摘要：
The residual sludge generated from steel wastewater treatment is abundant in iron resource and its recycling has attracted widespread attention. In this study, a novel iron-rich biochar (FSB) with acceptable environmental risk was developed by one-step pyrolysis using steel sludge as raw material, and its adsorption-reduction efficiency and column experiments for hexavalent chromium [Cr(VI)] were determined. The results showed that pyrolysis can effectively reduce the potential environmental risk of iron-rich sludge and effectively enrich iron resources in the biochar matrix. The heavy metal accumulation pattern, potential environmental risk and Cr(VI) adsorption-reduction performance of FSB were affected by pyrolysis temperature, and the optimal performance was achieved at a pyrolysis temperature of 500℃, and the maximum adsorption capacity of FSB pyrolyzed at 500℃ (FSB500) could be as high as 200 mg g −1 . The apparent model fitting showed that Cr(VI) removal by FSB500 was an adsorption-reduction-adsorption process as follows: (i) Cr(VI) was attracted onto FSB500 by electrostatic force; (ii) the oxygen-containing functional groups, persistent free radicals, and endogenous iron on the FSB500 surface acted as the electron donors to convert Cr(VI) to Cr(III); (iii) the released Cr(III) complexed on the FSB500 surface again. In the column experiment, FSB500 showed a high removal capacity of 55.94 mg g −1 under specific conditions. Thus, this study suggests that iron-rich sludge can be prepared into biochar for resource utilization and can be used as an effective alternative for Cr(VI) wastewater treatment.
The residual sludge generated from steel wastewater treatment is abundant in iron resource and its recycling has attracted widespread attention. In this study, a novel iron-rich biochar (FSB) with acceptable environmental risk was developed by one-step pyrolysis using steel sludge as raw material, and its adsorption-reduction efficiency and column experiments for hexavalent chromium [Cr(VI)] were determined. The results showed that pyrolysis can effectively reduce the potential environmental risk of iron-rich sludge and effectively enrich iron resources in the biochar matrix. The heavy metal accumulation pattern, potential environmental risk and Cr(VI) adsorption-reduction performance of FSB were affected by pyrolysis temperature, and the optimal performance was achieved at a pyrolysis temperature of 500℃, and the maximum adsorption capacity of FSB pyrolyzed at 500℃ (FSB500) could be as high as 200 mg g −1 . The apparent model fitting showed that Cr(VI) removal by FSB500 was an adsorption-reduction-adsorption process as follows: (i) Cr(VI) was attracted onto FSB500 by electrostatic force; (ii) the oxygen-containing functional groups, persistent free radicals, and endogenous iron on the FSB500 surface acted as the electron donors to convert Cr(VI) to Cr(III); (iii) the released Cr(III) complexed on the FSB500 surface again. In the column experiment, FSB500 showed a high removal capacity of 55.94 mg g −1 under specific conditions. Thus, this study suggests that iron-rich sludge can be prepared into biochar for resource utilization and can be used as an effective alternative for Cr(VI) wastewater treatment.
作者机构：
[Wu, Zhiyuan; Meng, Wenkang; Meng, WK] Changsha Univ Sci & Technol, Sch Hydraul & Ocean Engn, Changsha 410114, Peoples R China.;[Wu, Zhiyuan; Meng, Wenkang; Meng, WK] Key Lab Dongting Lake Aquat Ecoenvironm Control &, Changsha 410114, Peoples R China.;[Wu, Zhiyuan; Meng, Wenkang; Meng, WK] Key Lab Water Sediment Sci & Water Disaster Preven, Changsha 410114, Peoples R China.;[Li, Jia; Yu, Ching-hao; An, RD; Meng, Wenkang; An, Ruidong; Meng, WK] Sichuan Univ, Coll Water Resource & Hydropower, State Key Lab Hydraul & Mt River Engn, Chengdu 610065, Peoples R China.
通讯机构：
[An, RD ; Meng, WK] S;[Meng, WK ] C;Changsha Univ Sci & Technol, Sch Hydraul & Ocean Engn, Changsha 410114, Peoples R China.;Key Lab Dongting Lake Aquat Ecoenvironm Control &, Changsha 410114, Peoples R China.;Key Lab Water Sediment Sci & Water Disaster Preven, Changsha 410114, Peoples R China.
关键词：
Two-phase flow;Level set;Volume of fluid;WENO;Finite volume method
摘要：
The modeling of interfacial two-phase flows involves various fields such as hydraulic engineering, marine engineering, chemical industry, etc., whose difficulty lies in the accurate simulation of the two-phase flow interface. This paper presents a VOF(volume of fluid)-based LS (level set) method with WENO (weighted essentially non-oscillatory) scheme in the finite volume method. The proposed method initializes the LS function by transforming the VOF function, which does not have the characteristics of the distance function yet. Therefore, the next step is to re-distance the transformed LS function by solving the re-initialization equation. For solving the re-initialization equation, the WENO scheme in the finite volume method is employed, providing fifth-order accuracy for the convection term. To validate the proposed VOF-based LS method combined with the WENO scheme, five test cases are presented, including Zalesak's disk, vortex deformation, Rayleigh-Taylor instability, two-dimensional bubble rise, and dam break flow. The numerical results from these interfacial two-phase flow cases demonstrate that the VOF-based LS method with the WENO scheme in the finite volume method can achieve accurate capture of the interface while maintaining excellent mass conservation characteristics.
The modeling of interfacial two-phase flows involves various fields such as hydraulic engineering, marine engineering, chemical industry, etc., whose difficulty lies in the accurate simulation of the two-phase flow interface. This paper presents a VOF(volume of fluid)-based LS (level set) method with WENO (weighted essentially non-oscillatory) scheme in the finite volume method. The proposed method initializes the LS function by transforming the VOF function, which does not have the characteristics of the distance function yet. Therefore, the next step is to re-distance the transformed LS function by solving the re-initialization equation. For solving the re-initialization equation, the WENO scheme in the finite volume method is employed, providing fifth-order accuracy for the convection term. To validate the proposed VOF-based LS method combined with the WENO scheme, five test cases are presented, including Zalesak's disk, vortex deformation, Rayleigh-Taylor instability, two-dimensional bubble rise, and dam break flow. The numerical results from these interfacial two-phase flow cases demonstrate that the VOF-based LS method with the WENO scheme in the finite volume method can achieve accurate capture of the interface while maintaining excellent mass conservation characteristics.
