- 2020-01-31
- Posted by: E2metrix
- Category: Expertise
What are PFAS?
Per- and polyfluoroalkyl substances (PFAS) are a large group of environmentally-persistent, man-made chemicals used in industrial and commercial households. Currently there are over 600 of these compounds that the Environmental Protection Agency (EPA) has approved for sale or import into the United States. Recent reports indicate that the amounts of PFAS from landfill leachate may outstrip the amounts from currently identified PFC contaminated sites. This will generate a growing need for new PFAS treatment technologies beyond the capability of activated carbon or membranes.
Two PFAS that are most often found in drinking water are legacy compounds that are no longer manufactured but are still being found in the environment, including perfluorooctanoic acid (PFOA) and Perfluorooctanesulfonic acid (PFOS).
Why are they harmful?
There is evidence that continued exposure above specific levels to certain PFAS may lead to adverse health effects (USEPA 2016a, 2016b, ATSDR 2018a). Consumption has been tied to serious adverse health consequences. Very low doses in drinking water have been linked to an increased risk of cancer, reproductive and immune system harm, liver and thyroid disease, and other health problems.
Challenges of PFAS treatment
Current approaches for removal of PFAS from water to acceptable levels center around three main traditional technologies: a) adsorption using activated carbon, b) ion exchange, and c) reverse osmosis. While all three of these technologies can be highly effective, they do not result directly in destruction of PFAS compounds. Although the short-term treatment costs may be low, the long-term cost can become quite high due to solid and liquid disposal costs as well as site management.
All “effective” treatments do not destroy PFAS
Effective treatments concentrate PFAS onto the absorptive media, creating spent solid waste, and/or highly toxic reject water. Additional remediation costs are then incurred when the user is required to send the liquid concentrate for off-site incineration or the activated carbon for regeneration for reuse. All these steps require management and cost as well as a chain of custody of the toxic material.
ECOTHOR AOP™ Technology- Proven Sustainable CleanTech
E2metrix technology is based on a breakthrough in electrochemical oxidation reactor design. E2metrix technology applies electricity to electrodes made from advanced catalyst materials. Wastewater or aqueous waste flows through the reactor. Power is applied to electrodes and the process mineralizes and destroys all types of toxic, recalcitrant organics through multiple oxidation mechanisms. E2metrix’s advanced oxidation process (AOP) does not use hazardous chemicals and does not produce any solid or liquid waste. Catalyst materials and electrodes are selected depending on the treatment application.
Advanced technology integration:
ECOTHOR™ technology is currently protected by 13 patents (issued or pending). E2metrix has successfully integrated this process with nanofiltration and ozone systems. Pre-treatment with membrane technology allows for the waste stream to be concentrated and destroyed saving cost and avoiding management of activated carbon or ion-exchange waste. Pre-treatment with ozone allows the PFAS to be predegraded, with ECOTHOR-AOP™ completing the polishing. In both cases, the waste stream is destroyed with a one-pass treatment.
E2metrix is the world leader in electrochemical remediation technology. Its patented modular reactors and high efficiency anodes allow for high treatment throughput at low cost.
Example
Samples of underground water were treated with ECOTHOR-AOP™r. For each sample the raw water and the treated water were analyzed for PFAS compounds. Table 1 and Table 2 provide some results.
Table 1
| PFAS compound | Raw sample (ppb) | Treated sample (ppb) | Removal | |
| Perfluorobutanoic acid | PFBA | 3,00 | 0,60 | 80,00% |
| Perfluoropentanoic acid | PFPeA | 1,70 | 1,50 | 11,76% |
| Perfluorohexanoic acid | PFHxA | 3,00 | 2,50 | 16,67% |
| Perfluorooctanoic acid | PFOA | 0,95 | 0,10* | > 89,47%* |
| Perfluoropentane sulfonic acid | PFPeS | 1,70 | 1,10 | 35,29% |
| Perfluorohexane sulfonic acid | PFHxS | 20,00 | 14,00 | 30,00% |
| Perfluoroheptane sulfonic acid | PFHpS | 1,60 | 0,12 | 92,50% |
| Perfluorooctane sulfonic acid | PFOS | 110,00 | 1,80 | 98,36% |
| 6:2 Fluorotelomer sulfonic acid | 6:2-FTS | 3,40 | 1,40 | 58,82% |
*The value was below the detection limit of the analyzing method.
Table 2
| PFAS compound | Raw sample (ppb) | Treated sample (ppb) | Removal | |
| Perfluoropentanoic acid | PFPeA | 0,46 | 0,37 | 19,57% |
| Perfluorohexanoic acid | PFHxA | 0,80 | 0,48 | 40,00% |
| Perfluorooctanoic acid | PFOA | 0,33 | 0,034 | 89,70% |
| Perfluorobutane sulfonic acid | PFBS | 0,2* | 0,054 | 73,00% |
| Perfluoropentane sulfonic acid | PFPeS | 0,40 | 0,080 | 80,00% |
| Perfluorohexane sulfonic acid | PFHxS | 6,6 | 0,66 | 90,00% |
| Perfluoroheptane sulfonic acid | PFHpS | 0,59 | 0,024 | 95,93% |
| Perfluorooctane sulfonic acid | PFOS | 50 | 0,69 | 98,62% |
| 6:2 Fluorotelomer sulfonic acid | 6:2-FTS | 1,5 | 0,30 | 80,00% |