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In Situ Toxicity Identification Evaluation (iTIE)

The in situ Toxicity Identification Evaluation system is a tool to incorporate into weight-of-evidence studies at sites with numerous chemical toxicant classes present. The technology works by continuously sampling site water, immediately fractionating the water using diagnostic sorptive resins, and then exposing test organisms to the water to observe toxicity responses with minimal sample manipulation. It is compatible with various resins, test organisms, and common acute and chronic toxicity tests, and can be deployed at sites with a wide variety of physical and logistical considerations.

A Novel In Situ Toxicity Identification Evaluation (iTIE) System for Determining which Chemicals Drive Impairments at Contaminated Sites^[1]
An in situ toxicity identification and evaluation water analysis system: Laboratory validation^[2]
Sediment Toxicity Identification Evaluation (TIE) Phases I, II, and III Guidance Document- ^[3]
In Situ Toxicity Identification Evaluation (iTIE) Technology for Assessing Contaminated Sediments, Remediation Success, Recontamination and Source Identification- ^[4]

Introduction

In waterways impacted by numerous naturally occurring and anthropogenic chemical stressors, it is crucial for environmental practitioners to be able to identify which chemical classes are causing the highest degrees of toxicity to aquatic life. Previously developed methods, including the Toxicity Identification Evaluation (TIE) protocol developed by the US Environmental Protection Agency (EPA)^[5], can be confounded by sample manipulation artifacts and temporal limitations of ex situ organism exposures^[1]. These factors may disrupt causal linkages and mislead investigators during site characterization and management decision-making. The in situ Toxicity Identification Evaluation (iTIE) technology was developed to allow users to strengthen stressor-causality linkages and rank chemical classes of concern at impaired sites, with high degrees of ecological realism.

The technology has undergone a series of improvements in recent years, with the most recent prototype being robust, operable in a wide variety of site conditions, and cost-effective compared to alternative site characterization methods^[6]^[7]^[1]^[2]. The latest prototype can be used in any of the following settings: in marine, estuarine, or freshwater sites; to study surface water or sediment pore water; in shallow waters easily accessible by foot or in deep waters only accessible by pier or boat. It can be used to study sites impacted by a wide variety of stressors including ammonia, metals, pesticides, polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH), and per- and polyfluoroalkyl substances (PFAS), among others. The technology is applicable to studies of acute toxicity via organism survival or of chronic toxicity via responses in growth, reproduction, or gene expression^[1].

System Components and Validation

Figure 1: A schematic diagram of the iTIE system prototype. The system is divided into three sub-systems: 1) the Pore Water/Surface Water Collection Sub-System (blue); 2) the Pumping Sub-System (red); and 3) the iTIE Resin, Exposure, and Sampling Sub-System (green). Water first enters the system through the Pore Water/Surface Water Collection Sub-System. Porewater can be collected using Trident-style probes, or surface water can be collected using a simple weighted probe. The water is composited in a manifold before being pumped to the rest of the iTIE system by the booster pump. Once in the iTIE Resin, Exposure, and Sampling Sub-System, the water is gently oxygenated by the Oxygen Coil, separated from gas bubbles by the Drip Chamber, and diverted to separate iTIE Resin and Exposure Chambers (or iTIE units) by the Splitting Manifold. Water movement through each iTIE unit is controlled by a dedicated Regulation Pump. Finally, the water is gathered in Sample Collection bottles for analysis.

The latest iTIE prototype consists of an array of sorptive resins that differentially fractionate sampled water, and a series of corresponding flow-through organism chambers that receive the treated water in situ. Resin treatments can be selected depending on the chemicals suspected to be present at each site to selectively sequester certain chemical of concern (CoC) classes from the whole water, leaving a smaller subset of chemicals in the resulting water fraction for chemical and toxicological characterization. Test organism species and life stages can also be chosen depending on factors including site characteristics and study goals. In the full iTIE protocol, site water is continuously sampled either from the sediment pore spaces or the water column at a site, gently oxygenated, diverted to different iTIE units for fractionation and organism exposure, and collected in sample bottles for off-site chemical analysis (Figure 1). All iTIE system components are housed within waterproof Pelican cases, which allow for ease of transport and temperature control.

Porewater and Surface Water Collection Sub-system

Figure 2: a) Trident probe with auxiliary sensors attached, b) a Trident probe with end caps removed (the red arrow identifies the intermediate space where glass beads are packed to filter suspended solids), c) a Trident probe being installed using a series of push poles and a fence post driver

Given the importance of sediment porewater to ecosystem structure and function, investigators may employ the iTIE system to evaluate the toxic effects associated with the impacted sediment porewater. To accomplish this, the iTIE system utilizes the Trident probe, originally developed for Department of Defense site characterization studies^[8]. The main body of the Trident is comprised of a stainless-steel frame with six hollow probes (Figure 2). Each probe contains a layer of inert glass beads, which filters suspended solids from the sampled water. The water is drawn through each probe into a composite manifold and transported to the rest of the iTIE system using a high-precision peristaltic pump.

The Trident also includes an adjustable stopper plate, which forms a seal against the sediment and prevents the inadvertent dilution of porewater samples with surface water. (Figure 2). Preliminary laboratory results indicate that the Trident is extremely effective in collecting porewater samples with minimal surface water infiltration in sediments ranging from coarse sand to fine clay. Underwater cameras, sensors, passive samplers, and other auxiliary equipment can be attached to the Trident probe frame to provide supplemental data.

Alternatively, practitioners may employ the iTIE system to evaluate site surface water. To sample surface water, weighted intake tubes can collect surface water from the water column using a peristaltic pump.

Oxygen Coil, Overflow Bag and Drip Chamber

Figure 3. Contents of the iTIE system cooler. The pictured HDPE rack (47.6 cm length x 29.7 cm width x 33.7 cm height) is removable from the iTIE cooler. Water enters the system at the red circle, flows through the oxygen coil, and then travels to each of the individual iTIE units where diagnostic resins and organisms are located. The water then briefly leaves the cooler to travel through peristaltic regulation pumps before being gathered in sample collection bottles.

Porewater is naturally anoxic due to limited mixing with aerated surface water and high oxygen demand of sediments, which may cause organism mortality and interfere with iTIE results. To preclude this, sampled porewater is exposed to an oxygen coil. This consists of an interior silicone tube connected to a pressurized oxygen canister, threaded through an exterior reinforced PVC tube through which water is slowly pumped (Figure 3). Pump rates are optimized to ensure adequate aeration of the water. In addition to elevating DO levels, the oxygen coil facilitates the oxidation of dissolved sulfides, which naturally occur in some marine sediments and may otherwise cause toxicity to organisms if left in its reduced form.

Gas bubbles may form in the oxygen coil over the course of a deployment. These can be disruptive, decreasing water sample volumes and posing a danger to sensitive organisms like daphnids. To account for this, the water travels to a drip chamber after exiting the oxygen coil, which allows gas bubbles to be separated and diverted to an overflow system. The sample water then flows to a manifold which divides the flow into different paths to each of the treatment units for fractionation and organism exposure.

iTIE Units: Fractionation and Organism Exposure Chambers

Figure 4. A diagram of the iTIE prototype. Water flows upward into each resin chamber through the unit bottom. After being chemically fractionated in the resin chamber, water travels into the organism chamber, where test organisms have been placed. Water is drawn through the units by high-precision peristaltic pumps.

At the core of the iTIE system are separate dual-chamber iTIE units, each with a resin fractionation chamber and an organism exposure chamber (Figure 4). Developed by Burton et al.^[1], the iTIE prototype is constructed from acrylic, with rubber O-rings to connect each piece. Each iTIE unit can contain a different diagnostic resin matrix, customizable to remove specific chemical classes from the water. Sampled water flows into each unit through the bottom and is differentially fractionated by the resin matrix as it travels upward. Then it reaches the organism chamber, where test organisms are placed for exposure. The organism chamber inlet and outlet are covered by mesh to prevent the escape of the test organisms. This continuous flow-through design allows practitioners to capture the temporal heterogeneity of ambient water conditions over the duration of an in situ exposure. Currently, the iTIE system can support four independent iTIE treatment units.

After being exposed to test organisms, water is collected in sample bottles. The bottles can be pre-loaded with preservation reagents to allow for later chemical analysis. Sample bottles can be composed of polyethylene, glass or other materials depending on the CoC.

Pumping Sub-system

Figure 5. The iTIE system pumping sub-system. The sub-system consists of: A) a single booster pump, which is directly connected to the water sampling device and feeds water to the rest of the iTIE system, and B) a set of four regulation pumps, which each connect to the outflow of an individual iTIE unit. Each pump set is housed in a waterproof case with self-contained rechargeable battery power. A tablet is mounted inside the lid of the four pump case, which can be used to program and operate all of the pumps when connected to the internet.

Water movement through the system is driven by a series of high-precision, programmable peristaltic pumps (EcoTech Marine). Each pump set is housed in a Pelican storm travel case. Power is supplied to each pump by internal rechargeable lithium-iron phosphate batteries (Bioenno Power).

First, water is supplied to the system by a booster pump (Figure 5A). This pump is situated between the water sampling sub-system and the oxygen coil. The booster pump: 1) facilitates pore water collection, especially from sediments with high fine particle fractions; 2) helps water overcome vertical lifts to travel to the iTIE system; and 3) prevents vacuums from forming in the iTIE system interior, which can accelerate the formation of disruptive gas bubbles in the oxygen coil. The booster pump should be programmed to supply an excess of water to prevent vacuum formation.

Second, a set of four regulation pumps ensure precise flow rates through each independent iTIE unit (Figure 5B). Each regulation pump pulls water from the top of an iTIE unit and then dispenses that water into a sample bottle for further analysis.

Study Design Considerations

Diagnostic Resin Treatments

Several commercially available resins have been verified for use in the iTIE system. Investigators can select resins based on stressor classes of interest at each site. Each resin selectively removes a CoC class from site water prior to organism exposure.

DuPont Ambersorb 560 for removal of 1,4-dioxane and other organic chemicals^[9]
C18 for nonpolar organic chemicals
Bio-Rad Chelex for metals
Granular activated carbon for metals, general organic chemicals, sulfide^[10]
Waters Oasis HLB for general organic chemicals^[2]
Waters Oasis WAX for PFAS, organic chemicals of mixed polarity^[11]
Zeolite for ammonia, other organic chemicals

Resins must be adequately conditioned prior to use. Otherwise, they may inadequately adsorb toxicants or cause stress to organisms. New resins should be tested for efficacy and toxicity before being used in an iTIE system.