作者机构：
[Risen Yang; Sha Wu; Yangkai Liu; Le Luo; Hong Chen] Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province, School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha 410004, China;[Yanxiao Wei] RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan;[Jianhong Jiang; Qingchang Tang] China Machinery International Engineering Design & Research Institute Co., Ltd., Changsha 410007, China;[Xinying Kong] School of Chemistry and Chemical Engineering, University of South China, Hengyang, Hunan 421001, China;[Elsayed Ali EA] Agricultural Engineering Research Institute (AEnRI), Agricultural Research Center (ARC), Dokki, Giza 256, Egypt
通讯机构：
[Hong Chen] K;Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province, School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha 410004, China
摘要：
To explore the adaptive mechanisms of the partial nitritation-anammox (PNA) process under high salinity stress during kitchen wastewater treatment, focusing on their physiological and molecular responses through metagenomic analysis. An airlift inner-circulation partition bioreactor (AIPBR) was developed, featuring an inner cylinder and a flow guide tube to create distinct oxygen gradients, facilitating the study of microbial adaptation under varying salt conditions. The AIPBR was operated with synthetic wastewater containing ammonium concentrations of 1800 ± 100 mg/L and salinity gradients ranging from 1 to 10 g/L, followed by a fixed salinity period at 6 g/L, with ammonium concentrations approximately 850 mg/L. High-throughput metagenomic analysis revealed shifts in functional genes and metabolic pathways in response to salinity stress. Anammox bacteria adapted by enriching genes involved in the synthesis of osmoprotective compounds and activating energy-producing pathways like the TCA cycle. These adaptations, along with modifications in membrane composition, were essential for sustaining system stability under elevated salinity. Under prolonged high salinity stress, anaerobic ammonium oxidizing (AnAOB) exhibited improved salt tolerance, maintaining a total nitrogen removal efficiency above 85 % and stabilizing after an adaptation phase. The metagenomic data revealed a marked enrichment of genes associated with ion transport, stress response mechanisms, and DNA repair pathways. Changes in microbial community composition favored salt-tolerant species, supporting system stability. These findings highlight the applicability of the developed bioreactor for scaling up the PNA process to handle high-salinity wastewater, providing a promising avenue for sustainable nitrogen removal in challenging environments.
To explore the adaptive mechanisms of the partial nitritation-anammox (PNA) process under high salinity stress during kitchen wastewater treatment, focusing on their physiological and molecular responses through metagenomic analysis. An airlift inner-circulation partition bioreactor (AIPBR) was developed, featuring an inner cylinder and a flow guide tube to create distinct oxygen gradients, facilitating the study of microbial adaptation under varying salt conditions. The AIPBR was operated with synthetic wastewater containing ammonium concentrations of 1800 ± 100 mg/L and salinity gradients ranging from 1 to 10 g/L, followed by a fixed salinity period at 6 g/L, with ammonium concentrations approximately 850 mg/L. High-throughput metagenomic analysis revealed shifts in functional genes and metabolic pathways in response to salinity stress. Anammox bacteria adapted by enriching genes involved in the synthesis of osmoprotective compounds and activating energy-producing pathways like the TCA cycle. These adaptations, along with modifications in membrane composition, were essential for sustaining system stability under elevated salinity. Under prolonged high salinity stress, anaerobic ammonium oxidizing (AnAOB) exhibited improved salt tolerance, maintaining a total nitrogen removal efficiency above 85 % and stabilizing after an adaptation phase. The metagenomic data revealed a marked enrichment of genes associated with ion transport, stress response mechanisms, and DNA repair pathways. Changes in microbial community composition favored salt-tolerant species, supporting system stability. These findings highlight the applicability of the developed bioreactor for scaling up the PNA process to handle high-salinity wastewater, providing a promising avenue for sustainable nitrogen removal in challenging environments.
摘要：
Understanding the antiseepage and reinforcement mechanisms for pulse grouting remains inadequate at present compared with its engineering applications. To improve the theoretical framework of pulse grouting, a permeation diffusion model based on a Bingham fluid is developed, which incorporates the tortuosity of the slurry diffusion path and spatiotemporal variations in viscosity. The validity of the model is verified through a comparison of the theoretical predictions with the experimental results. The impacts of spatiotemporal viscosity variations and tortuosity on the slurry diffusion mechanism are evaluated via theoretical analysis. The permeation diffusion characteristics of pulse grouting and conventional methods are comparatively simulated and analysed via the COMSOL Multiphysics platform for secondary development. The results show that (i) the maximum relative discrepancy between the theoretical predictions and experimental measurements is less than 30 %, which can be further reduced to under 10 % with increasing grouting pressure, indicating that the theoretical model can offer valuable guidance for the design and implementation of pulse grouting projects. (ii) The spatiotemporal variations in slurry viscosity and the tortuosity of the diffusion path significantly affect permeation diffusion, which intensifies as the grouting pressure and duration increase. The theoretical diffusion distances without considering these two factors are 1.36 ∼ 1.74 times and 1.1 ∼ 1.32 times greater than the experimental results, respectively. (iii) The diffusion morphology of pulse grouting demonstrates a reduced range and a more uniform front under identical conditions, indicating that pulse grouting has significant advantages in the ability to control slurry diffusion compared with conventional methods.
Understanding the antiseepage and reinforcement mechanisms for pulse grouting remains inadequate at present compared with its engineering applications. To improve the theoretical framework of pulse grouting, a permeation diffusion model based on a Bingham fluid is developed, which incorporates the tortuosity of the slurry diffusion path and spatiotemporal variations in viscosity. The validity of the model is verified through a comparison of the theoretical predictions with the experimental results. The impacts of spatiotemporal viscosity variations and tortuosity on the slurry diffusion mechanism are evaluated via theoretical analysis. The permeation diffusion characteristics of pulse grouting and conventional methods are comparatively simulated and analysed via the COMSOL Multiphysics platform for secondary development. The results show that (i) the maximum relative discrepancy between the theoretical predictions and experimental measurements is less than 30 %, which can be further reduced to under 10 % with increasing grouting pressure, indicating that the theoretical model can offer valuable guidance for the design and implementation of pulse grouting projects. (ii) The spatiotemporal variations in slurry viscosity and the tortuosity of the diffusion path significantly affect permeation diffusion, which intensifies as the grouting pressure and duration increase. The theoretical diffusion distances without considering these two factors are 1.36 ∼ 1.74 times and 1.1 ∼ 1.32 times greater than the experimental results, respectively. (iii) The diffusion morphology of pulse grouting demonstrates a reduced range and a more uniform front under identical conditions, indicating that pulse grouting has significant advantages in the ability to control slurry diffusion compared with conventional methods.
