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Water, Volume 15, Issue 1 (January-1 2023) – 213 articles

Cover Story (view full-size image): A workshop was help in Poznan, Poland, with scientists, government officials, and flood managers to compile a European perspective on ice-jam flood risk assessment and mapping and determine if such floods should be explicitly addressed in the EU Floods Directive. It was determined that this is not the case since ice-jam floods are already required to be catalogued like other floods (pluvial and fluvial) in the directive. Special attention is not needed since ice-jam floods in the Nordic and eastern EU member states generally have exceedance probabilities that do not exceed those of open-water floods. This is not the case, however, in other regions of the world, for example, in Canada, where ice-jam floodwater levels can far outreach those of open-water floods. Many new advances in ice-jam flood hazard and risk assessments were also showcased at the workshop. View this paper
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13 pages, 7877 KiB  
Article
Effect of Contact Area on Deflection Flow Behavior in a Bifurcated Fracture
by Zhiyu Cheng, Rui Liu, Haichun Ma, Peichao Feng and Jiazhong Qian
Water 2023, 15(1), 213; https://doi.org/10.3390/w15010213 - 3 Jan 2023
Cited by 2 | Viewed by 2294
Abstract
The factors affecting the deflection flow in a bifurcated fracture under the effect of the fracture contact area are discussed. The effects of the contact area and cross-section on the deflection flow are determined using a combination of experiments and numerical simulations. The [...] Read more.
The factors affecting the deflection flow in a bifurcated fracture under the effect of the fracture contact area are discussed. The effects of the contact area and cross-section on the deflection flow are determined using a combination of experiments and numerical simulations. The contact and seepage changes in bifurcated fractures under a confining pressure are monitored using a pressure film. A parallel plate bifurcated fracture model with a single contact area is established, which is in good agreement with the results of the laboratory experiments. Based on numerical simulation experiments, under the effects of the contact area and cross-section, the change in the effective flow path is the main reason for the change in the deflection flow behavior. The proportion of the flow path of the entire fracture is used to reflect the deflection flow characteristics under different contact areas and cross-sectional areas. For a given contact area, the larger the cross-section of the contact area, the larger the difference in the outlet flow of the bifurcated fracture and the more obvious the deflection flow behavior. As the contact area increases and the cross-section is constant, the effective path of the fluid does not change, and the deflection flow behavior does not change. This explanation of the cause of fracture deflection flow is of great significance for studying fracture seepage. Full article
(This article belongs to the Section Hydrology)
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Figure 1

Figure 1
<p>Preparation of bifurcated fractures.</p> Full article ">Figure 2
<p>Schematic diagram of the fluid flow.</p> Full article ">Figure 3
<p>The structures of the bifurcated fractures (the contact area is defined as fracture A, that without contact area is defined as fracture B). (<b>a</b>–<b>f</b>): same cross-section and different areas (the cross-section is 3 mm); and (<b>g</b>–<b>l</b>): same area and different cross-sections (the contact area is 9 mm<sup>2</sup>).</p> Full article ">Figure 3 Cont.
<p>The structures of the bifurcated fractures (the contact area is defined as fracture A, that without contact area is defined as fracture B). (<b>a</b>–<b>f</b>): same cross-section and different areas (the cross-section is 3 mm); and (<b>g</b>–<b>l</b>): same area and different cross-sections (the contact area is 9 mm<sup>2</sup>).</p> Full article ">Figure 4
<p>Diagram of the experimental equipment used in the tests.</p> Full article ">Figure 5
<p>Curve change of flow rate and hydraulic slope in fracture seepage experiments.</p> Full article ">Figure 6
<p>Compression performance of pressure film under different pressures.</p> Full article ">Figure 7
<p>Variations in the velocities at the outlets of the bifurcated fractures for a constant cross-section.</p> Full article ">Figure 8
<p>Velocity variations in the bifurcated fracture B for a constant cross-section of 3 mm (velocity: m/s). (<b>a</b>–<b>f</b>): Velocity variations in the bifurcated fracture B for a constant cross-section of 3 mm with different contact areas.</p> Full article ">Figure 9
<p>Variations in velocities at the outlets of the bifurcated fractures for a constant contact area.</p> Full article ">Figure 10
<p>Velocity variations in the bifurcated fracture B for a constant contact area of the contact area is 9 mm<sup>2</sup> (velocity: m/s). (<b>a</b>–<b>f</b>): Velocity variations in the bifurcated fracture B for a constant area of 9 mm<sup>2</sup> with different contact cross-sections.</p> Full article ">Figure 11
<p>Outlet velocity difference of bifurcated fracture.</p> Full article ">
13 pages, 2612 KiB  
Article
Downward Trends in Streamflow and Sediment Yield Associated with Soil and Water Conservation in the Tingjiang River Watershed, Southeast China
by Sheng Ding, Feifei Wang, Hui Yue, Shaoyun Peng, Qizhen Ruan, Jinglan Lin and Wenzhi Cao
Water 2023, 15(1), 212; https://doi.org/10.3390/w15010212 - 3 Jan 2023
Cited by 1 | Viewed by 2248
Abstract
Soil erosion is one of the most serious environment problems in China. Soil and water conservation (SWC) measures play an important role in reducing streamflow and sediment yields. A nested watershed approach, together with the Mann–Kendall trend test, double mass curve, and path [...] Read more.
Soil erosion is one of the most serious environment problems in China. Soil and water conservation (SWC) measures play an important role in reducing streamflow and sediment yields. A nested watershed approach, together with the Mann–Kendall trend test, double mass curve, and path analysis were used to quantitatively explore hydrological effects of SWC measures in the Tingjiang River Watershed. Results showed the annual streamflow and sediment yields tended toward a remarkable downward trend since the implementation of SWC measures during 1982–2014, indicating that SWC measures produced significant hydrological effects. The contribution of precipitation to annual streamflow increased from 71% to 79% from the periods 1982–2000 to 2000–2014, indicating decreases in annual precipitation after 2003 and stronger impacts on streamflow than that of SWC measures. However, the contribution of SWC measures to sediment yields increased from 11% to 64% from 1982 to 2014 and gradually dominated contributions to the sediment yields in the watershed. An ecological threshold was established at which the proportion of the cumulative afforestation area due to SWC reaches 10% of the whole watershed, and the remarkable improvements of hydrological effects in the watershed can be observed. These findings could be used to evaluate performance of SWC measures in watersheds. Full article
(This article belongs to the Section Water Erosion and Sediment Transport)
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Figure 1
<p>Location of the Tingjiang River Watershed (BW, MW, and TW) in Fujian Province and two hydrological stations (<b>a</b>), the slope (<b>b</b>) and the soil type (<b>c</b>) of the Tingjiang River Watershed.</p> Full article ">Figure 2
<p>Flowchart of the datasets, watershed, and methodologies utilized in this study.</p> Full article ">Figure 3
<p>Annual streamflow and sediment yields at Guanyinqiao (<b>a</b>,<b>b</b>) and Shanghang station (<b>c</b>,<b>d</b>) from 1982 to 2014.</p> Full article ">Figure 4
<p>The changes in annual streamflow (<b>a</b>), sediment yields (<b>b</b>), and annual precipitation (<b>c</b>) in MW.</p> Full article ">Figure 5
<p>The accumulated SWC measures area from 1982 to 2014.</p> Full article ">Figure 6
<p>The MK trend test of annual precipitation.</p> Full article ">Figure 7
<p>MK trend test of annual streamflow and sediment yields for BW (<b>a</b>,<b>b</b>), TW (<b>c</b>,<b>d</b>), and MW (<b>e</b>,<b>f</b>).</p> Full article ">Figure 8
<p>Double mass curves of precipitation–streamflow and precipitation–sediment during 1982–2016 in BW (<b>a</b>,<b>b</b>), MW (<b>c</b>,<b>d</b>), and TW (<b>e</b>,<b>f</b>), respectively.</p> Full article ">Figure 9
<p>Relationship between soil and water control area and streamflow (<b>a</b>) and sediment yields (<b>b</b>) in MW.</p> Full article ">Figure 10
<p>Land-use maps of 1985 (<b>a</b>), 1995 (<b>b</b>), and 2005 (<b>c</b>).</p> Full article ">
25 pages, 3905 KiB  
Article
Spatiotemporal Characteristics of Meteorological Drought and Wetness Events across the Coastal Savannah Agroecological Zone of Ghana
by Johnson Ankrah, Ana Monteiro and Helena Madureira
Water 2023, 15(1), 211; https://doi.org/10.3390/w15010211 - 3 Jan 2023
Cited by 7 | Viewed by 3698
Abstract
Drought and wetness events have become common due to global warming, warranting the need for continuous analysis and monitoring of drought and wet events to safeguard people’s livelihoods. In this study, the Standardized Precipitation Evapotranspiration Index (SPEI) was utilized to analyze the spatiotemporal [...] Read more.
