Due to their recalcitrant nature and ubiquitous use, per-and polyfluoroalkyl substances (PFAS) will continue to be major water treatment hurdles. Although effective water treatment technologies exist for physical removal of many PFAS from water (e.g., activated carbon and ion-exchange resin), a PFAS-concentrated waste stream is generated as an end product that can potentially reintroduce PFAS back into the environment. Thus, there is an increased interest in developing destructive technologies to decompose and mineralize PFAS directly in water or in these waste streams. High energy electron beam (e-beam) accelerators have been used for water treatment to degrade a wide range of recalcitrant contaminants, including PFAS, since the 1960s. However, large-scale applications of e-beam for water treatment are restricted due to its high energy consumption and inability to treat large flow rates. Considering there are very few available technologies for destructive removal of PFAS, this study provides a critical review on the treatment of PFAS by direct irradiation of contaminated water by e-beam from an energy consumption point of view. To date, very limited studies have been conducted to investigate the success of this technology to treat PFAS. Results from the limited studies were not directly comparable due to the variation in operating conditions and water quality parameters used in the studies. Here, for the first time, we develop and apply the concept of electrical energy per order (EE/O) to assess the performance of e-beam for PFAS treatment. Results show that EE/O is a better performance parameter than the G value of e-beam for interstudy comparisons and to evaluate the effects of water quality and operating parameters on e-beam performance. We additionally developed a kinetic scheme to predict the performance of e-beam to treat PFAS and revealed that the competition between species to react with aqueous electrons is the determinant factor influencing PFAS degradation efficiency. Comparison of EE/O values of e-beam (range: 31−176 kWh m −3 order −1 ) with other destructive technologies (range: 5−9595 kWh m −3 order −1 ) suggest that e-beam, for PFAS treatment, is a promising approach under favorable conditions. This review further elucidates the feasibility and limitations of e-beam technology that could be improved upon to potentially make e-beam viable for large-scale water treatment applications.

Many environmentally relevant poly-/perfluoroalkyl substances (PFASs) including perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) exist in different isomeric (branched and linear) forms in the natural environment. The isomeric distribution of PFASs in the environment and source waters is largely controlled by the source of contamination and varying physicochemical properties imparted by their structural differences. For example, branched isomers of PFOS are relatively more reactive and less sorptive compared to the linear analogue. As a result, the removal of branched and linear PFASs during water treatment can vary, and thus the isomeric distribution in source waters can influence the overall efficiency of the treatment process. In this paper, we highlight the need to consider the isomeric distribution of PFASs in contaminated matrices while designing appropriate remediation strategies. We additionally summarize the known occurrence and variation in the physicochemical properties of PFAS isomers influencing their detection, fate, toxicokinetics, and treatment efficiency.

Poly-and perfluoroalkyl substances (PFAS) are known as "forever chemicals" due to their ubiquitous persistence in the environment, and their negative human health effects. Among them, short-chain PFAS are of increasing concern due to their high solubility and mobility in water, while possessing persistency and toxicity nature like their longer-chain analogs. The most common method for PFAS removal from water is by sorption with activated carbons or ion exchange resins, but these adsorbents only exhibit limited removal efficiency against short-chain PFAS, and they require frequent replacement leading to high operational cost. Here we review and discuss the potential of using bio-adsorbents, which can be derived from common biomass feedstocks, as low-cost alternatives to traditional adsorbents, while these materials can also possess good removal efficiency against short-chain PFAS. We further provide the perspective on the designs of low-cost, activated bio-adsorbent systems that can be implemented for effective removal of short-chain PFAS.

The application of electron beam (e-beam) technology for water treatment has been proposed to be a faster and safer approach to decomposing persistent contaminants in water, because of its ability...

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