Water

14 pages, 4614 KiB

Open AccessArticle

Ozonation Treatment of Simulated Wastewater Containing Characteristic Pollutants from the Petrochemical Industry

by Yangyang Zhou, Zhilin Yang, Siqi Chen, Wenquan Sun and Yongjun Sun

Water 2025, 17(4), 605; https://doi.org/10.3390/w17040605 - 19 Feb 2025

Viewed by 329

This study investigated key factors in the petrochemical industry and evaluated the oxidation performance of ozonation catalytic oxidation for treating phenol-simulated wastewater and actual wastewater spiked with phenol. In simulated phenol wastewater, optimal conditions (ozone dosage of 8 mg/L/min, pH 11, total dissolved [...] Read more.

This study investigated key factors in the petrochemical industry and evaluated the oxidation performance of ozonation catalytic oxidation for treating phenol-simulated wastewater and actual wastewater spiked with phenol. In simulated phenol wastewater, optimal conditions (ozone dosage of 8 mg/L/min, pH 11, total dissolved solids (TDSs) of 1000 mg/L, and initial phenol concentration of 50 mg/L) yielded a maximum chemical oxygen demand (COD) removal rate of 90.60%. For actual wastewater spiked with phenol under the same conditions, maximum removal rates of phenol, COD, and total organic carbon (TOC) were 65.45%, 63.57%, and 79.65%, respectively. The degradation mechanisms and changes in organic matter during ozonation were analyzed using three-dimensional fluorescence spectroscopy, ultraviolet spectroscopy, and gas chromatography–mass spectrometry (GC-MS). The findings demonstrate that ozonation oxidation is an effective wastewater treatment method, significantly reducing pollutant concentrations and enhancing water quality. Full article

(This article belongs to the Special Issue Application of Advanced Oxidation Technologies in Water and Wastewater Purification)

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20 pages, 4706 KiB

Open AccessArticle

A SMA-SVM-Based Prediction Model for the Tailings Discharge Volume After Tailings Dam Failure

by Gaolin Liu, Bing Zhao, Xiangyun Kong, Yingming Xin, Mingqiang Wang and Yonggang Zhang

Water 2025, 17(4), 604; https://doi.org/10.3390/w17040604 - 19 Feb 2025

Viewed by 311

Abstract

Tailings ponds can recycle water resources through the water recirculation system by clarifying and purifying the wastewater discharged from the mining production process. Due to factors such as flooding and heavy rainfall, once a tailings dams burst, the spread of heavy metals in [...] Read more.

Tailings ponds can recycle water resources through the water recirculation system by clarifying and purifying the wastewater discharged from the mining production process. Due to factors such as flooding and heavy rainfall, once a tailings dams burst, the spread of heavy metals in the tailings causes underground and surface water pollution, endangering the lives and properties of people downstream. To effectively assess the potential impact of tailings dams bursting, many problems such as the difficulty of taking values in predicting the volume of silt penetration through empirical formulae, model testing, and numerical simulation need to be solved. In this study, 65 engineering cases were collected to develop a sample dataset containing dam height and storage capacity. The Support Vector Machine (SVM) algorithm was used to develop a nonlinear regression model for tailings discharge volume after tailings dam failure. In addition, the model penalty parameter C and kernel function g were optimized using the powerful global search capability of the Slime Mold Algorithm (SMA) to develop an SMA–SVM prediction model for tailings discharge volume. The results indicate that the volume of tailings discharged increases nonlinearly with increasing dam height and tailings storage capacity. The SMA-SVM model showed higher prediction accuracy compared to the predictions made by the Random Forest (RF), Radial Basis Function (RBF), and Least Squares SVM (LS-SVM) algorithms. The average absolute error in tailings discharge volume compared to actual values was 30,000 m³, with an average relative error of less than 25%. This is very close to practical engineering scenarios. The ability of the SMA-SVM optimization algorithm to produce predictions with minimal error relative to actual values was further confirmed by the combination of numerical simulations. In addition, the numerical simulations revealed the flow characteristics and inundation area of the discharged sediment during tailings dam failure, and the research results can provide reference for water resource protection and downstream safety prevention and control of tailings ponds. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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18 pages, 3843 KiB

Open AccessArticle

Time Series Analysis for the Adaptive Prediction of Total Phosphorus in the Yangtze River: A Machine Learning Approach

by Tianqi Ma and Xing Chen

Water 2025, 17(4), 603; https://doi.org/10.3390/w17040603 - 19 Feb 2025

Viewed by 214

Abstract

Accurate prediction of total phosphorus (TP) in water quality is critical for monitoring ecosystem stability and eutrophication status. However, the distribution of natural environmental data such as total phosphorus (TP) in water quality tends to undergo complex changes over time. Stable and reliable [...] Read more.

Accurate prediction of total phosphorus (TP) in water quality is critical for monitoring ecosystem stability and eutrophication status. However, the distribution of natural environmental data such as total phosphorus (TP) in water quality tends to undergo complex changes over time. Stable and reliable prediction results not only require a certain degree of stability and periodicity of natural data but also require that the TP prediction model be highly adaptable to random fluctuations and distributional drifts of environmental data. Therefore, it is a challenge to adapt prediction models to the distributional drift of natural environmental data. In this study, the spatial and temporal variations in TP in the Yangtze River from 2019 to 2023 were described in detail. Using data mining techniques, time series data were analyzed to generate a forecast dataset focusing on the stability and periodicity of TP fluctuations. By comparing various time series prediction models, MTS-Mixers was finally selected as the experimental baseline model and different modes were used for time series prediction. The results show that after parameter adjustment, the model can achieve high prediction accuracy (MAE: 0.145; MSE: 0.277), which can guarantee the accuracy at 20 time steps. These research results not only comprehensively described and reliably predicted the changes in TP in the Yangtze River but also provided effective methods and tools for water quality monitoring and management. They provide a scientific basis for environmental protection and water quality improvement in the Yangtze River Basin which can help in the formulation and implementation of relevant policies and promote the sustainable development of the Yangtze River water environment. In addition, this study confirms the applicability of machine learning in hydrological prediction for responding to environmental changes. Full article

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17 pages, 2611 KiB

Open AccessArticle

Photocatalytic Removal of the Antibiotic Furazolidone Using g-C₃N₄ in the Presence of Persulfates Under Lab and Pilot Scale Conditions

by Christina Efthymiou, Christos Lykos, Vasiliki Boti, Ioannis Konstantinou and Triantafyllos Albanis

Water 2025, 17(4), 602; https://doi.org/10.3390/w17040602 - 19 Feb 2025

Viewed by 247

Abstract

Furazolidone, a nitrofuran antibiotic, has been broadly used in aquaculture and veterinary medicine, and its presence in water poses considerable environmental and health hazards due to its toxicity. This study investigated a hybrid photocatalytic process for the removal of furazolidone, employing graphitic carbon [...] Read more.

