Most ReadOzonation is an effective advanced treatment technology for textile dyeing and finishing wastewater; however, its large-scale application is primarily constrained by its intrinsically low ozone mass transfer efficiency. Membrane contactor reactors (MCRs) can significantly enhance ozone mass transfer by constructing microscale gas-liquid interfaces, offering advantages such as high mass transfer efficiency and the absence of secondary pollution. Nevertheless, issues including membrane fouling, high material costs, and poor operational stability still limit their engineering-scale implementation. This study systematically reviewed recent advances in the mechanisms of ozone mass transfer enhancement in MCRs. The principles of gas-liquid interfacial mass transfer and the design characteristics of hollow fiber membrane contactor configurations were introduced. The regulatory effects of membrane material properties (e.g., the selection of hydrophobic PTFE/PVDF), operating parameters (gas-liquid flow rates, transmembrane pressure, and pH), and mass transfer models on the volumetric ozone mass transfer coefficient were critically analyzed. Furthermore, the application efficiency of MCRs in textile dyeing and finishing wastewater treatment was evaluated, with particular emphasis on efficient dye removal, organic matter mineralization, and decolorization. Research demonstrated that optimized MCR systems could increase the volumetric ozone mass transfer coefficient by 5~10 times compared with conventional bubble column processes, thereby substantially enhancing the kinetics of pollutant degradation. However, challenges such as membrane fouling-induced flux decline, bromate by-product formation, and cost-benefit optimization remained to be addressed. Finally, future research directions were proposed, focusing on the rational design of multifunctional composite membranes integrating antifouling properties, corrosion resistance, and low cost; the elucidation of interfacial reaction mechanisms through coupling with intensified fields such as high-gravity and electrocatalytic processes; the development of intelligent parameter regulation systems based on process modeling; and comprehensive techno-economic and environmental risk assessments at the pilot scale. These efforts will provide theoretical support and technical guidance for the engineering application of MCR-ozone processes.
Against the backdrop of increasingly severe global sustainability challenges, Bipolar Membrane Electrodialysis (BMED) technology is emerging as a pivotal solution driving transformation in the chemical, environmental, and resource management sectors. This technology not only demonstrates remarkable efficiency and economic benefits in critical areas such as resource extraction, pollution control, and CO₂ capture but also exhibits substantial potential for large-scale commercial implementation. This review systematically outlines the working principles and fabrication methods of bipolar membranes, along with their applications across various industrial fields, highlighting their significant capacity to advance greener and more efficient industrial processes. Representative case studies in resource recovery, pollution mitigation, and CO₂ capture are presented to illustrate the promising industrial prospects of BMED and validate its practical value in enabling sustainable resource utilization and environmental protection.
This study reconceptualized partial nitrification from a microbial ecological perspective by elucidating the dynamic competition between AOB and NOB across the initiation, maintenance, and destabilization phases. Continuous selection pressure was proposed as the core determinant of process stability within a community-process coupled framework. The review indicates that the initiation depends on non-steady-state disturbances that amplify AOB growth advantages, whereas the maintenance phase is characterized by a metastable state with dynamic community structure but relatively stable function, where NOB persist at low abundance or under spatial constraint. When cumulative disturbances weaken AOB competitiveness, NOB can rapidly rebound, inducing a critical shift from partial to complete nitrification. Accordingly, operational strategies centered on resource supply, niche constraint, and community feedback are outlined, emphasizing window-period management to enhance system resilience. The alignment of time-resolved community data with key operational parameters is further discussed as a basis for identifying instability thresholds and early-warning signals to support predictive control and risk management in partial nitrification processes.
Nitrogenous pollutant discharges are rising with urbanization and industrialization, and their untreated release worsens aquatic nitrogen pollution. Currently, nitrogen removal from municipal and industrial wastewater is transitioning from an energy-intensive model to strategies emphasizing pollution reduction, carbon mitigation, and synergistic efficiency. Green and sustainable nitrogen removal technologies represent a key research frontier in water pollution control. This review systematically examined nitrogen pollution in China's wastewater, characterized nitrogen-laden industrial effluents, and highlighted challenges such as wide concentration ranges, complex compositions, and treatment recalcitrance. Based on this analysis, this paper comprehensively reviewed the principles and applications of advanced nitrogen removal technologies, including physicochemical, biological, electrochemical/bioelectrochemical, and advanced oxidation processes. Their treatment efficiency, advantages, and limitations were analyzed, with special emphasis on the application of advanced oxidation processes for refractory nitrogenous pollutants. Future efforts should prioritize adopting low-energy, low-chemical-consumption biological nitrogen removal processes, integrate electrochemical and advanced oxidation processes with conventional methods, enhance overall treatment efficiency, and reduce costs. These advancements are pivotal for achieving China's Dual Carbon Goals and advancing sustainable development.
