Technology Innovation News Survey

U.S. Department of Defense Logistics Agency, DLA Energy, Fort Belvoir, VA
Contract Opportunities on SAM.gov SPE603-24-R-5X04, 2024

When this solicitation is released on or about September 11, 2024, it will be competed as a total small business set-aside under NAICS code 562910. The U.S. Department of Defense Logistics Agency, DLA Energy, plans to issue a solicitation for environmental remediation, environmental compliance, and environmental facility maintenance services at its Defense Fuel Support Point (DFSP) in Charleston, South Carolina. DLA Energy's Engineering, Environmental and Property Division (LEV) is responsible for funding, supporting, and overseeing execution of DLA Energy's environmental requirements. Site closure is the primary goal of this effort while restoring and maintaining the facility in a cost-effective manner. This anticipated contract is expected to have a four-year period of performance from April 1, 2025, through March 31, 2029, and a six-month extension provision from April 1, 2029, through October 31, 2029. The award is expected to be one firm-fixed-price contract. There is no solicitation at this time. https://sam.gov/opp/4c00f89c083d41198f5ab573a037d8b9/view

Environmental Protection Agency, Funding Opportunity EPA-I-R10-PS-2024-001, 2024

The overall goal of the program to be established under the Notice of Funding Opportunity is to advance EJ by directing resources and ultimately environmental and community benefits toward overburdened, underserved, or communities adversely and disproportionately affected by environmental and human health harms or risks (communities with potential EJ concerns). EPA anticipates that the grant program will support improved, long-term funding integration of EJ principles into Puget Sound restoration and recovery. The successful applicant will develop and administer a support program that will fund projects and activities that focus on providing environmental and community benefits. In addition, the successful applicant will work collaboratively to support the Puget Sound restoration and recovery process and provide resource capacity and assistance for communities, subawardees, and other entities advancing EJ in the restoration and recovery of the Puget Sound ecosystem and its communities. EPA anticipates awarding up to $7 million over two years of incremental funding under this announcement. Applications are due by 11:59 pm ET on September 10, 2024. https://grants.gov/search-results-detail/355296

Environmental Protection Agency, Funding Opportunity EPA-G2024-STAR-G1, 2024

This funding opportunity is soliciting research to develop and demonstrate nanosensor technology with functionalized catalysts that have the potential to degrade selected contaminants in addition to detecting and monitoring pollutants. Specifically, EPA is seeking proposals that use nanotechnology to detect, monitor, and degrade PFAS in groundwater or surface water that may be used as drinking water sources. The Science to Achieve Results (STAR) Program's goal is to stimulate and support scientific and engineering research that advances EPA's mission to protect human health and the environment. It is a competitive, peer-reviewed, extramural research program that provides access to the nation's best scientists and engineers in academic and other nonprofit research institutions. STAR funds research on the environmental and public health effects of air quality, environmental changes, water quality and quantity, hazardous waste, toxic substances, and pesticides. EPA anticipates funding approximately one award under this funding opportunity up to $1,500,000 per award. Applications are due by 11:59 pm ET on November 13, 2024. https://grants.gov/search-results-detail/355752

Environmental Protection Agency, Funding Opportunity EPA-R1-HC-2024, 2024

The Healthy Communities Grant Program is a competitive grant program for EPA New England to fund direct work with communities to support EPA's mission to reduce environmental risks, protect and improve human health, and improve quality of life. The Healthy Communities Grant Program will achieve these goals by identifying and funding projects that:

• Target resources to benefit at-risk communities (environmental justice areas of potential concern and/or sensitive populations).
• Assess, understand, and reduce environmental and human health risks.
• Increase collaboration through partnerships and community-based projects.
• Build institutional and community capacity to understand and solve environmental and human health problems.
• Achieve measurable environmental and human health benefits.