Furazolidone, a nitrofuran antibiotic, has been broadly used in aquaculture and veterinary medicine, and its presence in water poses considerable environmental and health hazards due to its toxicity. This study investigated a hybrid photocatalytic process for the removal of furazolidone, employing graphitic carbon nitride (g-C₃N₄) and persulfate anions (PS) under both laboratory and pilot-scale conditions. The synergistic effect of g-C₃N₄ and PS enhanced the generation of reactive species, facilitating the efficient degradation of FZ in two different aqueous matrices. Through scavenging studies, positive holes were determined to be the dominant reactive species, followed by sulfate radicals. Seven transformation products of FZ were tentatively identified via UHPLC-LTQ/Orbitrap MS analysis. The optimized photocatalytic system (g-C₃N₄/PS) achieved a 100% removal of furazolidone in less than 60 min under simulated solar light, demonstrating its potential for large-scale application in wastewater remediation. Furthermore, pilot-scale experiments using real secondary treated municipal wastewater proved that the applied process is capable of achieving an 86.2% removal of furazolidone (k = 0.017 min⁻¹) as well as a 90% decrease in effluent ecotoxicity within 120 min of UV_A irradiation. This study provides insights into sustainable processes for the removal of antibiotic contaminants from wastewater and underscores the role of g-C₃N₄-based photocatalytic approaches in upper-scale applications. Full article

(This article belongs to the Special Issue New Perspectives for Water Quality and Wastewater Remediation: Advanced Oxidation Processes and Toxicity Assessments)

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14 pages, 3637 KiB

Open AccessArticle

Two-Dimensional Transient Flow in a Confined Aquifer with a Cut-Off Curtain Due to Dewatering

by Guangcheng Li, Huiming Lin, Min Deng, Lu Wang, Jianxiao Wang, Fanshui Kong, Yushan Zhang and Qinggao Feng

Water 2025, 17(4), 601; https://doi.org/10.3390/w17040601 - 19 Feb 2025

Viewed by 290

Abstract

Long, narrow, deep excavations commonly encountered in practice, such as those for subway stations, require effective groundwater management to prevent disasters in water-rich areas. To achieve this, a cut-off curtain and pumping well are typically employed during long, deep foundation pit dewatering. The [...] Read more.

Long, narrow, deep excavations commonly encountered in practice, such as those for subway stations, require effective groundwater management to prevent disasters in water-rich areas. To achieve this, a cut-off curtain and pumping well are typically employed during long, deep foundation pit dewatering. The unsteady groundwater flow behavior in the confined aquifer must consider the influence of the cut-off curtain during dewatering. This paper establishes a two-dimensional analytical model to describe transient groundwater flow in a confined aquifer with a cut-off curtain. Both the dewatering well pumped at a steady discharge inside the pit and the cut-off curtain are partially penetrating in the anisotropic confined aquifer. With the help of the Laplace and Fourier cosine transformations, the semi-analytical drawdown solution for the model is derived and validated against numerical solution and unsteady pumping test data. It is shown that the inserted cut-off curtain depth and the structural parameters of the pumping well significantly affect the drawdown inside the pit. Sensitivity analysis reveals that, regardless of whether the observation is made inside or outside the curtain, the drawdown is very sensitive to the change in pumping rate, aquifer thickness, storage coefficient, and horizontal hydraulic conductivity. Additionally, drawdown near the cut-off curtain outside the pit is sensitive to the vertical hydraulic conductivity of the aquifer, the width of the pit, and the interception depth of the cut-off curtain, while drawdown far from the curtain outside the pit is not sensitive to the location and length of the well screen. Full article

(This article belongs to the Special Issue Transient Flows: Mathematical Models, Laboratory Tests, Protection Elements and Systems)

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27 pages, 4816 KiB

Open AccessArticle

The Water Paradox of Bandung: Rich in Rain, Poor in Policy

by Anton Sunarwibowo, Erri Noviar Megantara, Herlina Agustin and Ridwan Sutriadi

Water 2025, 17(4), 600; https://doi.org/10.3390/w17040600 - 19 Feb 2025

Viewed by 296

Abstract

Water availability is an important aspect of life. With the increasing number of humans with the same water cycle, it is possible that water scarcity will occur, including in Bandung City, especially in Jatisari Village, Buahbatu District. Public awareness and regulation of water [...] Read more.

Water availability is an important aspect of life. With the increasing number of humans with the same water cycle, it is possible that water scarcity will occur, including in Bandung City, especially in Jatisari Village, Buahbatu District. Public awareness and regulation of water use are required. This study aims to analyze the influence of environmental communication on community behavior with the intervening variable of cognitive dissonance in household water use in Jatisari Village; explore environmental communication carried out and what the obstacles are; and also explore the scope of water policies in Bandung City. This study uses a mixed method with analysis using SPSS 25 and ATLAS.ti 23.1. The results of the Sobel test showed that the mediation coefficient of 0.0288 was significant, which means that cognitive dissonance has significant mediating influence in the relationship between environmental communication and perceptions for behavioral change. Meanwhile, environmental communication in Bandung City Government and non-Bandung City Government to maintain the sustainability of water has shown collaboration involving various stakeholders. Although there is much progress, there are still obstacles that need to be overcome, especially in coordination between actors and increasing public awareness. Also, six policies on water were found but showed that there is no policy that specifically regulates water conservation, water distribution, and limits on water use to support water availability. This is likely due to the absence of parameters that can convince the government to make policies on water conservation, for example, through the Water Scarcity Assessment Index. Full article

(This article belongs to the Special Issue Water Scarcity: From Ancient to Modern Times and the Future, Volume II)

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33 pages, 422 KiB

Open AccessReview

Modelling and Mapping Rapid-Onset Coastal Flooding: A Systematic Literature Review

by Alice Re, Lorenzo Minola and Alessandro Pezzoli

Water 2025, 17(4), 599; https://doi.org/10.3390/w17040599 - 19 Feb 2025

Viewed by 378

Abstract

Increases in the magnitude and frequency of extreme flood events are among the most impactful consequences of climate change. Coastal areas can potentially be affected by interactions among different flood drivers at the interface of terrestrial and marine ecosystems. At the same time, [...] Read more.

Increases in the magnitude and frequency of extreme flood events are among the most impactful consequences of climate change. Coastal areas can potentially be affected by interactions among different flood drivers at the interface of terrestrial and marine ecosystems. At the same time, socio-economic processes of population growth and urbanization can lead to increases in local vulnerability to climate extremes in coastal areas. Within this context, research focusing on modelling and mapping rapid-onset coastal flooding is essential (a) to support flood risk management, (b) to design local climate adaptation policies and (c) to increase climate resilience of coastal communities. This systematic literature review delineates the state-of-the art of research on rapid-onset coastal flooding. It provides a comprehensive picture of the broad range of methodologies utilised to model flooding and highlights the commonly identified issues, both from a scientific standpoint and in terms of the policy implications of translating research outputs into actionable information. As flood maps represent fundamental instruments in the communication of research outcomes to support decision making and increase climate resilience, a focus on the spatial representation of coastal floods proposed in the literature is adopted in this review. Full article

(This article belongs to the Special Issue Climate Risk Management, Sea Level Rise and Coastal Impacts)

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15 pages, 9065 KiB

Open AccessArticle

An Analysis of Multi-Coal Seam Mining Impacting Aquifer Water Based on Self-Organizational Maps

by Zhonglin Wei, Yuan Ji, Yuan Li, Huiming Fang, Donglin Dong and Lujia Yu

Water 2025, 17(4), 598; https://doi.org/10.3390/w17040598 - 19 Feb 2025

Viewed by 251

Abstract

The degradation of groundwater quality due to mining activities is a major public concern globally. This study employed a combination of methods (multivariate statistics, Self-organizing mapping, and PHREEQC hydrogeochemical simulation) to uncover the hydrochemical characteristics and processes of mine water in the Kailuan [...] Read more.

