Effective removal of per- and polyfluoroalkyl substances (PFAS) form contaminated waters remains a significant treatment challenge in remediation facilities due to their structural heterogenicity, high aqueous mobility, and frequent occurrence as complex multi-component mixtures. Although granular activated carbon (GAC) and ion exchange resins (IER) are widely used for PFAS treatment, their performance is strongly influenced by water-matrix composition and competitive adsorption among PFAS, which can accelerate breakthrough and reduce adsorption capacity. Consequently, treatment performance assessments and capacity estimates may remain uncertain under multi-component conditions. Accordingly, this study evaluates how structurally diverse PFAS compete during adsorption and displacement in single- and multi-solute systems. This unified comparison clarifies how GAC and IER chemistry influence PFAS competitive behavior. Coexisting organic and inorganic constituents, dissolved organic matter (DOM) and phosphate, were incorporated to simulate realistic water matrices and to quantify their influence on PFAS competition and displacement. Results revealed that PFAS chain length and functional group chemistry governed the competitive hierarchy, with sulfonates generally exhibiting greater surface stability and removal efficiency than carboxylates. In addition, the results demonstrated distinct surface-dependent competitive behavior across the studied sorbents. GAC exhibited pronounced inhibition and displacement of PFAS in the presence of dissolved organic matter, whereas IER maintained relatively higher selectivity toward PFAS but was more susceptible to phosphate-induced displacement, highlighting the distinct matrix sensitivities of the two sorbents. These findings provide critical insight into PFAS treatment in multi-component systems and emphasize the importance of water-matrix specific design considerations to improve treatment efficiency, particularly for short-chain PFAS.

The objective of this study is to evaluate and optimize an eco-friendly bioash–ground granulated blast furnace slag (GGBFS) binder for solidification/stabilization (S/S) of contaminated sandy–silt soil by identifying formulations that provide both mechanical strength and effective multi-element immobilization across curing time and carbonation aging. The soil contained elevated trace elements (As 403 mg/kg, Pb 806 mg/kg, Zn 398 mg/kg, Cu 526 mg/kg), exceeding Swedish guideline values for sensitive land use and requiring stabilization. A design-of-experiments (DoE) approach was used to define binder formulations. Mixtures were prepared at optimum moisture content (from Proctor compaction) and evaluated using unconfined compressive strength (UCS) testing and standardized batch leaching (SS-EN 12,457–2, L/S = 10). Leachates were analyzed for pH, electrical conductivity (EC), total organic carbon (TOC), inorganic carbon (IC), and dissolved trace elements. The dataset was analyzed using principal component analysis (PCA) and response-surface mapping to identify formulation regions that balance strength and leaching performance. Formulations (bioash 10–35%; GGBFS 5–15%) were cured for 28, 56, and 115 days. Carbonation aging was conducted for three weeks in sealed containers at laboratory temperature (19–24 °C) under CO₂ exposure. The formulation 35% bioash:15% GGBFS achieved the highest UCS (1438 ± 111 kPa at 56 days; n = 2) and strongly reduced leaching of cationic metals. Zn and Cd were below analytical limits (Zn < 2 µg/L; Cd < 0.05 µg/L), and Pb decreased by 99% relative to untreated soil. Arsenic leaching decreased by up to 43% after 28 and 115 days but increased transiently (20%) at 56 days. This increase coincided with CaCO₃ formation and lower-pH eluates with elevated Ca and IC, consistent with carbonation-driven changes in As retention. Compared with a cement-based binder, the bioash–GGBFS system moderated alkalinity while maintaining strength and improving Pb and As immobilization. Overall, the bioash–GGBFS system shows strong potential for sustainable remediation of metal-contaminated soils, although Cu and Ni require further optimization.

Remediation of former wood treatment sites is challenging due to the presence of contaminants with distinct physicochemical properties, such as arsenic (As) and polycyclic aromatic hydrocarbons (PAHs). This study evaluated a low-voltage electricity-induced soil remediation method designed to immobilize As while simultaneously degrading PAH in situ. A field pilot experiment was conducted at a highly contaminated site using iron (Fe) electrodes supplying pulsed direct current to promote PAH oxidation and Fe release from electrodes for As immobilization. Groundwater in five wells was monitored for concentrations of contaminants, their degradation byproducts, and microbial and fungal community structures. Over two years, dissolved PAH16 concentrations decreased by 62–94% across wells, with no accumulation of oxygenated or nitrogen-containing PAH. Dissolved As concentrations declined by up to 88% at low PAH levels, but reductions were weaker (55–57%) and more variable at very high PAH concentrations (hundreds to thousands μg L–1). Microbial communities, both prokaryotic and fungal, were characterized by taxa often found in contaminated aquifers and soils, with enrichment of PAH-degrading and As-tolerant Pseudomonas, Rugosibacter, and Duganella, but showed no adverse effect of the treatment. Overall, the method promoted concurrent PAH degradation and As immobilization with minimal secondary impacts, demonstrating potential for remediation of mixed-pollutant soils. 

