Jian Xiong

This study investigated seasonal variations in treatment performance, extracellular polymeric substances (EPS), microbial community structure, and functional potential in a full-scale high-altitude (3650 m) membrane bioreactor (MBR) wastewater treatment plant using shotgun metagenomic sequencing. Water temperature ranged from 9.9 °C in winter to 16.8 °C in summer, while pH remained neutral (7.1–7.6). The system maintained stable removal of suspended solids (>93%), chemical oxygen demand (COD) (effluent 13–21 mg/L), and 5-day biological oxygen demand (BOD₅) (effluent < 2.8 mg/L), and ammonium nitrogen (NH₄⁺-N) removal remained high (effluent < 0.2 mg/L) throughout the year. Notably, total nitrogen (TN) removal efficiency decreased significantly in winter, whereas total phosphorus (TP) removal was less seasonally sensitive. EPS peaked in winter (protein 49.8 mg/L, polysaccharide 9.2 mg/L), mainly driven by the protein fraction, indicating an adaptive response to low-temperature stress. Microbial richness and diversity were highest in spring and summer, decreased sharply in autumn, and partially recovered in winter through cold-adapted taxa. Dominant phyla (Chloroflexota, Pseudomonadota) and genera (Candidatus Villigracilis, Nitrospira) maintained nutrient removal through seasonal functional complementarity. Metagenomic analysis revealed higher carbon, nitrification, and denitrification gene abundances in spring and summer, while the relative abundances of nirK and nosZ shifted in autumn and winter. Phosphorus metabolism genes remained abundant, with pstS peaking in autumn. Overall, the high-altitude MBR exhibited strong adaptability through seasonal regulation of EPS, microbial communities, and metabolic functions, ensuring stable and efficient operation.

Cities in alpine and high-altitude regions are subject to technical, environmental and economic constraints, and there are problems such as imperfect evaluation systems and immature methods for domestic waste disposal technology, which urgently require the establishment of a scientifically perfect evaluation system. This study takes Lhasa as an example and uses comparative analysis, analytic hierarchy process (AHP), ArcGIS, mathematical model and fuzzy comprehensive evaluation methods to construct the evaluation system covering the whole process of ‘classification-transfer-transportation-disposal’. Considering the progress of waste classification in Lhasa, optimization measures such as regular collection and transportation, establishment of transfer and sorting centres and on-site resource treatment are needed. Based on the ArcGIS simulation analysis and actual transfer demand, three new transfer stations were planned, and it was found that the new transfer stations could significantly reduce transfer distances of urban-suburban routes by 45.91%, labour costs by 50.00% and total CO _2-eq emissions by 10.42%. Moreover, the AHP and fuzzy logic method were employed to establish an evaluation system for waste incineration power generation technology. Utilizing these methods, the comprehensive score assigned to the Lhasa waste incineration power generation technology was determined to be 91.97, thereby verifying the feasibility of the evaluation system and indicating that the technology is the leading one in China. However, environmental friendliness and economic feasibility still need improvements. This study provides a scientific basis for the decision-making process of efficient management of domestic waste in alpine and high-altitude regions.

Competitive uptake by coexisting divalent ions such as Ca2+ and Mg2+ significantly hinders the selective capture of Cu2+ from copper-containing wastewater. To address this challenge, a sulfur/nitrogen co-doped porous carbon material (KQZNS) was derived from furfural residue and applied as a flow electrode in a flow-electrode capacitive deionization (FCDI) system. Inspired by hard-soft acid-base (HSAB) interactions, this material was designed to promote Cu2+-favored interfacial electrosorption. Characterization showed that KQZNS possesses a highly developed microporous structure, excellent conductivity, and good colloidal stability. In FCDI tests, KQZNS achieved a Cu2+ removal efficiency of 93% within 1 h in a single-ion solution. In the mixed Cu2+/Ca2+/Mg2+ system, KQZNS showed both higher Cu2+ uptake and a clearer Cu2+-favored adsorption tendency than the control materials, reaching a Cu2+ adsorption capacity of 685.08 mg g-1, which was 1.53 and 2.39 times those of KQZN and KQZ, respectively. Density functional theory calculations and wavefunction analysis indicated that sulfur/nitrogen co-doping, particularly in the thiophene-S/pyridyl-N or pyrrolyl-N configurations, enhances electrostatic attraction and specific interactions between the carbon surface and hydrated Cu2+, thereby supporting the experimentally observed Cu2+-favored uptake. This work provides a low-cost and efficient route for preparing biomass-derived electrode materials, elucidates the HSAB-guided selective adsorption mechanism at the electronic scale, and offers theoretical support for the design of FCDI electrodes for ion-selective separation.

To address the comprehensive utilization of phosphogypsum, enhance the overall performance of vegetation-growing concrete, and achieve cost-effective rock slope restoration, this study examines the influence of modified phosphogypsum content on the physical and chemical properties of cementing materials at a low temperature of 10 °C, utilizing low-basicity sulphoaluminate cement. A specialized cementing material for vegetation-growing concrete with favorable mechanical properties and reduced alkalinity was developed, and its overall performance was validated. Isothermal calorimetry, X-ray diffraction (XRD), simultaneous thermal analysis (TG-DTG), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) were employed to compare the early hydration heat, hydration products, and microstructure of the modified phosphogypsum-low alkalinity sulphoaluminate cement system with those of ordinary Portland cement and low alkalinity sulphoaluminate cement. The findings indicate that incorporating 30% modified phosphogypsum into low alkalinity sulphoaluminate cement results in a cementing material with rapid early hydration, a compact matrix, reduced calcium hydroxide content, and superior mechanical properties. These characteristics achieve optimal comprehensive performance and exhibit favorable physical and chemical properties under low-temperature curing, meeting the requirements for vegetation-growing concrete and enhancing its overall performance.

