Water Science and Engineering - 开云电竞网

Rethinking drought definition and classification

Wen Wang, Hao Wang — 2025-04-03

Wen Wang, Hao Wang Water Science and Engineering. 2025 18(2): 125-128.

Degradation of tetracycline in water using hydrogen peroxide activated by soybean residue-derived magnetic biochar

2024-10-31

Van-Truc Nguyen, Nguyen Duy Dat, Thi-Giang-Huong Duong, Viet-Cuong Dinh, Thi-Dieu-Hien Vo Tetracyclines (TCs) are the second most commonly used antibiotics worldwide, utilized in medical treatments and animal husbandry. Although effective against various infectious diseases, TC residues persist in the environment and contribute to the emergence of antibiotic-resistant pathogens, posing significant risks to human health. This study employed the heterogeneous Fenton process to degrade TC using soybean residue-derived magnetic biochar (Fe-SoyB) as the catalyst. The Fe-SoyB sample was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and superconducting quantum interference device (SQUID) techniques. The effects of key parameters, including pH, H₂O₂ concentration, catalyst dosage, and initial TC concentration, on TC degradation were investigated. The results indicated that the TC removal efficiency decreased with increasing initial TC concentration, while it was improved with higher H₂O₂ concentrations and greater catalyst dosages. The optimal conditions for the Fenton-like process were determined: a pH of 3, a H₂O₂ concentration of 245 mmol/L, an initial TC concentration of 800 mg/L, and a catalyst dosage of 0.75 g/L, achieving a removal efficiency of 90.0% after 150 min. Additionally, the TC removal efficiency of the Fe-SoyB system varied significantly across different water matrices, with 87.1% for deionized water, 78.5% for tap water, and 72.5% for river water. The catalyst demonstrated notable stability, maintaining a TC removal efficiency of 79.7% after three cycles of use. Overall, Fe-SoyB shows promise as a cost-effective catalyst for the elimination of organic pollutants in aqueous solutions. Water Science and Engineering. 2025 18(2): 129-140.

Optimising a novel biofilm-based process using Neurospora discreta for enhanced treatment of lignin-rich wastewater

Himani Taneja, Shamas Tabraiz, Asma Ahmed — 2025-02-14

Himani Taneja, Shamas Tabraiz, Asma Ahmed Paper and pulp mills generate substantial volumes of wastewater containing lignin-derived compounds that are challenging to degrade using conventional wastewater treatment methods. This study presents a novel biofilm-based process for enhanced lignin removal in wastewater using the fungus Neurospora discreta, which effectively degrades lignin and forms robust biofilms at the air–liquid interface under specific conditions. The process was optimised using the Taguchi design of experiments approach, and three factors including pH, copper sulphate concentration, and trace element concentration were evaluated at three levels. Experimental data were analysed against three responses: lignin degradation efficiency and the activities of two ligninolytic enzymes (polyphenol oxidase and versatile peroxidase). The results indicated that wastewater pH was the most significant parameter affecting lignin degradation efficiency and enzyme activities. Over 70% lignin degradation was achieved at pH levels of 5 and 6 with copper sulphate concentrations above 4 mg/L, while degradation efficiency drastically dropped to 45% at a pH value of 7. Reversed-phase high-performance liquid chromatography analysis demonstrated the effects of the three factors on the polar and non-polar components of lignin in wastewater, revealing a clear decrease in all peak areas after treatment. Additionally, significant relationships were observed between biofilm properties (including porosity, water retention value, polysaccharide content, and protein content) and lignin removal efficiency. This study also reported for the first time the presence of versatile peroxidase, a ligninolytic enzyme, in Neurospora sp. Water Science and Engineering. 2025 18(2): 141-150.