Drought and wetness events have become common due to global warming, warranting the need for continuous analysis and monitoring of drought and wet events to safeguard people’s livelihoods. In this study, the Standardized Precipitation Evapotranspiration Index (SPEI) was utilized to analyze the spatiotemporal characteristics of drought and wetness events in the coastal Savannah agroecological zone from 1981 to 2021. Climate data from 14 locations across the zone were used to characterize drought and wetness events at the 3 and 12 month timescales. Except for September 1995 and November 2002, when changepoints occurred, the results revealed the homogeneous nature of temperature and rainfall in the zone. More drought events were observed in the dry and minor seasons, while the wet season had more wetness events under both the SPEI-3 and SPEI-12 timescales. The results also showed that, while moderate-to-severe drought events were common for most years, extreme drought events were more typical in the 1980s and 1990s than in the 2000s under both the SPEI-3 and SPEI-12. Furthermore, the 2000s saw more moderate-to-severe wetness events than the 1980s and 1990s, while the greatest number of extreme wetness events occurred in 1987, followed by 1997 and 2021 under the SPEI-3, and a few moderate-to-extreme wetness events occurred in 1987, 1991, 1997–1998, 2012–2013, 2018, and 2020–2021 under the SPEI-12. Under the SPEI-12, only extreme drought events showed a significant positive trend with a small magnitude of change. On the spatial scale, drought and wetness events occurred more frequently in the Central and Volta regions than in the Greater Accra region; however, the intensity and duration of the events were stronger and lasted longer in the Greater Accra and Central regions than in the Volta region. The regular monitoring of drought and wetness events is required to protect the livelihoods of people in the zone. Full article
(This article belongs to the Section Ecohydrology)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Map showing the location of the coastal Savannah agroecological zone, elevation, major towns, and measurement stations (<b>a</b>); average annual rainfall (from 1981 to 2021) (<b>b</b>); mean annual temperature (from 1981 to 2021) (<b>c</b>).</p> Full article ">Figure 2
<p>Changepoints in September temperature (<b>a</b>) and November rainfall (<b>b</b>) for the coastal Savannah agroecological zone of Ghana.</p> Full article ">Figure 3
<p>Temporal evolution of the mean monthly SPEI-3 and SPEI-12 for moderate, severe, and extreme drought (<b>a</b>,<b>b</b>) and wetness (<b>c</b>,<b>d</b>) from 1981–2021 over the coastal Savannah agroecological zone in Ghana.</p> Full article ">Figure 4
<p>Temporal evolution of the mean annual SPEI-3 and SPEI-12 for moderate-to-extreme drought (<b>a</b>,<b>b</b>), wetness (<b>c</b>,<b>d</b>), and all drought and wet events (<b>e</b>) from 1981–2021 over the coastal Savannah agroecological zone in Ghana.</p> Full article ">Figure 5
<p>Spatial distribution of the average values for SPEI-3 and SPEI-12 for extreme drought (<b>a</b>,<b>b</b>), severe drought (<b>c</b>,<b>d</b>), extreme wetness (<b>e</b>,<b>f</b>), and severe wetness (<b>g</b>,<b>h</b>) events in the coastal Savannah agroecological zone of Ghana from 1981 to 2021.</p> Full article ">Figure 6
<p>Spatial distribution of drought and wetness characteristics at SPEI-3 and SPEI-12 timescales in the coastal Savannah agroecological of Ghana from 1981–2021: Drought frequency (<b>a</b>,<b>b</b>) SPEI-3 and SPEI-12; drought duration (<b>c</b>,<b>d</b>) SPEI-3 and SPEI-12; drought intensity (<b>e</b>,<b>f</b>) SPEI-3 and SPEI-12; wetness frequency (<b>g</b>,<b>h</b>) SPEI-3 and SPEI-12; wetness duration (<b>i</b>,<b>j</b>) SPEI-3 and SPEI-12; wetness intensity (<b>k</b>,<b>l</b>) SPEI-3 and SPEI-12.</p> Full article ">Figure 6 Cont.
<p>Spatial distribution of drought and wetness characteristics at SPEI-3 and SPEI-12 timescales in the coastal Savannah agroecological of Ghana from 1981–2021: Drought frequency (<b>a</b>,<b>b</b>) SPEI-3 and SPEI-12; drought duration (<b>c</b>,<b>d</b>) SPEI-3 and SPEI-12; drought intensity (<b>e</b>,<b>f</b>) SPEI-3 and SPEI-12; wetness frequency (<b>g</b>,<b>h</b>) SPEI-3 and SPEI-12; wetness duration (<b>i</b>,<b>j</b>) SPEI-3 and SPEI-12; wetness intensity (<b>k</b>,<b>l</b>) SPEI-3 and SPEI-12.</p> Full article ">Figure 7
<p>Spatial distribution of drought/wetness trends in the coastal Savannah agroecological zone of Ghana: Drought trends under (<b>a</b>) SPEI-3 and (<b>b</b>) SPEI-12 timescales; wetness trends under (<b>c</b>) SPEI-3 and (<b>d</b>) SPEI-12 timescales.</p> Full article ">
32 pages, 4668 KiB  
Article
Simultaneous Scheduling and Synthesis of Industrial Water Allocation Networks
by Sudha Chauhan and Munawar A. Shaik
Water 2023, 15(1), 210; https://doi.org/10.3390/w15010210 - 3 Jan 2023
Viewed by 1723
Abstract
This work addresses integration of batch scheduling with water allocation, recycle and reuse opportunities for freshwater minimization in batch plants via sequential and simultaneous methodologies. The presented scheduling model is based on state task network representation and unit-specific event based continuous time formulation. [...] Read more.