Global antibiotic pollution (represented by tetracycline hydrochloride, TCH) threatens water environmental safety, and resource recovery of agricultural waste remains a key challenge for sustainable development. Given that utilizing biochar for adsorption is widely recognized as a circular economy-compliant method, this study aimed to verify its applicability in TCH pollution control while recycling agricultural waste by preparing modified biochar from the Xi Zang highland barley straw via chemical activation (KOH, H₃PO₄, NaHCO₃, and ZnCl₂) and pyrolysis at 750 °C. Among the products, H₃PO₄-modified (P-BC) and ZnCl₂-modified (Zn-BC) biochars performed best: their abundant micro/mesoporous structures and surface functional groups (–OH/–COOH) enabled excellent TCH adsorption, with the mechanism involving synergy of physical adsorption (dominated by pore filling) and chemical adsorption (hydrogen bonding, electrostatic attraction, cation bridging), alongside multi-layer adsorption. Adsorption was pH-dependent—acidic conditions favored it, while Zn-BC restored efficiency at pH = 9 via Zn²⁺ bridging. The two biochars were complementary: Zn-BC had higher adsorption capacity, while P-BC showed better stability and ionic interference resistance. Thus, Zn-BC suits high-concentration, low-ionic-strength TCH wastewater, and P-BC is ideal for complex high-ionic-strength water (e.g., industrial/aquaculture wastewater). This study provides theoretical and technical support for high-value utilization of regional agricultural waste and targeted TCH pollution control.

Amidst global imperatives for sustainable energy and environmental remediation, carbon aerogels (CAs) present a transformative alternative to conventional carbon materials (e.g., activated carbon, carbon fibers), overcoming limitations of disordered pore structures, unmodifiable surface chemistry, and functional inflexibility. This review systematically examines CA-based electrochemical systems as its primary focus, analyzing fundamental charge-storage mechanisms and establishing structure–property–application relationships critical to energy storage performance. We critically assess synthesis methodologies, emphasizing how stage-specific parameters govern structural/functional traits, and detail multifunctional modification strategies (e.g., heteroatom doping, composite engineering) that enhance electrochemical behavior through pore architecture optimization, surface chemistry tuning, and charge-transfer kinetics acceleration. Electrochemical applications are extensively explored, including the following: 1. Energy storage: supercapacitors (dual EDLC/pseudocapacitive mechanisms) and battery hybrids. 2. Electrocatalysis: HER, OER, ORR, and CO₂ reduction reaction (CO₂RR). 3. Electrochemical processing: capacitive deionization (CDI) and electrosorption. Beyond this core scope, we briefly acknowledge CA versatility in ancillary domains: environmental remediation (heavy metal removal, oil/water separation), flame retardancy, microwave absorption, and CO₂ capture.

The bacterial communities of activated sludge are correlative with influent characteristics, geographical discrepancies, and environmental variables, which are essential for wastewater treatment plants (WWTPs). However, the comprehensive deciphering of bacterial community diversity in high-altitude WWTPs is scarce in Tibet, China. This study collected activated sludge samples from four A²O WWTPs (2980–3650 m above sea level) in Tibet. Illumina NovaSeq high-throughput sequencing revealed that Proteobacteria was the most abundant phylum (46.2–62.9%), followed by Bacteroidetes (14.8–21.8%) and Actinobacteria (3.5–10.9%). Candidatus Accumulibacter (7.2–15.1%) was the dominant denitrifying polyphosphate-accumulating organisms (DPAOs). Moreover, a principal coordinate analysis (PCA) revealed strong correlations between environmental factors and dominant phyla, while Candidatus Accumulibacter as a dominant genus was unaffected by environmental factors. Additionally, the reaction mechanisms were analyzed based on the functional gene abundance of carbon, nitrogen, and phosphorus metabolic pathways in high-altitude WWTPs. The carbon metabolism pathway, especially carbohydrate metabolism (14.52%), has more abundant functional genes in Nyingchi (LZ). Nitrogen metabolism mainly consists of assimilatory nitrate reduction, dissimilatory nitrate reduction, and denitrification; the high abundance of functional genes in phosphorus metabolism ensures efficient phosphorus removal. The obtained microbial information in the WWTPs could provide essential guidance for the sustainable management of wastewater treatment systems in high-altitude environments. Future research should focus on monitoring the seasonal dynamics of bacterial communities in high-altitude WWTPs and responses to environmental disturbances, to optimize treatment efficiency and ensure long-term sustainability.

The safe and resource-efficient utilization of waste incineration fly ash (WIFA) has emerged as a pressing challenge in solid waste management. In this work, WIFA was used to prepare a bifunctional catalyst (Metals_x/4@WIFA-S) for the production of levulinic acid (LA) from glucose. The yield of LA was 42.3% with water as the solvent. Moreover, adding 20% γ-valerolactone (GVL) to the system increased the yield to 50.7%. Reaction kinetics and molecular dynamics simulations were applied to elucidate the mechanism by which the solvent system enhanced the catalytic performance of the Metals_x/4@WIFA-S catalyst. Additionally, the environmental risks of WIFA in the preparation of catalysts were evaluated. The dioxin decomposition rate in the catalyst was calculated to be 99.87%, effectively achieving the detoxification of the catalyst. The concentration of heavy metals in the hydrolysate complied with emission standards, thereby reducing environmental risk. This study confirms that waste incineration fly ash-based bifunctional catalysts are effective and safe catalysts with great potential for application in biomass catalysis.