The degradation of groundwater quality due to mining activities is a major public concern globally. This study employed a combination of methods (multivariate statistics, Self-organizing mapping, and PHREEQC hydrogeochemical simulation) to uncover the hydrochemical characteristics and processes of mine water in the Kailuan mining area. Self-organizing mapping (SOM) clustering divided the mine water into three groups, TDS values gradually increased from the first to the third group, and the hydrogeochemical type of mine water gradually changed from Na-HCO₃ and CaMg-HCO₃ to CaMg-SO₄, Na-Cl, and mixed types. Principal component analysis (PCA) revealed that water–rock action and evaporation concentration were major ion concentration factors. According to the molar ion concentration ratio method, the main ions in mine water in Kailuan mining area originate from silicate and sulfate, and a small amount from carbonate rock weathering, and they are influenced by cation exchange. As a result of the PHReactor EQuilibrium Code (PHREEQC) simulation results, it can be concluded that better hydrodynamic conditions in mines are primarily controlled by carbonate dissolution. Mine water with poorer hydrodynamic conditions is mainly controlled by sulfate and carbonate dissolution, with sulfate dissolution having a greater effect. The results of this study provide an important scientific basis for the safe mining of mines and the protection of groundwater resources. Full article

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20 pages, 9287 KiB

Open AccessArticle

Snow Melting Experimental Analysis on a Downscaled Shallow Landslide: A Focus on the Seepage Activity of the Snow–Soil System

by Lorenzo Panzeri, Michele Mondani, Monica Papini and Laura Longoni

Water 2025, 17(4), 597; https://doi.org/10.3390/w17040597 - 19 Feb 2025

Viewed by 297

Abstract

The stability of slopes is influenced by seasonal variations in thermal, hydrological, and mechanical processes. This study investigates the role of snowmelt in triggering shallow landslides through controlled laboratory experiments simulating winter, spring, and summer conditions. Snowpack dynamics and water movement were analyzed [...] Read more.

The stability of slopes is influenced by seasonal variations in thermal, hydrological, and mechanical processes. This study investigates the role of snowmelt in triggering shallow landslides through controlled laboratory experiments simulating winter, spring, and summer conditions. Snowpack dynamics and water movement were analyzed to understand filtration, infiltration, and runoff mechanisms. The results show that during winter, snow acts as a protective layer, slowing infiltration through its insulating and loading effects. In spring, rising temperatures melt snow, increasing water infiltration and filtration, accelerating soil saturation, and triggering slope failures. Summer rainfall-induced landslides exhibit distinct mechanisms, driven by progressive saturation. The transition from winter to spring highlights a critical phase where snowmelt interacts with warmer soils, intensifying slope instability risks. Numerical simulations using HYDRUS 1D validated the experimental findings, demonstrating its utility in modeling infiltration under varying thermal gradients. This study underscores the importance of incorporating snowmelt dynamics into landslide risk assessments and early warning systems, particularly as climate change accelerates snowmelt cycles in mountainous regions. These findings provide essential insights into seasonal variations in collapse mechanisms, emphasizing the need for further research to address the increasing impact of snowmelt in shallow landslides. Full article

(This article belongs to the Special Issue Water-Related Landslide Hazard Process and Its Triggering Events)

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17 pages, 1544 KiB

Open AccessArticle

Disinfection of Secondary Urban Wastewater Using Hydrogen Peroxide Combined with UV/Visible Radiation: Effect of Operating Conditions and Assessment of Microorganism Competition

by Ana L. R. Gomes, Sara Ribeirinho-Soares, Luis M. Madeira, Olga C. Nunes and Carmen S. D. Rodrigues

Water 2025, 17(4), 596; https://doi.org/10.3390/w17040596 - 19 Feb 2025

Viewed by 278

Abstract

The growing and unprecedented water crisis leads to the need to find alternative water resources, and the reuse of treated urban wastewater is an excellent approach. Accordingly, in this work, the disinfection of a secondary effluent (W) discharged from a wastewater treatment plant [...] Read more.

The growing and unprecedented water crisis leads to the need to find alternative water resources, and the reuse of treated urban wastewater is an excellent approach. Accordingly, in this work, the disinfection of a secondary effluent (W) discharged from a wastewater treatment plant (WWTP) by hydrogen peroxide combined with radiation (H₂O₂+UV/visible) was studied with the aim of obtaining treated water that can be reused. Firstly, the effect of hydrogen peroxide alone, radiation per se and the combined H₂O₂+UV/Visible process in the inactivation of enterobacteria were assessed. It was found that the oxidant alone is not efficient; the maximum inactivation is achieved when the oxidant and radiation are used simultaneously. For the first time, the effect of some operational parameters, namely the hydrogen peroxide concentration (between 50 and 125 mg/L), initial pH (from 5.0 to 7.0), temperature (between 15 and 25 °C), and radiation intensity (100 to 500 W/m²), on the efficiency of the disinfection process was assessed. When the process was carried out under the best operating conditions found ([H₂O₂] = 75 mg/L, pH = 5.0, T = 25 °C, and UV/visible light with I = 500 W/m²), total enterobacteria and total heterotrophs were inactivated and the abundance of the 16S rRNA, bla_TEM, qnrS, and intl1 genes was reduced. The cultivable microorganisms grew again after 3 days of storing the treated wastewater (TW), making it impossible to reuse such effluent after storage. Therefore, the potential capacity of a diverse bacterial community present in river water to inhibit the regrowth of potentially harmful bacteria present in the urban secondary wastewater after the application of the treatment process was also evaluated. To the authors’ knowledge, this has never been studied before. For this purpose, the TW was diluted with river water (R) at a volumetric percentage of 50/50—sample R+TW. It was found that, after storage, only the total heterotrophs grew, while the abundance of the targeted genes remained practically constant. The R+TW sample after storage met the legal limits for reuse in urban and agricultural applications. The results of this study suggest that the combination of the H₂O₂+UV/visible radiation treatment with dilution of the final treated effluent with natural surface water can contribute to reducing the burden of water scarcity. Full article

(This article belongs to the Special Issue Urban Stormwater Harvesting, and Wastewater Treatment and Reuse)

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17 pages, 5182 KiB

Open AccessArticle

Water Quality and Its Influence on Waterbird Habitat Distribution: A Study Along the Lieve River, Belgium

by Xingzhen Liu, Long Ho, Andrée De Cock, Nancy De Saeyer, Kim Pham, Diego Panique-Casso, Marie Anne Eurie Forio and Peter L. M. Goethals

Water 2025, 17(4), 595; https://doi.org/10.3390/w17040595 - 19 Feb 2025

Viewed by 295

Abstract

Freshwater ecosystems face increasing pressures from human activities, leading to degraded water quality and altered habitats for aquatic species. This study investigates the relationship between water quality and waterbird distribution along the Lieve River, Belgium, based on manually conducted waterbird counts and water [...] Read more.

Freshwater ecosystems face increasing pressures from human activities, leading to degraded water quality and altered habitats for aquatic species. This study investigates the relationship between water quality and waterbird distribution along the Lieve River, Belgium, based on manually conducted waterbird counts and water quality data collected from 48 transects in March 2024. Localized eutrophication was evident, with TN (2.7–5.6 mg L⁻¹), TP (up to 0.46 mg L⁻¹), and chlorophyll-a (median 70 ppb) exceeding environmental thresholds. Prati index analysis revealed that 58.3% of the sampling points along the Lieve River were categorized as “polluted”, reflecting extensive water quality degradation. Eurasian coots (71.4%) and wild ducks (72.4%) were predominantly found in polluted areas, thriving in nutrient-enriched habitats linked to high TP levels. In contrast, common moorhens (80.3%) preferred acceptable quality areas, indicating higher water quality requirements. These findings indicate that phosphate is a key driver of waterbody eutrophication, as evidenced by the TP concentrations measured on-site, which far exceed the thresholds set by environmental standards. Future research should explore advanced monitoring approaches to improve waterbird and water quality assessments, ensuring the conservation of the Lieve River as one of Europe’s oldest artificial canals, and the protection of its waterbird habitats. Full article

(This article belongs to the Special Issue Freshwater Ecosystems—Biodiversity and Protection)

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23 pages, 22633 KiB

Open AccessArticle

The Toppling Deformation and Failure Criteria of a Steep Bedding Rock Slope—The Case of a Bank Slope at the Duonuo Hydropower Station

by Tiantao Li, Xuan Li, Kaihong Wei, Jian Guo, Xi Heng, Jing Yuan, Weiling Ran and Xiangjun Pei

Water 2025, 17(4), 594; https://doi.org/10.3390/w17040594 - 18 Feb 2025

Viewed by 293

Abstract

In this study, statistical analysis was conducted to categorize a large number of actual typical cases and analyze the formation conditions of toppling deformation in bedding rock slopes. Based on geological prototypes and similarity theory, a bottom friction test was conducted on the [...] Read more.