Photocatalytic purification of dye-containing wastewater using a novel embedded hybrid TiO₂–slag catalyst heterojunction nanocomposite coupled with statistical models: A sustainable and techno-economic approach

Kingsley Safo, Norbert Onen Rubangakene, Hussien Noby, Ahmed H. El-Shazly — 2025-02-22

Kingsley Safo, Norbert Onen Rubangakene, Hussien Noby, Ahmed H. El-Shazly The steel industry produces many byproducts, requiring extensive land for storage and causing significant environmental contamination. Industrial effluents discharged into water bodies negatively impact both aquatic ecosystems and human health. To solve this problem, this study synthesized a composite of titanium dioxide (TiO₂) and steel slag nanocomposites (SSNC) at a 1:2 mass ratio to create a robust photocatalyst for the treatment of synthetic wastewater. The efficacy of this catalyst in degrading various dye pollutants, including methylene blue (MB), was tested under simulated solar light conditions. Comprehensive analyses were conducted to assess the physical and chemical characteristics, crystalline structure, energy gap, and point of zero charge of the composite. The TiO₂-SSNC composite catalyst exhibited excellent stability, with a point of zero charge at 8.342 and an energy gap of 2.4 eV. The degradation process conformed to pseudo-first-order kinetics. Optimization of operational parameters was achieved through the response surface methodology. Reusability tests demonstrated that the TiO₂-SSNC composite catalyst effectively degraded up to 93.41% of MB in the suspended mode and 92.03% in the coated mode after five cycles. Additionally, the degradation efficiencies for various dyes were significant, highlighting the potential of the composite for broad applications in industrial wastewater treatment. This study also explored the degradation mechanisms and identified byproducts, establishing a pathway for contaminant breakdown. The cost-benefit analysis revealed a total cost of 0.842 8 USD per cubic meter for each treatment activity, indicating low operational and production costs. These findings underscore the promise of the TiO₂-SSNC composite as a cost-effective and efficient alternative for wastewater purification. Water Science and Engineering. 2025 18(2): 151-164.

Immobilization of MnO₂ nanoflowers on coils using direct heating method for organic pollutant remediation

Sin Ling Chiam, Swee-Yong Pung, Chee Meng Koe, Fei Yee Yeoh — 2024-09-03

Sin Ling Chiam, Swee-Yong Pung, Chee Meng Koe, Fei Yee Yeoh The immobilization of catalysts on supporting substrates for the removal of organic pollutants is a crucial strategy for mitigating catalyst loss during wastewater treatment. This study presented a rapid and cost-effective direct heating method for synthesizing MnO₂ nanoflowers on coil substrates for the removal of organic pollutants. Traditional methods often require high power, expensive equipment, and long synthesis times. In contrast, the direct heating approach successfully synthesized MnO₂ nanoflowers in just 10 min with a heating power of approximately 40 W·h after the heating power and duration were optimized. These nanoflowers effectively degraded 99% Rhodamine B in 60 min with consistent repeatability. The catalytic mechanisms are attributed to crystal defects in MnO₂, which generate electrons to produce H₂O₂. Mn^²⁺ ions in the acidic solution further dissociate H₂O₂ molecules into hydroxyl radicals (·OH). The high efficiency of this synthesis method and the excellent reusability of MnO₂ nanoflowers highlight their potential as a promising solution for the development of supporting MnO₂ catalysts for organic dye removal applications. Water Science and Engineering. 2025 18(2): 165-176.

Reservoir water level prediction using combined CEEMDAN-FE and RUN-SVM-RBFNN machine learning algorithms

Lan-ting Zhou, Guan-lin Long, Can-can Hu, Kai Zhang — 2025-01-27

Lan-ting Zhou, Guan-lin Long, Can-can Hu, Kai Zhang Accurate prediction of water level changes in reservoirs is crucial for optimizing the operation of reservoir projects and ensuring their safety. This study proposed a method for reservoir water level prediction based on CEEMDAN-FE and RUN-SVM-RBFNN algorithms. By integrating the adaptive complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) method and fuzzy entropy (FE) with the new and highly efficient Runge–Kuta optimizer (RUN), adaptive parameter optimization for the support vector machine (SVM) and radial basis function neural network (RBFNN) algorithms was achieved. Regression prediction was conducted on the two reconstructed sequences using SVM and RBFNN according to their respective features. This approach improved the accuracy and stability of predictions. In terms of accuracy, the combined model outperformed single models, with the determination coefficient, root mean square error, and mean absolute error values of 0.997 5, 0.241 8 m, and 0.161 6 m, respectively. In terms of stability, the model predicted more consistently in training and testing periods, with stable overall prediction accuracy and a better adaptive ability to complex datasets. The case study demonstrated that the combined prediction model effectively addressed the environmental factors affecting reservoir water levels, leveraged the strength of each predictive method, compensated for their limitations, and clarified the impacts of environmental factors on reservoir water levels. Water Science and Engineering. 2025 18(2): 177-186.

