The removal of organic pollutants from water by advanced oxidation has been successfully achieved using iron–biochar (Fe–BC)-based material. By embedding iron particles on the biochar, the resulting Fe–BC composite possesses enhanced surface functionalities that promote electron transfer and generate reactive oxygen species (ROS). Characterizations using various analytical techniques confirm the successful formation of the Fe-based biochar and its improved catalytic features. Batch degradation experiments have demonstrated that Fe–BC exhibits significantly higher performance than unmodified biochar in the breakdown of organic contaminants, primarily through advanced oxidation processes (AOPs) facilitated by iron-induced radical (SO₄^•−, ^•OH, O₂^•−) formation, non-radical ROS (¹O₂), and electron transfer pathways. Finally, the advantages of Fe-BC in the catalytic degradation of organic pollutants are summarized, highlighting potential limitations and prompting further research to optimize Fe–BC performance and expand Fe–BC applicability.

The recent increase in wildfire activity has raised concerns among many water utilities that rely on forested watersheds susceptible to wildfire for drinking water supplies. An understanding of post-fire treatment challenges, and guidance on how water providers can prepare is needed. In this study, dark, charred, riverbank sediment deposits were collected from the High Park fire burn area in northern Colorado, USA and leached in the laboratory to simulate the impact of post-fire runoff on source water quality. A comparison of the sediment leachates to post-fire river samples collected during flow events indicated the turbidity, phosphorus, nitrogen and dissolved organic carbon concentrations were similar, although the leachates do not reflect extreme concentrations observed in the field. The treatability of the leachates was evaluated with conventional coagulation and additional unit processes (pre-oxidation, powdered activated carbon, biofiltration), and samples were analyzed for disinfection byproduct (DBP) formation. Material leached from the sediments was enriched in haloacetonitrile (HAN) and chloropicrin precursors compared to baseline organic material of source waters, whereas total trihalomethane and haloacetic acid precursor reactivity were not statistically different from baseline source waters. Sediment leachates were amenable to conventional coagulation (25 mg L⁻¹ aluminum sulfate), but may require additional treatment to meet DBP maximum contaminant levels. Enhanced coagulation (50 mg L⁻¹) or pre-ozonation followed by conventional treatment are recommended as the best options for reducing carbonaceous DBP formation. Pre-ozonation/coagulation/biofiltration resulted in the lowest HAN and chloropicrin formation of the sediment leachates.

Per-and polyfluoroalkyl substances (PFAS) present significant challenges for remediation due to their persistence in nature. Activated carbon is a widely used adsorbent for removing PFAS. In this study, three forms of activated carbon, granular activated carbon (GAC), powdered activated carbon (PAC), and ball-milled colloidal activated carbon (CAC_BM), are compared for their effectiveness in removing short and long-chain PFAS. Physical modification through ball-milling process enhanced the adsorptive properties of activated carbon, resulting in smaller particle size (d ₅₀ = 0.318 μm), increased surface area (968.59 m² g^–1), and improved suspension stability compared to conventional GAC and PAC. Kinetic experiments showed that CAC_BM demonstrated superior removal efficiencies of long-chain PFAS (up to 89% for perfluorooctanesulfonic acid (PFOS) and 73% for perfluorooctanoic acid (PFOA)), and moderate removal of short-chain PFAS (55% for perfluorobutanesulfonic acid (PFBS) and 30% for perfluorobutanoic acid (PFBA)). The pseudo-first-order model adequately described adsorption trends; however, the pseudo-second-order model provided a better fit, with intraparticle diffusion identified as the rate-limiting step. Isotherm studies indicated that PFAS adsorption aligned well with the Freundlich model. Competitive adsorption experiments revealed a hierarchical pattern. Overall, the study demonstrates CAC_BM as a promising adsorbent for remediation of PFAS-contaminated water systems.