In this study, statistical analysis was conducted to categorize a large number of actual typical cases and analyze the formation conditions of toppling deformation in bedding rock slopes. Based on geological prototypes and similarity theory, a bottom friction test was conducted on the toppling deformable body while considering the excavation process. Based on the deformation and failure phenomena observed in the bottom friction test model, along with the displacement curves at key points, the deformation process in steep bedding rock slopes can be divided into the following five distinct stages: the initial phase, the unloading–rebound phase, the tensile failure phase, the bending creep phase, and the bending–toppling damage phase. To evaluate the stability, a new constitutive model of the nonlinear viscoelastic–plastic rheology of rock masses was developed. This model is based on a nonlinear function derived from analyzing the creep test data of rock masses under fractional loading. Furthermore, a mechanical equilibrium differential equation for rock slabs was formulated to quantitatively describe the aging deformation and failure processes of slopes with delayed instability. Finally, a stability criterion and a quantitative evaluation model for toppling deformation slopes that considered time-varying factors were established. The stability of the model was calculated using a hydropower station slope case, and the results were found to be in good agreement with the actual situation. Full article

(This article belongs to the Special Issue Damage to Natural and Engineering Slopes (Dam Slopes) Caused by Water: Mechanism, Risk Assessment, Monitoring, Warning, and Prevention Technology)

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22 pages, 3998 KiB

Open AccessArticle

Fly Ash Waste Conversion to Zeolite and Its Application for Cd²⁺ and Ni²⁺ Adsorption from Aqueous Solutions

by Mirela Alina Constantin, Lucian Alexandru Constantin, Florenta Daniela Constantinov, Valeriu Robert Badescu, Cristina Mihaela Nicolescu and Marius Bumbac

Water 2025, 17(4), 593; https://doi.org/10.3390/w17040593 - 18 Feb 2025

Viewed by 281

Abstract

Adsorption methods represent a common practice used for heavy metals removal from aqueous solutions. As adsorbent material, zeolites have an excellent adsorption capacity and present low environmental impact. The zeolite used for this study was synthesized from fly ash, a residue generated by [...] Read more.

Adsorption methods represent a common practice used for heavy metals removal from aqueous solutions. As adsorbent material, zeolites have an excellent adsorption capacity and present low environmental impact. The zeolite used for this study was synthesized from fly ash, a residue generated by thermal power plants, considering the need to reduce fly ash deposits and transform it into useful materials as part of the circular economy. Fly ash conversion to zeolite was performed via a modified hydrothermal method. To investigate the synthetic zeolite structure Scanning Electronic Microscopy, Fourier Transformed Infrared spectroscopy, X-ray diffraction and Raman spectroscopy were used. Chemical composition was revealed by X-ray Fluorescence and thermal behavior was investigated by thermogravimetric analysis. The influence of adsorbent dose and pH upon adsorption capacity of synthesized zeolite for Ni²⁺ and Cd²⁺ was investigated. The effect of contact time on the adsorption capacity of Cd²⁺ and Ni²⁺ was evaluated and it was found that the system reaches equilibrium after 30 min for Ni²⁺ and 60 min for Cd²⁺ due to the saturation of zeolite pores with metallic ions. It was found that the Langmuir model (Lineweaver-Burk equation) better describes the adsorption of both Ni²⁺ and Cd²⁺. The adsorption kinetics obeys the pseudo-second-order kinetic model (k₂ = 0.0851 g/mg min for Ni²⁺ and k₂ = 0.1780 g/mg min for Cd²⁺). The adsorption capacity of synthesized was found to be 13 mg/g for Ni²⁺ (initial Ni²⁺ solution concentration = 30 mg/L) and 17 mg/g for Cd²⁺ (initial Cd²⁺ solution concentration = 35 mg/L) at an adsorbent dose of 2 g/L and a contact time of 30 min. Reusability of the zeolite was also tested and it was found that it can be used for 5 cycles. The experimental study revealed that zeolite obtained from fly ash waste generated by a thermal plant represents a viable and sustainable alternative for removal Cd²⁺ and Ni²⁺ from aqueous solution. Full article

(This article belongs to the Special Issue Removal of Heavy Metals and Other Pollutants from Aqueous Solutions)

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16 pages, 4171 KiB

Open AccessArticle

Study on the Impact of Seepage Filtration Under Wet–Dry Cycles on the Stability of Mudstone Limestone Slopes

by Rui Li, Puyi Wang, Xiang Lu, Wei Zhou, Yihan Guo, Rongbo Lei, Zixiong Zhao, Ziyu Liu and Yu Tian

Water 2025, 17(4), 592; https://doi.org/10.3390/w17040592 - 18 Feb 2025

Viewed by 318

Abstract

Open-pit mining often exposes weak rock layers, the strength of which significantly affects the stability of slopes. If these rock layers are also prone to disintegration and expansion, cyclic rainfall can exacerbate instability. Rainfall-induced changes in the seepage field also indirectly threaten the [...] Read more.

Open-pit mining often exposes weak rock layers, the strength of which significantly affects the stability of slopes. If these rock layers are also prone to disintegration and expansion, cyclic rainfall can exacerbate instability. Rainfall-induced changes in the seepage field also indirectly threaten the stability of slopes. Therefore, investigating the characteristics of mudstone limestone and the impact of the seepage field on slope instability under different wet–dry cycles is of great significance for the safe mining of open-pit mines. This paper takes the mudstone limestone slope of a certain open-pit mine in the southwest as the starting point and conducts experiments on saturated density, water absorption rate, permeability coefficient, compressive strength, and variable angle shear strength. Combined with scanning electron microscopy and phase analysis of X-ray diffraction analysis, the macroscopic and microscopic characteristics of the samples are comprehensively analyzed. FLAC3D software is used to explore the changes in the seepage field and the mechanism of instability. Our research found that for the preparation of mudstone limestone samples, a particle size of less than 1 mm and a drying temperature of 50 °C are optimal, with specific values for initial natural and saturated density, and natural water content. As the number of wet–dry cycles increases, the saturated density of mudstone limestone increases; the water absorption rate first rises sharply and then rises slowly; the permeability coefficient first rises sharply and then stabilizes, finally dropping sharply; the compressive and shear strength decreases slowly, and the internal friction angle changes little; frequent cycles also lead to mudification and seepage filtration. At the microscopic level, pores become larger and more regular, and the distribution is more concentrated; changes in mineral content weaken the strength. Combined with numerical simulation, the changes in the seepage field at the bottom of the slope exceed those at the slope surface and top, the transient saturated area expands, and the overall and local slope stability coefficients gradually decrease. During the third cycle, the local stability is lower than the overall stability, and the landslide trend shifts. In conclusion, wet–dry cycles change the pores and mineral content, affecting the physical and mechanical properties, leading to the deterioration of the transient saturated area, a decrease in matrix suction, and an increase in surface gravity, eventually causing slope instability. Full article

(This article belongs to the Special Issue Geotechnic and Geostructure Modelling for Landslides: Prediction and Control)

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15 pages, 2707 KiB

Open AccessArticle

Determination of the Occurrence of Trihalomethanes in the Drinking Water Supply of the City of Cuenca, Ecuador

by Bolívar Hernández, Paola Duque-Sarango, María Dolores Tonón, Mónica Abril-González, Verónica Pinos-Vélez, Cristian R. García-Sánchez and Manuel J. Rodríguez

Water 2025, 17(4), 591; https://doi.org/10.3390/w17040591 - 18 Feb 2025

Viewed by 461

Abstract

Water chlorination, fundamental for its microbiological safety, generates by-products, such as trihalomethanes (THMs), potentially associated with carcinogenic and reproductive risks. This study determined the levels of chloroform (CHCl₃) in drinking water in Cuenca, Ecuador, a topic that has been little explored [...] Read more.