This work addresses integration of batch scheduling with water allocation, recycle and reuse opportunities for freshwater minimization in batch plants via sequential and simultaneous methodologies. The presented scheduling model is based on state task network representation and unit-specific event based continuous time formulation. In the production scheduling model, a three-index finish time variable has been considered for handling multiple states having different processing time durations for the same task in a processing unit. The scheduling model introduces constraints to handle storage violations for production and consumption of the same state in the same unit. In the water network model for freshwater minimization, a regeneration unit along with a central water storage tank has been included to exploit the possibility of water reuse in the washing units. Four case studies are solved with single and multiple contaminants to evaluate the performance of the proposed model, which gives better savings in terms of freshwater consumption and thus also minimizes the effluent generation. Additionally, a preliminary analysis for two-objective optimization is presented where revenue is maximized, and the total water cost is minimized simultaneously using the weighted-sum method. Full article
(This article belongs to the Section Water Use and Scarcity)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Superstructure for water mass balance in each unit <span class="html-italic">j</span>.</p> Full article ">Figure 2
<p>Superstructure for water mass balance in central water storage tank.</p> Full article ">Figure 3
<p>Washing sequence with no unit wait policy for washing units.</p> Full article ">Figure 4
<p>STN representation for case study 1.</p> Full article ">Figure 5
<p>Production schedule obtained for the sequential approach.</p> Full article ">Figure 6
<p>Gantt chart for the sequential approach without using water storage tank for case study 1.</p> Full article ">Figure 7
<p>Gantt chart for the sequential approach using a water storage tank for case study 1.</p> Full article ">Figure 8
<p>Gantt chart for the simultaneous approach without a water storage tank for case study 1.</p> Full article ">Figure 9
<p>Gantt chart for the simultaneous approach with water storage tank for case study 1.</p> Full article ">Figure 10
<p>Gantt chart for the simultaneous approach for case study 2.</p> Full article ">Figure 11
<p>Reported Gantt chart from Majozi and Gouws [<a href="#B7-water-15-00210" class="html-bibr">7</a>] with overlapping time violation shown using red colored oval.</p> Full article ">Figure 12
<p>Gantt chart obtained for the simultaneous approach for case study 3 with water storage tank.</p> Full article ">Figure 13
<p>Gantt chart obtained for the simultaneous approach for case study 3 with water storage tank and regenerator.</p> Full article ">Figure 14
<p>Reported Gantt chart from Adekola and Majozi [<a href="#B11-water-15-00210" class="html-bibr">11</a>] with mass balance violation shown in red box.</p> Full article ">Figure 15
<p>Gantt chart for the simultaneous approach for case study 4 with water storage tank and regenerator.</p> Full article ">Figure 16
<p>Reported Gantt chart for case study 4 from Adekola and Majozi [<a href="#B11-water-15-00210" class="html-bibr">11</a>] with contaminant mass balance violation shown in red colored oval.</p> Full article ">Figure 17
<p>Pareto plots (<b>a</b>–<b>c</b>) for case studies 1, 2 and 3, for the two-objective optimization.</p> Full article ">
13 pages, 6198 KiB  
Article
The Effect of Multi-Source DEM Accuracy on the Optimal Catchment Area Threshold
by Honggang Wu, Xueying Liu, Qiang Li, Xiujun Hu and Hongbo Li
Water 2023, 15(1), 209; https://doi.org/10.3390/w15010209 - 3 Jan 2023
Cited by 3 | Viewed by 2075
Abstract
This study attempts to investigate the relationship between the accuracy of different Digital Elevation Model (DEM) and fractal dimension D and to solve the problem of determining the optimal catchment area threshold in plain watersheds. In this study, the fractal dimensions of the [...] Read more.
This study attempts to investigate the relationship between the accuracy of different Digital Elevation Model (DEM) and fractal dimension D and to solve the problem of determining the optimal catchment area threshold in plain watersheds. In this study, the fractal dimensions of the Shuttle Radar Topographic Survey Digital Elevation Model (SRTM) V4.1 DEM, Hydrology 1K (HYDRO1K) DEM, and Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM) with 90 m horizontal resolution and 30 m ASTER GDEM were calculated using the box dimension method, and the relationship between the horizontal resolution and accuracy of three data sources and fractal dimension D was studied. The optimal catchment area threshold in the study area was determined. The response of river network similarity and topographic features to DEM accuracy was explored, and the optimal catchment area threshold for the study area was verified. The result shows that, with the increase in the catchment area threshold, the fractal dimension D shows three stages of rapid decline, gentle fluctuation, and tend to 1. Compared with the horizontal resolution of DEM, the vertical accuracy has more influence on the fractal dimension D. The fractal dimension D accuracy increases with the increase in the vertical accuracy of DEM. The main order of influence of the three data sources is SRTM V4.1 DEM > ASTER GDEM > HYDRO1K DEM. The fractal dimension of the digital river network extracted by SRTM V4.1 DEM is 1.0245, the same as the fractal dimension of the actual river network. The optimal catchment area threshold of the study area is 4.05 km2, which has the highest coincidence with the actual river network. In summary, using the SRTM V4.1 DEM as the DEM data source is feasible to determine the optimal catchment area threshold in plain watersheds. Full article
(This article belongs to the Special Issue Artificial Intelligence, Machine Learning and Digital Innovation in Water Management)
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Figure 1

Figure 1
<p>Actual river network in the water source area of Tongjiyan.</p> Full article ">Figure 2
<p>The nearest neighbor distribution method (numbers represent elevation values).</p> Full article ">Figure 3
<p>Flow chart of river network extraction.</p> Full article ">Figure 4
<p>Fractal dimension <span class="html-italic">D</span> versus catchment area threshold.</p> Full article ">Figure 5
<p>Statistical eigenvalues of fractal dimensions of the four DEM data.</p> Full article ">Figure 6
<p>Effect of overlaying 3 kinds of DEM data sources. (<b>a</b>) SRTM V4.1 DEM. (<b>b</b>) HYDRO1K DEM. (<b>c</b>) ASTER GDEM.</p> Full article ">Figure 7
<p>Slope maps extracted from three types of DEM data sources. (<b>a</b>) SRTM V4.1 DEM. (<b>b</b>) HYDRO1KDEM. (<b>c</b>) ASTER GDEM.</p> Full article ">Figure 8
<p>Cumulative distribution of elevation extracted from three kinds of DEM data.</p> Full article ">
20 pages, 1483 KiB  
Review
A Review on the Water Dimensions, Security, and Governance for Two Distinct Regions
by Farhat Abbas, Salem Al-Naemi, Aitazaz A. Farooque and Michael Phillips
Water 2023, 15(1), 208; https://doi.org/10.3390/w15010208 - 3 Jan 2023
Cited by 7 | Viewed by 4695
Abstract
Non-arid region countries, including Canada, enjoy abundant water resources, while arid countries such as Qatar struggle to meet their water needs. However, climate change threats to water resources are similar for both climatic regions. Therefore, this article discusses water dimensions, security, and governance [...] Read more.
