Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202510084
The rapid expansion of lithium battery industries has elevated lithium resources to strategic importance, yet lithium extraction generates 8–10 tons of slag per ton of lithium salt, with complex heavy metal content and high leaching risks. This study improves conventional alkali activation by employing a composite activator and multi-stage thermal assistance to achieve self-solidification of lithium slag, simultaneously immobilizing multiple heavy metals while producing high-strength materials. Under full slag conditions, the mechanical strength of solidified materials ranged from 3.48 to 8.25 MPa; after optimization, strength increased by 137.07%. Average immobilization rates for various heavy metals rose from 97.26% to 99.77%. In simulated acidic, alkaline, neutral, high-salt, acid rain, and leachate environments, efficient immobilization was maintained, with leachate concentrations below regulatory limits. The improved activator and thermal process reduced structural defects, promoted formation of the key Si-O-Al framework, and ensured structural integrity, enhancing both mechanical strength and heavy metal immobilization. The cost of slag solidification was approximately 185–200 CNY per ton, significantly lower than conventional methods, with low energy consumption, no high-temperature calcination, and reduced equipment and reagent requirements, supporting scalability.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202510060
Wastewater treatment plant (WWTP) effluent is a significant pathway for emerging contaminants (ECs) to enter natural water bodies. This study investigated the removal of ECs by two field-scale gravel-based constructed wetlands: a horizontal subsurface flow constructed wetland (QL-CW) and a surface flow constructed wetland (BL-CW), both treating actual WWTP effluent. The influence of operation mode and wetland plant type on EC removal was examined. Using liquid chromatography-mass spectrometry, principal component analysis, and ecological risk assessment, the removal efficiencies and mechanisms for various ECs were explored. In QL-CW, biodegradation was more pronounced, particularly via ammonia-oxidizing bacteria co-metabolism, favoring ECs with benzyl, secondary amine, secondary amide, tertiary amide, halogenated, and carboxyl functional groups. In BL-CW, electrostatic attraction and hydrophobic interactions were more significant, with plant and root-microorganism uptake and adsorption playing key roles. Surface flow mode achieved significantly higher removal of antibiotics (45.3% vs. 34.1%) compared to horizontal subsurface flow, while no significant differences were observed for non-antibiotic pharmaceuticals (66.6% vs. 64.4%) and pesticides (49.8% vs. 34.2%). Planting Cyperus alternifolius (windmill grass) was more beneficial for antibiotic removal (43.6% vs. 30.1%) than planting Ipomoea aquatica (water spinach). The wetlands effectively reduced the ecological risks of most ECs to marginal levels. This study provides insights into the deep treatment of ECs in WWTP effluent by constructed wetlands.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202511011
The high cost of catalysts is a critical barrier to the upgrading and cost reduction of catalytic ozonation technology. This study developed a low-cost, long-life Fe–Mn-based ozone catalyst (FMG) derived from solid wastes (red mud and blast-furnace slag), leveraging iron and manganese components to construct dual active centers. A continuous manufacturing process was achieved by integrating alkali-activated cementitious reactions with disc pelletization via a cascade spray-coating and multi-stage curing technique. Under optimal conditions (ozone dosage 3.5 mg·L−1), the catalyst achieved 81.81% total organic carbon (TOC) removal of phenol solution within 60 min, retaining 87.27% of its initial activity after 15 reuse cycles. Long-term continuous-flow tests over 60 days demonstrated stable TOC removal between 69.44% and 75.46%. The production cost of FMG was 1,351.44 CNY·t−1, and the unit TOC removal cost was only 0.06 CNY·(g TOC)−1, representing a 78.69%–86.85% reduction compared to commercial catalysts (0.30–0.48 CNY·(g TOC)−1). This work provides a theoretical and technical foundation for cost-effective catalytic ozonation and high-value conversion of bulk solid wastes.