This study proposed a hybrid Long Short-Term Memory (LSTM)-Transformer model integrated with wavelet denoising for water quality prediction. Using hourly monitoring data (water temperature, turbidity, pH, conductivity, and dissolved oxygen) collected from two municipally controlled river cross-sections in South China from 2021 to 2024, the discrete wavelet transform was first applied for noise reduction. Subsequently, a predictive model combining LSTM and Transformer architectures was constructed. Experimental results demonstrated that the proposed model achieved outstanding performance in predicting dissolved oxygen (DO) concentrations for the next four hours at both sites (Site 1: coefficient of determination (R²)=0.8015, mean absolute error (MAE)=0.5169 mg/L, root mean square error (RMSE)=0.8494 mg/L; Site 2: R²=0.8873, MAE=0.4456 mg/L, RMSE=0.7143 mg/L), significantly outperforming standalone LSTM and Transformer models (the R² of the proposed model increased by 5.7%, while MAE and RMSE decreased by 20.2% and 10.4%, respectively).Furthermore, the SHAP interpretability method was employed for feature importance analysis and global impact interpretation, revealing that the key water quality factors influencing DO and their complex nonlinear relationships exhibited significant site-specific heterogeneity. This underscores the necessity of incorporating specific environmental contexts (e.g., geographical features, hydrological conditions, and pollution source distribution) for mechanistic interpretation. The findings of this study provide an effective and interpretable technical reference for high-precision real-time prediction and intelligent management of regional river water quality.
As global plastic production continues to rise, the quantity of plastic waste has also increased dramatically. Effectively addressing plastic pollution while achieving the resource recovery and recycling of plastic waste has become a global challenge. Compared with conventional recycling methods, the photothermal catalysis process, which integrates photocatalysis and thermocatalysis, offers significant advantages such as high conversion efficiency and mild reaction conditions. Herein, this review outlines the research progress of photothermal catalysis technology in the treatment and resource recovery of plastic waste. It first elaborates on the mechanism of photothermal conversion, including plasmonic localized heating, non-radiative relaxation of semiconductors, and molecular thermal vibration. Based on the roles of light and heat in photothermal catalytic reactions, photothermal catalysis is classified into three categories: thermal-assisted photocatalysis, photo-driven thermocatalysis, and photo-thermal co-catalysis. The type of catalytic material plays a crucial role in regulating catalytic performance during the photothermal catalytic conversion of plastics. This review summarizes the catalytic properties of three typical photothermal catalytic materials: plasmonic metal nanoparticles, metal oxide semiconductors, and carbon-based materials, providing material design directions for efficient plastic upcycling. Furthermore, starting with the upcycling mechanisms of two representative plastics, polyethylene and polyester, the review summarizes the reaction pathways for plastic upcycling to produce liquid fuels and organic acids. Finally, based on the current research status, this review also highlights the technical challenges of using photothermal catalysis for plastic upcycling. This review aims to provide technical support for the chemical recycling of plastic waste and offer new perspectives for its upcycling.
Denitrification is a critical process for advanced nitrogen removal in wastewater treatment, fundamentally governed by microbially driven electron transfer and electron allocation. As research has shifted from macroscopic treatment metrics toward microscopic regulation, elucidating denitrification mechanisms from an electron-flow perspective has emerged as a major research frontier. This review systematically summarized the theoretical framework of electron flow in denitrification systems, compared intracellular electron transport pathways and energy allocation characteristics between heterotrophic and autotrophic denitrifiers, and highlighted the central role of the quinone pool in electron collection and redistribution. Furthermore, from the perspective of interspecies microbial interactions, recent advances in indirect interspecies electron transfer (IIET) and direct interspecies electron transfer (DIET) were summarized, and competitive as well as cooperative interactions among microorganisms in mixed systems during electron donor and electron acceptor utilization were analyzed. Building on this framework, the impacts of carbon source characteristics, pH, oxidation-reduction potential (ORP), and coexisting contaminants on electron transport chains and electron allocation pathways were further discussed. Finally, in light of current limitations in the in situ quantification of electron fluxes, future research directions were proposed, including the development of multi-scale in situ characterization techniques, novel electron-conductive materials, and intelligent electron-flow regulation models.
