The elimination of PFOS, PFOA and related compounds during biological wastewater treatment combined with advanced oxidation processes - follow-up and whereabouts

摘要

Fluorinated surfactants have "unique properties" which made them irreplaceable in many applications. Discharged into wastewater they either pass wastewater treatment and can be observed in their original form in the environment or will be eliminated from wastewater adsorbed at excess sludge. Biological wastewater treatment applying microfiltration (MBR) combined with ozone (O_3) or advanced oxidation treatment (AOP) steps are known as efficient elimination techniques. While "conventional surfactants" to a great extent are even degraded in the biological wastewater treatment process, partly or perfluorinated surfactants are not only stable to biodegradation but also stable to oxidizing agents even against OH-radical attacks. Our objectives were to eliminate the fluorinated surfactants perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid {PFOA) by degradation with a balance of precursor compounds and follow-up of degradation products. Therefore municipal wastewater was spiked with these fluorinated surfactants before MBR was applied and permeates were treated using O_3 or different AOP methods. Ozone or hydrogen peroxide, both in combination with UV radiation or in combination with catalysts were applied. Degradation was monitored by arising fluoride ions while substance specific determination and identification was performed using high resolution mass spectrometry after high performance liquid chromatography (LC/MS and -MS~n) under a strict exclusion of Teflon and glass during all analytical procedures.