Water chlorination, fundamental for its microbiological safety, generates by-products, such as trihalomethanes (THMs), potentially associated with carcinogenic and reproductive risks. This study determined the levels of chloroform (CHCl₃) in drinking water in Cuenca, Ecuador, a topic that has been little explored in the region. During five months, water samples were collected from three water treatment systems (Cebollar, Tixan, and Sustag), and in situ measurements of physicochemical parameters such as free chlorine, pH, temperature, electrical conductivity, and turbidity were performed in the storage and distribution area. The determination of CHCl₃ was performed following the Hach protocol. For data analysis, the Kruskal–Wallis test was employed, followed by Dunn’s post hoc method and Spearman’s correlation coefficient. The results revealed a progressive decrease in free residual chlorine throughout the distribution systems. CHCl₃ concentrations ranged from 11.75 µg/L to 21.88 µg/L, remaining below the Ecuadorian regulatory limit of 300 µg/L. There was no consistent correlation between CHCl₃ and physicochemical parameters. These findings align with previous research, suggesting that the variability in CHCl₃ formation is associated with different water treatment conditions and environmental variables. This study highlights the importance of monitoring disinfection processes to minimize THMs and other DBPs, ensure public health, and contribute to sustainable drinking water management in Ecuador. Full article

(This article belongs to the Special Issue Occurrence, Risk Assessment and Removal of Emerging Contaminants in Aquatic Environment)

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18 pages, 4080 KiB

Open AccessArticle

Removal Efficiency and Mechanism of Typical PPCPs onto Novel Cyclodextrin–Graphene Oxide Composite Adsorbent in Aqueous Solutions

by Ziyang Zhang, Wenhui Wang, Fangyuan Liu, Hongrui Chen, Xiaoran Zhang, Chaohong Tan and Yongwei Gong

Water 2025, 17(4), 590; https://doi.org/10.3390/w17040590 - 18 Feb 2025

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Abstract

A novel β-cyclodextrin–graphene oxide (β-CD/GO) composite adsorbent was synthesized via a hydrothermal method. Removal efficiency and mechanisms of typical pharmaceutical and personal care products (PPCPs) by the β-CD/GO composite were investigated in aqueous solutions. The results demonstrated that the β-CD/GO composite was successfully [...] Read more.

A novel β-cyclodextrin–graphene oxide (β-CD/GO) composite adsorbent was synthesized via a hydrothermal method. Removal efficiency and mechanisms of typical pharmaceutical and personal care products (PPCPs) by the β-CD/GO composite were investigated in aqueous solutions. The results demonstrated that the β-CD/GO composite was successfully formed through cross-linking between β-CD and GO nanosheets, exhibiting enriched hydroxyl groups, a porous layered structure, and good thermal stability. The adsorption of cimetidine (CTD), sulfamethazine (SMZ), and diclofenac (DCF) onto the β-CD/GO composite was well described by pseudo-first-order and pseudo-second-order kinetic models, and Langmuir isotherm. The maximum adsorption capacities of CTD, SMZ, and DCF onto the β-CD/GO composite were 58.86, 35.62, and 29.11 mg g⁻¹ at 298 K, respectively. The adsorption process was rapid and reached equilibrium after 6 h. The adsorption followed a monolayer mechanism and was an exothermic process. The adsorption capacity decreased with increasing pH values and ion concentrations. The β-CD/GO composite exhibited maximum adsorption capacities of 17.69, 16.96, and 16.23 mg g⁻¹ for CTD, SMZ, and DCF, respectively, under a pH of 4 with a dosage of 1.0 g/L at 298 K for 6 h. Due to the combined impacts of electrostatic interaction, hydrogen bonding, and host–guest interaction, the adsorption of PPCPs onto β-CD/GO composite was fast and efficient. β-CD/GO composite exhibited superior adsorption efficacy and structural stability, which highlighted its promising application in the elimination of micropollutants from aqueous solutions. Full article

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19 pages, 7805 KiB

Open AccessArticle

Design and Test of a Cavitation Water Jet Net Box Cleaning Device Based on Ansys Fluent

by Yuke Xiong, Qingsong Xue, Kuo Li, Lei Bao, Zhixuan Fu, Zibo Liu and Hanbing Zhang

Water 2025, 17(4), 589; https://doi.org/10.3390/w17040589 - 18 Feb 2025

Viewed by 232

Abstract

This study addresses the issue of biofouling on marine aquaculture cages, where organisms like algae and purple mussels negatively impact both the safety of the aquaculture environment and the integrity of the cages. To solve this problem, the paper introduces a cage cleaning [...] Read more.

This study addresses the issue of biofouling on marine aquaculture cages, where organisms like algae and purple mussels negatively impact both the safety of the aquaculture environment and the integrity of the cages. To solve this problem, the paper introduces a cage cleaning device based on the cavitation jet principle. Using finite volume simulation software, the cavitation process of the device’s nozzle was modeled, with the gas-phase volume fraction used as the evaluation metric. Key experimental factors, such as the second section throat contraction angle, second section throat radius, and end diffusion angle, were analyzed through single-factor and quadratic regression orthogonal experiments to assess their effect on the cavitation performance. The optimal combination of nozzle parameters was determined to be a second section throat contraction angle of 41.047°, a second section throat radius of 0.834 mm, and an end diffusion angle of 35.495°. Under these conditions, the gas-phase volume fraction reached 0.941, indicating optimal cavitation performance. To validate these findings and further optimize the nozzle’s operational parameters, a nozzle cavitation test bench was constructed. Test results demonstrated that when the target distance was set at 15 mm and the angle at 20°, the surface roughness and maximum surface depth of the target were 6.215 μm and 22.030 μm, respectively, with the nozzle exhibiting the best cavitation effect at these settings. This nozzle design meets the requirements for efficient mesh cleaning, and the research provides valuable insights for future development and optimization of cleaning devices for aquaculture net cages. Full article

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13 pages, 2946 KiB

Open AccessArticle

Impact of the Reynolds Numbers on the Velocity of Floating Microplastics in Open Channels

by Jiachen Li, Zhichao Wang, Weiping Li, Shuangyi Jing, Caio Graco-Roza and Lauri Arvola

Water 2025, 17(4), 588; https://doi.org/10.3390/w17040588 - 18 Feb 2025

Viewed by 310

Abstract

Quantitatively analyzing the factors influencing the horizontal migration of microplastics (MPs) in water bodies and understanding their movement patterns are crucial for explaining and predicting their transport principles and final destinations. This study used nearly spherical polyethylene (PE), polypropylene (PP), and polystyrene (PS) [...] Read more.

Quantitatively analyzing the factors influencing the horizontal migration of microplastics (MPs) in water bodies and understanding their movement patterns are crucial for explaining and predicting their transport principles and final destinations. This study used nearly spherical polyethylene (PE), polypropylene (PP), and polystyrene (PS) MPs as experimental subjects. By tracking their motion characteristics through video recording, we established relationships among the Reynolds number (Re), MP density, and floating velocity. The results showed that the Re and MP density jointly affect the horizontal drift of MPs. The horizontal floating velocity of MPs significantly increases with the increase in the Re and shows a power function growth trend. The difference in density of MPs mainly affects their dispersion during the floating process. Moreover, the coefficient of variation (CV) of PP’s horizontal floating velocity increased with the Re, suggesting PP’s motion is more random and discrete than that of PE and PS. Ultimately, we fitted the horizontal floating velocity of MPs to the equation to comprehensively evaluate the relationship between the floating velocity, Re, and density of MPs. This analysis underscores that the Re predominantly influences the MP velocity in water, while the MP density chiefly impacts the discrete nature of their motion. Full article

(This article belongs to the Special Issue Mathematical, Physical, Chemical, and Biological Methods for Ice and Water Problems)

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16 pages, 6476 KiB

Open AccessArticle

Investigation of the Anion Migration Mechanism in Microbial Desalination Cells: Interaction and Actual Operational Impact

by Jinyue Liang, Yong Gao, Wei Wu, Siqi Tong and Yi Wang

Water 2025, 17(4), 587; https://doi.org/10.3390/w17040587 - 18 Feb 2025

Viewed by 254

Abstract

Microbial desalination cells (MDCs) are an efficient method for the desalination of saline wastewater driven by the metabolism of bacteria via an organic oxidation mechanism. Systematic studies have been conducted to elucidate anion-dominated interactions to avoid unforeseen risks in microbial desalination cells during [...] Read more.