Test Organism Species and Life Stages

Advantages

A UV/sulfite treatment system offers significant advantages for PFAS destruction compared to other technologies, including high defluorination percentage, high treatment efficiency for short-chain PFAS without mass transfer limitation, selective reactivity by e_aq^-, low energy consumption, and the production of no harmful byproducts. A summary of these advantages is provided below:

High efficiency for short- and ultrashort-chain PFAS: While the degradation efficiency for short-chain PFAS is challenging for some treatment technologies^[12]^[13]^[14], the UV/sulfite process demonstrates excellent defluorination efficiency for both short- and ultrashort-chain PFAS, including trifluoroacetic acid (TFA) and perfluoropropionic acid (PFPrA).
High defluorination ratio: As shown in Figure 3, the UV/sulfite treatment system has demonstrated near 100% defluorination for various PFAS under both laboratory and field conditions.
No harmful byproducts: While some oxidative technologies, such as electrochemical oxidation, generate toxic byproducts, including perchlorate, bromate, and chlorate, the UV/sulfite system employs a reductive mechanism and does not generate these byproducts.
Ambient pressure and low temperature: The system operates under ambient pressure and low temperature (<60°C), as it utilizes UV light and common chemicals to degrade PFAS.
Low energy consumption: The electrical energy per order values for the degradation of perfluorocarboxylic acids (PFCAs) by UV/sulfite have been reduced to less than 1.5 kilowatt-hours (kWh) per cubic meter under laboratory conditions. The energy consumption is orders of magnitude lower than that for many other destructive PFAS treatment technologies (e.g., supercritical water oxidation)^[15].
Co-contaminant destruction: The UV/sulfite system has also been reported effective in destroying certain co-contaminants in wastewater. For example, UV/sulfite is reported to be effective in reductive dechlorination of chlorinated volatile organic compounds, such as trichloroethene, 1,2-dichloroethane, and vinyl chloride^[16]^[17]^[18]^[19].

Limitations

Several environmental factors and potential issues have been identified that may impact the performance of the UV/sulfite treatment system, as listed below. Solutions to address these issues are also proposed.

Environmental factors, such as the presence of elevated concentrations of natural organic matter (NOM), dissolved oxygen, or nitrate, can inhibit the efficacy of UV/sulfite treatment systems by scavenging available hydrated electrons. Those interferences are commonly managed through chemical additions, reaction optimization, and/or dilution, and are therefore not considered likely to hinder treatment success.
Coloration in waste streams may also impact the effectiveness of the UV/sulfite treatment system by blocking the transmission of UV light, thus reducing the UV lamp's effective path length. To address this, pre-treatment may be necessary to enable UV/sulfite destruction of PFAS in the waste stream. Pre-treatment may include the use of strong oxidants or coagulants to consume or remove UV-absorbing constituents.
The degradation efficiency is strongly influenced by PFAS molecular structure, with fluorotelomer sulfonates (FTS) and perfluorobutanesulfonate (PFBS) exhibiting greater resistance to degradation by UV/sulfite treatment compared to other PFAS compounds.

State of the Practice

Figure 2. Field demonstration of EradiFluor^TM^[20] for PFAS destruction in a concentrated waste stream in a Mid-Atlantic Naval Air Station: a) Target PFAS at each step of the treatment shows that about 99% of PFAS were destroyed; meanwhile, the final degradation product, i.e., fluoride, increased to 15 mg/L in concentration, demonstrating effective PFAS destruction; b) AOF concentrations at each step of the treatment provided additional evidence to show near-complete mineralization of PFAS. Average results from multiple batches of treatment are shown here.

Figure 3. Field demonstration of a treatment train (SAFF + EradiFluor^TM^[20]) for groundwater PFAS separation and destruction at an Air Force base in California: a) Two main components of the treatment train, i.e. SAFF and EradiFluor^TM^[20]; b) Results showed the effective destruction of various PFAS in the foam fractionate. The target PFAS at each step of the treatment shows that about 99.9% of PFAS were destroyed. Meanwhile, the final degradation product, i.e., fluoride, increased to 30 mg/L in concentration, demonstrating effective destruction of PFAS in a foam fractionate concentrate. After a polishing treatment step (GAC) via the onsite groundwater extraction and treatment system, all PFAS were removed to concentrations below their MCLs.

The effectiveness of UV/sulfite technology for treating PFAS has been evaluated in two field demonstrations using the EradiFluor^TM^[20] system. Aqueous samples collected from the system were analyzed using EPA Method 1633, the total oxidizable precursor (TOP) assay, adsorbable organic fluorine (AOF) method, and non-target analysis. A summary of each demonstration and their corresponding PFAS treatment efficiency is provided below.

Under the Environmental Security Technology Certification Program (ESTCP) Project ER21-5152, a field demonstration of EradiFluor^TM^[20] was conducted at a Navy site on the east coast, and results showed that the technology was highly effective in destroying various PFAS in a liquid concentrate produced from an in situ foam fractionation groundwater treatment system. As shown in Figure 2a, total PFAS concentrations were reduced from 17,366 micrograms per liter (µg/L) to 195 µg/L at the end of the UV/sulfite reaction, representing 99% destruction. After the ion exchange resin polishing step, all residual PFAS had been removed to the non-detect level, except one compound (PFOS) reported as 1.5 nanograms per liter (ng/L), which is below the current Maximum Contaminant Level (MCL) of 4 ng/L. Meanwhile, the fluoride concentration increased up to 15 milligrams per liter (mg/L), confirming near complete defluorination. Figure 2b shows the adsorbable organic fluorine results from the same treatment test, which similarly demonstrates destruction of 99% of PFAS.
Another field demonstration was completed at an Air Force base in California, where a treatment train combining Surface Active Foam Fractionation (SAFF) and EradiFluor^TM^[20] was used to treat PFAS in groundwater. As shown in Figure 3, PFAS analytical data and fluoride results demonstrated near-complete destruction of various PFAS. In addition, this demonstration showed: a) high PFAS destruction ratio was achieved in the foam fractionate, even in very high concentration (up to 1,700 mg/L of booster), and b) the effluent from EradiFluor^TM^[20] was sent back to the influent of the SAFF system for further concentration and treatment, resulting in a closed-loop treatment system and no waste discharge from EradiFluor^TM^[20]. This field demonstration was conducted with the approval of three regulatory agencies (United States Environmental Protection Agency, California Regional Water Quality Control Board, and California Department of Toxic Substances Control).

References

^ ^1.0 ^1.1 ^1.2 ^1.3 ^1.4 Burton, G.A., Cervi, E.C., Meyer, K., Steigmeyer, A., Verhamme, E., Daley, J., Hudson, M., Colvin, M., Rosen, G., 2020. A novel In Situ Toxicity Identification Evaluation (iTIE) System for Determining which Chemicals Drive Impairments at Contaminated Sites. Environmental Toxicology and Chemistry, 39(9), pp. 1746-1754. doi: 10.1002/etc.4799
^ ^2.0 ^2.1 ^2.2 Steigmeyer, A.J., Zhang, J., Daley, J.M., Zhang, X., Burton, G.A. Jr., 2017. An in situ toxicity identification and evaluation water analysis system: Laboratory validation. Environmental Toxicology and Chemistry, 36(6), pp. 1636-1643. doi: 10.1002/etc.3696
^ United States Environmental Protection Agency, 2007. Sediment Toxicity Identification Evaluation (TIE) Phases I, II, and III Guidance Document, EPA/600/R-07/080. 145 pages. Free Download Report.pdf
^ In Situ Toxicity Identification Evaluation (iTIE) Technology for Assessing Contaminated Sediments, Remediation Success, Recontamination and Source Identification Project Website Final Report.pdf
^ Norberg-King, T., Mount, D.I., Amato, J.R., Jensen, D.A., Thompson, J.A., 1992. Toxicity identification evaluation: Characterization of chronically toxic effluents: Phase I. Publication No. EPA/600/6-91/005F. U.S. Environmental Protection Agency, Office of Research and Development. Free Download from US EPA Report.pdf
^ Burton, G.A. Jr., Nordstrom, J.F., 2004. An in situ toxicity identification evaluation method part I: Laboratory validation. Environmental Toxicology and Chemistry, 23(12), pp. 2844-2850. doi: 10.1897/03-409.1
^ Burton, G.A. Jr., Nordstrom, J.F., 2004. An in situ toxicity identification evaluation method part II: Field validation. Environmental Toxicology and Chemistry, 23(12), pp. 2851-2855. doi: 10.1897/03-468.1
^ Chadwick, D.B., Harre, B., Smith, C.F., Groves, J.G., Paulsen, R.J., 2003. Coastal Contaminant Migration Monitoring: The Trident Probe and UltraSeep System. Hardware Description, Protocols, and Procedures. Technical Report 1902. Space and Naval Warfare Systems Center.
^ Woodard, S., Mohr, T., Nickelsen, M.G., 2014. Synthetic media: A promising new treatment technology for 1,4-dioxane. Remediation Journal, 24(4), pp. 27-40. doi: 10.1002/rem.21402
^ Lemos, B.R.S., Teixeira, I.F., de Mesquita, J.P., Ribeiro, R.R., Donnici, C.L., Lago, R.M., 2012. Use of modified activated carbon for the oxidation of aqueous sulfide. Carbon, 50(3), pp. 1386-1393. doi: 10.1016/j.carbon.2011.11.011
^ Iannone, A., Carriera, F., Di Fiore, C., Avino, P., 2024. Poly- and Perfluoroalkyl Substance (PFAS) Analysis in Environmental Matrices: An Overview of the Extraction and Chromatographic Detection Methods. Analytica, 5(2), pp. 187-202. doi: 10.3390/analytica5020012 Open Access Article
^ Singh, R.K., Brown, E., Mededovic Thagard, S., Holson, T.M., 2021. Treatment of PFAS-containing landfill leachate using an enhanced contact plasma reactor. Journal of Hazardous Materials, 408, Article 124452. doi: 10.1016/j.jhazmat.2020.124452
^ Singh, R.K., Multari, N., Nau-Hix, C., Woodard, S., Nickelsen, M., Mededovic Thagard, S., Holson, T.M., 2020. Removal of Poly- and Per-Fluorinated Compounds from Ion Exchange Regenerant Still Bottom Samples in a Plasma Reactor. Environmental Science and Technology, 54(21), pp. 13973-80. doi: 10.1021/acs.est.0c02158
^ Nau-Hix, C., Multari, N., Singh, R.K., Richardson, S., Kulkarni, P., Anderson, R.H., Holsen, T.M., Mededovic Thagard S., 2021. Field Demonstration of a Pilot-Scale Plasma Reactor for the Rapid Removal of Poly- and Perfluoroalkyl Substances in Groundwater. American Chemical Society’s Environmental Science and Technology (ES&T) Water, 1(3), pp. 680-87. doi: 10.1021/acsestwater.0c00170
^ Nzeribe, B.N., Crimi, M., Mededovic Thagard, S., Holsen, T.M., 2019. Physico-Chemical Processes for the Treatment of Per- And Polyfluoroalkyl Substances (PFAS): A Review. Critical Reviews in Environmental Science and Technology, 49(10), pp. 866-915. doi: 10.1080/10643389.2018.1542916
^ Jung, B., Farzaneh, H., Khodary, A., Abdel-Wahab, A., 2015. Photochemical degradation of trichloroethylene by sulfite-mediated UV irradiation. Journal of Environmental Chemical Engineering, 3(3), pp. 2194-2202. doi: 10.1016/j.jece.2015.07.026
^ Liu, X., Yoon, S., Batchelor, B., Abdel-Wahab, A., 2013. Photochemical degradation of vinyl chloride with an Advanced Reduction Process (ARP) – Effects of reagents and pH. Chemical Engineering Journal, 215-216, pp. 868-875. doi: 10.1016/j.cej.2012.11.086
^ Li, X., Ma, J., Liu, G., Fang, J., Yue, S., Guan, Y., Chen, L., Liu, X., 2012. Efficient Reductive Dechlorination of Monochloroacetic Acid by Sulfite/UV Process. Environmental Science and Technology, 46(13), pp. 7342-49. doi: 10.1021/es3008535
^ Li, X., Fang, J., Liu, G., Zhang, S., Pan, B., Ma, J., 2014. Kinetics and efficiency of the hydrated electron-induced dehalogenation by the sulfite/UV process. Water Research, 62, pp. 220-228. doi: 10.1016/j.watres.2014.05.051
^ ^20.0 ^20.1 ^20.2 ^20.3 ^20.4 ^20.5 ^20.6 ^20.7 Cite error: Invalid <ref> tag; no text was provided for refs named EradiFluor