Quantification of backwater effect in Jingjiang Reach due to confluence with Dongting Lake using a machine learning model

Hai-xin Shang, Jun-qiang Xia, Chun-hong Hu, Mei-rong Zhou, Shan-shan Deng — 2025-02-22

Hai-xin Shang, Jun-qiang Xia, Chun-hong Hu, Mei-rong Zhou, Shan-shan Deng The backwater effect caused by tributary inflow can significantly elevate the water level profile upstream of a confluence point. However, the influence of mainstream and confluence discharges on the backwater effect in a river reach remains unclear. In this study, various hydrological data collected from the Jingjiang Reach of the Yangtze River in China were statistically analyzed to determine the backwater degree and range with three representative mainstream discharges. The results indicated that the backwater degree increased with mainstream discharge, and a positive relationship was observed between the runoff ratio and backwater degree at specific representative mainstream discharges. Following the operation of the Three Gorges Project, the backwater effect in the Jingjiang Reach diminished. For instance, mean backwater degrees for low, moderate, and high mainstream discharges were recorded as 0.83 m, 1.61 m, and 2.41 m during the period from 1990 to 2002, whereas these values decreased to 0.30 m, 0.95 m, and 2.08 m from 2009 to 2020. The backwater range extended upstream as mainstream discharge increased from 7 000 m³/s to 30 000 m³/s. Moreover, a random forest-based machine learning model was used to quantify the backwater effect with varying mainstream and confluence discharges, accounting for the impacts of mainstream discharge, confluence discharge, and channel degradation in the Jingjiang Reach. At the Jianli Hydrological Station, a decrease in mainstream discharge during flood seasons resulted in a 7%–15% increase in monthly mean backwater degree, while an increase in mainstream discharge during dry seasons led to a 1%–15% decrease in monthly mean backwater degree. Furthermore, increasing confluence discharge from Dongting Lake during June to July and September to November resulted in an 11%–42% increase in monthly mean backwater degree. Continuous channel degradation in the Jingjiang Reach contributed to a 6%–19% decrease in monthly mean backwater degree. Under the influence of these factors, the monthly mean backwater degree in 2017 varied from a decrease of 53% to an increase of 37% compared to corresponding values in 1991. Water Science and Engineering. 2025 18(2): 187-199.

Simultaneous assessment of effects of variations in temperature and hydraulic retention time on membrane fouling in membrane bioreactors

Horieh Akbari, Hossein Hazrati, Abbas Nazmkhah, Hanieh Shokrkar — 2025-03-08

Horieh Akbari, Hossein Hazrati, Abbas Nazmkhah, Hanieh Shokrkar Membrane fouling remains the primary economic barrier to the widespread implementation of membrane bioreactors (MBRs), despite the fact that they lead to the production of high-quality effluent. Operational conditions are critical factors influencing membrane fouling. This study aimed to investigate the simultaneous impacts of temperature and hydraulic retention time (HRT) variations on membrane fouling. Experiments were conducted at three different temperatures (18°C, 25°C, and 32°C) and HRTs (6 h, 9 h, and 15 h). The results demonstrated that increases in both temperature and HRT contributed to a reduction in membrane fouling. Additionally, a positive interaction between temperature and HRT was observed in the linear slope variation of membrane permeation, with temperature variations exerting a greater influence on membrane fouling than HRT variations. Fouling factor analysis revealed that increases in temperature and HRT led to decreased concentrations of soluble microbial products (SMP) and extracellular polymeric substances (EPS), particularly carbohydrates, in the activated sludge. Analyses of the cake layer of the membrane indicated that increasing temperature and HRT reduced EPS levels, particularly polysaccharides and proteins; altered primary protein structure; and increased the mean particle size distribution. Ultimately, these changes led to reductions in both reversible and irreversible hydraulic resistances. This study highlights the importance of optimizing operational parameters such as temperature and HRT to enhance membrane performance and treatment efficiency in MBR systems while mitigating fouling. Water Science and Engineering. 2025 18(2): 200-208.