Microbial desalination cells (MDCs) are an efficient method for the desalination of saline wastewater driven by the metabolism of bacteria via an organic oxidation mechanism. Systematic studies have been conducted to elucidate anion-dominated interactions to avoid unforeseen risks in microbial desalination cells during the long-term treatment of complex wastewater containing various anions. Despite different anion migration interactions having less effect on MDC operation compared with cations, they are influenced by their own properties (hydrated ion radius, diffusion coefficient and equivalent conductance) and the ambient solution. This also led to the removal efficiency of different anions in MDC in the following sequence: NO₃⁻ > Cl⁻ > SO₄²⁻. The high Gibbs hydration energy of SO₄²⁻ and the hydrophobicity of the anion exchange membrane affect the transmembrane migration of SO₄²⁻. However, the high steric hindrance formed on the membrane also inhibits reverse diffusion at the end of the cycle. In addition, the anodic biotopography and community caused by the migration of different anions change, such that the number of denitrifying bacteria increases and the relative abundance of electrogenic bacteria further improves. With decreasing anodic pH, electrogenic microorganisms form a shell to protect against anodic biogenesis. In this study, MDC was used to treat actual industrial tailwater, and the salt removal efficiency stabilized at 63.2–74.1%. Full article

(This article belongs to the Special Issue Low-Carbon Wastewater Treatment and Resource Recovery)

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11 pages, 3085 KiB

Open AccessArticle

Development of a Practical Surface Image Flowmeter for Small-Sized Streams

by Kwonkyu Yu, Junhyeong Lee and Byungman Yoon

Water 2025, 17(4), 586; https://doi.org/10.3390/w17040586 - 18 Feb 2025

Viewed by 239

Abstract

The purpose of this study was to demonstrate the series of processes involved in designing, manufacturing, installing, and operating a practical Surface Image Flowmeter (SIF) system, complete with suitable hardware and software. By ‘practical’, we mean a system capable of automatically measuring discharges [...] Read more.

The purpose of this study was to demonstrate the series of processes involved in designing, manufacturing, installing, and operating a practical Surface Image Flowmeter (SIF) system, complete with suitable hardware and software. By ‘practical’, we mean a system capable of automatically measuring discharges in a river 24 h a day, 365 days a year, at 2 min intervals. The equipment required for this practical SIF includes a CCTV camera, a water level gauge, a Linux-based PC for analysis, and lighting for night-time measurements. We also developed software to operate the system. Furthermore, we applied a coordinate transformation method using projective transformation to calculate the area of the measurement cross-section according to changes in water level and to adjust the positions of velocity analysis points within the image. The CCTV captured 20 s video clips every 2 min, which were then analyzed using the Spatio-Temporal Image Velocimetry (STIV) method. For the STIV method, measurement points were set at appropriate intervals on the measurement cross-section, and spatio-temporal images (STIs) were constructed at these points for analysis. The STIs were captured parallel to the main flow direction (perpendicular to the cross-section), and the resulting STIs were analyzed using the hybrid STIV method to calculate the discharge. When the constructed SIF system was tested in a steep-sloped channel at the Andong River Experiment Center, the velocity distribution showed a difference of less than 9% compared to measurements from a traditional current meter, and the discharge showed a difference of around 10% compared to measurements from an Acoustic Doppler Current Profiler (ADCP). Full article

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13 pages, 2881 KiB

Open AccessArticle

Can Climate-Resilient Tilapia Cage Culture Support Sustainable Livelihoods in Flood-Prone Bangladesh?

by Mohammed Ariful Islam, Mrityunjoy Kunda, Ahmed Harun-Al-Rashid, Atiqur Rahman Sunny, Mahmudul Hasan Mithun, Sharif Ahmed Sazzad and Md Khurshid Alam Bhuiyan

Water 2025, 17(4), 585; https://doi.org/10.3390/w17040585 - 18 Feb 2025

Viewed by 303

Abstract

The Haor region in northeastern Bangladesh, characterized by seasonal wetlands and a heavy reliance on fisheries, faces significant challenges due to climate change. Erratic rainfall, prolonged flooding, and ecosystem degradation threaten traditional fishing practices and community livelihoods. This study investigates the potential of [...] Read more.

The Haor region in northeastern Bangladesh, characterized by seasonal wetlands and a heavy reliance on fisheries, faces significant challenges due to climate change. Erratic rainfall, prolonged flooding, and ecosystem degradation threaten traditional fishing practices and community livelihoods. This study investigates the potential of climate-resilient cage aquaculture as a sustainable, alternative income-generating solution for vulnerable Haor communities. An 80-day experiment was conducted in five villages of Sunamganj district, Sylhet division, Bangladesh, where tilapia (Oreochromis niloticus) fry were reared in climate-resilient floating cages at five stocking densities: T1 (800 fry/m³), T2 (900 fry/m³), T3 (1000 fry/m³), T4 (1100 fry/m³), and T5 (1200 fry/m³). Key environmental parameters, including temperature (28.12–29.55 °C), dissolved oxygen (4.61–6.55 mg/L), pH (7.53–7.72), and ammonia (0.05–0.76 mg/L), remained within optimal ranges across treatments. Growth performance, survival rate, and economic feasibility were evaluated with T5 yielding the highest gross production (51.77 ± 4.80 kg/m³) and net benefits (7500 ± 500 BDT/m³), achieving a benefit–cost ratio of 1:2.86. The survey findings revealed that a majority of fishers (82%) identified tilapia cage culture as a promising alternative livelihood, yet financial constraints and limited access to credit hinder adoption. Despite these socioeconomic challenges, our findings suggest that tilapia cage culture offers a viable income-generating solution, particularly during flood periods. The study highlights floating cage aquaculture as a climate-resilient strategy to mitigate climate impacts, enhance food security, and improve economic resilience in flood-prone and ecologically sensitive regions. Full article

(This article belongs to the Special Issue Impact of Climate Change on Marine Ecosystems)

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9 pages, 771 KiB

Open AccessArticle

Trends in Compliance Monitoring Devices (CMDs) in Ships’ Ballast Water Treatment Systems

by Fikile Portia Ndlovu

Water 2025, 17(4), 584; https://doi.org/10.3390/w17040584 - 18 Feb 2025

Viewed by 194

Abstract

The International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM Convention) in 2024, gives us at least 7 years of data to analyze accounting for technology samples in marine and ships’ ballast water monitoring and forecasting. Marine technology [...] Read more.