@@ Line 1: / Line 1: @@
-==Supercritical Water Oxidation (SCWO)==
+==''In Situ'' Toxicity Identification Evaluation (iTIE)==
-Supercritical water oxidation (SCWO) is a single step wet oxidation process that transforms organic matter into water, carbon dioxide and, depending on the waste undergoing treatment, an inert mineral solid residue. The process is highly effective and can treat a variety of wet wastes without dewatering. The SCWO technology allows for the complete destruction of persistent and toxic organic contaminants such as [[perfluoroalkyl and polyfluoroalkyl substances (PFAS)]], [[1,4-dioxane]], and many more.
+The ''in situ'' Toxicity Identification Evaluation system is a tool to incorporate into weight-of-evidence studies at sites with numerous chemical toxicant classes present. The technology works by continuously sampling site water, immediately fractionating the water using diagnostic sorptive resins, and then exposing test organisms to the water to observe toxicity responses with minimal sample manipulation. It is compatible with various resins, test organisms, and common acute and chronic toxicity tests, and can be deployed at sites with a wide variety of physical and logistical considerations.
 <div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
 '''Related Article(s):'''
-* [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS)]]
+*[[Contaminated Sediments - Introduction]]
-* [[PFAS Transport and Fate]]
+*[[Contaminated Sediment Risk Assessment]]
-* [[PFAS Sources]]
-* [[PFAS Soil Remediation Technologies]]
-'''Contributor(s):''' [[Dr. Scott Grieco]] and [[James Hatton]]
+'''Contributors:''' Dr. G. Allen Burton Jr., Austin Crane
-'''Key Resource(s):'''
+'''Key Resources:'''
+*A Novel In Situ Toxicity Identification Evaluation (iTIE) System for Determining which Chemicals Drive Impairments at Contaminated Sites<ref name="BurtonEtAl2020">Burton, G.A., Cervi, E.C., Meyer, K., Steigmeyer, A., Verhamme, E., Daley, J., Hudson, M., Colvin, M.,  Rosen, G., 2020. A novel In Situ Toxicity Identification Evaluation (iTIE) System for Determining which Chemicals Drive Impairments at Contaminated Sites. Environmental Toxicology and Chemistry, 39(9), pp. 1746-1754. [https://doi.org/10.1002/etc.4799 doi: 10.1002/etc.4799]</ref>
+*An in situ toxicity identification and evaluation water analysis system: Laboratory validation<ref name="SteigmeyerEtAl2017">Steigmeyer, A.J., Zhang, J., Daley, J.M., Zhang, X., Burton, G.A. Jr., 2017. An in situ toxicity identification and evaluation water analysis system: Laboratory validation. Environmental Toxicology and Chemistry, 36(6), pp. 1636-1643. [https://doi.org/10.1002/etc.3696 doi: 10.1002/etc.3696]</ref>
+*Sediment Toxicity Identification Evaluation (TIE) Phases I, II, and III Guidance Document-	<ref>United States Environmental Protection Agency, 2007.  Sediment Toxicity Identification Evaluation (TIE) Phases I, II, and III Guidance Document, EPA/600/R-07/080. 145 pages. [https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1003GR1.txt Free Download]&nbsp; [[Media: EPA2007.pdf | Report.pdf]]</ref>
+*In Situ Toxicity Identification Evaluation (iTIE) Technology for Assessing Contaminated Sediments, Remediation Success, Recontamination and Source Identification-	<ref>In Situ Toxicity Identification Evaluation (iTIE) Technology for Assessing Contaminated Sediments, Remediation Success, Recontamination and Source Identification [https://serdp-estcp.mil/projects/details/88a8f9ba-542b-4b98-bfa4-f693435535cd/er18-1181-project-overview Project Website]&nbsp; [[Media: ER18-1181Ph.II.pdf | Final Report.pdf]]</ref>
-*[https://www.waterrf.org/resource/treatment-mitigation-strategies-poly-and-perfluorinated-chemicals Water Research Foundation (Drinking Water): Treatment Mitigation Strategies for PFAS]<ref name="Dickenson2016">Dickenson, E. and Higgins, C., 2016. Treatment Mitigation Strategies for Poly- and Perfluoroalkyl Substances, Report Number 4322. Water Research Foundation, Denver, Colorado. 123 pages. ISBN 978-1-60573-234-3</ref>
+==Introduction==
+In waterways impacted by numerous naturally occurring and anthropogenic chemical stressors, it is crucial for environmental practitioners to be able to identify which chemical classes are causing the highest degrees of toxicity to aquatic life. Previously developed methods, including the Toxicity Identification Evaluation (TIE) protocol developed by the US Environmental Protection Agency (EPA)<ref>Norberg-King, T., Mount, D.I., Amato, J.R., Jensen, D.A., Thompson, J.A., 1992. Toxicity identification evaluation: Characterization of chronically toxic effluents: Phase I. Publication No. EPA/600/6-91/005F. U.S. Environmental Protection Agency, Office of Research and Development. [https://www.epa.gov/sites/default/files/2015-09/documents/owm0255.pdf Free Download from US EPA]&nbsp; [[Media: usepa1992.pdf | Report.pdf]]</ref>, can be confounded by sample manipulation artifacts and temporal limitations of ''ex situ'' organism exposures<ref name="BurtonEtAl2020"/>. These factors may disrupt causal linkages and mislead investigators during site characterization and management decision-making. The ''in situ'' Toxicity Identification Evaluation (iTIE) technology was developed to allow users to strengthen stressor-causality linkages and rank chemical classes of concern at impaired sites, with high degrees of ecological realism.
-*[https://pfas-1.itrcweb.org/12-treatment-technologies/#12_2 Interstate Technical and Regulatory Council: PFAS Liquids Treatment Technologies]<ref name="ITRC2020">Interstate Technology and Regulatory Council (ITRC), 2020. PFAS Technical and Regulatory Guidance Document and Fact Sheets, PFAS-1. PFAS Team, Washington, DC.  [https://pfas-1.itrcweb.org/ Website]&nbsp;&nbsp; [[Media: ITRC_PFAS-1.pdf | Report.pdf]]</ref>
+The technology has undergone a series of improvements in recent years, with the most recent prototype being robust, operable in a wide variety of site conditions, and cost-effective compared to alternative site characterization methods<ref>Burton, G.A. Jr., Nordstrom, J.F., 2004. An in situ toxicity identification evaluation method part I: Laboratory validation. Environmental Toxicology and Chemistry, 23(12), pp. 2844-2850. [https://doi.org/10.1897/03-409.1 doi: 10.1897/03-409.1]</ref><ref>Burton, G.A. Jr., Nordstrom, J.F., 2004. An in situ toxicity identification evaluation method part II: Field validation. Environmental Toxicology and Chemistry, 23(12), pp. 2851-2855. [https://doi.org/10.1897/03-468.1 doi: 10.1897/03-468.1]</ref><ref name="BurtonEtAl2020"/><ref name="SteigmeyerEtAl2017"/>. The latest prototype can be used in any of the following settings: in marine, estuarine, or freshwater sites; to study surface water or sediment pore water; in shallow waters easily accessible by foot or in deep waters only accessible by pier or boat. It can be used to study sites impacted by a wide variety of stressors including ammonia, [[Metal and Metalloid Contaminants | metals]], pesticides, polychlorinated biphenyls (PCB), [[Polycyclic Aromatic Hydrocarbons (PAHs) | polycyclic aromatic hydrocarbons (PAH)]], and [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) | per- and polyfluoroalkyl substances (PFAS)]], among others. The technology is applicable to studies of acute toxicity via organism survival or of chronic toxicity via responses in growth, reproduction, or gene expression<ref name="BurtonEtAl2020"/>.
-*[https://www.sciencedirect.com/science/article/pii/S0301479717307934 Novel treatment technologies for PFAS compounds: A critical review.]<ref name="Kucharzyk2017"> Kucharzyk, K.H., Darlington, R., Benotti, M., Deeb, R. and Hawley, E., 2017. Novel treatment technologies for PFAS compounds: A critical review. Journal of Environmental Management, 204(2), pp. 757-764.  [https://doi.org/10.1016/j.jenvman.2017.08.016 DOI: 10.1016/j.jenvman.2017.08.016]&nbsp;&nbsp; Manuscript available from: [https://www.researchgate.net/profile/Katarzyna_kate_Kucharzyk/publication/319125507_Novel_treatment_technologies_for_PFAS_compounds_A_critical_review/links/5a06590b4585157013a3be77/Novel-treatment-technologies-for-PFAS-compounds-A-critical-review.pdf ResearchGate].</ref>
+==System Components and Validation==
+[[File: CraneFig1.png | thumb | 600 px | Figure 1: A schematic diagram of the iTIE system prototype. The system is divided into three sub-systems: 1) the Pore Water/Surface Water Collection Sub-System (blue); 2) the Pumping Sub-System (red); and 3) the iTIE Resin, Exposure, and Sampling Sub-System (green). Water first enters the system through the Pore Water/Surface Water Collection Sub-System. Porewater can be collected using Trident-style probes, or surface water can be collected using a simple weighted probe. The water is composited in a manifold before being pumped to the rest of the iTIE system by the booster pump. Once in the iTIE Resin, Exposure, and Sampling Sub-System, the water is gently oxygenated by the Oxygen Coil, separated from gas bubbles by the Drip Chamber, and diverted to separate iTIE Resin and Exposure Chambers (or iTIE units) by the Splitting Manifold. Water movement through each iTIE unit is controlled by a dedicated Regulation Pump. Finally, the water is gathered in Sample Collection bottles for analysis.]]
+The latest iTIE prototype consists of an array of sorptive resins that differentially fractionate sampled water, and a series of corresponding flow-through organism chambers that receive the treated water ''in situ''. Resin treatments can be selected depending on the chemicals suspected to be present at each site to selectively sequester certain chemical of concern (CoC) classes from the whole water, leaving a smaller subset of chemicals in the resulting water fraction for chemical and toxicological characterization. Test organism species and life stages can also be chosen depending on factors including site characteristics and study goals. In the full iTIE protocol, site water is continuously sampled either from the sediment pore spaces or the water column at a site, gently oxygenated, diverted to different iTIE units for fractionation and organism exposure, and collected in sample bottles for off-site chemical analysis (Figure 1). All iTIE system components are housed within waterproof Pelican cases, which allow for ease of transport and temperature control.