Target investment areas include Areas near New England Ports that are being Redeveloped to Support Offshore Wind and Related Industries, Environmental Justice Areas of Potential Concern, Geographic Priority Areas or Sectors in Northern & Southern New England, and/or Sensitive Populations. To qualify as eligible projects under the Healthy Communities Grant Program, proposed projects must meet the following criteria: (1) be located in and/or directly benefit one or more of the Target Investment Areas described below; and (2) identify how the proposed project will achieve measurable environmental and/or public health results in one or more of the Target Program Areas. EPA anticipates ~$500,000 in federal funding to be available for cooperative agreements under this announcement to fund ~15 awards. Applications may be submitted for amounts up to $40,000 in federal funding. It is anticipated that project periods for agreements awarded under this announcement will have one- or two-year project periods that will start no earlier than April 1, 2025. Although Applications are due by 11:59 pm ET on November 1, 2024. https://grants.gov/search-results-detail/355282

Fulkerson, M., C, Allen M. Perlmutter, T. Williams, D. Seadler, and B. Bentowski.
DCHWS East 2024 Spring Symposium, 10-12 April, Philadelphia, PA, 13 slides, 2024

Recycling chemical drums by emptying their residual contents on the ground surface, and then burning and crushing the drums resulted in TCE-contaminated groundwater at the Hemphill Road Superfund site. To accelerate and optimize the restoration process, EPA prepared an Interim Action Record of Decision that included a phased remedial action to address the areas with TCE concentrations >300 µg/L first and the residual groundwater plume (TCE concentrations >5 µg/L) later. Following pilot tests, ISCO was selected as the remedial approach, with potassium permanganate injected into the partially weathered rock (PWR) and saprolite overburden using hydraulic fracturing technology. The target treatment zone extended from the groundwater table (~30 ft bgs) to the top of the bedrock (~60 ft bgs). A baseline groundwater sampling event and a dynamic plume delineation investigation were conducted to confirm the area requiring treatment and finalize the ISCO design. Permanganate injections were conducted using proprietary hydraulic fracturing technology to distribute 182,000 lbs of RemOx-S at 26 locations throughout the plume on 30-ft centers. Fractures were created approximately every five vertical ft from the water table, at ~ 30 ft bgs, to bedrock. Performance monitoring will be conducted at 1, 3, and 6-month intervals post-injection to evaluate the effectiveness of the remedy and inform the need for additional injections. https://drive.google.com/file/d/1Vmm3N1LnzG2rDNXagD4-TMXRATmshned/view

Wachter, L.R., ǀ Battelle 2024 Chlorinated Conference, 2-6 June, Denver, CO, abstract only, 2024

The Industrial Waste Area Zone A at the Pasco Landfill NPL site is currently undergoing in situ thermal remediation (ISTR) by thermal conduction heating (TCH) to treat ~27,000 yd³ of soil with heterogenous patterns of cVOCs, total petroleum hydrocarbons (TPH), and other organic and non-organic analytes. ISTR and a final engineered cap will complete the final cleanup action. Following the removal action, post-excavation soil characterization was conducted to develop remediation levels (RELs) and the ISTR design. VOCs, SVOCs, and TPH were identified as the ISTR drivers, and RELs were developed for cVOCs (TCE, tetrachloroethene, and VC), BTEX, naphthalenes (naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene), gasoline-range organics, and diesel-range organics. RELs were based on bench-scale testing results to determine technical feasibility and account for the final engineered cap over Zone A that will eliminate future stormwater infiltration. The thermal treatment area was divided into two consecutive treatment phases to work within the limits of the existing onsite regenerative thermal oxidizer used during the interim soil vapor extraction system and to sustainably reuse heater and vapor recovery components between phases. Performance samples will be collected following both phases as system operation data indicates treatment is complete. A phase-tiered approach with multiple lines of evidence was developed to evaluate performance samples to account for the limited performance dataset following the first phase of treatment and shift toward statistical evaluation once the performance dataset is sufficient to ensure the final confirmation data set will achieve the RELs. ISTR installation and startup are ongoing at Zone A, with the first phase of treatment expected to be complete by September 2024 and the final cleanup completed in 2025. See Pasco Landfill NPL site for more information and to access all site documents: https://apps.ecology.wa.gov/cleanupsearch/site/1910

Popek, M.A., S. Dore, D. Vanetti, and D. MacDougall. ǀ Battelle 2024 Chlorinated Conference, 2-6 June, Denver, CO, abstract only, 2024

