Pilot Test of O3-BAC Process for Characteristics of Short-Chain PFCs and DOM Removal in WTP
Perfluorinated compounds(PFCs)are widely distributed and potentially toxic in the aqueous environment,and activated carbon adsorption is currently considered one of the effective technologies for PFCs removal in drinking water.However,there are fewer studies on the removal characteristics of ozone-bioactivated carbon(O3-BAC)for short-chain PFCs in real water bodies,and therefore there is an urgent need to assess the effectiveness of the application of this process in the context of the current increasing pollution levels of short-chain PFCs in surface water environments.In this study,the removal of three short-chain PFCs(PFBA,PFPeA,PFHxA)and dissolved organic matter(DOM)was investigated in an O3-BAC pilot plant that was operated continuously for 90 days using sand filtration effluent from a water treatment plant as the water source,and the effects of ozone shutdown and ozone dosage on the removal of short-chain PFCs and DOM were also investigated.The results showed that the removal rates of the three short-chain PFCs in the O3-BAC pilot plant decreased significantly with the increase of operation time and the phenomenon of penetration and desorption of PFCs appeared,and the degree of the removal rates decreased as follows:PFBA>PFPeA>PFHxA,while the removal rates of DOC,UV254 and Φ(T,n)indices related to DOM decreased relatively slowly.Ozone dosing could oxidize DOM to improve the adsorption and removal of short-chain PFCs in the charcoal filter,and DOM flowing into the charcoal filter after the ozone was turned off would seize the adsorption sites of adsorbed short-chain PFCs,causing the desorption of PFCs to occur prematurely.Excessive ozone dosage could in turn increase the more competitive low molecular weight organics,thus weakening the removal capacity of carbon filtration for short-chain PFCs.
ozone-bioactivated carbon(O3-BAC)perfluorinated compounds(PFCs)dissolved organic matter(DOM)pilot test triple-dimensional fluorescence spectroscopy(3D-EEM)