Per- and polyfluoroalkyl substances (PFAS) have become a key concern to both environmental and human health due to their extreme persistence in the environment and their ability to bioaccumulate in plants, animals, and humans. In this mesocosm study, Australian PFAS-contaminated soil with a mean total concentration of 8.05 mg/kg and a mean combined PFHxS + PFOS concentration of 7.89 mg/kg was treated with an immobilisation sorbent (RemBind®) at different application rates (0.5, 1, 1.5, 2, 3, 4, and 5% w/w). To assess the efficacy of this immobilisation treatment, PFAS leachability, PFAS plant uptake, and ecotoxicity tests were conducted. Leachability testing was performed according to the Australian Standard Leaching Procedure (ASLP) at pH 5 and 7. A grass species (Dactylis glomerata) was used to measure plant uptake of PFAS from untreated and treated contaminated soil. In addition, the Microtox test was used to assess the associated ecotoxicity. The immobilisation treatment resulted in a significant reduction of 88.5–99.8% in the total PFAS leachability and 88.7–99.8% in the combined PFOS and PFHxS leachability at pH 5. Similarly, significant reductions (5–12-fold) were observed in the plant uptake of total PFAS and combined PFOS and PFHxS in all treated soil samples. In addition, although the Microtox test showed relatively low ecotoxicity in all the experimental samples, including the untreated soil, a significant decrease in the ecotoxicity of treated soil samples was observed. The results from this study highlight that this treatment approach has the potential to reduce both PFAS leachability and plant bioavailability with a relatively low associated ecotoxicity. This is likely to reduce the risk of the transfer of PFAS into higher trophic levels. This immobilisation treatment may, therefore, reduce the risk associated with PFAS-contaminated soils and may be an important remediation tool for managing certain PFAS-contaminated soils. Graphical Abstract

Municipal solid waste (MSW) is projected to rise to 3.4 billion tonnes by 2050, with only 33% undergoing environmentally friendly management practices. Achieving a circular economy involves sustainable approaches, among which diverting waste from landfills to composting plays a crucial role. However, many of the products society uses and discards in MSW daily contain per- and polyfluoroalkyl substances (PFAS), raising concerns that composts may inadvertently introduce PFAS into the environment, posing a significant challenge to waste management and environmental sustainability. PFAS have been detected in compost at concentrations ranging between 1.26–11.84 µg/kg. Composts are therefore a source of PFAS contamination, posing risks to human and ecosystem health. Impactful technologies are therefore required for PFAS remediation during the composting process. This review examines the composting process as a sustainable organic waste management technology, examining the various systems employed, compost quality, and uses, particularly emphasising the challenge posed by PFAS contamination. The review provides novel insights into possible PFAS remediation technologies. A comprehensive understanding of PFAS origin, fate, and transformation during the composting process is lacking, creating substantial knowledge gaps regarding the inputs processes contributing most to PFAS accumulation in the final product. Addressing these gaps in future studies is crucial for minimising PFAS discharge into the environment and developing an effective remediation approach. This review highlights the urgent need for innovative solutions to mitigate PFAS contamination in compost and the importance of advancing research and technology to achieve sustainable waste management objectives.

Persistent organohalogen pollutants—including halogenated nitrophenols (HNCs), trichloroethylene (TCE), and per- and polyfluoroalkyl substances (PFAS)—pose serious environmental and health risks due to their stability, toxicity, and bioaccumulation potential. This review critically assesses current remediation technologies including advanced oxidation processes (AOPs), adsorption, membrane filtration, and thermal treatments. While these methods can be effective, they are often limited by high costs, energy demands, toxic byproduct formation, and sustainability concerns. Emerging biological approaches offer promising alternatives. Among these, fungal-based degradation methods (mycodegradation) remain significantly underrepresented in the literature, despite fungi demonstrating a high tolerance to contaminants and the ability to degrade structurally complex compounds. Key findings reveal that white-rot fungi such as Phanerochaete chrysosporium and Trametes versicolor possess enzymatic systems capable of breaking down persistent organohalogens under conditions that inhibit bacterial activity. This review also identifies critical research gaps, including the need for direct comparative studies between fungal and bacterial systems. The findings suggest that integrating mycodegradation into broader treatment frameworks could enhance the environmental performance and reduce the long-term remediation costs. Overall, this review highlights the importance of diversifying remediation strategies to include scalable, low-impact biological methods for addressing the global challenge of organohalogen contamination.

