Removal of poly- and perfluoroalkyl substances from water using the BDD electrode

Poly-and perfluoroalkyl substances (PFASs) have been used for a wide range of purposes due to their unique properties. Unfortunately, these compounds have been associated with several adverse health effects and high persistence in the environment, therefore, creating a need for their elimination from the environment. In this study, electrochemical oxidation using boron-doped diamond electrodes (BDD) was tested for its treatment efficiency of 12 PFAS. Three different water types were used that is: Millipore, dissolved organic carbon (DOC) and membrane reject water. Both Millipore and DOC water were spiked and tested with three different current densities that is: 0.95 mA cm-2, 4.8 mA cm-2 and 12 mA cm-2. Quality assurance tests on the electrode revealed that the electrode was consistently efficient throughout the study and that pH change influenced PFAS removal. In this study, 12 mA cm-2, proved to be the most efficient tested current density achieving > 80% removal for PFASs except perfluorohexane carboxylate (PFHxA) (79%) and perfluorobutane carboxylate (PFBS) (34%) after two hours. At all current densities used, perfluoropentane carbxylate (PFPeA), a compound that was not spiked, was observed to have been formed in differentgmnneyney quantities. In majority of the trials, PFAS removal was dependent on perfluorocarbon chain length and was found to increase with increase in perfluorocarbon chain length. The effect of water type on PFAS removal was dependent on the PFAS type. For example, while PFBS removal was enhanced in DOC water, for most of the compounds it was decreased. PFAS removal from membrane reject water was greater than that from DOC water except for PFHxA. In this study, short chained carboxylates had lower removals. This could be due to the treatment pathway undertaken by the BDD. This study examines factors that should be examined to transfer the treatment from a laboratory scale to water treatment plants. Further studies may examine wider ranges of water types as well as provide an account of all the products produced during water treatment

A novel method for extraction, clean-up and analysis of per- and polyfluoroalkyl substances (PFAS) in different plant matrices using LC-MS/MS

Per- and polyfluoroalkyl substances (PFAS) are chemicals of concern due to their persistence, bioaccumulation, and toxic properties. PFAS accumulation in plants poses a risk of human and animal exposure due to consumption of the affected plants, but also allows plants to be used in remediation of PFAS-contaminated soils and groundwater. Therefore, effective extraction, cleanup, and analytical methods for measuring PFAS concentrations in plants are fundamental for research on animal and environmental health. PFAS analysis in plant matrices is complex, due to high matrix interference, and scarcity of methods for analyzing different classes of PFAS. In this study, a simple sample preparation method for PFAS analysis in various plant tissues (leaves, needles, twigs, stems, roots from 10 different species) was developed and validated. Instrumental analysis was performed using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The method was optimized considering six different extraction conditions and three different cleanup techniques. Methanol as extraction solvent, combined with 1 g ENVI carb cartridges, showed best performance among all extraction conditions and cleanup techniques tested. Method validation showed good recovery (90–120%), high within-day and between-day precision (−1 dry weight (dw)) for different plant matrices. In tests of the method on soil and different plant tissues of silver birch (Betula pendula) and Norway spruce (Picea abies) at a PFAS-contaminated site, 16 of 24 target PFAS were detected in plants and 17 in soil. ƩPFAS concentration in soil was 43 ng g−1 dw. PFAS distribution in silver birch tissues ranged from 7.1 ng g−1 dw in roots to 64 ng g−1 dw in leaves, and in Norway spruce from 14 ng g−1 dw in roots to 16 ng g−1 dw in needles. This novel method for PFAS analysis in plants can be valuable in future monitoring, process understanding, remediation, and risk assessments

Occurrence and removal of chemicals of emerging concern in wastewater treatment plants and their impact on receiving water systems

