Drinking water nanofiltration with concentrate foam fractionation-A novel approach for removal of per- and polyfluoroalkyl substances (PFAS)

Per-and polyfluoroalkyl substances (PFAS) are recognized as persistent pollutants that have been found in drinking water sources on a global scale. Semi-permeable membrane treatment processes such as reverse osmosis and nanofiltration (NF) have been shown effective at removing PFAS, however, disposal of PFAS laden concentrate is problematic. Without treatment of the concentrate, PFAS is released into the environment. The present work examined a novel PFAS removal scheme for drinking water using NF filtration with treatment of the resulting NF concentrate via foam fractionation (FF) with and without co-surfactants. The NF-pilot removed 98% of PFAS from AFFF contaminated groundwater producing permeate with 1.4 ng L-1 total PFAS. Using FF resulted in EPFAS removal efficiency of 90% from the NF concentrate and with improved removal of 94% with addition of cationic co-surfactant. The resulting foamate composed approximately 2% of the NF feedwater volume and contained greater than 3000 ng L-1 PFAS or 41 times greater than the NF feedwater. Addition of the cationic co-surfactant to the FF process resulted in increased removal efficiency of the shorter chain PFAS, specifically 37% for PFPeA, 9% for PFHxA, and 34% for PFBS thus attaining 59%, 99% and 96% removal efficiency, respectively. PFOA, PFPeS, PFHxS, PFOS each attained 99% FF removal with or without co-surfactant addition

Foam fractionation removal of multiple per- and polyfluoroalkyl substances from landfill leachate

Per- and polyfluoroalkyl substances (PFAS) are a common contaminant inmunicipal landfill leachate and are recognized as a pollutant on global scale.The present work examined foam fractionation (FF) in batch and continuousmodes as an appropriate treatment technique for PFAS removal for the landfillleachate and found stable removal efficiency of greater than 90% for PFOA(C7), PFOS (C8), PFHxS (C6), and PFHpA (C6) and 6:2 FTSA (C6). For otherPFAS such as PFNA (C8), PFPeS (C4), PFHxA (C5), PFHpS (C7), and PFBS(C4), a less stable removal between 80% and 50% was achieved while between50% and 20% removal was observed for EtFOSAA (C8), PFBA (C3), PFDA (C9),FOSA (C8), PFPeA (C4), and MeFOSAA (C8). Increased air flowrate, additionof iron (III) oxide (Fe+3) coagulant, conductivity, and greater untreated leach-ate PFAS concentration were factors resulting in increased removal efficiencyfor the majority of PFAS

Pilot-Scale Continuous Foam Fractionation for the Removal of Per- and Polyfluoroalkyl Substances (PFAS) from Landfill Leachate

Per- and polyfluoroalkyl substances (PFAS) are of concern for their ubiquity in the environment combined with their persistent, bioaccumulative, and toxic properties. Landfill leachate is often contaminated with these chemicals, and therefore, the development of cost-efficient water treatment technologies is urgently needed. The present study investigated the applicability of a pilot-scale foam fractionation setup for the removal of PFAS from natural landfill leachate in a novel continuous operating mode. A benchmark batch test was also performed to compare treatment efficiency. The ΣPFAS removal efficiency plateaued around 60% and was shown to decrease for the investigated process variables air flow rate (Qair), collected foam fraction (%foam) and contact time in the column (tc). For individual long-chain PFAS, removal efficiencies above 90% were obtained, whereas the removal for certain short-chain PFAS was low

Removal of per- and polyfluoroalkyl substances (PFASs) in a full-scale drinking water treatment plant: Long-term performance of granular activated carbon (GAC) and influence of flow-rate

Per- and polyfluoroalkyl substances (PFASs) have been ubiquitously detected in drinking water whichposes a risk for human exposure. In this study, the treatment efficiency for the removal of 15 PFASs was examined in a full-scale drinking water treatment plant (DWTP) in the City of Uppsala, Sweden, over aperiod of two years (2015-2017). Removal of the five frequently detected PFASs was influenced by the total operation time of granular activated carbon (GAC)filters, GAC type and surface loading rate. The average removal efficiency of PFASs ranged from 92 to 100% for “young” GAC filters and decreased to 7.0-100% for “old” GAC filters (up to 357 operation days, 29 300 bed volumes (BV) treated). Flow-rates were adjusted in two full-scale GAC filters of different operational age to examine the removal of PFAS and organic matter depending on GAC operational age and operating flow. The decrease inflow-rate by10 L s(-1) from 39 to 29 L s(-1) led to an average increase of 14% and 6.5% in total PFAS removal efficiency for an “old”(264 operation days, 21 971 BV treated) and a “young” GAC filter (63 operation days, 5 725 BV treated), respectively. A cost-analysis for various operation scenarios illustrated the dominating effect of treatment goals and costs for GAC regeneration on overall GAC operation costs. The unit costs for GAC filters ranged from 0.08 to 0.10 E(-3) water treated and 0.020-0.025Vm E(-3) water treated for a treatment goal of 10 ng L(-1)and 85 ng L(-1), respectively, for Sigma(11)PFAS. Furthermore, it was concluded that prolonging the GAC service life by lowering the flow-rates after reaching the treatment goal could lead to a 26% cost-deduction. The results and methods presented in this study give drinking water providers valuable toolsfor the operation of a full-scale treatment train for the removal of PFAS in contaminated raw water

Long-distance transport of per- and polyfluoroalkyl 2 substances (PFAS) in a Swedish drinking water aquifer