-*[https://www.liebertpub.com/doi/abs/10.1089/ees.2016.0233 Degradation and removal methods for perfluoroalkyl and polyfluoroalkyl substances in water]<ref name="Merino2016">Merino, N., Qu, Y., Deeb, R.A., Hawley, E.L., Hoffmann, M.R., and Mahendra, S., 2016. Degradation and Removal Methods for Perfluoroalkyl and Polyfluoroalkyl Substances in Water. Environmental Engineering Science, 33(9), pp. 615-649.  [https://doi.org/10.1089/ees.2016.0233 DOI: 10.1089/ees.2016.0233]</ref>
+===Porewater and Surface Water Collection Sub-system===
+[[File: CraneFig2.png | thumb | 600 px | Figure 2: a) Trident probe with auxiliary sensors attached, b) a Trident probe with end caps removed (the red arrow identifies the intermediate space where glass beads are packed to filter suspended solids), c) a Trident probe being installed using a series of push poles and a fence post driver]]
+Given&nbsp;the&nbsp;importance&nbsp;of sediment porewater to ecosystem structure and function, investigators may employ the iTIE system to evaluate the toxic effects associated with the impacted sediment porewater. To accomplish this, the iTIE system utilizes the Trident probe, originally developed for Department of Defense site characterization studies<ref>Chadwick, D.B., Harre, B., Smith, C.F., Groves, J.G., Paulsen, R.J., 2003. Coastal Contaminant Migration Monitoring: The Trident Probe and UltraSeep System. Hardware Description, Protocols, and Procedures. Technical Report 1902. Space and Naval Warfare Systems Center.</ref>. The main body of the Trident is comprised of a stainless-steel frame with six hollow probes (Figure 2). Each probe contains a layer of inert glass beads, which filters suspended solids from the sampled water. The water is drawn through each probe into a composite manifold and transported to the rest of the iTIE system using a high-precision peristaltic pump.
-==Established PFAS Treatment Technologies==
+The Trident also includes an adjustable stopper plate, which forms a seal against the sediment and prevents the inadvertent dilution of porewater samples with surface water. (Figure 2). Preliminary laboratory results indicate that the Trident is extremely effective in collecting porewater samples with minimal surface water infiltration in sediments ranging from coarse sand to fine clay. Underwater cameras, sensors, passive samplers, and other auxiliary equipment can be attached to the Trident probe frame to provide supplemental data.
-Three technologies are well demonstrated for removal of [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) | PFAS]] from drinking water and non-potable groundwater (as described below):
-* membrane filtration including [[wikipedia: Reverse osmosis | reverse osmosis (RO)]] and [[Wikipedia: Nanofiltration | nanofiltration (NF)]]
-* granular [[Wikipedia: Activated carbon | activated carbon]] (GAC) and powdered activated carbon (PAC) adsorption
-* [[wikipedia: Ion_exchange | anion exchange (IX)]]
-However, these technologies are less demonstrated for removal of PFAS from more complex matrices such as wastewater and leachate.
+Alternatively, practitioners may employ the iTIE system to evaluate site surface water. To sample surface water, weighted intake tubes can collect surface water from the water column using a peristaltic pump.
-Site-specific considerations that affect the selection of optimum treatment technologies for a given site include water chemistry, required flow rate, treatment criteria, waste residual generation, residual disposal options, and operational complexity.  Treatability studies with site water are highly recommended because every site has different factors that may affect engineering design for these technologies.
-===Membrane Filtration===
+===Oxygen Coil, Overflow Bag and Drip Chamber===
-[[File: revOsmosisPlant.png | thumb | 500px | Figure 1.  A RO municipal drinking water plant in Arizona]]
+[[File: CraneFig3.png | thumb | left | 400 px | Figure 3. Contents of the iTIE system cooler. The pictured HDPE rack (47.6 cm length x 29.7 cm width x 33.7 cm height) is removable from the iTIE cooler. Water enters the system at the red circle, flows through the oxygen coil, and then travels to each of the individual iTIE units where diagnostic resins and organisms are located. The water then briefly leaves the cooler to travel through peristaltic regulation pumps before being gathered in sample collection bottles.]]
-Given their ability to remove dissolved contaminants at a molecular size level, RO and some NF membranes can be highly effective for PFAS removal. For RO systems (Figure 1), several studies have demonstrated effective removal of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) (see [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) | PFAS]] for nomenclature) from drinking water with removal rates well above 90%<ref name="Tang2006">Tang, C.Y., Fu, Q.S., Robertson, A.P., Criddle, C.S., and Leckie, J.O., 2006. Use of Reverse Osmosis Membranes to Remove Perfluorooctane Sulfonate (PFOS) from Semiconductor Wastewater. Environmental Science and Technology, 40(23), pp. 7343-7349.   [https://doi.org/10.1021/es060831q DOI: 10.1021/es060831q]</ref><ref name="Flores2013">Flores, C., Ventura, F., Martin-Alonso, J., and Caixach, J., 2013. Occurrence of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in NE Spanish surface waters and their removal in a drinking water treatment plant that combines conventional and advanced treatments in parallel lines. Science of the Total environment, 461, 618-626.  [https://doi.org/10.1016/j.scitotenv.2013.05.026 DOI: 10.1016/j.scitotenv.2013.05.026]</ref><ref name="Appleman2014">Appleman, T.D., Higgins, C.P., Quiñones, O., Vanderford, B.J., Kolstad, C., Zeigler-Holady, J.C., and Dickenson, E.R., 2014. Treatment of poly- and perfluoroalkyl substances in US full-scale water treatment systems. Water Research, 51, pp. 246-255.  [https://doi.org/10.1016/j.watres.2013.10.067 DOI: 10.1016/j.watres.2013.10.067]</ref>. RO potable water reuse treatment systems implemented in California have also demonstrated effective PFOS and PFOA removal as reported by the Water Research Foundation (WRF)<ref name="Dickenson2016"/>. Analysis of permeate at both sites referenced by the WRF confirmed that short and long chain PFAS concentrations in the treated water were reduced to levels below test method reporting limits.
+Porewater&nbsp;is&nbsp;naturally&nbsp;anoxic due to limited mixing with aerated surface water and high oxygen demand of sediments, which may cause organism mortality and interfere with iTIE results. To preclude this, sampled porewater is exposed to an oxygen coil. This consists of an interior silicone tube connected to a pressurized oxygen canister, threaded through an exterior reinforced PVC tube through which water is slowly pumped (Figure 3). Pump rates are optimized to ensure adequate aeration of the water. In addition to elevating DO levels, the oxygen coil facilitates the oxidation of dissolved sulfides, which naturally occur in some marine sediments and may otherwise cause toxicity to organisms if left in its reduced form.
-Full-scale studies using larger effective pore size NF membranes for PFAS removal are limited in number but are promising since NF systems are somewhat less costly than RO and may be nearly as effective in removing PFAS.  Recent laboratory or pilot studies have shown good performance of NF membranes<ref name="Steinle-Darling2008">Steinle-Darling, E., and Reinhard, M., 2008. Nanofiltration for Trace Organic Contaminant Removal: Structure, Solution, and Membrane Fouling Effects on the Rejection of Perfluorochemicals. Environmental Science and Technology, 42(14), pp. 5292-5297.  [https://doi.org/10.1021/es703207s DOI: 10.1021/es703207s]&nbsp;&nbsp; Free download from: [https://d1wqtxts1xzle7.cloudfront.net/48926882/es703207s20160918-21142-1xmqco5.pdf?1474189169=&response-content-disposition=inline%3B+filename%3DNanofiltration_for_Trace_Organic_Contami.pdf&Expires=1613000850&Signature=N-ZvvjOJX3TSOQzg7od3Q0LulNSZOqqjfummVEUfmiYlC3VasS4FuBHOgY52Xy~7FrKbOLhx0xx8QHdUsR~fbRTMQNXhiqbEslnU2gda2EcZHMMJj0mf-01wIA3jFIywA7IIabmTd3uMUGsIfT1D0PrGY00RmprYIQBoG3Dg~KjoizdfxYfvEgdZw2C~7D47pPiwMSnavZiGuvO0~dbRF8nawL7Prg91xt5BFTNUQQiIrIlMWc4PhVjzE5Su2CUZqnNlYdAW5Ck7B9lKmmVMPiOgz07vFnyp7m-q4UK3woa~aBFW9Wp~hjqN6vfohn8Hocv5oMpZNamhu8vBbPilKw__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA Academia].</ref><ref name="Appleman2013">Appleman, T.D., Dickenson, E.R., Bellona, C., and Higgins, C.P., 2013. Nanofiltration and granular activated carbon treatment of perfluoroalkyl acids. Journal of Hazardous Materials, 260, 740-746.  [https://doi.org/10.1016/j.jhazmat.2013.06.033 DOI: 10.1016/j.jhazmat.2013.06.033]</ref><ref name="Soriano2017">Soriano, Á., Gorri, D., and Urtiaga, A., 2017. Efficient treatment of perfluorohexanoic acid by nanofiltration followed by electrochemical degradation of the NF concentrate. Water Research, 112, 147-156.  [https://doi.org/10.1016/j.watres.2017.01.043 DOI: 10.1016/j.watres.2017.01.043]&nbsp;&nbsp; [[Media: Soriano2017.pdf | Author’s Manuscript.]]</ref><ref name="Zeng2017">Zeng, C., Tanaka, S., Suzuki, Y., Yukioka, S., and Fujii, S., 2017. Rejection of Trace Level Perfluorohexanoic Acid (PFHxA) in Pure Water by Loose Nanofiltration Membrane. Journal of Water and Environment Technology, 15(3), pp. 120-127.  [https://doi.org/10.2965/jwet.16-072 DOI: 10.2965/jwet.16-072]&nbsp;&nbsp; Free download from: [https://www.jstage.jst.go.jp/article/jwet/15/3/15_16-072/_pdf J-STAGE]</ref><ref name="Wang2018">Wang, J., Wang, L., Xu, C., Zhi, R., Miao, R., Liang, T., Yue, X., Lv, Y. and Liu, T., 2018. Perfluorooctane sulfonate and perfluorobutane sulfonate removal from water by nanofiltration membrane: The roles of solute concentration, ionic strength, and macromolecular organic foulants. Chemical Engineering Journal, 332, pp. 787-797.  [https://doi.org/10.1016/j.cej.2017.09.061 DOI: 10.1016/j.cej.2017.09.061]</ref>.
