURE technology have the potential to dramatically reduce the waste and costs associated with PFAS remediation. The prevalence of ECT2’s regenerative technology for treating PFAS is likely to increase as new and future regulations are put in place to protect public health.