This study evaluates a three-dimensional (3D) electrochemical process employing cork granules as particle electrodes for removing contaminants of emerging concern (CECs) from urban wastewater. Tests in two reactors of different dimensions (Reactor A - 150 mL; Reactor B - 750 mL), with and without spiking of sulfamethoxazole (SMX) and trimethoprim (TMP), were performed and compared with the conventional 2D process and the use of a commercial activated carbon as 3D particulate electrode. The 3D cork process outperformed both the 2D process and the use of activated carbon, achieving higher removal efficiencies and lower energy consumption. In fortified wastewater, Reactor A achieved removal rates of 87 % for SMX and 59 % for TMP within 30 min. Reactor B led to complete SMX removal (below detection limits) and 81 % reduction in TMP, also showing 35 % reduction in energy consumption due to an increased electrode active area to reactor volume ratio. When applied to urban wastewater, 26 CECs could be detected. Over 80 % of 19 compounds were removed, and 15 of them were eliminated (below detection limits). Although using sodium chloride as an electrolyte enhanced the process efficiency, producing chlorine-reactive species may cause a hazardous impact on aquatic ecosystems, according to the ecotoxicity tests performed, suggesting the need for their removal. The Life Cycle Assessment results further underscore the environmental competitiveness of the cork-based 3D electrochemical process, highlighting its potential as a sustainable quaternary treatment for urban wastewater. This study also provides insights into optimizing the process for future large-scale applications.

Soil health is a major environmental concern. Biochars are a promising solution to address both soil contamination and amendment. They represent a sustainable valorisation alternative for solid wastes produced in huge amounts, namely agroforestry residues and sludge from wastewater treatment plants. Biochar’s superior properties, enhanced pore structure and high specific surface area can contribute to restoring soil quality, by adsorbing several pollutants (e.g., pharmaceutical compounds, pesticides, and metals) from water and soil, enhancing water retention capacity, improving soil aggregation, regulating pH, and reducing the need for synthetic fertilisers. Multiple studies have reported removal efficiencies exceeding 70% for metals and 60% for organic compounds in soils, as well as over 40% for both organic compounds and metals in waters. These efficiencies depend on factors such as feedstock, pyrolysis conditions, modification strategies, and target contaminants. Recent advancements in the field have introduced both chemical and physical modifications that can enhance adsorption selectivity. This review provides a comprehensive analysis of the fundamentals of biochar production, modification strategies, and their environmental applications in soil remediation and water treatment. By comparing unmodified and modified biochars, this review highlights the crucial factors that influence the performance of this highly versatile and cost-effective solution.

In this study, quince-derived biochar was employed as a sustainable and multifunctional material for the removal of organic pollutants through different treatment alternatives depending on the pH (natural or modified), including adsorption and electro-Fenton degradation processes. The biochar, obtained by pyrolysis (500 °C, 14 h) of quince (Cydonia oblonga) biomass, exhibited a high intrinsic iron content (1296 mg/kg), which contributed to its electroactive properties and catalytic potential. Batch experiments demonstrated highly efficient adsorption of the target pollutant, the antibiotic sulfamethoxazole, achieving a maximum retention capacity of 35.51 mg/g. Regarding the degradation pathway, the electrochemical treatment achieved significant degradation rates under mild operating conditions, reaching total removal in less than 90 min. Both treatment options, under their respective optimal conditions, were subsequently evaluated using tertiary wastewater from a wastewater treatment plant, achieving good removal efficiencies exceeding 60% within 120 min. Finally, the treated effluent under optimal conditions was subjected to an ecotoxicity assay using the microalga Raphidocelis subcapitata, confirming the effectiveness of the treatment and the absence of harmful effects on this key microorganism in the aquatic food chain. These findings highlight the potential of iron-rich quince biochar as a low-cost and environmentally friendly material for various water treatment applications. Moreover, the results provide a promising approach for valorizing agricultural waste with inherent metallic content in heterogeneous electro-Fenton.

The Directive (EU) 2024/3019 on urban wastewater treatment (WWT) imposes new, stringent targets for nutrients and pharmaceutical compounds, thereby requiring the implementation of tertiary and quaternary treatments and promoting water reuse. This study evaluated the ecotoxicological impacts of advanced wastewater treatments applied to the effluent from a WWTP after secondary treatment: ultrafiltration (UF), ultraviolet radiation (UV), ozonation (OZ), and non-thermal plasma (NTP). Ecotoxicity assays were conducted using Raphidocelis subcapitata (chronic tests) and Daphnia magna (acute and chronic tests), representing primary producers and consumers, respectively. For R. subcapitata, no significant growth inhibition was observed for most treatments, while growth was promoted due to the presence of nutrients, except for OZ, which produced inhibitory effects. In D. magna, acute toxicity was low for most treatments, except for OZ, which showed significant toxicity. An additional chronic exposure experiment was conducted for the NTP-treated effluent, inducing adverse effects on growth and reproduction of D. magna; in contrast, R. subcapitata showed no effects, demonstrating species-specific sensitivity and trophic-level-dependent responses. These findings demonstrate that although advanced oxidation technologies enhance water quality, they may cause sublethal and lethal ecotoxicity effects, highlighting the importance of ecotoxicological evaluations in risk assessment of quaternary treatments, framed by Directive (EU) 2024/3019.