Wastewater treatment plants (WWTPs) are considered the main sources of chemicals of emerging concern (CECs) in aquatic environments, and can negatively impact aquatic ecosystems. In this study, WWTP influent, effluent, and sludge, and upstream and downstream waters from the WWTP recipient were investigated at 15 locations for a total of 164 CECs, including pharmaceuticals, personal care products, industrial chemicals, per- and polyfluoroalkyl substances (PFASs), and pesticides. In addition, zebrafish (Dania rerio) embryo toxicity tests (ZFET) were applied to WWTP influent and effluent, and upstream and downstream waters from WWTP recipients. A total of 119 CECs were detected in at least one sample, mean concentrations ranging from 0.11 ng/L (propylparaben) to 64,000 ng/L (caffeine), in wastewater samples and from 0.44 ng/L (ciprofloxacin) to 19,000 ng/L (metformin) in surface water samples. Large variations of CEC concentrations were found between the selected WWTPs, which can be explained by differences in CEC composition in influent water and WWTP treatment process. The sludge-water partitioning coefficient (K-d) of CECs showed a significant linear con-elation to octanol/warer partition coefficient (K-ow) (p < 0.001), and thus could be used for predicting their fare in the aqueous and solid phase. The Sigma CEC concentrations in WWTPs declined by on average 60%, based on comparisons of WWTP influent and effluent concentrations. The high concentrations of CECs in WWTP effluent resulted in, on average, 50% higher concentrations of CECs in water downstream of WWTPs compared with upstream. Some WWTP samples showed toxicity in ZFET compared with the respective control group, but no individual CECs or groups of CECs could explain this toxicity. These results could provide a theoretical basis for optimization of existing treatment systems of different designs, and could significantly contribute to protecting recipient waters. (C) 2020 The Authors. Published by Elsevier B.V

Phytoremediation of soil contaminated with per- and polyfluoroalkyl substances (PFAS)

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic compounds recognised for their persistence, mobility and potential toxicity. This thesis examines the efficacy of phytoremediation as a potential technique for managing PFAS-contaminated soil and groundwater. First, an extraction and clean-up method was developed to measure PFAS in different plant tissues. A solid-liquid extraction method using methanol and ENVICarb cartridge as clean-up showed satisfactory performance and was selected for validation and application. PFAS were then analysed in plants, soil and groundwater at one landfill and three former fire training sites. The aim was to investigate the phytoextraction potential of trees growing at these sites. Plant tissue concentration and composition profiles highly depended on the soil and groundwater fingerprints. Birch and willow showed the highest PFAS concentrations in the field. Furthermore, the phytoextraction potential of five plants (i.e. sunflower, mustard, hemp, willow and poplar) was also investigated in pot experiments. Parameters such as species-specific uptake, bioaccumulation in different plant tissues, duration of PFAS exposure and effects of supplements were assessed. The supplements i.e. fertilizer, microbes and hormones had limited influence on plant concentration in some cases increased plant biomass, which in turn increased total mass PFAS removal by the plants. Willow and sunflower showed the highest PFAS removal efficiency of all investigated plants. The highest PFAS removal obtained was for short chain PFAS (C3 – C6), with up 34% removal by the plants after 90 days of exposure. These results can be useful for field application of phytoremediation. Further work is required to improve the efficiency of the method and to study the fate of PFAS in plant biomass following remediation

Phytoextraction of per- and polyfluoroalkyl substances (PFAS) and the influence of supplements on the performance of short-rotation crops

Per-and polyfluoroalkyl substances (PFAS) are anthropogenic compounds threatening water quality and food safety worldwide. Phytoremediation is a nature-based, cost-effective, and scalable solution with high potential for treating PFAS-contaminated sites. However, there is a large knowledge gap regarding choice of plant species and methods to enhance performance. This study assessed the PFAS phytoextraction potential of sunflower (Helianthus annuus), mustard (Brassica juncea), and industrial hemp (Cannabis sativa) in a greenhouse experiment, using inorganic fertilizer and a microbial mixture as supplements. PFAS concentrations were measured using UPLC-MS/MS, and bioconcentration factors for different plant tissues and removal efficiency were determined. Perfluoroalkyl carboxylic acid (PFCA) accumulation was 0.4-360 times higher than that of perfluoroalkyl sul-fonic acid (PFSA) homologues of similar perfluorocarbon chain length. Inorganic fertilizer significantly (p < 0.001) reduced PFAS concentration in all plant tissues, whereas the microbial mixture tested did not affect PFAS concentration. PFAS uptake ranged from 0.2 to 33% per crop cycle. Overall, the potential number of crop cycles required for removal of 90% of individual PFAS ranged from six (PFPeA) to 232 (PFOA) using sunflower, 15 (PFPeA) to 466 (PFOS) using mustard and nine (PFPeA) to 420 (PFOS) using Hemp. In this study, the percentage of PFAS removal by plants was determined, and an estimation of the time required for PFAS phytoextraction was determined for the first time. This information is important for practical phytoremediation applications