摘要：
In the single-stage partial nitritation-anammox process for high-ammonium wastewater treatment, the presence of sufficient biomass with high activity is essential. This study developed an innovative airlift inner-circulation partition bioreactor (AIPBR) with a dual-cylinder structure. During the 362 days’ operation, the AIPBR exhibited robust and stable nitrogen removal performance under diverse influent ammonium spanning from 300 to 1800 mg N/L. Notably, when the influent ammonium was 1820 ± 34 mg N/L, the nitrogen removal rate reached 3.194 ± 0.074 kg N/m³/d, accompanied by removal efficiency of 87.6 ± 1.5%. The unique design of the reactor enabled the formation of dissolved oxygen gradient, which improved the synergy of functional microorganisms by facilitating mass transfer within the sludge. Additionally, it maintained appropriate hydraulic shear in the inner cylinder to support granule formation and simultaneously reduced excessive flow in the outer cylinder to prevent sludge loss. Through the cyclic granulation, the system fostered a symbiotic consortium of flocculent and granular sludge with particle size predominantly distributed within the range of 200–400 μm, which enhanced the activity of microorganisms. These findings highlight the potential of AIPBR as a novel and effective strategy for high-ammonium wastewater treatment.
In the single-stage partial nitritation-anammox process for high-ammonium wastewater treatment, the presence of sufficient biomass with high activity is essential. This study developed an innovative airlift inner-circulation partition bioreactor (AIPBR) with a dual-cylinder structure. During the 362 days’ operation, the AIPBR exhibited robust and stable nitrogen removal performance under diverse influent ammonium spanning from 300 to 1800 mg N/L. Notably, when the influent ammonium was 1820 ± 34 mg N/L, the nitrogen removal rate reached 3.194 ± 0.074 kg N/m³/d, accompanied by removal efficiency of 87.6 ± 1.5%. The unique design of the reactor enabled the formation of dissolved oxygen gradient, which improved the synergy of functional microorganisms by facilitating mass transfer within the sludge. Additionally, it maintained appropriate hydraulic shear in the inner cylinder to support granule formation and simultaneously reduced excessive flow in the outer cylinder to prevent sludge loss. Through the cyclic granulation, the system fostered a symbiotic consortium of flocculent and granular sludge with particle size predominantly distributed within the range of 200–400 μm, which enhanced the activity of microorganisms. These findings highlight the potential of AIPBR as a novel and effective strategy for high-ammonium wastewater treatment.
摘要：
While carbonate sediment transport processes over coral reefs have been extensively investigated in the past decade，very few studies have focused on the morphodynamic response of sandy reef flats to wave action. In this study, a set of innovative wave-flume laboratory experiments was conducted for the first time to investigate the evolution of reef flat based on a barrier reef profile. Various monochromatic wave conditions (incident wave height, incident wave period and initial reef-flat water level) and sediment layer thicknesses were tested. A sand layer was paved on the reef flat to simulate a moveable bed and the reef surface roughness was replicated using an array of cylinders. Subsequently, a phase-resolving non-hydrostatic model (XBeach-NH) was adopted to simulate both the hydrodynamic and morphodynamic processes in the reef environment. A vegetation module was incorporated into Xbeach-NH to represent the rough reef surface. The adopted model was validated against the laboratory dataset for the first time as reported in this study. It was then used to examine the impacts of varying fore-reef slopes, sediment grain sizes and reef surface roughness on the morphodynamic response of sandy reef flats to monochromatic wave action. Model outputs suggested that projected sea-level rise, reduced reef surface roughness and increased storminess due to climate change have profound impacts on the morphodynamic processes on the reef flat thus may eventually contribute the geomorphological sustainability of reef islands.
While carbonate sediment transport processes over coral reefs have been extensively investigated in the past decade，very few studies have focused on the morphodynamic response of sandy reef flats to wave action. In this study, a set of innovative wave-flume laboratory experiments was conducted for the first time to investigate the evolution of reef flat based on a barrier reef profile. Various monochromatic wave conditions (incident wave height, incident wave period and initial reef-flat water level) and sediment layer thicknesses were tested. A sand layer was paved on the reef flat to simulate a moveable bed and the reef surface roughness was replicated using an array of cylinders. Subsequently, a phase-resolving non-hydrostatic model (XBeach-NH) was adopted to simulate both the hydrodynamic and morphodynamic processes in the reef environment. A vegetation module was incorporated into Xbeach-NH to represent the rough reef surface. The adopted model was validated against the laboratory dataset for the first time as reported in this study. It was then used to examine the impacts of varying fore-reef slopes, sediment grain sizes and reef surface roughness on the morphodynamic response of sandy reef flats to monochromatic wave action. Model outputs suggested that projected sea-level rise, reduced reef surface roughness and increased storminess due to climate change have profound impacts on the morphodynamic processes on the reef flat thus may eventually contribute the geomorphological sustainability of reef islands.
摘要：
Geopolymer concrete is a potential partial substitute for Portland cement (PC) concrete in civil engineering. Understanding chloride-binding behavior and mechanisms in geopolymers is essential for evaluating durability of geopolymer concrete in chloride-rich environments. This study investigated the chloride-binding behavior of metakaolin (MK) geopolymers by examining the influence of chloride ion concentrations, alkali activator concentrations, and pore solution pH levels on their chloride-binding capacities. The correlation between the bound chloride ion content and the geopolymerization degree of MK was analyzed. The experimental results indicated that the binding of MK geopolymer to chloride ions is physical adsorption under the competition of hydroxide ions. Thus when the pH of pore solution decreases from 11.69 to 10.55, the amount of bound chloride increases by 1.95 times. The chloride-binding capacity of the MK geopolymer was primarily determined by the N-A-S-H gel content and the pH of pore solution. Under the same pH levels and chloride ion concentration, the chloride ion content bound per unit N-A-S-H gel remained constant, independent of N-A-S-H gel content. Based on these findings, a new method was proposed to evaluate the geopolymerization degree of MK by mearsuring the chloride-binding capacity of the N-A-S-H gel. The proposed method shows a small margin of error (<5 %) compared to selective acid dissolution analysis, providing valuable insights for research into geopolymer precursor reactions.