Non-arid region countries, including Canada, enjoy abundant water resources, while arid countries such as Qatar struggle to meet their water needs. However, climate change threats to water resources are similar for both climatic regions. Therefore, this article discusses water dimensions, security, and governance for these different regions, i.e., non-arid Canada and arid Qatar, that distinctly respond to their water-related challenges. Limitations of the article include lesser water-related literature availability for Qatar than for Canada. Canada’s water resources appear vulnerable to climate change as it is projected to face >0.6 °C above the global average of 1.6 °C for the 20th-century temperature. Qatar is extremely vulnerable to dust storms, and rising sea levels, with the maximum temperature approaching 50 °C during the summer, and flooding during the winter. The sustainable use of water resources needs to address social, economic, political, climate change, and environmental dimensions of water. Other than climate change impacts and high per capita consumption of water, Qatar faces challenges of a rise in population (~29 million as of now), acute shortage of freshwater from rainfall (~80 mm per annum), high evapotranspiration (~95% of the total rainfall), depletion of groundwater, and low agricultural productivity due to infertile lands and water scarcity, all leading to food insecurity. The sustainable use of water resources requires improved regulations for water governance and management. Comparisons of water sustainability issues, dimensions, security, and governance facilitate discussions to improve water governance structures for resource sustainability, food security, and climate change adaptability, and show how one country could learn from the experiences of the other. Full article
(This article belongs to the Section Water Resources Management, Policy and Governance)
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Figure 1
<p>(<b>a</b>) The geo-referenced map of Canada showing its location on the globe in North America (the inset) as well as the provincial boundaries and (<b>b</b>) spatial distribution of renewable freshwater distribution in Canada [<a href="#B34-water-15-00208" class="html-bibr">34</a>].</p> Full article ">Figure 2
<p>(<b>a</b>) The geo-referenced map of Qatar showing its location on the globe (the inset), in the Persian Gulf, and on the only land border of Saudi Arabia; (<b>b</b>) characteristics of five groundwater basins of Qatar [<a href="#B38-water-15-00208" class="html-bibr">38</a>]; and (<b>c</b>) the country’s reliance on desalination, groundwater, and treated sewage effluent [<a href="#B39-water-15-00208" class="html-bibr">39</a>].</p> Full article ">
24 pages, 6902 KiB  
Article
Change Analysis of Karst Landforms, Hydrogeological Conditions and Effects of Tunnel Excavation on Groundwater Environment in Three Topography Grades in China
by Yige Tang, Qiang Zhang, Jihong Qi, Mo Xu, Xiao Li, Chenhao Qu, Lei Yi and Dong Wang
Water 2023, 15(1), 207; https://doi.org/10.3390/w15010207 - 3 Jan 2023
Cited by 2 | Viewed by 2062
Abstract
One-third of the Earth in China is formed by Karst topography, which exposes different Karst landforms in three topography grades from southeast to northwest, corresponding to below several hundred meters for the first grade, one to two thousand meters for the second grade, [...] Read more.
One-third of the Earth in China is formed by Karst topography, which exposes different Karst landforms in three topography grades from southeast to northwest, corresponding to below several hundred meters for the first grade, one to two thousand meters for the second grade, and more than 4000 m for the in Qinghai-Tibet Plateau. Through the hydrochemical and D-18O stable isotopes of 64 water samples collected along two railway lines and the topography fractal characteristics of three typical Karst areas in different topography grades, the changes in Karst development degree, changes in groundwater activities, and the influence of tunnel excavation effects on groundwater environment were analyzed. The results indicated that: (1) the Karst development degree and the influence of Karst tunnel excavation on the groundwater environment are somehow similar in the first and second grades, while there are significant differences between the slopes area from second to third grade and the third grade area. (2) In detail, the relatively weaker Karst development degree and flow seeping in the second grade relatively weaken the influences of tunnel excavation, including the distribution pattern of water resources, the groundwater flow field, and water circulation, while the tunnel elevation has little room to rise. (3) There are many large faults in the north-southward direction in the third topography grade, and the transportation lines in the eastern-western direction will inevitably encounter them. In the intersection area, the tunnel excavation has great effects on the groundwater environment. (4) The lighter hydrogen and oxygen isotopes are enriched in Karst water from the first grade to the third grade, indicating that the recharge source of Karst water presents obvious elevation effect. Full article
(This article belongs to the Special Issue Hydrogeology and Geochemistry of Karst Aquifers)
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Figure 1
<p>(<b>a</b>) Distribution map of provinces in China and Study area. (<b>b</b>) Three altitude grades of topography in the study area ranging from 200 m to over 5000 m. (<b>c</b>) Water sample location and tunnel distribution.</p> Full article ">Figure 2
<p>(<b>a</b>) Relationship between the number of Karst peaks and Karst development stages. (<b>b</b>) Relationship between the height standards and Karst development stages.</p> Full article ">Figure 3
<p>The morphology of Karst depressions for different Karst stages 1, 2, and 3 represent three Karst development stages from strong to weak degree.</p> Full article ">Figure 4
<p>The morphology of contour for different Karst stages 1, 2, and 3 represent three Karst development stages from strong to weak degree.</p> Full article ">Figure 5
<p>The typical hydrogeological system for three topography grades and tunnel layout. (<b>a-1</b>). Layout of the Pingguo tunnel and the hydrogeology systems located in the first topography area; (<b>a-2</b>). The polygon distribution jointing the Karst peaks around Karst depressions. (<b>b-1</b>). Layout of the Dongfeng tunnel and the hydrogeology systems in the second topography area; (<b>c</b>). Layout of the Batang tunnel and the hydrogeologic system in the third topography area. (<b>a-2</b>,<b>b-2</b>) are used to obtain the fractal dimension representing the Karst development degree.</p> Full article ">Figure 6
<p>Lithology and water-bearing characteristics of study areas traversed by three typical railroad tunnels.</p> Full article ">Figure 7
<p>SI-<sub><math display="inline"><semantics> <mrow> <mi>CaCO</mi> <mn>3</mn> </mrow> </semantics></math></sub> of calcium carbonate in samples. ① SI ranges from 0 to 0.25; ② SI ranges from −0.25 to 0; ③ SI ranges from −0.5 to−0.25; ④ SI ranges from −0.5 to −0.75.</p> Full article ">Figure 8
<p>Relationship between <span class="html-italic">δ</span><sup>18</sup>O (V−SMOW, permill) and <span class="html-italic">δ</span><sup>2</sup>H (V−SMOW, permill).</p> Full article ">Figure 9
<p>Elevation difference between supply area and appearing area of water samples.</p> Full article ">Figure 10
<p>The altitude distribution and the contours in three typical study areas (the data come from the SRTMDEM 90M given by Geospatial Data Cloud, and these data are used to obtain the fractal Dimensions). (<b>a-1</b>,<b>a-2</b>) are for Pingguo System, which is divided into the strong groundwater bearing area and mild groundwater bearing area. (<b>b-1</b>,<b>b-2</b>) are for Dongfeng System, which is divided into deeply buried groundwater and shallowly buried groundwater. (<b>c-1</b>,<b>c-2</b>) are for Batang system, which is divided into a strong water-bearing stratum (C + D), a moderate water-bearing stratum (S), and the weak water-bearing stratum (P<sub>1-2</sub>).</p> Full article ">Figure 11
<p>Fractal relationship between area and circumference of polygon connecting the Karst peaks and saddle zones around Karst depressions (shown in <a href="#water-15-00207-f005" class="html-fig">Figure 5</a>(a-2,b-2)). (<b>a</b>) Pingguo System; (<b>b</b>) Dongfeng System.</p> Full article ">Figure 12
<p>(<b>a</b>) Relationship between the height standards and Karst development stages (From <a href="#water-15-00207-f002" class="html-fig">Figure 2</a>b). (<b>b</b>) Karst development phrase of the Pingguo System and Dongfeng System.</p> Full article ">Figure 13
<p>Relationship between lnδ and ln(N(δ)). (<b>a</b>) Dongfeng System; (<b>b</b>) Batang system; (<b>c</b>) Pingguo System.</p> Full article ">Figure 14
<p>Relationship between tunnel, terrain and groundwater level in three grades. (<b>a</b>) Third grade; (<b>b</b>) second grade; (<b>c</b>) first grade.</p> Full article ">Figure 15
<p>Influence pattern of tunnel excavation on groundwater environment of three topography stages in China.</p> Full article ">
11 pages, 1715 KiB  
Article
Reliability Treatment of Silicon in Oilfield Wastewater by Electrocoagulation
by Weiwei Teng, Shijie Liu, Xin Zhang, Feng Zhang, Xianglu Yang, Mengxiao Xu and Junwei Hou
Water 2023, 15(1), 206; https://doi.org/10.3390/w15010206 - 3 Jan 2023
Cited by 4 | Viewed by 1787
Abstract
Scaling caused by silicate in oilfield wastewater gathering system pipelines can cause serious pipeline blockage. Therefore, this study adopts facile, effective and environment friendly electrocoagulation method to remove the silicon in oilfield wastewater. After confirming the level of factors through single factor experiments, [...] Read more.
