What is PFAS?
PFAS stands for Per- and Poly-Fluoroalkyl Substances, a group of more than 4700 widely used synthetic chemicals. They all contain carbon-fluorine bonds, which are one of the strongest chemical bonds in organic chemistry, thus they are not easy-degradable and remain in the environment. Furthermore, they accumulate in animal and human tissue and are toxic at low levels of bioaccumulation, causing endocrine, nervous system, and several other health problems.
PFAS have been used extensively worldwide since the 1940s in various products such as non-stick household items, food-packaging, cosmetics, electronics, and firefighting foams.
As the awareness of the presence and environmental and health impacts of PFAS has been growing, several countries have published guidelines and regulations addressing PFAS concentrations in drinking water. The US Environmental Protection Agency has set the PFOA and PFOS (individually or combined) limit in drinking water to 70 ng/L, whereas for the UK, Germany, Italy, Netherlands, and Sweden, it is 10, 300, 30–500, 200–390, and 90 ng/L, respectively.
PFAS Removal Technologies
PFAS are found in rivers, lakes, and reservoirs all over the world. The most common types of PFAS detected are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), which have already been phased out of production in Europe and the United States. The highest levels of PFAS contamination are found in industrial and urban areas, as well as in areas with a high population density.
PFAS projects include:
Cleanup of municipal wastewater treatment water, prior to discharge (recycling back into the environment).
Cleanup of industrial wastewater prior to being discharged into a receiving body.
Treatment of municipal drinking water that has been contaminated with PFAS.
At IDE we offer a complete range of removal solutions:
Carbon adsorption
Specialty anion ion exchange resin
Reverse osmosis or nanofiltration
Other typical water purification techniques, include biodegradation, micron filtration, sand filtration, ultrafiltration, coagulation, flocculation, clarification, and oxidation by ultraviolet light, hypochlorite, chlorine dioxide, chloramine, ozone, or permanganate, are not able to effectively remove PFAS from water/wastewater.
Granular Activated Carbon (GAC):
GAC can remove low concentrations (ng/L) from drinking water. Long-chain PFAS (e.g. legacy PFAS as PFOA and PFOS) are efficiently (>90%) removed by GAC depending on the flow rate of the water, carbon bed depth, empty bed contact time and the temperature of the medium. The presence of other organic matters reduces adsorption efficiency. Inefficient for removal of short-chain PFAS. The carbon media may be recycled for use elsewhere after the PFAS is burned off.
Ion-Exchanger (IX):
An ion-exchanger is efficient for removal of anionic and long-chain PFAS at low concentrations (ng/L). Adsorption capacity is higher compared to GAC and the adsorption kinetics is faster. It is less efficient for water containing organic or inorganic matter and is limited in removal of short-chain PFAS. The media is typically used once and incinerated but the resin lasts a long time, so the economics are attractive.
Membrane (RO/NF):
Membrane technology is effective for short-chain as well as long-chain PFAS. Other organic and inorganic impurities are also removed. High removal rate and time-efficiency. Fouling of membranes due to inorganic, organic, biological, and colloidal impurities. Requires brine management, which can be overcome by partnering it with a destruction process or further treated with carbon, or in some cases, ion exchange before discharge. As the volume of rejected water is small relative to the feed, the economics may succeed. The stream could also be deep well injected or treated by evaporation-crystallization followed by incineration or landfill. The energy requirement for membrane wastewater treatment is high compared to adsorption or ion exchange resin.