In situ chemical reduction using zero-valent iron (ZVI) was selected to remediate soil and chlorinated solvent-impacted groundwater at a former heavy equipment manufacturing site in Batavia, New York. VOC-impacted soil, primarily consisting of chlorinated VOCs, was present in two areas of concern (AOC #1 and AOC#2). The most heavily impacted soil had total VOC concentrations >500 ppm. Groundwater concentrations had decreased through natural anaerobic degradation before remediation but were still above the NY groundwater standards. Soil in a ~0.43-acre portion of AOC #1 and a ~0.15-acre portion of AOC #2 was remediated using large-diameter auger soil mixing with Daramend®, which is anticipated to enhance the natural anaerobic conditions present in the mixing areas. The primary remedial goal was to decrease VOC concentrations in soil to mitigate potential continued contaminant loading to groundwater. An innovative method of auger soil mixing was developed to reduce the volume of water with a two-step low-fluid process and reduce the risk of fluids containing VOCs discharging from the mixing areas into the adjacent wetlands. Approximately 500,000 lbs of Daramend were introduced into grids consisting of 804 locations to specified treatment depths within AOC #1 and AOC #2 and vertically distributed before mixing. The soil was then mixed in 616 columns using an 8-ft diameter mixing auger to achieve horizontal distribution and homogenization. The system treated ~300,000 ft³ of soil to a maximum depth of ~16 ft bgs. Successfully minimizing the risk of fluid discharge to the adjacent wetlands by minimizing water usage shows that this new soil mixing method may be appropriate at other sites with proximate natural features requiring protection. Using this method, only ~175,000 gals of water were introduced into the subsurface, a precut was not required, and the max post-mixing swell was < ~1.5 ft. The new method reduced concerns relative to potential fluid discharges, incorporated sustainable use of water resources and landfill space, and left the site in better condition for post-remedial management.

EPA Enforcement and Compliance Assurance News Release, 26 July, 2024

EPA and the U.S. Army announced a joint project to conduct sampling and testing of private drinking water wells near Army installations for PFAS. This effort will inform Army remedial actions if results indicate that PFAS is found in drinking water because PFAS contamination has spread and may potentially be impacting the drinking water wells of nearby residents. The joint sampling and testing project, which is being implemented nationally, has identified a priority list of nine installations out of 235 locations. As initial work is completed, EPA and the Army will evaluate additional installations to expand the pilot. If sampling indicates PFAS is present in groundwater or drinking water above the new MCLs established by EPA, the Army will work with EPA and state regulators to assess additional actions necessary to mitigate exposure. EPA and the Army will share information and update both EPA's and DoD's PFAS websites as information becomes available. https://www.epa.gov/newsreleases/epa-and-us-army-announce-joint-sampling-project-identify-pfas-contamination-near-army

Johnson, T., J. Thomle, J. Robinson, and R. Mackley. PNNL Report PNNL-35781, 46 pp, 2024

In situ soil flushing was tested at the 100-KE Area at the Hanford site to accelerate Cr(VI) removal in the vadose zone using 3D time-lapse electrical resistivity tomography (ERT) to monitor the distribution of flush water. Previous efforts to remediate the chromium involved excavation and offsite treatment of contaminated soil, which removed much of the chromium. However, contamination still exists in native soil between the water table and the bottom of the pit, which has since been backfilled. Results of 3D time-lapse ERT imaging during two separate soil flushing campaigns generally showed that: 1) Pit backfill materials appear to nominally have larger permeability than native soils; the boundary between pit backfill and native soil significantly impacted flush water migration, causing some flush water to migrate along the pit boundary to the bottom of the pit. 2) Non-uniform flows, likely caused by variations in hydrogeologic properties, developed in the pit backfill materials, resulting in uneven flush water distribution on the southern margin of the soil flushing zone. 3) Redistribution of water at the interface between backfill materials and the formation materials likely facilitated an elevated and uniform distribution of flush water within native soils beneath the deeper parts of the pit boundary beneath the center of the flush zone, which presumably overlies soil with elevated chromium contamination. These areas appear to have been infiltrated by higher volumes of flush water than the northern and southern margins of the flush zone. 4) High flush water application rates significantly improved flush water distribution throughout the target flushing zone. 5) Imaging resolution was limited to a depth of ~20 m bgs due primarily to limitations on the lateral extent of the surface ERT array. https://www.pnnl.gov/main/publications/external/technical_reports/PNNL-35781.pdf?__hstc=249664665.a9a129fdf6de41fcdb7070a79e0485f1.1714071786022.1720553183596.1721059619727.8&__hssc=249664665.2.1721059619727&__hsfp=742543691