Use of per-and polyfluoroalkyl substance (PFAS)-containing aqueous film-forming foams (AFFF) at firefighting training sites (FFTS) has been linked to PFAS contamination of drinking water. This study investigated PFAS transport and distribution in an urban groundwater aquifer used for drinking water production that has been affected by PFAS-containing AFFF. Soil, sediment, surface water and drinking water were sampled. In soil (n = 12) at a FFTS with high perfluorooctane sulfonate (PFOS) content (87% of sigma PFAS), the sigma PFAS concentration (n = 26) ranged from below detection limit to 560 ng g(-1)dry weight. In groundwater (n = 28), the sigma PFAS concentration near a military airbase FFTS reached 1000 ng L-1. Principal component analysis (PCA) identified the military FFTS as the main source of PFAS contamination in drinking water wellfields > 10 km down-gradient. Groundwater samples taken close to the military FFTS site showed no sigma PFAS concentration change between 2013 and 2021, while a location further down-gradient showed a transitory 99.6% decrease. Correlation analysis on PFAS composition profile indicated that this decrease was likely caused by dilution from an adjacent conflating aquifer. sigma PFAS concentration reached 15 ng L-1 (PFOS 47% and PFHxS 41% of sigma PFAS) in surface river water (n = 6) and ranged between 1 ng L-1 and 8 ng L-1(PFHxS 73% and PFBS 17% of sigma PFAS) in drinking water (n = 4). Drinking water had lower PFAS concentrations than the wellfields due to PFAS removal at the water treatment plant. This demonstrates the importance of monitoring PFAS concentrations throughout a groundwater aquifer, to better understand variations in transport from contamination sources and resulting impacts on PFAS concentrations in drinking water extraction areas

Artificial infiltration in drinking water production: Addressing chemical hazards using effect-based methods

Artificial infiltration is an established managed aquifer recharge method that is commonly incorporated into drinking water processes. However, groundwater sourced from this type of purification method is prone to contamination with chemical hazards. Such an instance was previously shown at a Swedish DWTP where the river water was contaminated by hazardous chemicals during artificial infiltration. Further, there remains a paucity of research studying the quality of drinking water following this type of treatment from an effect-based bioanalytical perspective. In the current study, an effect-based assessment for chemical hazards was conducted for a Swedish drinking water system comprised of two DWTPs fed artificially-infiltrated river water. In this system, artificial infiltration of the river water takes approximately six to eight months. A sampling event was conducted in the autumn season and the samples were enriched by solid phase extraction. A panel of cell-based reporter gene assays representing several toxicity pathways was selected: oxidative stress response (Nrf2 activity), aryl hydrocarbon receptor (AhR) activation, and hormone receptor-mediated effects (estrogen receptor [ER], androgen receptor [AR]). AhR and ER bioactivities were detected in samples collected from the river intake and in the open-air infiltration basins prior to artificial infiltration. However, the AhR activity decreased and ER activity was effectively removed following artificial infiltration. In the Nrf2 and AR assays, no bioactivities above cut-off levels were detected in any samples collected along the entire treatment process of the drinking water production from source to tap. Using a suite of bioassays, the current study highlighted the effectiveness of artificial infiltration in reducing bioactive compounds in this raw river water. Although artificial infiltration is a common purification method in drinking water production, the limited number of effect-based studies evaluating the effectiveness of this method emphasizes the need for further research to better understand the risks and benefits of this water treatment process

Electrochemical Oxidation for Treatment of PFAS in Contaminated Water and Fractionated Foam─A Pilot-Scale Study

publishedVersio

Denitrification using a microporous membrane immobilized biofilm in a two chambered reactor /

Degree granted in Civil and Environmental Engineering.Thesis (M.S.)--University of California, Davis, 1994.Mode of access: Internet

The Price of Really Clean Water: Combining Nanofiltration with Granular Activated Carbon and Anion Exchange Resins for the Removal of Per- And Polyfluoralkyl Substances (PFASs) in Drinking Water Production

The removal of per- and polyfluoroalkyl substances (PFASs) presents a challenge for drinking water providers. Guidelines for PFAS concentrations in final drinking water are regularly updated to ever-decreasing values, and conventional drinking water treatment plants are not designed to remove PFASs. Currently, the most frequently used removal technique, adsorption to granular activated carbon (GAC), is often considered challenging. High-pressure membranes, such as nanofiltration (NF), have been shown to remove PFASs efficiently. However, the creation of a waste stream comprised of at least 10% of the feedwater volume is recognized as a major drawback of this technique. In this study, a NF pilot plant was operated at a drinking water treatment plant in the city of Uppsala, Sweden, for six months. NF removed up to >98% of PFASs and fulfilled other water quality targets, such as the removal of uranium-238, dissolved organic carbon (DOC), and mineral hardness from the raw water. The concentrate from the pilot plant was treated with two different GAC materials and two different anion exchange (AIX) resins in column tests, where the superior performance of AIX over GAC was observed in terms of PFAS removal. PFAS adsorption curves for GAC were found to superimpose each other for the two water types if normalized to the specific throughput of DOC. The application of the freely available PHREEQC model revealed improvement possibilities in terms of resin properties. A cost analysis using the column test results compared GAC filtration to the combination of NF with adsorption materials. Treatment costs were found to be largely dependent on the PFAS drinking water treatment goals and concentrate discharge requirements, which highlight the economic consequences of prevailing guidelines for drinking water and discharge to the environment. The results of this study provide both the scientific community as well as drinking water providers with important insights into the application of NF for PFAS removal during drinking water treatment as well as that mechanistic and economic aspects of NF treatment and the management of the resulting concentrate