Foam fractionation is emerging as a promising option to remove and concentrate PFAS from polluted water and soil resources. Here, we investigate the electrochemical treatment of foamate resulting from the simultaneous application of soil washing and foam fractionation for the remediation of PFAS-contaminated soil. The effect of the applied current density, flowrate, initial PFAS concentration and organic matter content was first assessed on a synthetic solution. Fractionated foam was then treated, and concentration profiles of detected C4-C8 perfluoroalkane sulfonic acids (PFSAs), the fluorotelomer sulfonate 6:2 FTS, and C4-C8 perfluoroalkyl carboxylic acids (PFCAs) were investigated. Electrochemical degradation of the fractionated foam proceeded through the generation of short chain intermediates. Most of PFOS degradation occurred within the first 10 min of treatment, with a resulting reduction of ∼68% of the initial total PFAS content. However, no further significant reduction of PFOS was observed within 5 h, concentration of C < 8 PFSAs did not decrease, while PFCAs concentration increased likely due to their generation as degradation intermediates. Electrochemical treatment of fractionated foam must be further studied to extend the degradation performance to several PFSAs, as well as to ensure complete mineralization of PFCAs within a reasonable timeframe. To this aim, matrix-specific interferences demand investigation. Furthermore, advancement in reactor configuration may guarantee enhanced performance driven by maximized PFAS contact with the electrode surface.

Despite advances in reactor-based process intensification, the influence of hydrodynamic conditions on PFAS removal remains poorly understood. In particular, rotating bed reactors (RBRs), which are designed to enhance mass transfer, have not been systematically evaluated for PFAS removal or compared with conventional batch and fixed-bed column systems. This lack of comparative understanding limits the ability to assess their practical relevance for PFAS remediation. In this study, PFAS removal was investigated under intensified hydrodynamic conditions using an RBR and compared with batch and small-scale column systems with special focus on short-chain PFAS compounds. The RBR significantly enhanced adsorption kinetics, with pseudo-first-order rate constants increasing by 3 to 16-fold across PFAS, particularly for short-chain PFAS. For instance, PFBA exhibited near-complete removal within 12 h in the RBR, whereas only ~50% removal was achieved in batch conditions. However, faster kinetics did not translate into superior long-term breakthrough performance compared to the column treatment system. After 50 treatment cycles using ion exchange resin, PFBA reached approximately 40% C/C0 in the RBR, while the column system maintained C/C0 below 5%; similar trends were observed for PFPeA (15% vs. ~0.5%) and PFHxA (6.2% vs. ~0.2%). These findings reveal a fundamental trade-off between kinetic intensification and long-term treatment performance. The results highlight distinct design roles, with RBR systems enabling rapid and intensified treatment (e.g., staged or parallel configurations), while conventional column systems perform better for continuous operation and compliance control in PFAS remediation.

Conventional validation of low-carbon stabilization binders often relies on short curing periods and batch leaching tests, which do not adequately capture long-term durability or transport-controlled contaminant release. In this study, a bioash–GGBFS binder was evaluated for stabilization/solidification of metal-contaminated soil from Näsudden, Sweden, using an integrated program of extended curing, wet–dry and freeze–thaw cycling, and standardized percolation and diffusion leaching tests. The treated mixture (50% soil, 35% bioash, and 15% GGBFS) developed unconfined compressive strength in the MPa range and maintained high strength after durability exposure, with 1635 ± 308 kPa after wet–dry cycling and 2047 ± 100 kPa after freeze–thaw cycling. Percolation testing at L/S = 10 showed strong reductions in leaching compared with untreated soil, including 96% for As, 98% for Cd, 90% for Pb, 92% for Zn, 88% for Ni, and 65% for Cu. Diffusion testing confirmed low release for most elements, while Cu showed the highest cumulative release and mobility, indicating an element-specific limitation. Overall, the results demonstrate that the bioash–GGBFS binder can provide both durable mechanical performance and sustained immobilization of most priority contaminants under transport-relevant conditions. The findings support its potential as a low-carbon alternative for stabilization and reuse of contaminated soils, although additional measures may be needed where Cu governs compliance