-Although membrane RO and NF processes are generally capable of providing uniform removal rates relative to short and long chain PFAS compounds (see [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) | PFAS]] for nomenclature), other aspects of these treatment technologies are more challenging:
+Gas bubbles may form in the oxygen coil over the course of a deployment. These can be disruptive, decreasing water sample volumes and posing a danger to sensitive organisms like daphnids. To account for this, the water travels to a drip chamber after exiting the oxygen coil, which allows gas bubbles to be separated and diverted to an overflow system. The sample water then flows to a manifold which divides the flow into different paths to each of the treatment units for fractionation and organism exposure.
-* Membranes must be flushed and cleaned periodically, such that overall water recovery rates (process water volumes consumed, wasted, and lost vs. treated water volumes produced) are much lower than those for GAC and IX processes. Membrane fouling can be slowed or avoided depending on operating conditions, membrane modifications, and feed modifications<ref name="LeRoux2005">Le Roux, I., Krieg, H.M., Yeates, C.A. and Breytenbach, J.C., 2005. Use of chitosan as an antifouling agent in a membrane bioreactor. Journal of Membrane Science, 248(1-2), pp. 127-136.  [https://doi.org/10.1016/j.memsci.2004.10.005 DOI: 10.1016/j.memsci.2004.10.005]</ref>. Typically, 70-90% of the water supplied into a membrane RO process is recoverable as treated water. The remaining 10-30% is reject containing approximately 4 to 8 times the initial PFAS concentration (depending on recovery rate).
+===iTIE Units: Fractionation and Organism Exposure Chambers===
+[[File: CraneFig4.png | thumb | 300px | Figure 4. A diagram of the iTIE prototype. Water flows upward into each resin chamber through the unit bottom. After being chemically fractionated in the resin chamber, water travels into the organism chamber, where test organisms have been placed. Water is drawn through the units by high-precision peristaltic pumps.]]
+At the core of the iTIE system are separate dual-chamber iTIE units, each with a resin fractionation chamber and an organism exposure chamber (Figure 4). Developed by Burton ''et al.''<ref name="BurtonEtAl2020"/>, the iTIE prototype is constructed from acrylic, with rubber O-rings to connect each piece. Each iTIE unit can contain a different diagnostic resin matrix, customizable to remove specific chemical classes from the water. Sampled water flows into each unit through the bottom and is differentially fractionated by the resin matrix as it travels upward. Then it reaches the organism chamber, where test organisms are placed for exposure. The organism chamber inlet and outlet are covered by mesh to prevent the escape of the test organisms. This continuous flow-through design allows practitioners to capture the temporal heterogeneity of ambient water conditions over the duration of an in situ exposure. Currently, the iTIE system can support four independent iTIE treatment units.
-* These cleaning and flushing processes create a continuous liquid waste stream, which periodically includes harsh membrane cleaning chemicals as well as a continuous flow of concentrated membrane reject chemicals (i.e., PFAS) that must be properly managed and disposed of.  Management often includes further treatment to remove PFAS from the liquid waste.
+After being exposed to test organisms, water is collected in sample bottles. The bottles can be pre-loaded with preservation reagents to allow for later chemical analysis. Sample bottles can be composed of polyethylene, glass or other materials depending on the CoC.
-* RO and NF systems are inherently more expensive and complicated systems to implement, operate, and maintain compared to adsorption processes. Treatment system operator certification and process monitoring requirements are correspondingly markedly higher for RO and NF than they are for GAC and IX.
+===Pumping Sub-system===
+[[File: CraneFig5.png | thumb | 300px | Figure 5. The iTIE system pumping sub-system. The sub-system consists of: A) a single booster pump, which is directly connected to the water sampling device and feeds water to the rest of the iTIE system, and B) a set of four regulation pumps, which each connect to the outflow of an individual iTIE unit. Each pump set is housed in a waterproof case with self-contained rechargeable battery power. A tablet is mounted inside the lid of the four pump case, which can be used to program and operate all of the pumps when connected to the internet.]]
+Water movement through the system is driven by a series of high-precision, programmable peristaltic pumps ([https://ecotechmarine.com/ EcoTech Marine]). Each pump set is housed in a Pelican storm travel case. Power is supplied to each pump by internal rechargeable lithium-iron phosphate batteries ([https://www.bioennopower.com/ Bioenno Power]).
-* Water feed pressures required to drive flow through membrane RO and NF processes are considerably higher than those involved with GAC and IX processes. This results in reduced process efficiency and higher pumping and electrical operating costs.
+First, water is supplied to the system by a booster pump (Figure 5A). This pump is situated between the water sampling sub-system and the oxygen coil. The booster pump: 1) facilitates pore water collection, especially from sediments with high fine particle fractions; 2) helps water overcome vertical lifts to travel to the iTIE system; and 3) prevents vacuums from forming in the iTIE system interior, which can accelerate the formation of disruptive gas bubbles in the oxygen coil. The booster pump should be programmed to supply an excess of water to prevent vacuum formation.
-* Membrane systems can also be subject to issues with irreversible membrane fouling, clogging, and scaling or other physical membrane damage and failures. Additional water pretreatment and higher levels of monitoring and maintenance are then required, further adding to the higher costs of such systems.
+Second, a set of four regulation pumps ensure precise flow rates through each independent iTIE unit (Figure 5B). Each regulation pump pulls water from the top of an iTIE unit and then dispenses that water into a sample bottle for further analysis.
-===Activated Carbon Adsorption===
+==Study Design Considerations==
-[[File: GAChouse.JPG | thumb| 500px | Figure 2.  Typical private water supply well GAC installation for removal PFAS. Pressure gages and sample ports located before the first (or lead) vessel, at the midpoint, and after the second (or lag) vessel allow monitoring for pressure drop due to fouling and for contaminant breakthrough.]]
+===Diagnostic Resin Treatments===
-Activated carbon is a form of carbon processed to have small pores that increase the surface area available for adsorption of constituents from water. Activated carbon is derived from many source materials, including coconut shells, wood, lignite, and bituminous coal. Different types of activated carbon base materials have varied adsorption characteristics such that some may be better suited to removing certain contaminant compounds than others.  Results from laboratory testing, pilot evaluations, and full-scale system operations suggest that bituminous coal-based GAC is generally the best performing carbon for PFAS removal<ref name="McNamara2018">McNamara, J.D., Franco, R., Mimna, R., and Zappa, L., 2018. Comparison of Activated Carbons for Removal of Perfluorinated Compounds from Drinking Water. Journal‐American Water Works Association, 110(1), pp. E2-E14.  [https://doi.org/10.5942/jawwa.2018.110.0003 DOI: 10.5942/jawwa.2018.110.0003]</ref><ref name="Westreich2018">Westreich, P., Mimna, R., Brewer, J., and Forrester, F., 2018. The removal of short‐chain and long‐chain perfluoroalkyl acids and sulfonates via granular activated carbons: A comparative column study. Remediation Journal, 29(1), pp. 19-26.  [https://doi.org/10.1002/rem.21579 DOI: 10.1002/rem.21579]</ref>.
+Several commercially available resins have been verified for use in the iTIE system. Investigators can select resins based on stressor classes of interest at each site. Each resin selectively removes a CoC class from site water prior to organism exposure.
+*[https://www.dupont.com/products/ambersorb560.html DuPont Ambersorb 560] for removal of 1,4-dioxane and other organic chemicals<ref>Woodard, S., Mohr, T., Nickelsen, M.G., 2014. Synthetic media: A promising new treatment technology for 1,4-dioxane. Remediation Journal, 24(4), pp. 27-40. [https://doi.org/10.1002/rem.21402 doi: 10.1002/rem.21402]</ref>
+*C18 for nonpolar organic chemicals
+*[https://www.bio-rad.com/en-us Bio-Rad] [https://www.bio-rad.com/en-us/product/chelex-100-resin?ID=6448ab3e-b96a-4162-9124-7b7d2330288e Chelex] for metals
+*Granular activated carbon for metals, general organic chemicals, sulfide<ref>Lemos, B.R.S., Teixeira, I.F., de Mesquita, J.P., Ribeiro, R.R., Donnici, C.L., Lago, R.M., 2012. Use of modified activated carbon for the oxidation of aqueous sulfide. Carbon, 50(3), pp. 1386-1393. [https://doi.org/10.1016/j.carbon.2011.11.011 doi: 10.1016/j.carbon.2011.11.011]</ref>
+*[https://www.waters.com/nextgen/us/en.html Waters] [https://www.waters.com/nextgen/us/en/search.html?category=Shop&isocode=en_US&keyword=oasis%20hlb&multiselect=true&page=1&rows=12&sort=best-sellers&xcid=ppc-ppc_23916&gad_source=1&gad_campaignid=14746094146&gbraid=0AAAAAD_uR00nhlNwrhhegNh06pBODTgiN&gclid=CjwKCAiAtLvMBhB_EiwA1u6_PsppE0raci2IhvGnAAe5ijciNcetLaGZo5qA3g3r4Z_La7YAPJtzShoC6LoQAvD_BwE Oasis HLB] for general organic chemicals<ref name="SteigmeyerEtAl2017"/>