Geopolymer concrete is a potential partial substitute for Portland cement (PC) concrete in civil engineering. Understanding chloride-binding behavior and mechanisms in geopolymers is essential for evaluating durability of geopolymer concrete in chloride-rich environments. This study investigated the chloride-binding behavior of metakaolin (MK) geopolymers by examining the influence of chloride ion concentrations, alkali activator concentrations, and pore solution pH levels on their chloride-binding capacities. The correlation between the bound chloride ion content and the geopolymerization degree of MK was analyzed. The experimental results indicated that the binding of MK geopolymer to chloride ions is physical adsorption under the competition of hydroxide ions. Thus when the pH of pore solution decreases from 11.69 to 10.55, the amount of bound chloride increases by 1.95 times. The chloride-binding capacity of the MK geopolymer was primarily determined by the N-A-S-H gel content and the pH of pore solution. Under the same pH levels and chloride ion concentration, the chloride ion content bound per unit N-A-S-H gel remained constant, independent of N-A-S-H gel content. Based on these findings, a new method was proposed to evaluate the geopolymerization degree of MK by mearsuring the chloride-binding capacity of the N-A-S-H gel. The proposed method shows a small margin of error (<5 %) compared to selective acid dissolution analysis, providing valuable insights for research into geopolymer precursor reactions.
作者：
Yang, Shuanglin;Deng, Yiyi;Jiang, Jingyi;Kong, Zhe;Ali, Elsayed A. E.;...
期刊：
Journal of Water Process Engineering,2025年71:107201 ISSN：2214-7144
通讯作者：
Chen, H
作者机构：
[Xu, Ronghua; Chen, Hong; Chen, H; Deng, Yiyi; Yang, Shuanglin; Jiang, Jingyi] Changsha Univ Sci & Technol, Sch Hydraul & Environm Engn, Key Lab Water Sediment Sci & Water Disaster Preven, Changsha 410114, Peoples R China.;[Kong, Zhe] Suzhou Univ Sci & Technol, Sch Environm Sci & Engn, Suzhou Natl Joint Lab Green & Low Carbon Wastewate, Suzhou 215009, Peoples R China.;[Ali, Elsayed A. E.] Agr Engn Res Inst AEnRI, Agr Res Ctr ARC, POB 256, Giza, Egypt.;[Deng, Zhengyu] China Machinery Int Engn Design & Res Inst Co Ltd, Changsha 410007, Peoples R China.;[Jiang, Wang] Hunan Prov Architectural Design Inst Grp Co Ltd, Changsha 410208, Peoples R China.
通讯机构：
[Chen, H ] C;Changsha Univ Sci & Technol, Sch Hydraul & Environm Engn, Key Lab Water Sediment Sci & Water Disaster Preven, Changsha 410114, Peoples R China.
关键词：
Sponge cities;Runoff pollution;Bioretention facilities;Soil environmental factors;Microbial community structure
摘要：
To investigate the long-term removal mechanisms of field-scale bioretention facilities using different media for roof runoff treatment, volcanic rock-based (VBF) and zeolite-based bioretention facilities (ZBF) were constructed, and their pollutant removal, soil characteristics, and microbial community dynamics were monitored. It was shown that VBF exhibited higher removal rates for chemical oxygen demand (COD, 84.9 %), ammonia nitrogen (NH 4 + –N, 82.3 %), and total phosphorus (TP, 65.6 %), which can be ascribed to the larger specific surface area and higher iron‑aluminum oxide contents of volcanic rocks. In contrast, ZBF demonstrated superior NO 3 − –N removal efficiency (60.3 %). However, the accumulation of total organic carbon, NH 4 + –N, NO 3 − –N, and TP in VBF was 1.04–1.16 times higher than in ZBF, and redundancy analysis revealed that functional bacteria in VBF were more sensitive to the changes of soil environmental factors (e.g., pH, NH 4 + –N and TP). Furthermore, long-term pollutant inputs resulted in a higher abundance of bacteria involved in organic matter degradation and phosphate solubilization ( Gaiellales , A4b , Vicinamibacteraceae , etc.) in VBF, while ZBF contained a higher abundance of nitrifying and denitrifying bacteria ( Arthrobacter , Roseiflexaceae , KD4-96 , Hyphomicrobium , etc.). These microbial differences contributed to the varying pollutant removal performances between the two facilities, especially for NH 4 + -N and NO 3 − -N. This study provides valuable insights into the long-term pollution control performance and potential media modifications for assembled bioretention facilities.
To investigate the long-term removal mechanisms of field-scale bioretention facilities using different media for roof runoff treatment, volcanic rock-based (VBF) and zeolite-based bioretention facilities (ZBF) were constructed, and their pollutant removal, soil characteristics, and microbial community dynamics were monitored. It was shown that VBF exhibited higher removal rates for chemical oxygen demand (COD, 84.9 %), ammonia nitrogen (NH 4 + –N, 82.3 %), and total phosphorus (TP, 65.6 %), which can be ascribed to the larger specific surface area and higher iron‑aluminum oxide contents of volcanic rocks. In contrast, ZBF demonstrated superior NO 3 − –N removal efficiency (60.3 %). However, the accumulation of total organic carbon, NH 4 + –N, NO 3 − –N, and TP in VBF was 1.04–1.16 times higher than in ZBF, and redundancy analysis revealed that functional bacteria in VBF were more sensitive to the changes of soil environmental factors (e.g., pH, NH 4 + –N and TP). Furthermore, long-term pollutant inputs resulted in a higher abundance of bacteria involved in organic matter degradation and phosphate solubilization ( Gaiellales , A4b , Vicinamibacteraceae , etc.) in VBF, while ZBF contained a higher abundance of nitrifying and denitrifying bacteria ( Arthrobacter , Roseiflexaceae , KD4-96 , Hyphomicrobium , etc.). These microbial differences contributed to the varying pollutant removal performances between the two facilities, especially for NH 4 + -N and NO 3 − -N. This study provides valuable insights into the long-term pollution control performance and potential media modifications for assembled bioretention facilities.
摘要：
The stepped paddy fields (SPFs) are important for food security and sustainable development. The unique spatial structure and complex hydrological processes in this system make it difficult to understand the migration of pollutants. In this study, microplastic pollution was investigated in the water and soil from Ziquejie SPFs, China. Samples were taken according to different stages of rice cultivation, different altitudes, and soil depths. Before rice planting, the average abundance in the water and soil samples was 1.3 ± 1.1 items/L and 292.2 ± 260.8 items/kg, respectively. After rice harvesting, the average abundance in soil increased to 495.37 ± 175.46 items/kg. More microplastics were found in depths of 0–15 cm than that of 15–30 cm, but the difference was not significant. Major microplastics were small (<1 mm) polyethylene (PE) and polypropylene (PP) fibers, with the main color of blue and transparent. The study found that SPFs hindered the migration of microplastics in irrigation water and hydraulic conditions affected the accumulation of microplastics. The edge areas in paddy fields where the water flowed slowly and were prone to vortices made it easier for microplastics to stay. Most of the microplastics accumulated in the upper SPF. After rice harvesting, the overall abundance of microplastics in the SPFs increased. Fibers and fragments exhibited different characteristics in migration. This study attempts to draw attention to the ecological risks caused by microplastic pollution in SPFs, especially in the upper paddy field and the effluent. The results are helpful for the protection of the SPF ecosystem and provide valuable references for future research.