Impact of damming on nutrient transport and transformation in river systems: A review

2024-11-28

Jia-wen Gan, Xun Wang, Qiu-sheng Yuan, Xiao-lei Xing, Sheng Liu, Cheng-gong Du, Yu-ran Zheng, Yun-xin Liu Large-scale damming has emerged as a prevalent global trend, significantly impacting nutrient transport and transformation, as well as the downstream ecological environment. Nitrogen and phosphorus are fundamental elements of primary productivity in aquatic ecosystems and serve as key limiting factors in reservoir eutrophication. This review focuses on the impact of damming on the transport and transformation of nitrogen and phosphorus, regarding changes in nutrient concentrations, fluxes, and proportions. Spatial changes in nitrogen and phosphorus concentrations primarily occur at the inlet and outlet of reservoirs, while temporal changes often exhibit seasonal patterns. At a global scale, phosphorus is preferentially removed from reservoirs compared to nitrogen. The factors influencing the transport and transformation processes of nitrogen and phosphorus in reservoirs include the physicochemical properties of water bodies and human activities. Additionally, nitrogen dynamics are affected by reservoir age, storage capacity, and water storage regulation modes, whereas phosphorus dynamics are also influenced by hydrodynamic conditions. Finally, this review summarizes the impact of damming on the downstream ecological environment and outlines future research directions, providing theoretical support for the management of river–reservoir ecosystems and promoting the green and sustainable development of hydropower in the context of carbon peaking and carbon neutrality goals. Water Science and Engineering. 2025 18(2): 209-220.

Energy flow rate equation for river networks

Sai-yu Yuan, Jia-wei Lin, Hong-wu Tang — 2025-04-06

Sai-yu Yuan, Jia-wei Lin, Hong-wu Tang Rational allocation of water flow energy in river networks is essential to addressing water-related issues in river network areas. However, current methods of calculating the spatiotemporal distribution of flow energy in river networks lack precision and efficiency. This paper introduces a novel hydrodynamic representation, the energy flow rate, defined as the product of the flow rate and kinetic energy head, to quantify the kinetic energy stored and transported in river networks. A linear equation system for the energy flow rate in a river network has been theoretically derived, enabling rapid calculations under steady flow conditions. A simplified equation is proposed to describe the exponential decay of the energy flow rate, accompanied by potential energy conversion. The coefficients in the linear equation system are determined using control equations at flow confluence and diversion nodes. This study provides foundational insights that can be used to develop new hydrodynamic modeling strategies to regulate water flow energy and achieve coordinated management of water-related issues in river networks. Water Science and Engineering. 2025 18(2): 221-224.

Evaluation of scale effects in physical modeling of combined ogee and sharp-crested weir flow using a 3D CFD model

James Zulfan, Bobby Minola Ginting, Ravi Anthony Tartandyo — 2024-11-28

James Zulfan, Bobby Minola Ginting, Ravi Anthony Tartandyo Research on scale effects on flows over weirs has been conducted on a limited basis, primarily focusing on flows upstream of a single-type weir, such as ogee, broad-crested, and sharp-crested (linear and non-linear) weirs. However, the scale effects downstream of these single-type weirs have not been thoroughly investigated. This study examined the scale effects on flows over a combined weir system consisting of an ogee weir and a sharp-crested weir, both upstream and downstream, utilizing physical modeling at a 1:33.33 scale based on Froude similarity and three-dimensional (3D) computational fluid dynamics (CFD) modeling. The sharp-crested weir in this study was represented by two sluice gates that remain closed and submerged during flood events. The experimental data confirmed that the equivalent discharge coefficients of the combined weir system behaved similarly to those of a sharp-crested weir across various H/P (where H is the total head, and P is the weir height) values. However, scale effects on the discharge rating curve due to surface tension and viscosity could only be minimized when H/P > 0.4, Re > 26 959, and We > 240 (where Re and We are the Reynolds and Weber numbers, respectively), provided that the water depth exceeded 0.042 m above the crest. Additionally, Re greater than 4 × 10⁴ was necessary to minimize scale effects caused by viscosity in flows in the spillway channel and stilling basin (with baffle blocks). The limiting criteria aligned closely with existing literature. This study offers valuable insights for practical applications in hydraulic engineering in the future. Water Science and Engineering. 2025 18(2): 225-235.

