Zhaoyang You

Aerobic granular sludge (AGS) technology is limited by slow granulation and structural instability. To overcome the shortcomings of existing carrier materials (e.g., activated carbon, sponge) regarding poor biocompatibility, inadequate pore connectivity, and surface chemical inertness, this study proposes a rapid AGS construction strategy based on a novel L-carrier (a renewable polymer material modified by alkali‑ultrasonic treatment to obtain hydrophilic, hierarchical porous, and high surface charge properties). Using sequencing batch reactors, the effects of the L-carrier on granulation progress, structural stability, and pollutant removal performance were systematically evaluated. Results showed that the L-carrier shortened the maturation time of the pre-formed composite granules to 5 days (defined as the time required to achieve stable granule morphology, settling velocity > 70 m h⁻¹,and TN removal rate increases), representing an 80% reduction compared to conventional self-aggregation. The obtained AGS exhibited a density of 1.062 g·(cm³)⁻¹, structural integrity > 0.95, and an average settling velocity of 70.9–74.2 m h⁻¹, which are significantly superior to reported activated-carbon-assisted AGS (settling velocity 55–65 m h⁻¹) and sponge-carrier systems (integrity ≤ 0.85). COD removal exceeded 90%, and total nitrogen removal reached 70–85%, which is significantly higher than typical values reported for conventional self-aggregated AGS (TN removal 50–70%) and sponge-carrier systems (55–70%), representing a 10–15% point improvement over similar carrier-assisted systems. High-throughput microbial analysis revealed that the L-carrier surface selectively enriched genera such as Thauera, Thermomonas, and Pseudoxanthomonas (total abundance > 25%), and their EPS (extracellular polymeric substances) production (especially polysaccharides in tightly bound EPS) was 2.3 times higher than that of carrier‑free systems. In summary, the L‑carrier not only serves as a physical scaffold but also enhances granule structural integrity and functional performance by modulating the interfacial micro‑ecology, providing a new approach for engineering application of AGS. Graphical abstract

To address the issue of low nitrogen removal efficiency caused by insufficient carbon sources when treating low C/N ratio polluted water in constructed wetlands (CWs), this study constructed a pyrite-coupled biochar intensified CW system (System S4). The results indicated that under conditions of HRT=24 h, 20°C, and influent TN=15 mg/L (NH4+-N: NO3--N = 1:1), the average removal efficiencies for NH4+-N and NO3--N reached 89.74% and 90.36%, respectively, with no NO2--N accumulation. Mechanistic investigations confirmed that pyrite serves as a slow-release electron donor driving autotrophic denitrification, while biochar exerts a synergistic effect through adsorption and microenvironmental regulation. Microbial analysis revealed a significant enrichment of the genus Thiobacillus within the system, alongside a substantial increase in the abundance of key denitrification functional genes (nirS, narG). This study provides critical technical parameters and theoretical support for the intensification of CWs treating low C/N wastewater.

Introduction: Arbuscular mycorrhizal fungi (AMF) show significant potential for improving plant tolerance to vanadium (V) stress. However, the pattern and physiological mechanisms behind this effect are not fully understood.Methods: To investigate this, we used green foxtail (Setaria viridis) as a test plant and inoculated this plant with (+AMF) or without (-AMF) Rhizophagus irregularis. These +AMF and -AMF plants were grown in soils with low (150 mg kg^-1), medium (500 mg kg^-1), and high (1000 mg kg^-1) V pollution levels.Results: Our results showed root colonization of +AMF plants, whereas no such colonization was observed in -AMF plants. Compared to -AMF plants, +AMF plants showed a more organized arrangement of leaf cells, intact chloroplasts, fewer starch granules, and an intact nuclear membrane. AMF increased leaf chlorophyll a concentration by 49% under high V pollution and that of chlorophyll b by 18% under low V pollution and 36% at medium soil V levels. AMF reduced the concentration of malondialdehyde (MDA) by 36%-40% in leaves and increased the activities of superoxide dismutase (SOD) by 20%-84%, catalase (CAT) by 5%-13%, and peroxidase (POD) by 12%-16%. +AMF plants exhibited 13%-32% greater plant height, 17%-23% longer root length, 42%-78% higher shoot biomass, 61%-73% greater root biomass, 16% increased root-to-shoot ratio (at high V pollution), and 7%-13% elevated leaf phosphorus concentration than -AMF plants. Furthermore, +AMF shoots had 16%-30% lower V concentrations than -AMF plants while +AMF roots exhibited 52%-73% smaller V concentrations than the -AMF control.Discussion: These results suggest that AMF increase plant tolerance to V stress by protecting leaf ultrastructure, increasing chlorophyll concentration, reducing oxidative damage as well as biomass-driven V dilution and these effects of AMF were independent of soil V concentrations.

The recent COVID-19 pandemic has increased the use of disposable face masks (DFMs). Due to a lack of manufacturing and disposal guidelines, DFMs are among the most common solid wastes worldwide. Common masks are made of polypropylene, which releases (nano)microplastics into the environment as it ages, causing environmental problems. In this work, the mechanism of aging of DFMs under UV radiation is studied and also the interaction mechanism of three antibiotics (ciprofloxacin (CIP), sulfamethoxazole (SMX) and tetracycline (TC)) with the original and UV-aged (nano)microplastics of the mask is investigated. The results showed that aging caused more antibiotics to be adsorbed onto the mask (nano)microplastics, mainly due to the oxygen-containing groups on the surface of the aged-mask. The adsorption capacity of the different layers of the (nano)microplastic mask for antibiotics was in descending order: inner-layer > outer-layer > middle-layer. The adsorption affinity of new and aged mask (nano)microplastics for antibiotics followed SMX > CIP > TC, which positively correlated with the octanol–water partition coefficient (log K_ow) of antibiotics. In general, the adsorption process of antibiotics on (nano)microplastics is mainly governed by membrane-diffusion and distribution mechanisms, and hydrophobic interactions regulate the adsorption process.