Verfahrensvergleich zur Behandlung PFAS-belasteter Wässer

Remediation methods for PFAS-contaminated waters can be categorized into non-destructive, destructive, and combined approaches. Non-destructive methods are used for the separation and concentration of contaminants and include activated carbon adsorption, ion exchange resins, membrane processes, foam and ozone fractionation, pressure-relief flotation, air stripping, and coagulation-flocculation. Destructive methods aim at the mineralization of PFAS. Potential techniques for contaminant degradation include electrochemical oxidation, supercritical water oxidation, ultrasonic degradation, and advanced reduction/oxidation processes. In combined approaches, a concentration step precedes the mineralization process using a destructive method.
In experimental investigations, the activated carbon "PHO 8x30" from Eurocarb Products Limited was tested to analyze the influence of Total Organic Carbon (TOC) on PFOS adsorption. Two RSSCT experiments were conducted, and breakthrough curves indicated PFOS breakthrough already at 1.000 bed volumes. In the experiment involving TOC, higher PFOS concentrations were observed after 6.500 bed volumes. Due to the TOC, less pollutant was retained by the activated carbon.
A process combination of foam fractionation and electrochemical oxidation developed by ferroDECONT GmbH was tested. A sample from a soil washing plant containing 38.36 μg/L PFAS was introduced into the foam fractionation system. By binding PFAS to the air-water interface and subsequently separating it as a concentrate, the PFAS contamination in the main stream was reduced. After four hours, 2.2 L of concentrate with a PFAS concentration of 24.04 μg/L was collected. The electrochemical oxidation exhibited a relatively low efficiency due to the low volumetric flow rate. However, more specific conclusions regarding the effectiveness of the process could not be drawn from the experiment, as significant mass loss occurred due to the adsorption of contaminants within the reactor. This factor has a considerable influence and requires further investigation.
For PFOS analysis, a UV/VIS photometer was tested using a cuvette test for anionic surfactants. PFOS as a pure substance could be measured, enabling the creation of a calibration curve. However, challenges remain regarding the influence of other substances in the sample and the limited measurement range of the method.