The stepped paddy fields (SPFs) are important for food security and sustainable development. The unique spatial structure and complex hydrological processes in this system make it difficult to understand the migration of pollutants. In this study, microplastic pollution was investigated in the water and soil from Ziquejie SPFs, China. Samples were taken according to different stages of rice cultivation, different altitudes, and soil depths. Before rice planting, the average abundance in the water and soil samples was 1.3 ± 1.1 items/L and 292.2 ± 260.8 items/kg, respectively. After rice harvesting, the average abundance in soil increased to 495.37 ± 175.46 items/kg. More microplastics were found in depths of 0–15 cm than that of 15–30 cm, but the difference was not significant. Major microplastics were small (<1 mm) polyethylene (PE) and polypropylene (PP) fibers, with the main color of blue and transparent. The study found that SPFs hindered the migration of microplastics in irrigation water and hydraulic conditions affected the accumulation of microplastics. The edge areas in paddy fields where the water flowed slowly and were prone to vortices made it easier for microplastics to stay. Most of the microplastics accumulated in the upper SPF. After rice harvesting, the overall abundance of microplastics in the SPFs increased. Fibers and fragments exhibited different characteristics in migration. This study attempts to draw attention to the ecological risks caused by microplastic pollution in SPFs, especially in the upper paddy field and the effluent. The results are helpful for the protection of the SPF ecosystem and provide valuable references for future research.
摘要：
High-performance fiber-reinforced concrete (HPFRC) offers exceptional strength, ductility, and durability, making it highly promising for electric power pipe jacking applications. However, limited research exists on the mechanical properties of HPFRC pipes, especially regarding reinforcement schemes. This study bridges this gap by using a combination of three-point testing, analytical calculations, and numerical simulations to investigate the mechanical behavior and performance of HPFRC pipes under various reinforcement configurations. The results show that the load–displacement curve of HPFRC pipes initially follows a linear elastic relationship, but as the load exceeds 200 kN/m, displacement increases and cracks form, with failure occurring at 410 kN/m. HPFRC pipes demonstrate significantly enhanced load-bearing and crack resistance capabilities, with reduced reinforcement and wall thickness compared to traditional materials, maintaining high load-bearing capacity even after damage. The three analysis methods generally align in terms of load-bearing and failure processes, though the analytical method reveals limitations in accurately predicting crack widths. The study also reveals that reinforcement schemes significantly affect the pipes’ structural performance, with double layer and inner layer reinforcement providing superior damage resistance. This study contributes new insights into HPFRC pipe performance and provides a basis for optimizing reinforcement designs in pipe jacking projects.
作者机构：
[Chen, Long; Yao, Yu; Sun, Zhenkai; Wang, Hao] Changsha Univ Sci & Technol, Sch Hydraul & Ocean Engn, Changsha 410114, Hunan, Peoples R China.;[Yao, Yu; Chen, Long] Key Lab Water Sediment Sci & Water Disaster Preven, Changsha 410114, Hunan, Peoples R China.;[Chen, Long] Res Inst Innovat Dev Transportat & Energy Integrat, Changsha 410114, Hunan, Peoples R China.;[Chin, Ren-Jie] Univ Tunku Abdul Rahman, Lee Kong Chian Fac Engn & Sci, Dept Civil Engn, Kajang 43000, Malaysia.
通讯机构：
[Chen, L ] C;Changsha Univ Sci & Technol, Sch Hydraul & Ocean Engn, Changsha 410114, Hunan, Peoples R China.
关键词：
Power fluctuation;Tidal turbine fatigue;Seabed bathymetry;Blockage ratio;Wake flow
摘要：
The combination of waves, currents, and seabed bathymetry can result in large hydrodynamic loads that can lead to excessive loading, tidal turbine fatigue and power fluctuations. In this work, a 1:50 scaled tidal stream turbine model is utilized to further the fundamental understanding of tidal turbine behavior with present of seabed bathymetry. The influence of seabed bathymetry proximity on tidal turbines power and loading fluctuations are assessed in terms of spectral density. In the spectral domain of power coefficient, the presence of seabed bathymetry effectively reduces the energy cascade. For thrust coefficient, the frequency decay depicted peaks nearly at the harmonics along the rotor's rotational ( fr ). The coupled effects of seabed bathymetry and blockage ratio were also examined by a transient numerical analysis. The implication of blockage effects is not only to increase the hydrodynamic performance but also shifting the optimum performance TSR to a higher value. The presence of seabed bathymetry resulted in skewed wake flows and the seabed element obstruction is the primary mechanism for reduced performance at close proximity. The results of this study provide recommendations for turbine positioning and fatigue analysis in such flows.
The combination of waves, currents, and seabed bathymetry can result in large hydrodynamic loads that can lead to excessive loading, tidal turbine fatigue and power fluctuations. In this work, a 1:50 scaled tidal stream turbine model is utilized to further the fundamental understanding of tidal turbine behavior with present of seabed bathymetry. The influence of seabed bathymetry proximity on tidal turbines power and loading fluctuations are assessed in terms of spectral density. In the spectral domain of power coefficient, the presence of seabed bathymetry effectively reduces the energy cascade. For thrust coefficient, the frequency decay depicted peaks nearly at the harmonics along the rotor's rotational ( fr ). The coupled effects of seabed bathymetry and blockage ratio were also examined by a transient numerical analysis. The implication of blockage effects is not only to increase the hydrodynamic performance but also shifting the optimum performance TSR to a higher value. The presence of seabed bathymetry resulted in skewed wake flows and the seabed element obstruction is the primary mechanism for reduced performance at close proximity. The results of this study provide recommendations for turbine positioning and fatigue analysis in such flows.