The International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM Convention) in 2024, gives us at least 7 years of data to analyze accounting for technology samples in marine and ships’ ballast water monitoring and forecasting. Marine technology played a crucial role in closing the gap between the adoption of the Convention and its coming into force, a 13-year gap that involved world-wide experimentation and investment in marine technologies which had to be approved for compliance by the International Maritime Organization (IMO) as well as Port States. Compliance Monitoring Devices (CMDs) with rapid results have been generally used in providing marine environmental invasion controls and have been used by Port States to enforce compliance in ballast water management. Qualitative, regulatory and quantitative data have been synthesized in this study from select experiments to test for compliance monitoring success. Going forward, rapid result devices will remain ideal in ship and port time management, particularly with a move towards electronic ballast water record books which also serve as an important forecasting tool for compliance as such data can be pre-delivered to the electronic records of the Port State for reaction prior to ship arrival, that way major issues can be dealt with while the ship is en voyage, for pre-emptive national security measures. Full article

(This article belongs to the Special Issue Monitoring and Forecasting Technologies for Marine Environments and Hazards)

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1 pages, 120 KiB

Open AccessCorrection

Correction: Patel et al. Application of the Weighted Arithmetic Water Quality Index in Assessing Groundwater Quality: A Case Study of the South Gujarat Region. Water 2023, 15, 3512

by Divya D. Patel, Darshan J. Mehta, Hazi M. Azamathulla, Mohdzuned Mohmedraffi Shaikh, Shivendra Jha and Upaka Rathnayake

Water 2025, 17(4), 583; https://doi.org/10.3390/w17040583 - 18 Feb 2025

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Abstract

There was an error in the original publication [...] Full article

14 pages, 2992 KiB

Open AccessArticle

Exploratory Analysis on the Chemical Composition of Aquatic Macrophytes in a Water Reservoir—Rio de Janeiro, Brazil

by Robinson Antonio Pitelli, Rafael Plana Simões, Robinson Luiz Pitelli, Rinaldo José da Silva Rocha, Angélica Maria Pitelli Merenda, Felipe Pinheiro da Cruz, Antônio Manoel Matta dos Santos Lameirão, Arilson José de Oliveira Júnior and Ramon Hernany Martins Gomes

Water 2025, 17(4), 582; https://doi.org/10.3390/w17040582 - 18 Feb 2025

Viewed by 330

Abstract

This study explores the chemical composition of different macrophyte species and infers their potential in extracting nutrients and some heavy metals from water as well as the use of macrophytes’ biomass as natural fertilizers. It used a dataset obtained from a previous study [...] Read more.

This study explores the chemical composition of different macrophyte species and infers their potential in extracting nutrients and some heavy metals from water as well as the use of macrophytes’ biomass as natural fertilizers. It used a dataset obtained from a previous study composed of 445 samples of chemical concentrations in the dried biomass of 16 macrophyte species collected from the Santana Reservoir in Rio de Janeiro, Brazil. Correlation tests, analysis of variance, and factor analysis of mixed data were performed to infer correspondences between the macrophyte species. The results showed that the macrophyte species can be grouped into three different clusters with significantly different profiles of chemical element concentrations (N, P, K⁺, Ca²⁺, Mg²⁺, S, B, Cu²⁺, Fe²⁺, Mn²⁺, Zn²⁺, Cr³⁺, Cd²⁺, Ni²⁺, Pb²⁺) in their biomass (factorial map from PCA). Most marginal macrophytes have a lower concentration of chemical elements (ANOVA p-value < 0.05). Submerged and floating macrophyte species presented a higher concentration of metallic and non-metallic chemical elements in their biomass (ANOVA p-value < 0.05), revealing their potential in phytoremediation and the removal of toxic compounds (such as heavy metal molecules) from water. A cluster of macrophyte species also exhibited high concentrations of macronutrients and micronutrients (ANOVA p-value < 0.05), indicating their potential for use as soil fertilizers. These results reveal that the plant’s location in the reservoir (marginal, floating, or submerged) is a relevant feature associated with macrophytes’ ability to remove chemical components from the water. The obtained results can contribute to planning the management of macrophyte species in large water reservoirs. Full article

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16 pages, 9783 KiB

Open AccessArticle

Mineralogical and Chemical Characteristics of Sediments in the Lhasa River Basin: Implications for Weathering and Sediment Transport

by Heyulu Zhang, Tianning Li, Changping Mao, Zhengjin Song and Wenbo Rao

Water 2025, 17(4), 581; https://doi.org/10.3390/w17040581 - 18 Feb 2025

Viewed by 221

Abstract

The Lhasa River, as one of the major rivers on the Tibetan Plateau, is of great value for the study of climate and environmental changes on the Tibetan Plateau. In this paper, the grain size and the mineralogical and geochemical characteristics of the [...] Read more.

The Lhasa River, as one of the major rivers on the Tibetan Plateau, is of great value for the study of climate and environmental changes on the Tibetan Plateau. In this paper, the grain size and the mineralogical and geochemical characteristics of the sediments from the Lhasa River were investigated. The results show the following: (1) The average grain size of the Lhasa River sediments is coarse (65.5% sand, 23.6% silt), and the sorting is overall poor; the skewness is mostly positive, and the kurtosis is wide, which reflects the obvious characteristics of river sand deposition. (2) The mineral composition of the Lhasa River sediments is dominated by quartz (38.4%), feldspar, and plagioclase feldspar, followed by clay minerals, and the content of carbonate minerals is relatively low; the content of clay minerals in the illite content is as high as 83.3%, while the chlorite content is slightly higher than kaolinite, and smectite content is very low. The chemical index of illite is less than 0.4, indicating that illite is mainly iron-rich magnesium illite. (3) The value of the chemical weathering index (CIA) of the sediments is low, implying that the sediments are in a weak–moderate chemical weathering state and dominated by physical weathering. Comprehensive analyses further revealed that the weathering process of the sediments in the Lhasa River was influenced by both climate and lithology, i.e., sediment composition is influenced not only by chemical weathering in a dry, cold climate but also by physical weathering of granites exposed over large areas. The results of this study can provide scientific references for further in-depth research on the environmental and climatic effects of the Tibetan Plateau. Full article

(This article belongs to the Section Water Erosion and Sediment Transport)

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4 pages, 129 KiB

Open AccessEditorial

Water Quality Engineering and Wastewater Treatment III

by Yung-Tse Hung, Rehab O. Abdel Rahman, Hamidi Abdul Aziz, Issam A. Al-Khatib and Tsuyoshi Imai

Water 2025, 17(4), 580; https://doi.org/10.3390/w17040580 - 18 Feb 2025

Viewed by 414

Abstract

The provision of clean water is a vital element to ensure life sustainability; this can be achieved by designing and implementing effective prevention and control measures to protect water resources [...] Full article

(This article belongs to the Special Issue Water Quality Engineering and Wastewater Treatment III)

21 pages, 757 KiB

Open AccessReview

The Need to Increase Strain-Specific DNA Information from the Invasive Cyanobacteria Sphaerospermopsis aphanizomenoides and Cuspidothrix issatschenkoi

by Daniela R. de Figueiredo

Water 2025, 17(4), 579; https://doi.org/10.3390/w17040579 - 17 Feb 2025

Viewed by 423

Abstract

Climate change is promoting the occurrence of Harmful Cyanobacterial Blooms (HCBs) across freshwaters, posing serious risks for the ecosystems and human health. Under these warmer conditions, particularly blooms of invasive Aphanizomenon-like species such as Cuspidothrix issatschenkoi and Sphaerospermopsis aphanizomenoides (previously known as [...] Read more.