Morales, M. ǀ 19th Annual Environmental Professionals of Arizona Conference, 26-27 February, Tempe, AZ, 31 slides, 2024

The Arizona Department of Environmental Quality (ADEQ) conducted a pilot study to evaluate the effectiveness of in situ micro-diffusion ozone (MD-O₃) to remediate PCE-contaminated groundwater at a ~1/2-acre former dry cleaner site. Post-soil vapor extraction (SVE) PCE concentrations in source area groundwater were up to 55 µg/L. Objectives were to remediate the residual source area to below the 5 µg/L aquifer water quality standard, map the distribution of O₃, and evaluate cost-effectiveness. Using an O₃ generator, O₃ was directed into five specially designed ozone saturation injection (OSI) wells. These wells were screened from 120 to 125 ft bgs, enabling targeted delivery of ozone-saturated groundwater, followed by a mixture of gaseous ozone and compressed air, into a coarse-grained lithologic layer (predominantly gravel) underlying a less permeable layer (silts and clays). This facilitated diffusion into an overlying fine-grained layer. Monitoring included testing for VOCs, redox parameters, and metals. O₃ dispersion was measured using a field gas meter and O₃ test strips for water. Wells were periodically acid-washed, and diffusers were replaced as required. The pulsed system delivered ~13,500 lb of O₃ to the source area aquifer. PCE concentrations in the hotspot declined by 95%. O₃ extended beyond the anticipated area to ~250 feet downgradient from the OSI wells. The absence of near-term rebound suggests that the O₃ diffused into the fine-grained layers and treated the adsorbed fraction. Dissolved Cr was liberated proximal to select OSI wells. Long-term rebound monitoring will evaluate PCE and dissolved Cr concentrations; Cr transport is not anticipated. https://www.epaz.org/assets/docs/Conference/2024/Day1_1b_ADEQ%20Experience_Morales.pdf
Website that includes all site documents: https://azdeq.gov/ecp-24th-gc

Potter, P., B. Crone, and M. Mills. ACS Spring 2024 National Meeting, New Orleans, LA, 17-20 March, 22 slides, 2024

Results from a pilot-scale system used to perform both biosolid incineration and GAC regeneration will be presented along with a summary of current EPA research in this field.https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=361218&Lab=CESER&simplesearch=0&showcriteria=2&sortby=pubDate&timstype=&datebeginpublishedpresented=06/15/2019&searchall=thermal

Tesfamariam, E., D. Ssekimpi, S. Hoque, H. Chen, J. Howe, C. Zhou, Y. Shen, and Y. Tang.
Water Science & Technology 89(9):2440-2456(2024)

In this study, 1,4-dioxane-metabolizing mixed cultures were enriched by periodically spiking 1,4-dioxane at low concentrations (≤1 mg/L). Five 1,4-dioxane-metabolizing pure strains (LCD6B, LCD6D, WC10G, WCD6H, and WD4H) were isolated and characterized. Partial 16S rRNA gene sequencing showed that the five strains were related to Dokdonella sp. (98.3%), Acinetobacter sp. (99.0%), Afipia sp. (99.2%), Nitrobacter sp. (97.9%), and Pseudonocardia sp. (99.4%), respectively. Nitrobacter sp. WCD6H is the first reported 1,4-dioxane-metabolizing bacterium in the genus of Nitrobacter. The net specific growth rates of these five cultures were consistently higher than those reported in the literature with 1,4-dioxane concentrations of <0.5 mg/L. Compared to the literature, the newly discovered strains have lower half-maximum-rate concentrations (1.8 to 8.2 mg-dioxane/L), lower maximum specific 1,4-dioxane utilization rates (0.24 to 0.47 mg-dioxane/(mg-protein and • d), higher biomass yields (0.29 to 0.38 mg-protein/mg-dioxane), and lower decay coefficients (0.01 to 0.02 d^-1). These are characteristics of microorganisms living in oligotrophic environments. https://iwaponline.com/wst/article/89/9/2440/101990/Isolation-and-characterization-of-pure-cultures