Scaling caused by silicate in oilfield wastewater gathering system pipelines can cause serious pipeline blockage. Therefore, this study adopts facile, effective and environment friendly electrocoagulation method to remove the silicon in oilfield wastewater. After confirming the level of factors through single factor experiments, the optimal scheme for electrocoagulation was selected by orthogonal experiments and verification tests, the silicon content would be dramatically decreased from 81.51 mg/L to 21.88 mg/L when pH = 6, reaction time = 20 min, current density = 27 mA/cm2 and wastewater temperature = 35 °C. In addition, the silicon removal rate would reach up to 85.90% when the pH of oilfield wastewater was kept as its original condition without changing other optimal factors; such an enhanced silicon removal effect could be attributed to the calcium ions chemical coagulation after the mechanism investigation. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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<p>Schematic diagram of electrocoagulation setup.</p> Full article ">Figure 2
<p>The impact of initial pH (<b>a</b>), current density (<b>b</b>), reaction time (<b>c</b>) and wastewater temperature (<b>d</b>) on silicon removal rate.</p> Full article ">Figure 3
<p>Silica scale particle size after 20 min (<b>b</b>), 30 min (<b>d</b>) and 40 min (<b>f</b>) electrocoagulation and corresponding blank control group (<b>a</b>,<b>c</b>,<b>e</b>).</p> Full article ">Figure 4
<p>The impact of Ca<sup>2+</sup> and Mg<sup>2+</sup> on silicon removal rate.</p> Full article ">Figure 5
<p>Silicon removal mechanism of electrocoagulation.</p> Full article ">
15 pages, 3453 KiB  
Article
Characteristics of Shallow Flows in a Vegetated Pool—An Experimental Study
by Parsa Parvizi, Hossein Afzalimehr, Jueyi Sui, Hamid Reza Raeisifar and Ali Reza Eftekhari
Water 2023, 15(1), 205; https://doi.org/10.3390/w15010205 - 3 Jan 2023
Cited by 4 | Viewed by 1842
Abstract
Pools are often observed in gravel-bed rivers, together with the presence of vegetation patches. In the present study, a conceptual model of a gradual varied flow with both convective deceleration and acceleration flow sections has been constructed in a flume to study turbulent [...] Read more.
Pools are often observed in gravel-bed rivers, together with the presence of vegetation patches. In the present study, a conceptual model of a gradual varied flow with both convective deceleration and acceleration flow sections has been constructed in a flume to study turbulent flow structures. Vegetation patches with extended canopies were planted in the pool sections in order to increase the thickness of the boundary layer inside the inner zone. The effects of different flows (namely decelerating, uniform and accelerating flows) along an artificial pool on flow velocity, shear stress and bursting events have been investigated. In addition, due to the occurrence of secondary currents in shallow streams, the characteristics of turbulent shallow flow have been investigated along two axes that are parallel to the sidewall of the flume. The results showed that the application of the log law should be used with care to estimate shear velocity along a pool with a vegetated bed. The presence of a vegetation patch causes an increase in Reynolds shear stress, especially along the entrance section of the pool where the flow decelerates. The results of the quadrant analysis reveal that the sweep and ejection events have the most dominant influence over the vegetation patch in the pool; however, the contributions of outward and inward events increase near the bed, especially in the entrance section of the pool where the flow is decelerating. The distribution of stream-wise RMS of turbulence intensity along the pool generally presents a convex shape. Full article
(This article belongs to the Special Issue Fluvial Hydraulics in the Presence of Vegetation in Channels)
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<p>Experimental setup. (<b>a</b>) Vegetated pool; (<b>b</b>) sandy pool; (<b>c</b>) vegetated boundary.</p> Full article ">Figure 2
<p>Distributions of shear velocity determined using two methods: (<b>A</b>) Clauser’s method; (<b>B</b>) the boundary layer method.</p> Full article ">Figure 3
<p>Validity of the logarithmic law method. (<b>a</b>) Central axis; (<b>b</b>) Second axis.</p> Full article ">Figure 4
<p>Distributions of stream-wise velocity profiles. Note: green line: central axis over vegetated bed with w/h = 2; black line: central axis over sandy bed with w/h = 2; gray line: central axis over vegetated bed with w/h= 2.7; blue line: second axis over vegetated bed with w/h = 2.</p> Full article ">Figure 5
<p>Distributions of velocity profiles. Note: green line: central axis over vegetated bed with w/h = 2; black line: central axis over sandy bed with w/h = 2; gray line: central axis over vegetated bed with w/h = 2.7; blue line: second axis over vegetated bed with w/h = 2.</p> Full article ">Figure 6
<p>Bursting events in quadrant analysis.</p> Full article ">Figure 7
<p>Distribution of Reynolds shear stress. Note: green line: central axis over vegetated bed with w/h = 2; black line: central axis over sandy bed with w/h = 2; gray line: central axis over vegetated bed with w/h = 2.7; blue line: second axis over vegetated bed with w/h = 2.</p> Full article ">Figure 8
<p>Distribution of stream-wise RMS of turbulence intensity. Note: green line: central axis over vegetated bed with w/h = 2; black line: central axis over sandy bed with w/h = 2; gray line: central axis over vegetated bed with w/h = 2.7; blue line: second axis over vegetated bed with w/h = 2.</p> Full article ">
19 pages, 2198 KiB  
Article
Modelling of Deep Learning-Based Downscaling for Wave Forecasting in Coastal Area
by Didit Adytia, Deni Saepudin, Dede Tarwidi, Sri Redjeki Pudjaprasetya, Semeidi Husrin, Ardhasena Sopaheluwakan and Gegar Prasetya
Water 2023, 15(1), 204; https://doi.org/10.3390/w15010204 - 3 Jan 2023
Cited by 8 | Viewed by 3704
Abstract
Wave prediction in a coastal area, especially with complex geometry, requires a numerical simulation with a high-resolution grid to capture wave propagation accurately. The resolution of the grid from global wave forecasting systems is usually too coarse to capture wave propagation in the [...] Read more.