Per- and polyfluoroalkyl substances (PFASs) are frequently detected at elevated concentrations in water bodies of the lower Yangtze River, posing risks to drinking water safety and human health. This study investigated the occurrence of 23 typical PFASs in source water, treated water, and tap water from eight drinking water treatment plants (DWTPs) in the lower reaches of the Yangtze River. The removal efficiency of PFASs by the treatment processes and their priority for control were also assessed. The results revealed the presence of 19 PFASs across the eight DWTPs, with total concentrations ranging from 32.02 to 167.68 ng/L and an average of 85.86 ng/L. Among these, 14 long-chain and 5 short-chain PFASs were identified, contributing 35.7% and 64.3% to the total concentration, respectively, indicating that short-chain PFASs were the predominant pollutants. The major contaminant monomers were perfluorooctanoic acid (PFOA), perfluorobutanoic acid (PFBA), perfluorobutanesulfonic acid (PFBS), and perfluorohexanoic acid (PFHxA). The overall removal efficiency of PFASs by the drinking water treatment processes was 17.8%, with a removal efficiency of 22.2% for long-chain and 15.1% for short-chain congeners. Notably, concentrations of 14 PFASs increased during distribution from the treatment plant to the tap, resulting in an overall rebound rate of 39.6%. PFBA, PFOA, and PFBS were the primary contributors, accounting for over 92.8% of this concentration increase. Modeling assessment identified PFOA, perfluorononanoic acid (PFNA), perfluorododecanoic acid (PFDoA), and perfluorooctanesulfonic acid (PFOS) as priority PFASs requiring enhanced monitoring and control measures.
The widespread use of tetracycline has resulted in elevated antibiotic concentrations in natural water bodies, posing significant threats to aquatic ecosystems and public health. Although iron-manganese modified biochar (IMBC) can effectively remove tetracycline, its powdered form is prone to leaching during application, leading to reduced utilization efficiency and potential system clogging. In this study, foam concrete (FC) was employed as an immobilization matrix to fabricate a novel iron-manganese modified biochar foam concrete (IMBC-FC) composite. The results showed that sufficient hydration reactions occurred during the immobilization process, endowing IMBC-FC with a highly porous structure that effectively avoided the masking of active sites on IMBC. The tetracycline removal efficiency of IMBC-FC reached 87.7%, and the impact of immobilization on the removal performance of IMBC was less than 10%. Removal pathway analysis indicated that oxidative degradation contributed approximately 56.9% to tetracycline removal, and singlet oxygen (¹O₂) was identified as the dominant reactive oxygen species (ROS) in the system. Functional groups such as hydroxyl (—OH) and carboxyl (—COO⁻) generated during hydration likely participated in both ROS generation and electron transfer, thus synergistically facilitating the degradation process. Furthermore, a comprehensive evaluation of the engineering application performance of IMBC-FC was carried out in accordance with relevant standards for water treatment filter media and constructed wetland substrates. The results demonstrated that IMBC-FC exhibits excellent advantages in porosity, mechanical strength, and tetracycline removal efficiency, indicating its promising engineering application prospects. This study is expected to provide a reliable technical pathway and theoretical support for the efficient immobilization of metal-modified biochar.
In the context of global carbon neutrality goals and energy transformation,it is urgent to develop new technologies that efficiently convert CO2 into renewable energy carriers such as CH4. Microbial electrolysis cells (MECs), which couple electrochemistry with microbial metabolism for CO₂ conversion, exhibit performance that is heavily dependent on the electron transfer capabilities and biocompatibility of the cathode.Therefore,Nafion was employed to load nanoscale Fe3O4 and carboxylated multi-walled carbon nanotubes onto nickel foam (NF). The electrochemical performance of the modified NF was characterized using techniques such as electrochemical impedance spectroscopy (EIS),cyclic voltammetry (CV),and linear sweep voltammetry (LSV). The results indicated that the modified NF exhibited lower internal resistance,a larger electrochemical active surface area,and enhanced hydrogen evolution capabilities.Ultimately,this modified cathode was employed in a constant current dual-chamber anaerobic methanogenic MECs for the electrochemical reduction of CO2 to CH4.The results demonstrated that under a constant current of -0.1 A,the CH4 concentration of the nanoscale Fe3O4 and carboxylated multi-walled carbon nanotube-modified NF group could reach 90%,surpassing the 80% CH4 concentration of the NF group. Moreover,the daily CH4 production of the modified group was 295 mL,higher than the 260 mL daily methane production of the NF group,reflecting an increase of 13%. It was found that the modified NF exhibited higher hydrogen production and lower internal resistance, creating a more favorable environment for the growth and enrichment of hydrogenotrophic methanogens, thereby facilitating the electrochemical reduction of CO2 to CH4. Subsequent microbial community analysis also indicated that the relative abundance of the hydrogenotrophic methanogen Methanobacterium in the reactor with the modified NF was higher than that in the NF group,further facilitating the process of H2 serving as an electron donor for CO2 reduction to CH4. This research provides new ideas and experimental evidence for the development of novel non-precious metal composite cathode materials in bioelectrochemical systems.