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Per- and polyfluoroalkyl substances (PFAS) are a complex group of recalcitrant substances that are present globally in many landfill wastewater leachates and have potential ecological and human health risks. Conventional treatment technologies have shown limited efficacy for many PFAS due to the stable C–F bonds. Therefore, there is growing interest in applying advanced oxidation processes (e.g., photocatalysis) to decrease the aqueous concentrations of PFAS in contaminated wastewater and mitigate risks. The goal of this study was to evaluate the photocatalytic performance of treating PFAS in landfill leachate using a novel photocatalyst composite. Treatment structures were fabricated using polylactic acid (PLA) and compounded with TiO2 (15 wt%), and 3D printed into tiles. The appeal to 3D printing the photocatalytic composites for environmental applications is for limitless geometric customization for the application, including optimizing surface area and prototyping for research improvements prior to scale-up. A pilot-scale treatment system was designed to promote photocatalysis using 3D composite structures and UV irradiance intensity of 1.0 mW cm−2 (λ = 280–400 nm) following 24- and 36-h hydraulic retention times. Photocatalytic degradation was achieved for seven of the 11 PFAS evaluated in this study: PFOS, PFOA, PFHPA, PFHxS, PFNA, PFDA, and PFOSAm. Greater than 80% removal of PFOS, PFNA, PFDA, and PFOSAm was observed after 24 h of photocatalysis. These results indicate photocatalysis using TiO2 polymer composites can achieve beneficial levels of PFAS degradation. This study provides a proof-of-principle approach to inform the application of additive manufacturing of photocatalytic composites for use in the treatment of PFAS-contaminated wastewater. [ABSTRACT FROM AUTHOR]

Coastal Louisiana (USA) continues to sustain immense land and habitat losses due to subsidence, sea‐level rise, and storm events. Approximately 65 million m3 (85 million cubic yards) of sediment is dredged annually from Gulf Coast federal navigation channels to maintain safe waterway passage. The beneficial use of these sediments continues to increase, and now this sediment is recognized as a critical resource in large‐scale (estimated multibillion dollar) ecosystem restoration efforts to mitigate land and habitat losses along the US Gulf Coast. However, the documentation of restoration benefits where dredged sediments are the primary resource is lacking, which limits the potential for future applications. Therefore, this study documents the progress to restore marsh habitat and the resultant benefits in West Bay, Louisiana, and investigates how the restoration practices align with principles of the US Army Corps of Engineers (USACE) Engineering with Nature® (EWN®) and UN Sustainable Development Goals (UN SDGs). West Bay, a 4964‐ha subdelta adjacent to the Mississippi River, typifies risks of coastal land loss that also threatens the integrity of the adjacent federal navigation channel. To help restore coastal marsh habitat on a large spatial and temporal scale, the USACE constructed an uncontrolled diversionary channel from the Mississippi River and with subsequent direct and strategic placement of dredged sediment. Restoration performance was assessed through remotely sensed methods using data spanning approximately 70 years. To date, placement of dredged sediment in the bay has facilitated the creation of over 800 ha of new land in the formerly open waters of West Bay. The West Bay restoration project aligns with the principles of the EWN initiative, which supports more sustainable practices to deliver economic, environmental, and social benefits through collaborative processes and meaningfully integrates 10 of the UN SDGs designed to achieve a better and more sustainable future. Integr Environ Assess Manag 2022;18:1162–1173. Published 2021. This article is a U.S. Government work and is in the public domain in the USA. Key Points: The beneficial use of dredged sediment from Gulf Coast federal navigation channels continues to increase and is now being used as a means of restoring coastal ecosystems to mitigate land and habitat losses along the US Gulf Coast due to subsidence, sea‐level rise, and storm events.This study documents the progress to restore marsh habitat in a 4,964‐ha subdelta and the resultant benefits in West Bay, Louisiana and investigates how these restoration practices align with principles of the USACE Engineering with Nature® (EWN®) and UN Sustainable Development Goals (UNSDGs).From 2005 to 2020, direct sediment placement activities in West Bay have contributed to an increase in 646 ha of land, while nature‐based features have contributed to an additional 292 ha of land area.The West Bay project provides a more complete understanding of project successes such that these techniques can be integrated into other dredging projects in coastal Louisiana and elsewhere. [ABSTRACT FROM AUTHOR]

Algaecides are commonly used to control noxious algal growths in water resources. In order to make accurate predictions about responses of target and non-target species to algaecide exposures, reliable methods are needed to confirm exposures in the laboratory and the field. The focus of this research was to evaluate the I method for measuring hydrogen peroxide (HO) exposures associated with applications of a sodium carbonate peroxyhydrate (SCP)-based algaecide. To meet this overall objective, method detection limits, interferences from field waters (turbidity, color, and algal cell density), and storage stability of samples were measured. The method detection limits were 0.2 ( p < 0.0001) and 0.25 mg HO/L ( p = 0.0002) for laboratory and field waters, respectively. The upper method detection limit was 7.5 mg HO/L for both waters. Turbidity (25.3 NTU) and color of field-collected water did not interfere with measurements. Algal cell densities of 10, 10, and 10 cells/mL of two planktonic algal species in laboratory water did not interfere with measurements. Measurements of samples stored in dark refrigeration and on ice remained stable over 4 days, while measurements of samples stored in direct sunlight in ambient temperatures were altered after 1 day. The I method accurately measured HO exposures in the laboratory water, field water, and laboratory water containing planktonic algae used in this experiment within the range of concentrations that would be applied in a field setting. These data demonstrated that this method has utility for confirming exposures after laboratory and field treatments of SCP-based algaecides. [ABSTRACT FROM AUTHOR]

Rietveld refinement of room temperature (RT) neutron diffraction (ND) data reveals 12R-type hexagonal perovskites Ba3LaNb3O12 (BLN) and Sr3LaNb3O12 (SLN) to adopt space group R3 with tilted NbO6 octahedra. The presence of an octahedral tilt transition (Ttilt) at 465 K in BLN from R3 to R3m is proposed from a combination of high temperature ND data and fixed frequency permittivity measurements. Ttilt is estimated to be much higher at ∼720 K for SLN. The large difference in the RT temperature coefficient of the resonant frequency (τf), -100 ppm/K for BLN compared to -5 ppm/K for SLN, is attributed to the closer proximity of Ttilt to RT for BLN. τf in these 12R-type hexagonal perovskites can therefore be tuned by controlling the tolerance factor and therefore Ttilt in a manner similar to that used for many Ba- and Sr-based 3C-type ABO3 perovskites. [ABSTRACT FROM AUTHOR]