期刊：
Journal of Hydrology,2025年:133497 ISSN：0022-1694
通讯作者：
Boyuan Zhu
作者机构：
School of Hydraulic and Ocean Engineering, Changsha University of Science & Technology, Changsha 410114, China;Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province, Changsha 410114, China;[Lingling Zhu] Hydrology Bureau of Changjiang Water Resources Commission, Wuhan 430010, China;[Lingfeng Liu] Design Institute of CCCC First Highway Engineering Group Water Engineering Co., Ltd., Changsha 410006, China;[Wenjun Yu] Changjiang Waterway Survey and Design Institute (Wuhan) Co., Ltd., Wuhan 430040, China
通讯机构：
[Boyuan Zhu] S;School of Hydraulic and Ocean Engineering, Changsha University of Science & Technology, Changsha 410114, China<&wdkj&>Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province, Changsha 410114, China
摘要：
Swings of ebb flow axes among branching channels alter the lateral hydrodynamics within bifurcating estuaries, causing the channels to undergo erosion–deposition transitions. This study examines the three-order bifurcation system of the Yangtze Estuary through integrated analysis of observed water–sediment and terrain data from 1950 to 2022 and simulations by a shallow flow model based on Delft 3D. The model is shown to perform well in hindcasting the flow behavior in the Yangtze Estuary and in identifying critical runoff discharges at which the ebb flow axis migrates between the north and south branching channels of each-order bifurcation under corresponding tidal ranges. These critical runoff discharges occur at mutation points where ebb partition ratios of the north/south branching channels increase/decrease abruptly with gradually increasing runoff. By applying linear regression to critical runoff discharges and corresponding tidal ranges at each bifurcation order, the value domain divides into two subareas corresponding to the position of the ebb flow axis in north and south branching channels. We find the multiyear average duration days of ebb-flow-axis location to be effective as an indicator of the mean and spread of erosion–deposition in the branching channels and detect the critical values at erosion–deposition transitions. Other influence factors, including peak river discharge, sediment flux, offshore dynamics, and local engineering projects, also impact on erosion–deposition in the branching channels. The ranked orders of critical runoff discharges and critical duration days among the three-order bifurcations are interpreted, and these critical indexes are linked to the water excavating force, indicating their reliability and effectiveness. Seasonal flattening of runoff discharge, controlled by large cascade reservoirs in the upper Yangtze, has greatly shortened and lengthened location duration of ebb flow axis in the north and south branching channels at each-order bifurcation, and is likely to maintain their respective deposition and erosion behaviors in the future.
Swings of ebb flow axes among branching channels alter the lateral hydrodynamics within bifurcating estuaries, causing the channels to undergo erosion–deposition transitions. This study examines the three-order bifurcation system of the Yangtze Estuary through integrated analysis of observed water–sediment and terrain data from 1950 to 2022 and simulations by a shallow flow model based on Delft 3D. The model is shown to perform well in hindcasting the flow behavior in the Yangtze Estuary and in identifying critical runoff discharges at which the ebb flow axis migrates between the north and south branching channels of each-order bifurcation under corresponding tidal ranges. These critical runoff discharges occur at mutation points where ebb partition ratios of the north/south branching channels increase/decrease abruptly with gradually increasing runoff. By applying linear regression to critical runoff discharges and corresponding tidal ranges at each bifurcation order, the value domain divides into two subareas corresponding to the position of the ebb flow axis in north and south branching channels. We find the multiyear average duration days of ebb-flow-axis location to be effective as an indicator of the mean and spread of erosion–deposition in the branching channels and detect the critical values at erosion–deposition transitions. Other influence factors, including peak river discharge, sediment flux, offshore dynamics, and local engineering projects, also impact on erosion–deposition in the branching channels. The ranked orders of critical runoff discharges and critical duration days among the three-order bifurcations are interpreted, and these critical indexes are linked to the water excavating force, indicating their reliability and effectiveness. Seasonal flattening of runoff discharge, controlled by large cascade reservoirs in the upper Yangtze, has greatly shortened and lengthened location duration of ebb flow axis in the north and south branching channels at each-order bifurcation, and is likely to maintain their respective deposition and erosion behaviors in the future.
摘要：
Predisintegrated carbonaceous mudstone (PCM) that exhibits low strength and continuous disintegration is prone to wetting deformation after repeated seasonal rainfall. A reasonable assessment of wetting deformation is required to facilitate the settlement control of the PCM embankment when exposed to repeated rainfall. Herein, to reveal the wetting deformation mechanism of the PCM subjected to drying-wetting cycles, the effects of drying-wetting cycles on the wetting deformation characteristics of the PCM are investigated using the double-line method. Microscopic pore characteristics of the PCM under different drying-wetting cycles were analyzed through scanning electron microscope (SEM) micrographs. Comparative analysis of the wetting deformation data between the tests and the constitutive model considering the damage of drying-wetting cycles was carried out. The results showed that the deviator stress-strain relationship curves of the PCM exhibit the strain hardening without obvious peak and no strain softening phenomena. The critical wetting strain of the PCM was positively correlated with the number of drying-wetting cycles, while the critical deviator stress decreased with an increase in the number of drying-wetting cycles. As the number of cycles increased, the gelling material between the particles dissolved, the volume of pores inside the PCM increased, and the number of pores inside the PCM decreased. The porosity of PCM had a significant quadratic function with the number of drying-wetting cycles. A wetting deformation damage model was developed to calculate the wetting deformation of the PCM by considering the effects of drying-wetting cycles, which can be useful for evaluating rainfall-induced settlements of relevant engineering structures made from PCM.
摘要：
In recent years, microplastics (MPs) in freshwater lake have been receiving increasing attention; however, the microbial communities on the surface of MPs have not been well studied. To investigate the potential risk posed by MPs to the lake ecosystem and its surface microbial community structure, MPs samples were collected in September 2023 in the freshwater Dongting Lake, Hunan, China, at five sites, and the differences in bacterial species community composition and structure between MPs and water samples were analyzed. Results show that MPs (13.71 +/- 3.32 items/L) in the samples were mostly black in color, fiber in shape, and PES in composition, and those <0.5 mm in size are dominant. The bacterial composition in water was different from that on MPs. At phylum level, Proteobacteria, Actinobacteria, Cyanobacteria, and Bacteroidetes were dominated in relative abundance in both water and MPs. Proteobacteria was more abundant in MPs than in water. The relative abundance of Bacteroidota and Actinobacteriota was significantly lower in MPs than in water. At genus level, Pantoea and Pseudomonas were potentially pathogenic genera in MPs surfaces. The presence of Cyanobacteria and pathogenic bacteria is undoubtedly a potential risk to the deterioration of the water quality. This study revealed the difference in the distribution of bacterial community in water and MPs in Dongting Lake and provided new perspectives to further understanding of MPs pollution in freshwater lakes.
