Pilot-scale field demonstration of a hybrid nanofiltration and UV-sulfite treatment train for groundwater contaminated by per- and polyfluoroalkyl substances (PFASs)

Removal of per- and polyfluoroalkyl substances from contaminated groundwater by granular activated carbon and anion exchange resins: a pilot-scale comparative assessment

“…31 Although recent studies have detected a much greater diversity of PFASs in AFFF solutions, especially perfluoroalkyl acid (PFAA) precursors, the lack of detection of PFAA precursors in this groundwater may be due to the transformation of these compounds to PFAAs including PFCAs and PFSAs before reaching the source water well. 2,3,34 Feed water quality parameters were also monitored and found to be consistent throughout the study (ESI † section S4).…”

Reductive Removal and Recovery of As(V) and As(III) from Strongly Acidic Wastewater by a UV/Formic Acid Process

“…In addition, the UV energy consumption, that is, electrical energy per order of arsenic removal (EE/O) value, was calculated to be 29.7 kW h m –3 order –1 in our study (Text S21), which is of the same order of magnitude as that of widely reported ARPs, for example, nitrogen removal by the UV/formate process (17 kW h m –3 order –1 ) and by the UV/sulfite process (38.21–82.13 kW h m –3 order –1 ), bromate degradation by the UV/sulfite process (36 kW h m –3 order –1 ), trichloroacetic acid removal by the UV/formate/TiO 2 process (58.92 kW h m –3 order –1 ), and 2,4,6-trichlorophenol degradation by the UV/sulfite process (23.44 kW h m –3 order –1 ) in bench-scale tests. The application prospect of these ARPs, such as PFOA and bromate degradation by the UV/sulfite process, has been verified by pilot-scale studies. , Thus, the proposed method may also have good application potential. Even though EE/O values in our study are higher than those of the full-scale UV/H 2 O 2 , UV/O 3 , and UV/persulfate processes (0.1–1 kW h m –3 order –1 ), the UV energy efficiency can be improved by further optimizing the operation and reaction parameters.…”

“…The application prospect of these ARPs, such as PFOA and bromate degradation by the UV/sulfite process, has been verified by pilot-scale studies. 62,63 Thus, the proposed method may also have good application potential. Even though EE/O values in our study are higher than those of the full-scale UV/ H 2 O 2 , UV/O 3 , and UV/persulfate processes (0.1−1 kW h m −3 order −1 ), 64 the UV energy efficiency can be improved by further optimizing the operation and reaction parameters.…”

Critical Review of UV-Advanced Reduction Processes for the Treatment of Chemical Contaminants in Water

“…UV-ARP studies are often performed in buffered, laboratory grade water that has been sparged with an inert gas like nitrogen to remove dissolved O 2 . However, prior research shows that a residual [O 2 ] of approximately 0.2 mg/L (∼6 μM) remains even after sparging with nitrogen (25 mL/s) for 1 h. 55 An [O 2 ] of 6 μM in deaerated solutions will still exhibit a high e aq − scavenging capacity (k S,t=0 ′ = 1.2 × 10 5 s −1 ), which will impact the initial [e aq − ] and thereby the 32,51 The impact of residual [O 2 ] will also depend on the solution conditions and target contaminant. Residual [O 2 ] will have the largest impact on the degradation of contaminants that have an e aq − bimolecular rate constant comparable to O 2 and thus react on similar time scales.…”

“…For example, although the microheterogeneous UV/indoleacetic acid/micelle system reported recently was described as "efficient," a very high-powered lamp (500 W) was used to treat only 10 mL of solution, 28 resulting in a high E EO (Table 5). A recent study by Liu et al combined nanofiltration (NF) with UV-sulfite treatment at the pilot scale and found an E EO of 3.7 kWh m −3 for PFOA, 32 which is approximately 4-fold lower than the E EO for PFOA in a bench-scale photochemical system (15.8 kWh m −3 ) reported by Bentel et al 30,31 The much lower value reported by Liu et al results from the fact that they considered the total volume of water treated in the NF-UV/ sulfite process, which was approximately an order of magnitude greater than the volume treated by UV-sulfite. E EO values for PFOA treatment via UV-ARP in Table 5 tend to be lower than most other degradative technologies.…”