+*[https://www.waters.com/nextgen/us/en.html Waters] [https://www.waters.com/nextgen/us/en/search.html?category=All&enableHL=true&isocode=en_US&keyword=Oasis%20WAX%20&multiselect=true&page=1&rows=12&sort=most-relevant Oasis WAX] for PFAS, organic chemicals of mixed polarity<ref>Iannone, A., Carriera, F., Di Fiore, C., Avino, P., 2024. Poly- and Perfluoroalkyl Substance (PFAS) Analysis in Environmental Matrices: An Overview of the Extraction and Chromatographic Detection Methods. Analytica, 5(2), pp. 187-202. [https://doi.org/10.3390/analytica5020012 doi: 10.3390/analytica5020012]&nbsp; [[Media: IannoneEtAl2024.pdf | Open Access Article]]</ref>
+*Zeolite for ammonia, other organic chemicals
-The removal efficiency of individual PFAS compounds using GAC is a function of both the PFAS functional group (carboxylic acid versus sulfonic acid) and also the perfluoro-carbon chain length<ref name="McCleaf2017">McCleaf, P., Englund, S., Östlund, A., Lindegren, K., Wiberg, K., and Ahrens, L., 2017. Removal efficiency of multiple poly-and perfluoroalkyl substances (PFASs) in drinking water using granular activated carbon (GAC) and anion exchange (AE) column tests. Water Research, 120, pp. 77-87.  [https://doi.org/10.1016/j.watres.2017.04.057 DOI: 10.1016/j.watres.2017.04.057]</ref><ref name="Eschauzier2012">Eschauzier, C., Beerendonk, E., Scholte-Veenendaal, P., and De Voogt, P., 2012. Impact of Treatment Processes on the Removal of Perfluoroalkyl Acids from the Drinking Water Production Chain. Environmental Science and Technology, 46(3), pp. 1708-1715.  [https://doi.org/10.1021/es201662b DOI: 10.1021/es201662b]</ref>(see [[Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) | PFAS]] for nomenclature):
+Resins must be adequately conditioned prior to use. Otherwise, they may inadequately adsorb toxicants or cause stress to organisms. New resins should be tested for efficacy and toxicity before being used in an iTIE system.
-* perfluoro-sulfonate acids (PFSAs) are more efficiently removed than perfluoro-carboxylic acids (PFCAs) of the same chain length
-* long chain compounds of the same functional group are removed better than the shorter chains
-Activated carbon may be applied in drinking water systems as GAC or PAC<ref name="Dudley">Dudley, L.A., Arevalo, E.C., and Knappe, D.R., 2015. Removal of Perfluoroalkyl Substances by PAC Adsorption and Anion Exchange. Water Research Foundation Project #4344.  Free  download of Executive Summary from: [https://www.waterrf.org/system/files/resource/2019-04/4344_ProjectSummary.pdf Water Research Foundation (Public Plus account)]</ref><ref name="Qian2017">Qian, J., Shen, M., Wang, P., Wang, C., Li, K., Liu, J., Lu, B. and Tian, X., 2017. Perfluorooctane sulfonate adsorption on powder activated carbon: Effect of phosphate (P) competition, pH, and temperature. Chemosphere, 182, pp. 215-222.  [https://doi.org/10.1016/j.chemosphere.2017.05.033 DOI: 10.1016/j.chemosphere.2017.05.033]</ref>. GAC has larger granules and is reusable, while PAC has much smaller granules and is not typically reused.  PAC has most often been used as a temporary treatment because costs associated with disposal and replacement of the used PAC tend to preclude using it for long-term treatment. A typical GAC installation for a private drinking water well is shown in Figure 2. Contrary to PAC, GAC used to treat PFAS can be reactivated by the manufacturer, driving the PFAS from the GAC and into off-gas. The extracted gas is then treated with thermal oxidation (temperatures often 1200&deg;C to 1400&deg;C).  The reactivated GAC is then brought back to the site and reused.  Thus, GAC can ultimately be a destructive treatment technology.
-[[File: IXcycle.png | thumb | 400px | left | Figure 3.  Operational cycle of a packed bed reactor with anion exchange resin beads]]
+===Test Organism Species and Life Stages===
-===Anion Exchange===
-Anion exchange has also been demonstrated for the adsorption of PFAS, and published results note higher sorption per pound than GAC<ref name="McCleaf2017"/><ref name=" Senevirathna2010">Senevirathna, S.T.M.L.D., Tanaka, S., Fujii, S., Kunacheva, C., Harada, H., Shivakoti, B.R., and Okamoto, R., 2010. A comparative study of adsorption of perfluorooctane sulfonate (PFOS) onto granular activated carbon, ion-exchange polymers and non-ion-exchange polymers. Chemosphere, 80(6), pp. 647-651.  [https://doi.org/10.1016/j.chemosphere.2010.04.053 DOI: 10.1016/j.chemosphere.2010.04.053]&nbsp;&nbsp; Free download from: [https://www.researchgate.net/profile/Chinagarn_Kunacheva/publication/44672056_A_comparative_study_of_adsorption_of_perfluorooctane_sulfonate_PFOS_onto_granular_activated_carbon_ion-exchange_polymers_and_non-ion-exchange_polymers/links/5a3380510f7e9b2a288a2b21/A-comparative-study-of-adsorption-of-perfluorooctane-sulfonate-PFOS-onto-granular-activated-carbon-ion-exchange-polymers-and-non-ion-exchange-polymers.pdf ResearchGate]</ref><ref name="Woodard2017">Woodard, S., Berry, J., and Newman, B., 2017. Ion exchange resin for PFAS removal and pilot test comparison to GAC. Remediation Journal, 27(3), pp. 19-27.  [https://doi.org/10.1002/rem.21515 DOI: 10.1002/rem.21515]</ref>. The higher capacity is believed to be due to combined hydrophobic and ion exchange adsorption mechanisms, whereas GAC mainly relies on hydrophobic attraction. Anion exchange resins can be highly selective, or they can also remove other contaminants based on design requirements and water chemistry. Resins have greater affinity for PFAS subgroup PFSA than for PFCA, and affinity increases with carbon chain length.
-[[Wikipedia: Ion-exchange resin | Anion exchange resins]] are a viable alternative to GAC for ''ex situ'' treatment of PFAS anions, and several venders sell resins capable of removing PFAS. Resins available for treating PFAS include regenerable resins that can be used multiple times (Figure 3) and single-use resins that must be disposed or destroyed after use<ref name=" Senevirathna2010"/>. Regenerable resins generate a solvent and brine solution, which is distilled to recover the solvent prior to the brine being adsorbed onto a small quantity of GAC or resin for ultimate disposal. This use of one treatment technology (GAC, IX) to support another (RO) is sometimes referred to as a “treatment train” approach. Single-use resins can be more fully exhausted than regenerable resins can and may be a more cost-effective solution for low concentration PFAS contamination, while regenerable resins may be more cost effective for higher concentration contamination.
-==Developing PFAS Treatment Technologies==
+<br clear="left"/>
-{| class="wikitable" style="float:right; margin-left:10px;"
-|+ Table 1.  Developmental Technologies
-|-
-! Stage
-! Separation/Transfer
-! Destructive*
-|-
-| Developing
-|
-* Biochar<ref name="Guo2017">Guo, W., Huo, S., Feng, J., and Lu, X., 2017. Adsorption of perfluorooctane sulfonate (PFOS) on corn straw-derived biochar prepared at different pyrolytic temperatures. Journal of the Taiwan Institute of Chemical Engineers, 78, pp. 265-271.  [https://doi.org/10.1016/j.jtice.2017.06.013 DOI: 10.1016/j.jtice.2017.06.013]</ref><ref name="Kupryianchyk2016">Kupryianchyk, D., Hale, S.E., Breedveld, G.D., and Cornelissen, G., 2016. Treatment of sites contaminated with perfluorinated compounds using biochar amendment. Chemosphere, 142, pp. 35-40.  [https://doi.org/10.1016/j.chemosphere.2015.04.085 DOI: 10.1016/j.chemosphere.2015.04.085]&nbsp;&nbsp; Free download from: [https://www.researchgate.net/profile/Sarah_Hale3/publication/276067521_Treatment_of_sites_contaminated_with_perfluorinated_compounds_using_biochar_amendment/links/5cdbe03b299bf14d959895d9/Treatment-of-sites-contaminated-with-perfluorinated-compounds-using-biochar-amendment.pdf ResearchGate]</ref><ref name="Inyang2017">Inyang, M., and Dickenson, E.R., 2017. The use of carbon adsorbents for the removal of perfluoroalkyl acids from potable reuse systems. Chemosphere, 184, pp. 168-175.  [https://doi.org/10.1016/j.chemosphere.2017.05.161 DOI: 10.1016/j.chemosphere.2017.05.161]</ref>
-* Modified Zeolites<ref name="Espana2015">Espana, V.A.A., Mallavarapu, M., and Naidu, R., 2015. Treatment technologies for aqueous perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA): A critical review with an emphasis on field testing. Environmental Technology and Innovation, 4, pp. 168-181.  [https://doi.org/10.1016/j.eti.2015.06.001 DOI: 10.1016/j.eti.2015.06.001]&nbsp;&nbsp; Free download from: [https://www.researchgate.net/profile/Ravi_Naidu2/publication/341241612_Recent_advances_in_the_analysis_of_per-and_polyfluoroalkyl_substances_PFAS-A_review/links/5eb9e3d892851cd50dab441c/Recent-advances-in-the-analysis-of-per-and-polyfluoroalkyl-substances-PFAS-A-review.pdf ResearchGate]</ref><ref name="CETCO2019">CETCO, 2019. FLUORO-SORB&reg; Adsorbent (product sales brochure).  [https://www.mineralstech.com/docs/default-source/performance-materials-documents/cetco/environmental-products/brochures/ps_fluorosorb_am_en_201905_v1.pdf Free download]&nbsp;&nbsp; [[Media:  FluoroSorb2019.pdf | Fluoro-Sorb.pdf]]</ref>
-* Specialty adsorbents<ref name="Zhang2011">Zhang, Q., Deng, S., Yu, G., and Huang, J., 2011. Removal of perfluorooctane sulfonate from aqueous solution by crosslinked chitosan beads: sorption kinetics and uptake mechanism. Bioresource Technology, 102(3), pp. 2265-2271.  [https://doi.org/10.1016/j.biortech.2010.10.040 DOI: 10.1016/j.biortech.2010.10.040]</ref><ref name="Cao2016">Cao, F., Wang, L., Ren, X., and Sun, H., 2016. Synthesis of a perfluorooctanoic acid molecularly imprinted polymer for the selective removal of perfluorooctanoic acid in an aqueous environment. Journal of Applied Polymer Science, 133(15).  [https://doi.org/10.1002/app.43192 DOI: 10.1002/app.43192]</ref><ref name="Hu2016">Hu, L., Li, Y., and Zhang, W., 2016. Characterization and application of surface-molecular-imprinted-polymer modified TiO2 nanotubes for removal of perfluorinated chemicals. Water Science and Technology, 74(6), pp. 1417-1425.  [https://doi.org/10.2166/wst.2016.321 DOI: 10.2166/wst.2016.321]&nbsp;&nbsp; [[Media: Hu2016.pdf | Free access article.]]</ref>