摘要：
There has been significant interest in post-tsunami surveys regarding how effective fringing reefs are at protecting coastlines from inundation caused by tsunamis. Limited attention has been given to the wave transformation characteristics and wave run-up dynamics within a complex reef-lagoon-channel system compared to the extensively studied two-dimensional horizontal fringing reefs. In response to this research gap, a three-dimensional numerical wave tank has been created, incorporating the incompressible Reynolds-averaged Navier-Stokes equations accompanied with k-ω SST turbulence model. The volume of fluid (VOF) strategy is employed to track the free surface, accompanied by advanced grid cascading encryption technology. Laboratory measurements (Swigler, 2009; Briggs et al., 1995) of the waves are utilized for model validation. The influence of incident wave height, reef flat submergence, fore-reef slope, and channel width on wave propagation characteristics were examined. The results reveal that the relative run-up decreases with larger wave heights and decreases near channels as reef flat submergences rise. Initially, smaller channels reduce relative run-up, but it increases again with widening, shifting the maximum relative run-up location away from the channel, while fore-reef slope changes minimally affect run-up.
There has been significant interest in post-tsunami surveys regarding how effective fringing reefs are at protecting coastlines from inundation caused by tsunamis. Limited attention has been given to the wave transformation characteristics and wave run-up dynamics within a complex reef-lagoon-channel system compared to the extensively studied two-dimensional horizontal fringing reefs. In response to this research gap, a three-dimensional numerical wave tank has been created, incorporating the incompressible Reynolds-averaged Navier-Stokes equations accompanied with k-ω SST turbulence model. The volume of fluid (VOF) strategy is employed to track the free surface, accompanied by advanced grid cascading encryption technology. Laboratory measurements (Swigler, 2009; Briggs et al., 1995) of the waves are utilized for model validation. The influence of incident wave height, reef flat submergence, fore-reef slope, and channel width on wave propagation characteristics were examined. The results reveal that the relative run-up decreases with larger wave heights and decreases near channels as reef flat submergences rise. Initially, smaller channels reduce relative run-up, but it increases again with widening, shifting the maximum relative run-up location away from the channel, while fore-reef slope changes minimally affect run-up.
期刊：
Rock Mechanics and Rock Engineering,2025年58(3):3461-3477 ISSN：0723-2632
通讯作者：
Zhu, XY;Chen, XD
作者机构：
[Zhu, Xiangyi] Changsha Univ Sci & Technol, Sch Hydraul & Environm Engn, Changsha 410114, Peoples R China.;[Zhu, Xiangyi] Key Lab Water Sediment Sci & Water Disaster Preven, Changsha 410114, Peoples R China.;[Guo, Yuzhu] Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Peoples R China.;[Bu, Jingwu] Yangzhou Univ, Sch Water Conservancy Sci & Engn, Yangzhou 225009, Peoples R China.;[Chen, Xudong] Hohai Univ, Coll Civil & Transportat Engn, Nanjing 210098, Peoples R China.
通讯机构：
[Zhu, XY ] C;[Chen, XD ] H;Changsha Univ Sci & Technol, Sch Hydraul & Environm Engn, Changsha 410114, Peoples R China.;Key Lab Water Sediment Sci & Water Disaster Preven, Changsha 410114, Peoples R China.;Hohai Univ, Coll Civil & Transportat Engn, Nanjing 210098, Peoples R China.
关键词：
Rock-concrete combined body;Triaxial test;Failure mechanism;Real aggregates;Triaxial DEM model
摘要：
The triaxial mechanical properties of rock–concrete combined bodies are crucial for the safe operation of concrete engineering on rock foundations. Hence, this study uses a combination of mechanical experiments, theoretical analysis, and numerical simulations to investigate the triaxial responses of different rock–concrete combined bodies under different confining pressures. The results indicate that the order of the triaxial strength and deformation resistance of rock–concrete combined bodies is G-C50, S-C50, G-C30, and S-C30, from large to small, due to the effect of the low-strength materials. With the increase of confining pressure, the peak deviatoric stress of the rock–concrete combined body increases exponentially, whereas the axial ultimate strain, radial ultimate strain, and elastic modulus, which characterize the deformation resistance of the combined body, all show a linear increasing trend, and the sensitivity of the combined body to the confining pressure is becoming stronger. For combined bodies with the same bedrock and different concrete grades, the increase in cohesion exceeds 20%, whereas for combined bodies with different bedrock and the same concrete grade, the increase in the cohesion is less than 11%. Moreover, the internal friction angle of the combined body also exhibits a similar variation pattern. Based on the experimental analysis results, a triaxial DEM model for rock–concrete combined bodies considering real aggregates is established, and the effectiveness of the model in predicting the triaxial mechanical properties of rock–concrete combined bodies is verified, which has important theoretical significance and application value.
摘要：
This study employed the k – ω Shear StressTransport turbulence model and the Arbitrary Lagrangian–Eulerian dynamic mesh method in OpenFOAM to investigate the effects of the oscillation frequency ratio ( f r ) on flow characteristics around a square cylinder at Re = 2.2 × 10 4 . The results revealed that the time-averaged drag coefficient ( C d ¯ ) and the Root Mean Square (RMS) of the lift coefficient ( C l ′ ) reached the peak values when f r = 1.0. For f r ≥ 2.5, the time-averaged pressure coefficient ( C p ¯ ) on the leeward side of the square cylinder exhibited a distribution pattern characterized by higher values in the middle and lower values near the edges, while the RMS of the pressure coefficient ( C p ′ ) demonstrated the opposite trend. As f r increased, the secondary recirculation bubbles along the sidewalls of the square cylinder gradually diminished, while the primary recirculation bubbles in the wake and near the sidewalls shortened. Additionally, the RMS of the transverse velocity ( U y ′ ) exceeded that of the streamwise velocity ( U x ′ ) in the wake region. The energy transfer coefficient ( C E ) in the synchronous range was significantly lower than that in the non-synchronous range at different f r . It is worth noting that in the synchronous range, the energy transferred from the cylinder to the fluid attained its maximum value. The amplitude spectrum of the lift coefficient exhibited chaotic characteristics, containing exclusively odd-order superharmonics. With increasing f r , the vortex structures on both sides of the cylinder became increasingly fragmented, and the wake's vortex pattern transitioned from a single-row to a double-row structure. These findings provide a deeper theoretical understanding of turbulence and the flow-induced motion of structures.