Wave prediction in a coastal area, especially with complex geometry, requires a numerical simulation with a high-resolution grid to capture wave propagation accurately. The resolution of the grid from global wave forecasting systems is usually too coarse to capture wave propagation in the coastal area. This problem is usually resolved by performing dynamic downscaling that simulates the global wave condition into a smaller domain with a high-resolution grid, which requires a high computational cost. This paper proposes a deep learning-based downscaling method for predicting a significant wave height in the coastal area from global wave forecasting data. We obtain high-resolution wave data by performing a continuous wave simulation using the SWAN model via nested simulations. The dataset is then used as the training data for the deep learning model. Here, we use the Long Short-Term Memory (LSTM) and Bidirectional LSTM (BiLSTM) as the deep learning models. We choose two study areas, an open sea with a swell-dominated area and a rather close sea with a wind-wave-dominated area. We validate the results of the downscaling with a wave observation, which shows good results. Full article
(This article belongs to the Section Oceans and Coastal Zones)
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<p>Snapshot of significant wave height from global forecast model GFS, with grid size of 0.25<math display="inline"><semantics> <msup> <mrow/> <mo>°</mo> </msup> </semantics></math>.</p> Full article ">Figure 2
<p>Flowchart of statistical downscaling (<b>left</b>) and dynamical downscaling (<b>right</b>).</p> Full article ">Figure 3
<p>Illustration of Long Short-Term Memory’s architecture.</p> Full article ">Figure 4
<p>Illustration of the architecture of Bidirectional Long Short-Term Memory.</p> Full article ">Figure 5
<p>Flowchart of wave data generation. The wave dataset is obtained by performing continuous wave simulation using phase-averaged wave model SWAN.</p> Full article ">Figure 6
<p>Snapshot of significant wave height on 6 December 2020, at 06:00 UTC, from SWAN simulation in domain I.</p> Full article ">Figure 7
<p>As in <a href="#water-15-00204-f006" class="html-fig">Figure 6</a>, for domains II (<b>left plot</b>) and III (<b>right plot</b>) for Jakarta Bay area.</p> Full article ">Figure 8
<p>Snapshot of significant wave height on 1 March 2020, at 00:00 UTC, from wave simulation using SWAN model for domains II (<b>left plot</b>) and III (<b>right plot</b>) for Meulaboh area.</p> Full article ">Figure 9
<p>Flowchart of machine learning optimisation. The wave dataset from the previous step is used as training data for machine learning.</p> Full article ">Figure 10
<p>Location of wave observation at Jakarta Bay.</p> Full article ">Figure 11
<p>The spatial correlation map at Jakarta Bay was obtained by calculating the correlation coefficient (CC) between Hs at the global grid and Hs at the targeted local domain. Big dots denote CC values: upper left plot for CC values ≥ 0.70, upper right plot for ≥0.80, and lower plot for ≥0.90.</p> Full article ">Figure 12
<p>Comparison of significant wave height from wave observation with result of prediction by using BiLSTM at Jakarta Bay.</p> Full article ">Figure 13
<p>Location of wave observation at Meulaboh, West Aceh Regency, Indonesia.</p> Full article ">Figure 14
<p>Spatial correlation maps at Meulaboh offshore, obtained by calculating the correlation coefficient (CC) between Hs at the global grid with Hs at a targeted local domain. Big dots denote CC values: in the upper plot for CC values ≥ 0.70, the lower plot for CC values ≥ 0.80, and the lower plot for CC values ≥ 0.90.</p> Full article ">Figure 15
<p>Comparison of significant wave height from wave observation with result of prediction by using BiLSTM at offshore of Meulaboh.</p> Full article ">
20 pages, 5328 KiB  
Article
Water-Use Strategies and Habitat Adaptation of Four Tree Species in Karstic Climax Forest in Maolan
by Fangjun Ding, Congjun Yuan, Ting Zhou, Juan Cheng, Peng Wu and Yuyan Ye
Water 2023, 15(1), 203; https://doi.org/10.3390/w15010203 - 3 Jan 2023
Cited by 4 | Viewed by 1750
Abstract
The technique of stable hydrogen and oxygen isotope tracing has become an important means to study the mechanism of water movement due to its high sensitivity and traceability. In this study, four dominant tree species in the karst forest of Maolan, Guizhou Province, [...] Read more.
The technique of stable hydrogen and oxygen isotope tracing has become an important means to study the mechanism of water movement due to its high sensitivity and traceability. In this study, four dominant tree species in the karst forest of Maolan, Guizhou Province, were selected, and their water-use strategies and the mechanism of maintenance of tree species diversity were investigated using the stable hydrogen and oxygen isotope tracing technique. The results show that: (1) The regional precipitation varied evidently with the alternation of seasons, i.e., the values of δD and δ18O in precipitation had a positive bias in spring and a negative bias in summer and autumn. The value of deuterium excess (d-excess) was between 11.67‰ and 31.02‰, with a mean value of 22.98‰. (2) The soil temperature (ST), soil water content (SWC) and precipitation, which have a significant positive correlation, imposed a joint impact on the dynamics of the soil evaporative fractionation. (3) The line-conditioned excess (LC-excess) varied seasonally in different water bodies, i.e., the relative evaporative fractionation of the rhizosphere soil of deciduous tree species was stronger than that of evergreen tree species, and the evaporative fractionation of hydrogen and oxygen isotopes in the leaf water of evergreen tree species was stronger than that of deciduous tree species in spring and summer. However, that of the latter was stronger than that of the former in autumn. (4) The soil water was the most important potential water source for dominant tree species in karst terrain (71%), followed by epikarstic water, which made up an effective supplement (29%). (5) Finally, trees of different life forms and species varied in capacity and proportion in terms of using the potential water sources in different seasons, i.e., deciduous tree species had a greater capacity for using water from potential sources and variable water-use strategies. This may be a major water-limiting mechanism that maintains photosynthesis in the leaves of evergreen tree species (leaves are evergreen and plants continue to grow via photosynthesis) and constrains photosynthesis in deciduous tree species (leaves fall and plants become dormant and stop growing). These results lead to the conclusion that the dominant tree species in karstic forests resist water stress and adjust water-use strategies towards each potential water source to adapt to the harsh karstic habitat through root plasticity and leaf defoliation. Full article
(This article belongs to the Special Issue Forest Hydrology: Advances in Measuring and Modelling the Influences of Forests on Water Cycles)
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<p>Location of study area in Southwest China.</p> Full article ">Figure 2
<p>Images of the four tree species.</p> Full article ">Figure 3
<p>Accumulated precipitation by month (<b>a</b>) and by season (<b>b</b>).</p> Full article ">Figure 4
<p>Seasonal variation in (<b>a</b>) δD and δ<sup>18</sup>O original values, (<b>b</b>) average value of δD and δ<sup>18</sup>O original values and (<b>c</b>) d-excess value in terms of atmospheric precipitation and d-excess (‰). Red line stands for positive (upper and right) and negative (down and left) standard deviation.</p> Full article ">Figure 5
<p>Soil water content and soil temperature in different soil layers at sampling site from January to December 2020. (<b>a</b>) By month. (<b>b</b>) By season. Blue and red line represents standard deviation.</p> Full article ">Figure 6
<p>Seasonal variation in (<b>a</b>) Δd, (<b>b</b>) δ<sup>18</sup>O and (<b>c</b>) d-excess of soil water in different soil layers. Black line represents standard deviation.</p> Full article ">Figure 7
<p>Correlation of soil temperature and soil water content for different soil layers and precipitation levels. (<b>a</b>) In spring. (<b>b</b>) In summer. (<b>c</b>) In autumn. (<b>d</b>) In winter.</p> Full article ">Figure 8
<p>(<b>a</b>) Seasonal variation in LC-excess values of rhizosphere soil water of different tree species; (<b>b</b>) description of life forms at sample site; (<b>c</b>) seasonal variation in LC-excess values of leaf water (LW) of different tree species and different life forms at sample site; (<b>d</b>) seasonal variation in LC-excess values of community sample site soil water (CSSTW, CSSSW), atmospheric precipitation (AP), epikarstic water (EPW), and leaf water (LW).</p> Full article ">Figure 9
<p>Characteristics of δD and δ<sup>18</sup>O in xylem and leaf water before and after rainfall in summer. Black line represents standard deviation.</p> Full article ">Figure 10
<p>Linear relationship of δD and δ<sup>18</sup>O in soil water (CSSW), xylem water (XW), leaf water (LW), local atmospheric precipitation (LMWL), global atmospheric precipitation (GMWL) and epikarstic water (EPW).</p> Full article ">Figure 11
<p>Correlation of plant xylem water, atmospheric precipitation, soil water and epikarstic water in different seasons. (<b>a</b>) In spring. (<b>b</b>) In summer. (<b>c</b>) In summer (Ar.). (<b>d</b>) In autumn.</p> Full article ">Figure 12
<p>Plant water-use contribution from potential sources by season and before/after rainfall: (<b>a</b>,<b>f</b>) in Spring; (<b>b</b>,<b>g</b>) in Summer; (<b>c</b>,<b>h</b>) in Summer (after Rainfall); (<b>d</b>,<b>i</b>) in autumn; (<b>e</b>,<b>j</b>) in growing season. Blue solid line in e and j represents standard deviation.</p> Full article ">
16 pages, 5220 KiB  
Article
Removal of Amoxicillin Antibiotic from Polluted Water by a Magnetic Bionanocomposite Based on Carboxymethyl Tragacanth Gum-Grafted-Polyaniline
by Seyedeh Soghra Mosavi, Ehsan Nazarzadeh Zare, Hossein Behniafar and Mahmood Tajbakhsh
Water 2023, 15(1), 202; https://doi.org/10.3390/w15010202 - 3 Jan 2023
Cited by 25 | Viewed by 3165
Abstract
Removal of antibiotics from contaminated water is very important because of their harmful effects on the environment and living organisms. This study describes the preparation of a bionanocomposite of carboxymethyl tragacanth gum-grafted-polyaniline and γFe2O3 using an in situ [...] Read more.