Three-dimensional numerical simulation of mixing patterns at open channel confluences

Ali Aghazadegan, Ali Shokri — 2024-08-08

Ali Aghazadegan, Ali Shokri Open channel confluences, where two streams or rivers converge, play a crucial role in hydraulic engineering and river dynamics. These confluences are characterized by complex hydrodynamics influenced by the discharge ratios of merging water bodies. This study investigated the mixing structure at open channel confluences using three-dimensional numerical modeling. A comprehensive three-dimensional numerical model was developed and validated against a dataset obtained from controlled laboratory experiments. This dataset incorporated three-dimensional time-averaged velocity measurements. The skew-induced and stress-induced equation systems were adopted as the core governing equations, providing a framework for simulating various scenarios. A total of ten different cases were analyzed. The results highlighted the effect of discharge ratios on turbulence, lateral and vertical vorticities, and the distribution of mixing, which intensified with higher magnitudes of discharge ratios. The mixing structure, driven by velocity gradients and vorticity, revealed the significant role of lateral and vertical vorticities in determining hydrodynamic behaviors and mixing distributions at confluences. Specifically, the momentum ratio of incoming flows governed the spatial evolution of mixing processes. This study revealed that the distribution of mixing served as a key indicator for identifying the formation of mid-channel scours. High normalized velocities induced toward the left bank led to the superelevation of the water surface, enhancing the potential for bed material and the formation of significant scour holes beneath the elevated water surface. This novel approach provides a deeper understanding of the mixing patterns at confluences, particularly in scenarios with equilibrated discharge ratios but in different magnitudes. Water Science and Engineering. 2025 18(2): 236-246.

Computational and experimental analysis of flow velocity and complex vortex formation around a group of bridge piers

2025-01-27

Nima Ikani, Jaan H. Pu, Prashanth Reddy Hanmaiahgari, Bimlesh Kumar, Ebrahim Hamid Hussein Al-Qadami, Mohd Adib Mohammad Razi, Shu-yan Zang In this study, the flow characteristics around a group of three piers arranged in tandem were investigated both numerically and experimentally. The simulation utilised the volume of fluid (VOF) model in conjunction with the k–ɛ method (i.e., for flow turbulence representations), implemented through the ANSYS FLUENT software, to model the free-surface flow. The simulation results were validated against laboratory measurements obtained using an acoustic Doppler velocimeter. The comparative analysis revealed discrepancies between the simulated and measured maximum velocities within the investigated flow field. However, the numerical results demonstrated a distinct vortex-induced flow pattern following the first pier and throughout the vicinity of the entire pier group, which aligned reasonably well with experimental data. In the heavily narrowed spaces between the piers, simulated velocity profiles were overestimated in the free-surface region and underestimated in the areas near the bed to the mid-stream when compared to measurements. These discrepancies diminished away from the regions with intense vortices, indicating that the employed model was capable of simulating relatively less disturbed flow turbulence. Furthermore, velocity results from both simulations and measurements were compared based on velocity distributions at three different depth ratios (0.15, 0.40, and 0.62) to assess vortex characteristic around the piers. This comparison revealed consistent results between experimental and simulated data. This research contributes to a deeper understanding of flow dynamics around complex interactive pier systems, which is critical for designing stable and sustainable hydraulic structures. Furthermore, the insights gained from this study provide valuable information for engineers aiming to develop effective strategies for controlling scour and minimizing destructive vortex effects, thereby guiding the design and maintenance of sustainable infrastructure. Water Science and Engineering. 2025 18(2): 247-258.