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PFAS removal 

What are PFAS, PFAA, PFOS and PFOA?

Perfluorinated compounds (PFCs) such as Perfluorinated alkyl acids (PFAA), Perfluorooctane sulfonate (PFOS) and Per- and polyfluoroalkyl (PFAS) substances are diverse groups of synthetic chemical structures with unique properties, such as thermal stability and the ability to create smooth surfaces which repel water, oil and dirt.

This makes PFCs useful components in a wide variety of consumer and industrial products, including preservatives, lubricants, paints, foams, non-stick cookware, food packaging, waterproof clothing, fabric stains protectors and firefighting foams. PFAS and PFOS are among the most known compounds, customarily defined as perfluorinated molecules containing eight fluorinated carbon atoms.

One of the most common application is fire foam which has been used to quench fire effectively. The wide spread use of these foams globally through fire extinguishing exercise fields has caused PFAS and PFOS to trickle into groundwater aquifers. This has lead to extensive contamination of drinking water.

 

Emerging pollutants and directives

Large volumes of PFAS have been produced since the 1950s and in recent years production has shifted more towards short-chain compounds and perfluoroether carboxylic and sulfonic acids, which already has been reflected in environmental waters. However, these specific compounds represent only a fraction of the PFASs marketed globally. Some production has also been replaced by other highly fluorinated compounds such as fluorotelomer alcohols that can slowly degrade to PFOA.

PFCs are recognized by an increasing number of members of the science community as emerging environmental pollutants because of their chemical stability and toxic effects combined with their ubiquitous occurrence in the environment, biota and humans. The direct exposure pathways of these chemicals to humans are somewhat unclear and concerns for PFC-polluted water sources have risen dramatically in recent years in the eyes of the public around the world. Tap water and bottled water are two potential sources of PFCs, explaining part of their occurrence in human blood.

In 2020, The European parliament issued updated directives on the quality of water intended for human consumption (EU directive 2020/2184). This has lead to local and regional implementation of PFAS removal down to levels of 2 ng/L for drinking water in Denmark and 4 ng/L in Belgium and Sweden. European Food and Safety Authority (EFSA) stipulates PFAS 4* limits of 4 ng/L which is being applied gradually in the EU and other countries. Various limits pertaining to PFAS 11, PFAS 20, PFAS 21* are being investigated and implemented.

Treating PFAS

The chemically very stable compounds of PFCs complicate any potential decomposition process of the substance. Various methods have been investigated in efforts to decompose and/or remove PFCs from polluted water, and strong oxidizing agents need to be used.

In efforts to reach a sufficiently high oxidation potential a combination of different Advanced Oxidation Process (AOP) techniques must be considered, for example, a combination of ozone and catalyzed hydroxyl formation. Further complications include the matrix of the sample to be treated.

For example, water rich in organic particles or TOC (Total Organic Content) cause problems for the PFAA removal due to the tendency of the oxidizing agent to react primarily with less stable organic compounds.It is of environmental and social importance to effectively decompose and remove PFCs in drinking water treatment.

Solutions

PFC compounds can be reduced, degraded or completely removed by various methods as listed below and in many cases a combination of techniques is the ultimate solution to solve the problem.

Oxidation

To break down PFC compounds in water one typically needs stronger than “ordinary” oxidants.

Advanced oxidantion techniques, combining different oxidants, have proven to be effective with the right mixing technique. A combination, of for example, ozone and hydrogen peroxide (H2O2)  and/ or  special catalysts raises the oxidation potetional which enables the degradation of PFCs.

Reverse osmosis

Reverse osmosis (RO) is a simple and traditional purification method already used in many water treatment systems.

Our RENA RO systems can remove the contaminants before it is delivered to the households in the affected municipalities. The reverse osmosis technology, which is used, efficiently separates salts from the water and makes this method suitable for that reduction of PFAA-pollutants in drinking water.

Ozonetech offers a variety of state-of-the-art turn-key water treatment systems based on our own ozone technology combined with our in-house developed AOP technology to decompose and remove PFCs in water.

Pilot project

Reducing or eliminating PFCs is a complex task and requires a tailored full-scale solution.

The design process starts with our engineers’ pilot study resulting in a setup including possible critical parameters and best available technologies (BAT) to achieve the optimal process design. By conducting multiple pilot-runs and at the same time incrementally adjusting each parameter of the system individually.

Our engineers determine the optimal design for a full-scale system. Water is sampled throughout the whole pilot process and submitted to a third party lab for analysis to verify the results.

Read more about Pilot projects & Tailored systems and our AOP System RENA Vitro

*PFAS 21 is the definition of 21 different types of PFAS substances: Perfluorobutane acid (PFBA), Perfluoropentane acid (PFPA), Perfluorohexane acid (PFHxA), Perfluoroheptane acid (PFHpA), Perfluorooctane acid (PFOA), Perfluorononane acid (PFNA), Perfluorodecane (PFDA), Perfluoroundecane acid (PFUnDA), Perfluoro dodecane acid (PFDoDA), Perfluortridekansyra (PFTrDA), Perfluorbutane sulfonic acid (PFBS), Perfluoropentane sulfonic acid (PFPS), Perfluorohexanesulfonic acid (PFHxS), Perfluoroheptane sulfonic acid (PFHpS), Perfluoroctane sulfonic acid (PFOS), Perfluorononane sulfonic acid (PFNS), Perfluorodecan sulfonic acid (PFDS), Perfluoroundecan sulfonic acid (PFUnDS), Perfluorododecane sulfonic acid (PFDoDS), Perfluorotridecan sulfonic acid (PFTrDS), Fluorotelomer sulfonic (6:2 FTS).

PFAS 4 includes: Perfluoroctane sulfonic acid (PFOS), Perfluoroctane acid (PFOA), Perfluorononane acid (PFNA), Perfluorhexane sulfonic acid (PFHxS).

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