Abaie, E., M. Kumar, N. Kumar, Y. Sun, J. Guelfo, Y. Shen, and D. Reible.
Toxics 12(4):264(2024)

A study assessed the effectiveness of three different β-cyclodextrin (β-CD) adsorbents in removing a mixture of PFAS, including anionic, neutral, and zwitterionic compounds, at neutral pH. Linear partition coefficient (K_d) values were calculated to quantify the adsorption affinity of each PFAS. β-CD polymers crosslinked with hexamethylene diisocyanate (β-CD-HDI) and epichlorohydrin (β-CD-EPI) displayed some PFAS adsorption. Benzyl chloride β-CD (β-CD-Cl) was also synthesized and tested for PFAS adsorption. β-CD-Cl exhibited higher PFAS adsorption than β-CD-HDI and β-CD-EPI, with log K_d values ranging from 1.9 L/g to 3.3 L/g. β-CD-Cl displayed no affinity for zwitterionic compounds, as opposed to β-CD-HDI and β-CD-EPI, which removed N-dimethyl ammonio propyl perfluorohexane sulfonamide (AmPr-FHxSA). Comparing K_d values and log K_ow of PFAS confirmed the significant role of hydrophobic interactions in the adsorption mechanism. This effect was stronger in β-CD-Cl, compared to β-CD-HDI and β-CD-EPI. While no effect of PFAS charge was observed in β-CD-Cl, some influence of charge was observed in β-CD-HDI and β-CD-EPI, with fewer negative compounds being more adsorbed. PFAS adsorption by β-CD-Cl was similar in magnitude to other adsorbents proposed in the literature. However, unlike many commonly proposed adsorbents, it offers the advantage of not containing fluorine. https://www.mdpi.com/2305-6304/12/4/264

Ali, M., U. Thapa, J. Antle E. Tanim, J. Aguilar, I. Bradley, D. Aga and N. Aich.
Journal of Hazardous Materials 469:133912(2024)

This study evaluated how and to what extent different environmental and operational parameters, such as initial PFAS concentration, H₂O₂ dose, pH, ionic strength, and natural organic matter (NOM), influenced PFOS and PFOA removal using graphene and zero-valent-iron based- nanohybrid (rGO-nZVI NH). With an initial increase in PFAS concentration (from 0.4 to 50 ppm), pH (3 to 9), ionic strength (0 to 100 mM), and NOM (0 to 10 ppm), PFOS removal reduced by 20%, 30%, 2%, and 6%, respectively, while PFOA removal reduced by 54%, 76%, 11%, and 33% respectively. In contrast, PFOS and PFOA removal increased by 10% and 41%, respectively, with an increase in H₂O₂ (from 0 to 1 mM). Overall, the effect of changes in environmental and operational parameters was more pronounced for PFOA than PFOS. Mechanistically, •OH radical generation and availability showed a profound effect on PFOA removal. Another key removal factor was the electrostatic interaction between rGO-nZVI NH and deprotonated PFAS compounds. Results confirm that rGO-nZVI in the presence of H₂O₂ can degrade PFOS and PFOA to some extent by identifying important by-products such as acetate, formate, and fluoride.

Senior, L.A. and A.R. Fiore. U.S. Geological Survey in cooperation with the U.S. Navy, Open-File Report 2024-1007, 156 pp, 2024