Climate change is promoting the occurrence of Harmful Cyanobacterial Blooms (HCBs) across freshwaters, posing serious risks for the ecosystems and human health. Under these warmer conditions, particularly blooms of invasive Aphanizomenon-like species such as Cuspidothrix issatschenkoi and Sphaerospermopsis aphanizomenoides (previously known as Aphanizomenon issatschenkoi and Aphanizomenon/Anabaena aphanizomenoides, respectively) have been reported to spread to higher latitudes, leading to increased toxic risks. Aphanizomenon and Anabaena genera have undergone several taxonomical revisions in recent years due to their morphological ambiguity, also corroborated by a high phylogenetic diversity. Furthermore, there is also a high phenotypic and genotypic variability within each one of these species, leading to diverse physiological and ecological traits. Therefore, DNA-based information is crucial not only to overcome possible species misidentifications, but also to provide information at the strain level. However, for the invasive Cuspidothrix issatschenkoi and Sphaerospermopsis aphanizomenoides, there is still a lack of geographically dispersed strains with available nucleotide sequences in databases, limiting deeper ecological studies to better understand their ecology and invasive trend. This review aimed to compile and discuss the geographical distribution of Cuspidothrix issatschenkoi and Sphaerospermopsis aphanizomenoides strains found in the NCBI nucleotide database and make some recommendations on the need to increase these numbers under the exponential inputs from DNA-metabarcoding. The integration of DNA-based information in water quality monitoring programmes is crucial to identify reoccurring bloom-forming strains and better understand their physiology and invasive ecology, ultimately leading to their effective forecast, and mitigation of their potential massive growth in target freshwater bodies. Full article

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20 pages, 3264 KiB

Open AccessArticle

Energy of Sorghum Biomass Under Deficit Irrigation Strategies in the Mediterranean Area

by Simone Pietro Garofalo, Anna Francesca Modugno, Gabriele de Carolis and Pasquale Campi

Water 2025, 17(4), 578; https://doi.org/10.3390/w17040578 - 17 Feb 2025

Viewed by 242

Abstract

The growing demand for renewable energy sources and the need to optimize water use in agriculture, particularly in water-scarce regions, highlights the importance of growing species suitable for semi-arid areas, such as sorghum (Sorghum bicolor L. Moench). Deficit irrigation strategies allow water [...] Read more.

The growing demand for renewable energy sources and the need to optimize water use in agriculture, particularly in water-scarce regions, highlights the importance of growing species suitable for semi-arid areas, such as sorghum (Sorghum bicolor L. Moench). Deficit irrigation strategies allow water savings by optimizing water use efficiency. However, the potential of sorghum for bioethanol production with deficit irrigation strategies is still not well studied. This work investigates the impact of three irrigation strategies (full, deficit, and regulated deficit) on the biomass yield, ethanol production, and water use efficiency of sorghum (‘KWS Bulldozer’) in a semi-arid Mediterranean area (the Apulia region, Southeastern Italy) over three growing seasons (2013, 2014, and 2017); irrigation needs were calculated from crop evapotranspiration using standard crop coefficients and soil water content measurements. Harvested biomass was analyzed for cellulose and hemicellulose content, and ethanol production was estimated using conversion models. The full irrigation treatment resulted in the highest biomass and ethanol production in all seasons (22,633 kg × ha⁻¹, 28,367 kg × ha⁻¹, and 23,835 kg × ha⁻¹, in 2013, 2014, and 2017, respectively), highlighting the relationship between a full water supply and yield optimization. However, deficit irrigation showed a higher biomass and ethanol water productivity (10.93 kg × m⁻³ and 3.23 L × m⁻³, respectively) than other treatments, suggesting that moderate irrigation strategies can effectively balance production and sustainable water use. The results suggest the importance of adjusting irrigation practices to specific environmental conditions to improve the efficiency and productivity of sorghum. Full article

(This article belongs to the Special Issue Agricultural Practices to Improve Irrigation Sustainability, 2nd Edition)

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19 pages, 2621 KiB

Open AccessArticle

Multi-Scale Debris Flow Warning Technology Combining GNSS and InSAR Technology

by Xiang Zhao, Linju He, Hai Li, Ling He and Shuaihong Liu

Water 2025, 17(4), 577; https://doi.org/10.3390/w17040577 - 17 Feb 2025

Viewed by 305

Abstract

The dynamic loads of fluid impact and static loads, such as the gravity of a rock mass during the formation of debris flows, exhibit a coupled effect of mutual influence. Under this coupling effect, surface monitoring points in disaster areas experience displacement. However, [...] Read more.

The dynamic loads of fluid impact and static loads, such as the gravity of a rock mass during the formation of debris flows, exhibit a coupled effect of mutual influence. Under this coupling effect, surface monitoring points in disaster areas experience displacement. However, existing methods do not consider the dynamic–static coupling effects of debris flows on the surface. Instead, they rely on GNSS or InSAR technology for dynamic or static single-scale monitoring, leading to high Mean Absolute Percentage Error (MAPE) values and low warning accuracy. To address these limitations and improve debris flow warning accuracy, a multi-scale warning method was proposed based on Global Navigation Satellite System (GNSS) and Synthetic Aperture Radar Interferometry (InSAR) technology. GNSS technology was utilized to correct coordinate errors at monitoring points, thereby enhancing the accuracy of monitoring data. Surface deformation images were generated using InSAR and Small Baseline Subset (SBAS) technology, with time series calculations applied to obtain multi-scale deformation data of the surface in debris flow disaster areas. A debris flow disaster morphology classification model was developed using a support vector mechanism. The actual types of debris flow disasters were employed as training labels. Digital Elevation Model (DEM) files were utilized to extract datasets, including plane curvature, profile curvature, slope, and elevation of the monitoring area, which were then input into the training model for classification training. The model outputted the classification results of the hidden danger areas of debris flow disasters. Finally, the dynamic and static coupling variables of surface deformation were decomposed into valley-type internal factors (rock mass static load) and slope-type triggering factors (fluid impact dynamic load) using the moving average method. Time series prediction models for the variable of the dynamic–static coupling effects on surface deformation were constructed using polynomial regression and particle swarm optimization (PSO)–support vector regression (SVR) algorithms, achieving multi-scale early warning of debris flows. The experimental results showed that the error between the predicted surface deformation results using this method and the actual values is less than 5 mm. The predicted MAPE value reached 6.622%, the RMSE value reached 8.462 mm, the overall warning accuracy reached 85.9%, and the warning time was under 30 ms, indicating that the proposed method delivered high warning accuracy and real-time warning. Full article

(This article belongs to the Special Issue Flowing Mechanism of Debris Flow and Engineering Mitigation)

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23 pages, 21288 KiB

Open AccessArticle

Analysis of Detailed Series Based on the Estimation of Hydrogeological Parameters by Indirect Methods Based on Fluvial and Piezometric Fluctuations

by José Luis Herrero-Pacheco, Javier Carrasco and Pedro Carrasco

Water 2025, 17(4), 576; https://doi.org/10.3390/w17040576 - 17 Feb 2025

Viewed by 317

Abstract

Piezometers located near watercourses experiencing periodic fluctuations provide a means to analyse soil properties and derive key hydrogeological parameters through pressure wave transmission analysis, which is affected in amplitude and time (lag). These techniques are invaluable for hydrogeological characterizations, such as assessing pollutant [...] Read more.

Piezometers located near watercourses experiencing periodic fluctuations provide a means to analyse soil properties and derive key hydrogeological parameters through pressure wave transmission analysis, which is affected in amplitude and time (lag). These techniques are invaluable for hydrogeological characterizations, such as assessing pollutant diffusion, conducting construction projects below the water table, and evaluating flood zones. While traditionally applied to study tidal influences in coastal areas, this research introduces their application to channels indirectly affected by tidal oscillations due to downstream confluences with tidal waterways. This innovative approach combines the analysis of tidal barriers with the effects of storms and droughts. This study synthesises findings from an experimental monitoring field equipped with advanced recording technologies, allowing for high-resolution, long-term analysis. The dataset, spanning dry periods, major storms, and channel overflows, offers unprecedented precision and insight into aquifer responses. This study analyses the application of wave transmission calculations using continuous level recording in a river and in observation piezometers. Two methods of analysis are applied to the series generated, one based on the variation in the amplitude and the other based on the phase shift produced by the transmission of the wave through the aquifer, both related to the hydrogeological characteristics of the medium. This study concludes that the determination of the fluctuation period is key in the calculation, being particularly more precise in the analysis of the amplitude than in the analysis of the phase difference, which has led to disparate results in previous studies. The results obtained make it possible to reconstruct and extrapolate real or calculated series of rivers and piezometers as a function of distance from the diffusivity obtained. Using the fluctuation period and diffusivity, it is possible to construct the wave associated with any event based on data from just one river or piezometer. Full article

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