-|
-* Electro-oxidation<ref name="Zhang2016">Zhang, C., Tang, J., Peng, C., and Jin, M., 2016. Degradation of perfluorinated compounds in wastewater treatment plant effluents by electrochemical oxidation with Nano-ZnO coated electrodes. Journal of Molecular Liquids, 221, pp. 1145-1150.  [https://doi.org/10.1016/j.molliq.2016.06.093 DOI: 10.1016/j.molliq.2016.06.093]</ref><ref name="Urtiaga2015">Urtiaga, A., Fernández-González, C., Gómez-Lavín, S., and Ortiz, I., 2015. Kinetics of the electrochemical mineralization of perfluorooctanoic acid on ultrananocrystalline boron doped conductive diamond electrodes. Chemosphere, 129, pp. 20-26.  [https://doi.org/10.1016/j.chemosphere.2014.05.090 DOI: 10.1016/j.chemosphere.2014.05.090]&nbsp;&nbsp; Free download from: [https://d1wqtxts1xzle7.cloudfront.net/39233145/00b7d53b67db54fca5000000.pdf?1445006282=&response-content-disposition=inline%3B+filename%3DKinetics_of_the_electrochemical_minerali.pdf&Expires=1613074964&Signature=Bfvds3n9udSs5F9J00Embf8MRJxumQVJoaj5jEni5mqPnmo2QFGGN3fUvWISkRD1yKfoIhNEDQ0a-ISxfZ9vW9jBTkTjN7ud7aSC3rBelIFdtFasfpEXgPvnqsLfKRTWI5S~QRsHbvK5XbwnKo2VyFAmUcuJUjVFP1PK1kEY9-gB2d-8FwSJWbCAAd83fNWm3zHzbOvdchJ~fjAqlydgq7Pu~AwEeH4Zl1LhcYxajzcenTSiBWmMStfOUpTyETSCpSwF7XKuhKMYGePsit8fAWpxH4dleYWmvOi9Gc9YyTB32qBziOTfeqjhTsA-uqECz9bxyD65voHUW7sEchkrKw__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA Academia.edu]</ref><ref name="Schaefer2018">Schaefer, C.E., Choyke, S., Ferguson, P.L., Andaya, C., Burant, A., Maizel, A., Strathmann, T.J. and Higgins, C.P., 2018. Electrochemical Transformations of Perfluoroalkyl Acid (PFAA) Precursors and PFAAs in Groundwater Impacted with Aqueous Film Forming Foams. Environmental Science and Technology, 52(18), pp. 10689-10697.  [https://doi.org/10.1021/acs.est.8b02726 DOI: 10.1021/acs.est.8b02726]</ref>
-* Heat activated persulfate<ref name="Park2016">Park, S., Lee, L.S., Medina, V. F., Zull, A., and Waisner, S., 2016. Heat-activated persulfate oxidation of PFOA, 6: 2 fluorotelomer sulfonate, and PFOS under conditions suitable for in-situ groundwater remediation. Chemosphere, 145, pp. 376-383.  [https://doi.org/10.1016/j.chemosphere.2015.11.097 DOI: 10.1016/j.chemosphere.2015.11.097]</ref>
-* Alkaline perozone<ref name="Lin2012">Lin, A.Y.C., Panchangam, S.C., Chang, C.Y., Hong, P.A., and Hsueh, H.F., 2012. Removal of perfluorooctanoic acid and perfluorooctane sulfonate via ozonation under alkaline condition. Journal of Hazardous Materials, 243, pp. 272-277.  [https://doi.org/10.1016/j.jhazmat.2012.10.029 DOI: 10.1016/j.jhazmat.2012.10.029]</ref>
-* Sonolysis<ref name="Campbell2015">Campbell, T., Hoffmann, M.R., 2015. Sonochemical degradation of perfluorinated surfactants: Power and multiple frequency effects. Separation and Purification Technology, 156(3), pp. 1019-1027.  [https://doi.org/10.1016/j.seppur.2015.09.053 DOI: 10.1016/j.seppur.2015.09.053]&nbsp;&nbsp; Free download from: [https://www.researchgate.net/profile/Tammy_Campbell5/publication/282583363_Sonochemical_Degradation_of_Perfluorinated_Surfactants_Power_and_Multiple_Frequency_Effects/links/5bfc40bd92851cbcdd74449b/Sonochemical-Degradation-of-Perfluorinated-Surfactants-Power-and-Multiple-Frequency-Effects.pdf ResearchGate]</ref><ref name="Cheng2010">Cheng, J., Vecitis, C.D., Park, H., Mader, B.T., Hoffmann, M.R., 2010. Sonochemical Degradation of Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoate (PFOA) in Groundwater: Kinetic Effects of Matrix Inorganics. Environmental Science and Technology, 44(1), pp. 445-450.  [https://doi.org/10.1021/es902651g DOI: 10.1021/es902651g]</ref><ref name="Gole2018a">Gole, V.L., Sierra-Alvarez, R., Peng, H., Giesy, J.P., Deymier, P., Keswani, M., 2018. Sono-chemical treatment of per- and poly-fluoroalkyl compounds in aqueous film-forming foams by use of a large-scale multi-transducer dual-frequency based acoustic reactor. Ultrasonics Sonochemistry, 45, pp. 213-222.  [https://doi.org/10.1016/j.ultsonch.2018.02.014 DOI: 10.1016/j.ultsonch.2018.02.014]&nbsp;&nbsp; [https://www.sciencedirect.com/science/article/pii/S1350417718301937 Open access article.]&nbsp;&nbsp; [[Media: Gole2018a.pdf | Report.pdf]]</ref><ref name="Gole2018b">Gole, V.L., Fishgold, A., Sierra-Alvarez, R., Deymier, P., Keswani, M., 2018. Treatment of perfluorooctane sulfonic acid (PFOS) using a large-scale sonochemical reactor. Separation and Purification Technology, 194, pp. 104-110.  [https://doi.org/10.1016/j.seppur.2017.11.009 DOI: 10.1016/j.seppur.2017.11.009]</ref>
-* Super Critical Water Oxidation
-|-
-| Maturing and</br>Demonstrated
-|
-* Chemical coagulation<ref name="Cornelsen2015">Cornelsen Ltd., 2015. PerfluorAd, PFC Water Treatment Solution (product sales site). [http://www.cornelsen.co.uk/perfluorad-pfc-treatment/ Website]</ref>
-* Electrocoagulation<ref name="Wang2016">Wang, Y., Lin, H., Jin, F., Niu, J., Zhao, J., Bi, Y., and Li, Y., 2016. Electrocoagulation mechanism of perfluorooctanoate (PFOA) on a zinc anode: Influence of cathodes and anions. Science of the Total Environment, 557, pp. 542-550.  [https://doi.org/10.1016/j.scitotenv.2016.03.114 DOI: 10.1016/j.scitotenv.2016.03.114]</ref>
-* Foam fractionation<ref name="Horst2018">Horst, J., McDonough, J., Ross, I., Dickson, M., Miles, J., Hurst, J., and Storch, P., 2018. Water Treatment Technologies for PFAS: The Next Generation. Groundwater Monitoring and Remediation, 38(2), pp. 13-23.  [https://doi.org/10.1111/gwmr.12281 DOI: 10.1111/gwmr.12281]</ref><ref name="EPC2017">EPC Media Group Pty Ltd., 2017. OPEC systems delivers PFAS contamination breakthrough. Waste + Water Management Australia, 44(3), 26-27.  [https://search.informit.org/doi/10.3316/informit.253699294687114 DOI: 10.3316/informit.253699294687114]   ISSN: 1838-7098</ref>
-|
-* Low temperature plasma<ref name="Stratton2017">Stratton, G.R., Dai, F., Bellona, C.L., Holsen, T.M., Dickenson, E.R., and Mededovic Thagard, S., 2017. Plasma-Based Water Treatment: Efficient Transformation of Perfluoroalkyl Substances in Prepared Solutions and Contaminated Groundwater. Environmental Science and Technology, 51(3), pp. 1643-1648.  [https://doi.org/10.1021/acs.est.6b04215 DOI: 10.1021/acs.est.6b04215]</ref><ref name="Singh2019">Singh, R.K., Multari, N., Nau-Hix, C., Anderson, R.H., Richardson, S.D., Holsen, T.M. and Mededovic Thagard, S., 2019. Rapid Removal of Poly- and Perfluorinated Compounds from Investigation-Derived Waste (IDW) in a Pilot-Scale Plasma Reactor. Environmental Science and Technology, 53(19), pp. 11375-11382.  [https://doi.org/10.1021/acs.est.9b02964 DOI: 10.1021/acs.est.9b02964]</ref>
-|-
-| colspan="3" style="background:white;" | * There are several other destructive technologies such as alternative oxidants, and activation</br>methods of oxidants, but for the purpose of this article, the main categories are presented here.
-|}
-Numerous&nbsp;separation&nbsp;and destructive technologies are in the developmental stages of bench-scale testing or limited field-scale demonstrations.  Some of these are listed in Table&nbsp;1:
-==Conclusions==
+==Advantages==
-The well established processes for removing PFAS from water all produce residuals that require management, and it is likely that newer processes under development will also produce some residuals.  Often, it is the residuals that limit the usefulness of the process.  For instance, RO and NF may currently provide the most complete treatment of water, but the production of a relatively high volume of PFAS-containing liquid reject (the portion of the liquid that retains the contaminants and is “rejected” from the process) limits their application.  Often, a second treatment technology such as an adsorbent is required to support the main technology by concentrating or treating the residuals.
+A UV/sulfite treatment system offers significant advantages for PFAS destruction compared to other technologies, including high defluorination percentage, high treatment efficiency for short-chain PFAS without mass transfer limitation, selective reactivity by ''e<sub><small>aq</small></sub><sup><big>'''-'''</big></sup>'', low energy consumption, and the production of no harmful byproducts. A summary of these advantages is provided below:
-As more testing and operational data on adsorbents are generated, it is becoming evident that no adsorbent technology outperforms the others in all cases.  Whether GAC, ion exchange or another technology is the most technically efficient and cost effective long term option for a given site depends on influent water geochemistry and contaminant concentrations, treatment standards, co-contaminants, duration of treatment, and required flow rates. New generation adsorbents are rapidly being introduced into the market at “evaluation scale” which may provide advantages over commercially available adsorbents.
+*'''High efficiency for short- and ultrashort-chain PFAS:''' While the degradation efficiency for short-chain PFAS is challenging for some treatment technologies<ref>Singh, R.K., Brown, E., Mededovic Thagard, S., Holson, T.M., 2021. Treatment of PFAS-containing landfill leachate using an enhanced contact plasma reactor. Journal of Hazardous Materials, 408, Article 124452. [https://doi.org/10.1016/j.jhazmat.2020.124452 doi: 10.1016/j.jhazmat.2020.124452]</ref><ref>Singh, R.K., Multari, N., Nau-Hix, C., Woodard, S., Nickelsen, M., Mededovic Thagard, S., Holson, T.M., 2020. Removal of Poly- and Per-Fluorinated Compounds from Ion Exchange Regenerant Still Bottom Samples in a Plasma Reactor. Environmental Science and Technology, 54(21), pp. 13973-80. [https://doi.org/10.1021/acs.est.0c02158 doi: 10.1021/acs.est.0c02158]</ref><ref>Nau-Hix, C., Multari, N., Singh, R.K., Richardson, S., Kulkarni, P., Anderson, R.H., Holsen, T.M., Mededovic Thagard S., 2021. Field Demonstration of a Pilot-Scale Plasma Reactor for the Rapid Removal of Poly- and Perfluoroalkyl Substances in Groundwater. American Chemical Society’s Environmental Science and Technology (ES&T) Water, 1(3), pp. 680-87. [https://doi.org/10.1021/acsestwater.0c00170 doi: 10.1021/acsestwater.0c00170]</ref>, the UV/sulfite process demonstrates excellent defluorination efficiency for both short- and ultrashort-chain PFAS, including [[Wikipedia: Trifluoroacetic acid | trifluoroacetic acid (TFA)]] and [[Wikipedia: Perfluoropropionic acid | perfluoropropionic acid (PFPrA)]].