USGS collected data on the vertical distribution of hydraulic head, specific capacity, and water quality using aquifer-interval-isolation tests and other vertical profiling methods in 15 boreholes completed in fractured sedimentary bedrock in Northampton, Warminster, and Warwick Townships, Bucks County, Pennsylvania from 2018-19. The work was conducted to support detailed investigations at and near the former Naval Air Warfare Center (NAWC) Warminster, where PFOS and PFOA were measured in groundwater samples from supply and monitoring wells at concentrations above EPA health advisory levels for drinking water. The vertical distribution of aquifer properties and water quality was assessed through hydraulic tests and sampling of aquifer intervals using a straddle-packer system (13 boreholes) or depth-discrete point sampling under known borehole-flow conditions (2 boreholes). Geophysical and video logs were used to identify potential water-bearing fractures in 15 boreholes, ranging in depth from 210 to 604 ft, including six boreholes and nine existing wells on or near the site. The hydrogeologic framework, in conjunction with the vertical distribution of hydraulic heads and water quality, may assist in evaluating the locations of various PFAS sources and potential migration pathways of PFAS in groundwater. https://pubs.usgs.gov/of/2024/1007/ofr20241007.pdf

Wanzek, T.A., J.A. Field, and K. Kostarelos. Environmental Science & Technology 58(3):1659-1668(2024)

Repeated AFFF applications, composed of 14 anionic and 23 zwitterionic PFAS, were conducted on a single one-dimensional saturated soil column to quantify PFAS retention. An electrofluorination-based (3M)Milspec AFFF above the mixture's critical micelle concentration (CMC) was at application strength (3%, v/v). Retention and retardation of PFAS mass increased with each successive AFFF addition, though PFAS concentration profiles for subsequent applications differed from the initial. A greater degree of mass retention and retardation correlated with longer PFAS carbon-fluorine chain length and charged-headgroup type and as a function of AFFF application number. Anionic PFAS were increasingly retained with each subsequent AFFF application, while zwitterionic PFAS exhibited an alternating pattern of sorption and desorption. Surfactant-surfactant adsorption and competition during repeat AFFF applications at concentrations above the CMC resulted in adsorbed PFAS from the first application, changing the nature of the soil surface with preferential sorption of anionic PFAS and release of zwitterionic PFAS due to competitive elution. An application of a polyparameter quantitative structure-property relationship developed to describe sorption of AFFF-derived PFAS to uncontaminated, saturated soil was attempted for experimental conditions. The model had been derived for data where AFFF is below the apparent CMC. Experimental conditions that included the presence of mixed micelles (aggregates consisting of different kinds of surfactants that exhibit characteristics and properties different from micelles composed of a single surfactant) resulted in overall PFAS mass retained by an average of 27.3% ± 2.7% above the predicted values. The correlation was significantly improved by adding a "micelle parameter" to account for cases where the applied AFFF was above the apparent CMC. Results highlight the importance of interactions between the AFFF components that can only be investigated by employing complex PFAS mixtures at actual AFFF concentrations and application strength above their apparent CMC. In AFFF source zones, competitive desorption of PFAS may result in downgradient PFAS retention when desorbed PFAS becomes resorbed to uncontaminated soil.

Leclerc, M., D.E. Ponton, F. Bilodeau, D. Planas, and M. Amyot. Environmental Science & Technology 57(49):20792-20801(2024)

A study investigated periphyton and benthic communities from different habitats of the St. Maurice River (Quebec, Canada) affected by two run-of-river (ROR) power plants and their effect on the bioaccumulation and biomagnification of monomethylmercury (MMHg). Proportion of total mercury as MMHg reached maximum values ~2.9 times higher in flooded sites compared to unflooded sites. Impoundment by ROR would, therefore, provide favorable environments for periphyton growth, which can produce and accumulate MMHg. Periphyton MMHg concentrations significantly explained concentrations in some benthic macroinvertebrates, reflecting a local transfer. The analyses of δ13C and δ15N signatures found that flooding, which created scattered lenthic habitats, led to modifications in trophic structures by introducing new organic matter sources. The computed trophic magnification slopes did not show significant differences in the transfer efficiency of MMHg between sectors, while intercepts of flooded sectors were higher. Increased MMHg concentrations in flooded areas are likely due to the impoundment combined with watershed disturbances, and the creation of small habitats favorable to periphyton, which should be included in future predictive models.

Okorie, C.J., T. Ojeyemi, A. Egbemhenghe, M.Q. Ali, E.C. Emenike, K.O. Iwuozor, and A.G. Adeniyi. Remediation 34(2):e21777(2024)

The latest advancements in modifying activated carbon (AC) to enhance PFAS absorption are reviewed in this article. It explores chemical and physical modifications, including metal/metal oxide nanoparticle deposition, polymer-based coatings, surfactants, and advanced oxidation processes, offering insights into their mechanisms and effectiveness. Analysis of modified AC materials is valuable for developing efficient and sustainable strategies to address PFAS contamination in water sources.