Rising concerns about solid waste management globally necessitate the adoption of sustainable practices, particularly in dealing with organic waste, which constitutes a significant portion of municipal solid waste (MSW). Composting is an effective waste management strategy that can reduce both the environmental impact and greenhouse gas emissions of organic wastes, while producing valuable organic material (compost) for soil enhancement. However, the presence of persistent contaminants such as per- and polyfluoroalkyl substances (PFAS) in compost poses environmental and human health risks, challenging the sustainable management of organic wastes. This study investigates the fate of 33 PFAS compounds in two composting systems-windrow and in-vessel-focusing on the transformation and persistence of these compounds through the composting process, with the aim of collecting information which will support the identification of strategies to mitigate PFAS contamination in composting practices. The findings indicate significant reductions in total PFAS concentrations after composting, with reductions of 88.3% and 86.3% in the windrow and in-vessel systems, respectively. Notably, certain PFAS compounds, such as PFBS, appeared after composting, while PFPeA, became undetectable, suggesting potential leaching or transformation. Across both leachate and dust samples, PFAS concentrations were relatively low, with only a few compounds detected in each matrix. The final compost products met Australia's proposed NEMP 3.0 guidelines. However, considering the variation in PFAS content within similar categories of waste (feedstock), compliance with regulatory limits may vary. These results highlight the need for continued research into PFAS behaviour during composting and the development of best practices to mitigate contamination risks.

Despite increasing interest in fungal remediation systems for the treatment of persistent contaminants, the mechanisms governing fungal transformation of halogenated organic compounds remain poorly resolved. The aim of this study was to determine whether the transformation of halogenated nitrophenols is driven by isolated extracellular enzymes and cofactor-dependent oxidative activity or instead reflects coordinated system-level fungal metabolism. To address this question, we investigated the transformation of 2-chloro-4-nitrophenol (2C4NP) and 5-fluoro-2-nitrophenol (5F2NP) by ascomycete fungi Caldariomyces fumago (C. fumago) and Curvularia sp. under varying nutrient and cofactor conditions. Whole-culture transformation, crude supernatant activity, purified enzyme assays, intracellular detoxification responses, and genome-resolved functional annotation were integrated to evaluate the relative contributions of extracellular and intracellular processes. Transformation was strongly dependent on fungal species, substrate identity, nutrient availability, and cofactor composition. C. fumago achieved complete transformation of 2C4NP and up to 85.3% transformation of 5F2NP, whereas Curvularia sp. exhibited strict Na₃VO₄-dependent transformation of 5F2NP. Crude supernatants retained partial transformation capacity, achieving ~40–45% substrate depletion under conditions supporting whole-culture activity. Purified chloroperoxidase and laccase showed negligible independent activity and did not reproduce whole-culture transformation behavior. Lignin peroxidase activity was consistently induced during contaminant exposure and peaked during periods of maximum transformation. Cytochrome P450 inhibition did not prevent transformation. Baseline glutathione S-transferase activity was detected in both fungi, and comparative genome analysis identified conserved intracellular detoxification-associated enzyme alongside divergent extracellular oxidative enzyme repertoires. Together, these findings demonstrate that transformation of halogenated nitrophenols by fungi cannot be explained by isolated extracellular enzymes alone but is consistent with coordinated extracellular and intracellular system-level metabolism. These findings highlight an underexplored role for integrated fungal metabolic systems in bioremediation and provide a mechanistic basis for developing a scalable fungal platform for treatment of persistent halogenated contaminants.