Risk-based land management emphasises remediation to manage risks from land contamination, aiming to reduce human and environmental risks while enabling site reuse and redevelopment. Since the mid-2000s, sustainable remediation has gained prominence, driven by global sustainability agendas such as the United Nations 2030 Agenda and the European Green Deal. These frameworks encourage integrated approaches that maximise remediation benefits and minimise negative impacts. Low-input remediation techniques (LIRT) represent a family of approaches characterised by lower energy and resource demands, often leveraging natural processes, renewable resources, or energy sources. Examples include methods using biochar, photosynthesis, or renewable energy systems. LIRT overlap with concepts like gentle remediation options (GRO) and nature-based solutions (NBS), which employ natural processes to address contamination while delivering environmental and societal benefits. While LIRT are typically effective for pathway management rather than source control, they offer sustainable outcomes such as stabilisation, containment, and destruction of biodegradable contaminants. They also contribute to broader sustainability goals, such as reducing carbon footprints and preserving soil functionality, and can support site reuse for biofeedstocks, habitats, or amenity spaces. LIRT are particularly valuable for stalled or economically unviable sites, offering cost-effective and flexible solutions. However, achieving sustainable outcomes depends on site-specific factors, and LIRT often work best when integrated into a broader remedial strategy combining intensive and low-input methods. This paper explores LIRT's potential applications, technical characteristics, and challenges, alongside their benefits for sustainable land management and the restoration of underutilised sites.

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals found worldwide in several industrial and consumer products. The extensive use of these fluorinated organic compounds, together with their high stability, has led to a broad contamination of water and soil resources. Among the technologies under development for their remediation, sonochemistry stands out. Propagation of ultrasounds in aqueous media results in sonophysical and sonochemical effects, able to collaboratively mineralize most of PFAS. Oxidative additives, as well as surfactants, may enhance the performance of the technique, which is also affected by organic matter, residual solvents, pH and temperature of the solution. PFAS concentration is a crucial factor in terms of treatment efficiency since it defines the rate order, while differences in functional group, chain length, and extent of fluorination affect hydrophobicity, surface activity and thermal activation energy of PFAS. Reaction pathways, solution chemistry, reactor configuration, and operational parameters including flowrate, atmosphere condition, US frequency and power density are discussed within this critical review, with the aim of boosting the implementation of this technology for PFAS remediation.

Per- and polyfluoroalkyl substances (PFASs) include thousands of fluorinated organic compounds of anthropogenic origin. Their extensive use, combined with their high stability, has led to the widespread contamination of water and soil resources. Here, single-step foam fractionation enhanced soil washing was carried out for the remediation of PFAS-contaminated soil. Concentrations of target Perfluoroalkyl Carboxylic Acids (PFCAs) and Perfluoroalkane Sulfonic Acids (PFSAs) were monitored in foam and leachate along the duration of the treatment. Among PFCAs, only long-chain compounds peaked in foam at the beginning of the treatment. This was consistent with the increase in the sorption affinity to the air–water interface with chain length. The same behavior was observed also in PFSAs by comparing PFHXs, PFHpS and PFOS. The fraction of PFCAs still in the leachate after 40 min of treatment was found to decrease with chain length, with PFSAs showing a similar trend. PFAS removal significantly increased with soil particle size, ranging from 48.2 ± 3.2% (fraction < 0.063 µm) to 64.1 ± 1.9% (fraction > 2 mm). Final mass balance analyses detail PFAS distribution among soil, leachate, and foam, providing valuable information for the additional treatment required to destroy the PFAS load extracted from the contaminated soil.

Per- and polyfluoroalkyl substances (PFAS) are frequently found in soil, groundwater, and landfill leachate, in the vicinity where materials containing PFAS have been disposed of, or in areas where activities involving the use of aqueous film-forming foams (AFFF) have been executed. Removing PFAS via adsorption is a cost-effective and practical method to clean PFAS from contaminated waters. However, challenges arise with the inefficient adsorption of short-chain PFAS and the breakthrough of the contaminant, demanding further advancement. The current study investigates the removal of PFAS using a byproduct generated during the production of Float Adsorb (GP) in combination with electrochemical oxidation (EO). The byproduct was modified by incorporating iron oxyhydroxides. Batch experiments were conducted to assess PFAS adsorption onto the iron-modified material (Fe-P) and (GP), followed by column experiments simulating upscaled treatment. Electrochemical oxidation was then applied to degrade PFAS that broke through the adsorbent. Results showed that iron-coated adsorbent (Fe-P) had a higher capability to retain PFAS than uncoated material (GP). The removal of PFAS in groundwater on batch mode reached an average of 84.5 ± 1.1 % using GP and 94.5 ± 0.3 %∑11PFAS using Fe-P with an L/S ratio of 10. The EO following column treatment effectively degraded PFAS not adsorbed by the Fe-P adsorbent, showing promising potential for PFAS treatment in solutions. Up to 94 % of ∑11 PFAS were removed in contaminated groundwater and 76 % in leachate. Our study highlighted the potential of combined sorption and electrochemical oxidation methods to remediate PFAS in contaminated waters.