Removal of antibiotics from contaminated water is very important because of their harmful effects on the environment and living organisms. This study describes the preparation of a bionanocomposite of carboxymethyl tragacanth gum-grafted-polyaniline and γFe2O3 using an in situ copolymerization method as an effective adsorbent for amoxicillin antibiotic remediation from polluted water. The prepared materials were characterized by several analyses. The vibrating sample magnetometer and thermal gravimetric analysis showed that the carboxymethyl tragacanth gum-grafted-polyaniline@ γFe2O3 bionanocomposite has a magnetization saturation of 25 emu g−1 and thermal stability with a char yield of 34 wt%, respectively. The specific surface area of bionanocomposite of about 8.0794 m2/g was obtained by a Brunauer–Emmett–Teller analysis. The maximum adsorption capacity (909.09 mg/g) of carboxymethyl tragacanth gum-grafted-polyaniline@ γFe2O3 was obtained at pH 7, an agitation time of 20 min, a bioadsorbent dose of 0.005 g, and amoxicillin initial concentration of 400 mg/L. The Freundlich isotherm and pseudo-second-order kinetic models were a better fit with the experimental data. The kinetic model showed that chemical adsorption is the main mechanism for the adsorption of amoxicillin on the bioadsorbent. In addition, the maximum adsorption capacity for amoxicillin compared to other reported adsorbents showed that the prepared bionanocomposite has a higher maximum adsorption capacity than other adsorbents. These results show that carboxymethyl tragacanth gum-grafted-polyaniline@ γFe2O3 would be a favorable bioadsorbent for the remediation of amoxicillin from contaminated water. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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<p>Schematic illustration of the preparation of carboxymethyl tragacanth gum (CMT) and carboxymethyl tragacanth gum-<span class="html-italic">grafted</span>-polyaniline@γFe<sub>2</sub>O<sub>3</sub> (CMT-g-PANI@Fe<sub>2</sub>O<sub>3</sub>) bionanocompsite.</p> Full article ">Figure 2
<p>FTIR spectra (<b>A</b>) and XRD patterns (<b>B</b>) of TG, CMT, Fe<sub>2</sub>O<sub>3</sub>, CMT-g-PANI, and CMT-g-PANI@Fe<sub>2</sub>O<sub>3</sub>.</p> Full article ">Figure 3
<p>EDX spectra (<b>A</b>) and FESEM micrographs (<b>B</b>) of CMT, Fe<sub>2</sub>O<sub>3</sub>, CMT-g-PANI, and CMT-g-PANI@Fe<sub>2</sub>O<sub>3</sub>.</p> Full article ">Figure 4
<p>VSM curves of Fe<sub>2</sub>O<sub>3</sub>, and CMT-g-PANI@Fe<sub>2</sub>O<sub>3</sub> (<b>A</b>) and TGA thermograms (<b>B</b>) of TG, CMT, CMT-g-PANI, and CMT-g-PANI@Fe<sub>2</sub>O<sub>3</sub>.</p> Full article ">Figure 5
<p>N<sub>2</sub> adsorption/desorption isotherms of Fe<sub>2</sub>O<sub>3</sub> (<b>A</b>) and CMT-g-PANI@Fe<sub>2</sub>O<sub>3</sub> (<b>B</b>).</p> Full article ">Figure 6
<p>(<b>A</b>) Effect of pH (4–9), (biosorbent dose = 0.015 g, amoxicillin concentration = 100 mg/L, time = 15 min and temperature = 298 K), (<b>B</b>) biosorbent dosage (0.005–0.025 g), (pH 7, <span class="html-italic">amoxicillin</span> concentration = 100 mg/L, time = 15 min and temperature = 298 K), (<b>C</b>) time (5–30 min), (pH 7, biosorbent dosage = 0.005 g, <span class="html-italic">amoxicillin</span> concentration = 100 mg/L, V = 10 mL, and temperature = 298 K), (<b>D</b>) <span class="html-italic">amoxicillin</span> concentration (50–400 mg/L), (pH 7, biosorbent dosage = 0.005 g, V = 10 mL, time = 20 min, temperature = 298 K).</p> Full article ">Figure 7
<p>(<b>A</b>) Langmuir and (<b>B</b>) Freundlich isotherms (condition: <span class="html-italic">amoxicillin</span> concentration (50–400 mg/L), pH 7, biosorbent dosage = 0.005 g, contact time = 20 min, T = 298 K).</p> Full article ">Figure 8
<p>(<b>A</b>) Pseudo-first-order and (<b>B</b>) pseudo-second-order models (Contact time (5–30 min), pH 7, biosorbent dosage = 0.005 g, <span class="html-italic">amoxicillin</span> concentration = 400 mg/L, T = 298 K)).</p> Full article ">Figure 9
<p>Desorption and reusability of the CMT-g-PANI@Fe<sub>2</sub>O<sub>3</sub> bioadsorbent for <span class="html-italic">amoxicillin</span> adsorption.</p> Full article ">Figure 10
<p>A schematic of the suggested mechanism of <span class="html-italic">amoxicillin</span> adsorption by CMT-g-PANI@Fe<sub>2</sub>O<sub>3</sub> bioadsorbent.</p> Full article ">
15 pages, 2513 KiB  
Article
Water Quality Assessment and Environmental Impact of Heavy Metals in the Red Sea Coastal Seawater of Yanbu, Saudi Arabia
by Abdelbaset S. El-Sorogy, Mohamed Youssef and Mansour H. Al-Hashim
Water 2023, 15(1), 201; https://doi.org/10.3390/w15010201 - 3 Jan 2023
Cited by 22 | Viewed by 3900
Abstract
The Yanbu industrial city along the Red Sea coast includes industries associated with crude oil and natural gas production and refining and support industries that produce manufactured goods for domestic and/or internal consumption. This study investigates the potential environmental impact and the possible [...] Read more.