-Several newer technologies are being evaluated in the lab and in the field which include electro-oxidation, heat-activated persulfate, sonolysis, electrocoagulation, low temperature plasma, super critical water oxidation, and foam fractionation. These and other potential treatments for PFAS are still largely in the developmental stage. Several technologies show promise for improved management of PFAS sites. However, it is unlikely that a single technology will be adequate for full remediation at many sites. A multi-technology treatment train approach may be necessary for effective treatment of this complicated group of compounds.
+*'''High defluorination ratio:''' As shown in Figure 3, the UV/sulfite treatment system has demonstrated near 100% defluorination for various PFAS under both laboratory and field conditions.
+*'''No harmful byproducts:''' While some oxidative technologies, such as electrochemical oxidation, generate toxic byproducts, including perchlorate, bromate, and chlorate, the UV/sulfite system employs a reductive mechanism and does not generate these byproducts.
+*'''Ambient pressure and low temperature:''' The system operates under ambient pressure and low temperature (<60°C), as it utilizes UV light and common chemicals to degrade PFAS.
+*'''Low energy consumption:''' The electrical energy per order values for the degradation of [[Wikipedia: Perfluoroalkyl carboxylic acids | perfluorocarboxylic acids (PFCAs)]] by UV/sulfite have been reduced to less than 1.5 kilowatt-hours (kWh) per cubic meter under laboratory conditions. The energy consumption is orders of magnitude lower than that for many other destructive PFAS treatment technologies (e.g., [[Supercritical Water Oxidation (SCWO) | supercritical water oxidation]])<ref>Nzeribe, B.N., Crimi, M., Mededovic Thagard, S., Holsen, T.M., 2019. Physico-Chemical Processes for the Treatment of Per- And Polyfluoroalkyl Substances (PFAS): A Review. Critical Reviews in Environmental Science and Technology, 49(10), pp. 866-915. [https://doi.org/10.1080/10643389.2018.1542916 doi: 10.1080/10643389.2018.1542916]</ref>.
+*'''Co-contaminant destruction:''' The UV/sulfite system has also been reported effective in destroying certain co-contaminants in wastewater. For example, UV/sulfite is reported to be effective in reductive dechlorination of chlorinated volatile organic compounds, such as trichloroethene, 1,2-dichloroethane, and vinyl chloride<ref>Jung, B., Farzaneh, H., Khodary, A., Abdel-Wahab, A., 2015. Photochemical degradation of trichloroethylene by sulfite-mediated UV irradiation. Journal of Environmental Chemical Engineering, 3(3), pp. 2194-2202. [https://doi.org/10.1016/j.jece.2015.07.026 doi: 10.1016/j.jece.2015.07.026]</ref><ref>Liu, X., Yoon, S., Batchelor, B., Abdel-Wahab, A., 2013. Photochemical degradation of vinyl chloride with an Advanced Reduction Process (ARP) – Effects of reagents and pH. Chemical Engineering Journal, 215-216, pp. 868-875. [https://doi.org/10.1016/j.cej.2012.11.086 doi: 10.1016/j.cej.2012.11.086]</ref><ref>Li, X., Ma, J., Liu, G., Fang, J., Yue, S., Guan, Y., Chen, L., Liu, X., 2012. Efficient Reductive Dechlorination of Monochloroacetic Acid by Sulfite/UV Process. Environmental Science and Technology, 46(13), pp. 7342-49. [https://doi.org/10.1021/es3008535 doi: 10.1021/es3008535]</ref><ref>Li, X., Fang, J., Liu, G., Zhang, S., Pan, B., Ma, J., 2014. Kinetics and efficiency of the hydrated electron-induced dehalogenation by the sulfite/UV process. Water Research, 62, pp. 220-228. [https://doi.org/10.1016/j.watres.2014.05.051 doi: 10.1016/j.watres.2014.05.051]</ref>.
-<br clear="left" />
+==Limitations==
+Several environmental factors and potential issues have been identified that may impact the performance of the UV/sulfite treatment system, as listed below. Solutions to address these issues are also proposed.
+*Environmental factors, such as the presence of elevated concentrations of natural organic matter (NOM), dissolved oxygen, or nitrate, can inhibit the efficacy of UV/sulfite treatment systems by scavenging available hydrated electrons. Those interferences are commonly managed through chemical additions, reaction optimization, and/or dilution, and are therefore not considered likely to hinder treatment success.
+*Coloration in waste streams may also impact the effectiveness of the UV/sulfite treatment system by blocking the transmission of UV light, thus reducing the UV lamp's effective path length. To address this, pre-treatment may be necessary to enable UV/sulfite destruction of PFAS in the waste stream. Pre-treatment may include the use of strong oxidants or coagulants to consume or remove UV-absorbing constituents.
+*The degradation efficiency is strongly influenced by PFAS molecular structure, with fluorotelomer sulfonates (FTS) and [[Wikipedia: Perfluorobutanesulfonic acid | perfluorobutanesulfonate (PFBS)]] exhibiting greater resistance to degradation by UV/sulfite treatment compared to other PFAS compounds.
+==State of the Practice==
+[[File: XiongFig2.png | thumb | 500 px | Figure 2. Field demonstration of EradiFluor<sup><small>TM</small></sup><ref name="EradiFluor"/> for PFAS destruction in a concentrated waste stream in a Mid-Atlantic Naval Air Station: a) Target PFAS at each step of the treatment shows that about 99% of PFAS were destroyed; meanwhile, the final degradation product, i.e., fluoride, increased to 15 mg/L in concentration, demonstrating effective PFAS destruction; b) AOF concentrations at each step of the treatment provided additional evidence to show near-complete mineralization of PFAS. Average results from multiple batches of treatment are shown here.]]
+[[File: XiongFig3.png | thumb | 500 px | Figure 3. Field demonstration of a treatment train (SAFF + EradiFluor<sup><small>TM</small></sup><ref name="EradiFluor"/>) for groundwater PFAS separation and destruction at an Air Force base in California: a) Two main components of the treatment train, i.e. SAFF and EradiFluor<sup><small>TM</small></sup><ref name="EradiFluor"/>; b) Results showed the effective destruction of various PFAS in the foam fractionate. The target PFAS at each step of the treatment shows that about 99.9% of PFAS were destroyed. Meanwhile, the final degradation product, i.e., fluoride, increased to 30 mg/L in concentration, demonstrating effective destruction of PFAS in a foam fractionate concentrate. After a polishing treatment step (GAC) via the onsite groundwater extraction and treatment system, all PFAS were removed to concentrations below their MCLs.]]
+The effectiveness of UV/sulfite technology for treating PFAS has been evaluated in two field demonstrations using the EradiFluor<sup><small>TM</small></sup><ref name="EradiFluor"/> system. Aqueous samples collected from the system were analyzed using EPA Method 1633, the [[Wikipedia: TOP Assay | total oxidizable precursor (TOP) assay]], adsorbable organic fluorine (AOF) method, and non-target analysis. A summary of each demonstration and their corresponding PFAS treatment efficiency is provided below.
+*Under the [https://serdp-estcp.mil/ Environmental Security Technology Certification Program (ESTCP)] [https://serdp-estcp.mil/projects/details/4c073623-e73e-4f07-a36d-e35c7acc75b6/er21-5152-project-overview Project ER21-5152], a field demonstration of EradiFluor<sup><small>TM</small></sup><ref name="EradiFluor"/> was conducted at a Navy site on the east coast, and results showed that the technology was highly effective in destroying various PFAS in a liquid concentrate produced from an ''in situ'' foam fractionation groundwater treatment system. As shown in Figure 2a, total PFAS concentrations were reduced from 17,366 micrograms per liter (µg/L) to 195 µg/L at the end of the UV/sulfite reaction, representing 99% destruction. After the ion exchange resin polishing step, all residual PFAS had been removed to the non-detect level, except one compound (PFOS) reported as 1.5 nanograms per liter (ng/L), which is below the current Maximum Contaminant Level (MCL) of 4 ng/L. Meanwhile, the fluoride concentration increased up to 15 milligrams per liter (mg/L), confirming near complete defluorination. Figure 2b shows the adsorbable organic fluorine results from the same treatment test, which similarly demonstrates destruction of 99% of PFAS.
+*Another field demonstration was completed at an Air Force base in California, where a treatment train combining [https://serdp-estcp.mil/projects/details/263f9b50-8665-4ecc-81bd-d96b74445ca2 Surface Active Foam Fractionation (SAFF)] and EradiFluor<sup><small>TM</small></sup><ref name="EradiFluor"/> was used to treat PFAS in groundwater. As shown in Figure 3, PFAS analytical data and fluoride results demonstrated near-complete destruction of various PFAS. In addition, this demonstration showed: a) high PFAS destruction ratio was achieved in the foam fractionate, even in very high concentration (up to 1,700 mg/L of booster), and b) the effluent from EradiFluor<sup><small>TM</small></sup><ref name="EradiFluor"/> was sent back to the influent of the SAFF system for further concentration and treatment, resulting in a closed-loop treatment system and no waste discharge from EradiFluor<sup><small>TM</small></sup><ref name="EradiFluor"/>. This field demonstration was conducted with the approval of three regulatory agencies (United States Environmental Protection Agency, California Regional Water Quality Control Board, and California Department of Toxic Substances Control).
 ==References==
 <references />
 ==See Also==

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In Situ Toxicity Identification Evaluation (iTIE)

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