Xu, H., H. Zhang, C. Qin, X. Li, D. Xu, and Y. Zhao.
Chemosphere 360:142395(2024)

This article presents a review and bibliometric analysis of the literature on the interest area "Cr(VI) in groundwater" published in the Web of Science Core Collection from 1999 to 2022. It summarizes information on 203 Cr(VI)-contaminated groundwater sites worldwide and derives basic characteristics of the sources and concentrations of contamination. Of the 203 contaminated sites, 69% were due to human causes, and 56% had Cr(VI) concentrations ranging from 0-10 mg/L. At groundwater sites with high Cr(VI) contamination due to natural causes, 75% of the sites had Cr(VI) concentrations < 0.2 mg/L. A total of 936 papers on "Cr(VI) in groundwater" were retrieved for bibliometric analysis: interest in research on Cr(VI) in groundwater has grown rapidly in recent years, and 59% of the papers were published in the field of environmental sciences. A systematic review of the progress of studies on the Cr(VI) removal/remediation based on reduction, adsorption, and biological processes is presented. Of 666 papers on Cr(VI) removal/remediation, 512, 274, and 75 papers dealt with reduction, adsorption, and bioremediation, respectively. In addition, several studies demonstrated the potential applicability of natural attenuation to remediate Cr(VI)-contaminated groundwater.

Hakeem, I.G., P. Halder, S. Patel, E. Selezneva, N. Rathnayake, M.H. Marzbali, G. Veluswamy, A. Sharma, S. Kundu, A. Surapaneni, M. Megharaj, D.J. Batstone, and K. Shah.
Chemical Engineering Journal 493:152537(2024)

The current knowledge on PFAS transformation, destruction, and final fate before, during, and after thermal treatment of biosolids is consolidated in this review, which covers lab, pilot scale, and industrial studies. PFAS degradation mechanisms during thermal treatment of biosolids may differ from the established pathways for pure PFAS salts, given that biosolids have a complex organic and inorganic matrix and typically have low PFAS concentrations. Among thermal treatment techniques, pyrolysis has received extensive investigations at different scales of operation. However, for all techniques, treatment temperatures and residence time need to be sufficiently optimized for designing realistic large-scale thermal systems relevant to biosolids' compositional peculiarities for PFAS destruction. https://www.sciencedirect.com/science/article/pii/S1385894724040245

Skinner, J., A.G. Delgado, M. Hyman, and M.-Y.J. Chu.
Science of The Total Environment 925:171667(2024)

This paper reviews 14 well-documented field-scale aerobic cometabolic bioremediation studies and summarizes the underlying microbiological factors that may affect the performance observed in these field studies. The combination of microbiological and engineering principles gained from field testing leads to insights and recommendations on the planning, design, and operation of an in situ aerobic cometabolic treatment system. The article also presents several novel topics and future research directions that can potentially enhance technology development and foster success in implementing this technology for environmental restoration. https://www.sciencedirect.com/science/article/pii/S0048969724018096

Wallace, M.A.G., M.G. Smeltz, J.M. Mattila, H.K. Liberatore, S.R. Jackson, E.P. Shields, X. Xhani, E.Y. Li, J.H. Johansson. ǀ Chemosphere 358:142129(2024)

A literature review presents the last two decades of research characterizing PFAS in outdoor and indoor air, focusing on active and passive air sampling and analytical methods. The PFAS classes targeted and detected in air samples include fluorotelomer alcohols, perfluoroalkane sulfonamides, perfluoroalkane sulfonamido ethanols, perfluorinated carboxylic acids, and perfluorinated sulfonic acids. Although manufacturing of PFOS and PFOA has largely been phased out, these PFAS are often detected in air samples. Recent estimates indicate that thousands of PFAS are likely present in the air that are not currently monitored by air methods. Advances in air sampling methods are needed to fully characterize the atmospheric transport of PFAS.