作者：
Yi Li;Ping Xue;Yaning Liu;Jingrui Wang*;Wenjie Yin
期刊：
Energy,2025年322:135592 ISSN：0360-5442
通讯作者：
Jingrui Wang
作者机构：
[Ping Xue] School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, 430068, China;Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, Wuhan, 430068, China;[Yi Li] School of Hydraulic Engineering, Changsha University of Science and Technology, Changsha, 410114, China;[Yaning Liu] Department of Mathematical and Statistical Sciences, University of Colorado Denver, Denver, CO, 80204, USA;[Jingrui Wang] Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing, 100012, China
通讯机构：
[Jingrui Wang] T;Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing, 100012, China
摘要：
Compressed air energy storage in aquifers (CAESA) is a novel large-scale energy storage technology. However, the permeability effects on underground processes and responsive wellhead performance require further investigation. In this study, a coupled wellbore and aquifer model is developed based on the practical Dezhou CAESA test in flat aquifers. A novel index, the Pressure Fluctuation Index (PFI), is proposed to evaluate energy storage performance from the perspective of wellhead pressure fluctuations, alongside efficiency and gas recovery. It is found that the balance between effective air support loss due to diffusion and the aquifer’s inherent deliverability controls response performance at different permeability levels. The dominance between these two competing factors shifts as permeability increases. An optimal permeability of 100md is identified for achieving the best energy storage performance. With a cyclic rate increase, the performance shows the opposite trends in different permeability regions and the optimum permeability becomes larger. When considering the initial air bubble, better energy storage performance and a larger optimum permeability can be achieved with greater mass. In high-permeability regions, larger injection rates improve efficiency and gas recovery, while pressure fluctuations perform slightly worse in low-permeability regions. The findings provide valuable insights for site selection and engineering optimization.
Compressed air energy storage in aquifers (CAESA) is a novel large-scale energy storage technology. However, the permeability effects on underground processes and responsive wellhead performance require further investigation. In this study, a coupled wellbore and aquifer model is developed based on the practical Dezhou CAESA test in flat aquifers. A novel index, the Pressure Fluctuation Index (PFI), is proposed to evaluate energy storage performance from the perspective of wellhead pressure fluctuations, alongside efficiency and gas recovery. It is found that the balance between effective air support loss due to diffusion and the aquifer’s inherent deliverability controls response performance at different permeability levels. The dominance between these two competing factors shifts as permeability increases. An optimal permeability of 100md is identified for achieving the best energy storage performance. With a cyclic rate increase, the performance shows the opposite trends in different permeability regions and the optimum permeability becomes larger. When considering the initial air bubble, better energy storage performance and a larger optimum permeability can be achieved with greater mass. In high-permeability regions, larger injection rates improve efficiency and gas recovery, while pressure fluctuations perform slightly worse in low-permeability regions. The findings provide valuable insights for site selection and engineering optimization.
摘要：
Radical- and nonradical-based advanced oxidation processes (AOPs) have been widely used as water cleaning technologies. It is a great challenge to achieve a synergy between these two methodologies for enhancing the performance of water purification. Here we report a novel strategy of permanganate (PM)-promoted photocatalytic oxidation by using TiO 2 with different ratios of (101) and (001) facets as model photocatalysts to achieve a synergy of nonradical-radical relay oxidation process. This approach can simultaneously trigger PM activation by photogenerated electrons and result in the selective deposition of Mn on TiO 2 (101) facet with the formation of single-atom Mn photocatalyst (Mn@TiO 2 ). Conversely, the formed Mn@TiO 2 photocatalyst has a remarkable photocatalytic activity with significantly enhanced radical generation ability due to the regulation of electronic structure of catalyst and the creation of interfacial electric field between Mn and O (TiO 2 ). This approach is highly efficient for the degradation of refractory organic pollutants with superior performances. Physical, theoretical and in situ spectroscopy investigations indicate the crucial role of PM, which is the source of nonradical and radical species, and is the key compound for preparing Mn@TiO 2 . This study provides new insights into the design of efficient single-atom (photo)catalyst, and offers a versatile AOPs for water purification.
Radical- and nonradical-based advanced oxidation processes (AOPs) have been widely used as water cleaning technologies. It is a great challenge to achieve a synergy between these two methodologies for enhancing the performance of water purification. Here we report a novel strategy of permanganate (PM)-promoted photocatalytic oxidation by using TiO 2 with different ratios of (101) and (001) facets as model photocatalysts to achieve a synergy of nonradical-radical relay oxidation process. This approach can simultaneously trigger PM activation by photogenerated electrons and result in the selective deposition of Mn on TiO 2 (101) facet with the formation of single-atom Mn photocatalyst (Mn@TiO 2 ). Conversely, the formed Mn@TiO 2 photocatalyst has a remarkable photocatalytic activity with significantly enhanced radical generation ability due to the regulation of electronic structure of catalyst and the creation of interfacial electric field between Mn and O (TiO 2 ). This approach is highly efficient for the degradation of refractory organic pollutants with superior performances. Physical, theoretical and in situ spectroscopy investigations indicate the crucial role of PM, which is the source of nonradical and radical species, and is the key compound for preparing Mn@TiO 2 . This study provides new insights into the design of efficient single-atom (photo)catalyst, and offers a versatile AOPs for water purification.
通讯机构：
[Yao, Y ] C;Changsha Univ Sci & Technol, Sch Hydraul Engn, Changsha 410114, Peoples R China.
关键词：
Wave energy;Oscillating water column;Shore protection;Viscous energy loss
摘要：
A closely spaced U-OWC pile array with circular main tube cross-sections as both wave farm and breakwater for wave energy extraction and shore protection is investigated experimentally and numerically. The design is intended to operate in relatively deep coastal water under long-period swell conditions. In the laboratory experiments, it was found that the wave energy extraction efficiency and wave attenuation are significantly improved when U-OWC devices are integrated with pile breakwaters. The numerical model validated well with experimental data. Further applications of the numerical model have shown that compared to standalone circular U-OWC devices, the viscous loss in the U-shaped duct is less intensive when the device is placed in a pile array, and that the overall viscous loss effect in the vicinity of the U-OWC pile array is dominated by the large vortices formed by the oscillatory contraction jet flows in the narrow gaps between the piles. Compared to conventional circular OWC pile arrays, the circular U-OWC pile array demonstrated superior performance in a lower frequency range commonly found in swell conditions.
A closely spaced U-OWC pile array with circular main tube cross-sections as both wave farm and breakwater for wave energy extraction and shore protection is investigated experimentally and numerically. The design is intended to operate in relatively deep coastal water under long-period swell conditions. In the laboratory experiments, it was found that the wave energy extraction efficiency and wave attenuation are significantly improved when U-OWC devices are integrated with pile breakwaters. The numerical model validated well with experimental data. Further applications of the numerical model have shown that compared to standalone circular U-OWC devices, the viscous loss in the U-shaped duct is less intensive when the device is placed in a pile array, and that the overall viscous loss effect in the vicinity of the U-OWC pile array is dominated by the large vortices formed by the oscillatory contraction jet flows in the narrow gaps between the piles. Compared to conventional circular OWC pile arrays, the circular U-OWC pile array demonstrated superior performance in a lower frequency range commonly found in swell conditions.