The Yanbu industrial city along the Red Sea coast includes industries associated with crude oil and natural gas production and refining and support industries that produce manufactured goods for domestic and/or internal consumption. This study investigates the potential environmental impact and the possible sources of heavy metals (HMs), and it evaluates the quality of coastal surface seawater in the vicinity of Yanbu, along the Red Sea coast of Saudi Arabia. Thirty seawater samples have been collected and analyzed using an inductively coupled plasma mass spectrometer (ICP-MS) in order to determine the concentration values of Fe, Cr, Pb, Sb, Mn, Cu, Zn, Al, Ni, As, Cd, Co, and Hg. Reported HMs averages (μg/L) are in the following sequence: Ni (4.424) > As (4.297) > Cu (2.447) > Zn (1.667) > Al (1.133) > Fe (0.983) > Cr (0.723) > Mn (0.328) > Cd (0.309) > Pb (0.276) > Sb (0.238) > Co (0.144) > Hg (0.058). The contamination index (Cd) showed low contamination levels in all of the analyzed samples, whereas the index of heavy metal pollution (HPI) revealed medium contamination levels in 28 samples and low levels in two samples. Reported high HMs variations within samples are attributed to the multiplication of sources. The statistical analyses indicated anthropogenic sources for Cd, Co, Hg, Zn, and Ni, which may have originated from industrial, farming, or fishing activities around Yanbu city, while the remaining metals might be originated from combined lithogenic and human sources. Full article
(This article belongs to the Section Water Quality and Contamination)
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<p>Study area map showing seawater sampling locations.</p> Full article ">Figure 2
<p>Distribution of As, Cu, Ni, Zn, Al, Cd, and Mn of the analyzed seawaters.</p> Full article ">Figure 3
<p>Distribution of Co, Hg, Pb, Sb, Fe, and Cr in seawater samples.</p> Full article ">Figure 4
<p>Distribution of degree of contamination (C<sub>d</sub>) and heavy metal pollution index (HPI) of Yanbu seawater samples.</p> Full article ">Figure 5
<p>R mode HCA of the investigated HMs.</p> Full article ">Figure 6
<p>Q mode HCA of Yanbu seawater samples.</p> Full article ">
28 pages, 2436 KiB  
Review
A Review of the Hydraulic Performance of Permeable Reactive Barriers Based on Granular Zero Valent Iron
by Stefania Bilardi, Paolo Salvatore Calabrò and Nicola Moraci
Water 2023, 15(1), 200; https://doi.org/10.3390/w15010200 - 3 Jan 2023
Cited by 16 | Viewed by 2937
Abstract
Permeable reactive barriers (PRBs) based on the use of zero valent iron (ZVI) represent an efficient technology for the remediation of contaminated groundwater, but the literature evidences “failures”, often linked to the difficulty of fully understanding the long-term performance of ZVI-based PRBs in [...] Read more.
Permeable reactive barriers (PRBs) based on the use of zero valent iron (ZVI) represent an efficient technology for the remediation of contaminated groundwater, but the literature evidences “failures”, often linked to the difficulty of fully understanding the long-term performance of ZVI-based PRBs in terms of their hydraulic behavior. The aim of this paper is to provide an overview of the long-term hydraulic behavior of PRBs composed of ZVI mixed with other reactive or inert materials. The literature on the hydraulic performance of ZVI-based PRBs in full-scale applications, on long-term laboratory testing and on related mathematical modeling was thoroughly analyzed. The outcomes of this review include an in-depth analysis of factors influencing the long-term behavior of ZVI-based PRBs (i.e., reactive medium, contamination and the geotechnical, geochemical and hydrogeological characteristics of the aquifer) and a critical revision of the laboratory procedures aimed at investigating their hydraulic performance. The analysis clearly shows that admixing ZVI with nonexpansive granular materials is the most suitable choice for obtaining a long-term hydraulically efficient PRB. Finally, the paper summarizes a procedure for the correct hydraulic design of ZVI-based PRBs and outlines that research should aim at developing numerical models able to couple PRBs’ hydraulic and reactive behaviors. Full article
(This article belongs to the Special Issue The Remediation of Groundwater Polluted by Metals)
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<p>PRB configurations and their main characteristics.</p> Full article ">Figure 2
<p>The environmental, economic and social impacts of PRBs.</p> Full article ">Figure 3
<p>The factors that influence the long-term behavior of ZVI-based PRBs.</p> Full article ">Figure 4
<p>An example of a column test apparatus.</p> Full article ">Figure 5
<p>The expected breakthrough curve for a fixed sampling port.</p> Full article ">Figure 6
<p>A representation of a ZVI particle, showing corroded iron volume, iron expansion volume and iron corrosion products.</p> Full article ">Figure 7
<p>A schematic representation of the clogging phenomenon in pure ZVI and ZVI dispersed in an admixing agent.</p> Full article ">Figure 8
<p>The typical grain size distributions of internally unstable (broadly graded and gap-graded soils) and stable soils (uniform soils).</p> Full article ">Figure 9
<p>A flowchart of the design of hydraulically efficient ZVI-based PRBs.</p> Full article ">
14 pages, 1419 KiB  
Article
Chemodynamics of Mercury (Hg) in a Southern Reservoir Lake (Cane Creek Lake, Cookeville, TN, USA): I—Estimation of the Kinetics of Photochemical Reduction of Aquatic Hg(II) Using Field-Measured Data of Hg Water/Air Exchange and Dissolved Gaseous Hg
by Lesta S. Fletcher, William C. Crocker and Hong Zhang
Water 2023, 15(1), 199; https://doi.org/10.3390/w15010199 - 3 Jan 2023
Viewed by 1768
Abstract
An alternative, independent estimation of the kinetics of aquatic Hg(II) photochemical reduction featuring dissolved gaseous mercury (DGM) emission from water in consideration was obtained by using a mass balance box model. An interactive Excel spreadsheet was constructed to implement the model equations to [...] Read more.
An alternative, independent estimation of the kinetics of aquatic Hg(II) photochemical reduction featuring dissolved gaseous mercury (DGM) emission from water in consideration was obtained by using a mass balance box model. An interactive Excel spreadsheet was constructed to implement the model equations to yield the rate constants and the rates of the Hg(II) photoreduction. The model calculations used field-measured data of DGM paired with its emission flux coupled with the corresponding field sampling times. This data set came from a previous, separate, year-long field study conducted at a southern reservoir lake (Cane Creek Lake, Cookeville, Putnam County, TN). The mean value of the model-calculated rate constants (kDGM) of the Hg(II) photoreduction for the warm season (June–August) (4.5 fM h−1/pg L−1) is higher than that for the cold season (October–January) (2.2 fM h−1/pg L−1). The rate constants were found to be the highest (22.5 fM h−1/pg L−1) in August whereas the lowest (0.03 fM h−1/pg L−1) in January. The model-calculated rate constants are clearly higher in value than but comparable in order of magnitude to the published kinetic data. The model-calculated rates (rDGM) of the Hg(II) photoreduction are significantly higher, by one order of magnitude (102 vs. 101) than the apparent rates calculated using the same field DGM data without consideration of the Hg emission from the water. A sensitivity analysis of the model parameters points to a high sensitivity of Hg emission flux to the rate constant under modeled realistic environmental conditions. The initial Hg(II) concentration is also a sensitive model parameter under certain conditions. The results of our model study support the conclusion that DGM emission from water has a strong impact on the kinetics of aquatic Hg(II) photoreduction and the model calculation can provide an independent, valuable approach for estimating the kinetics of aquatic Hg(II) photoreduction. Full article
(This article belongs to the Special Issue Transformation and Transport of Chemicals in Aquatic Systems)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>A schematic diagram of a mass balance box model for cycling and photochemodynamics of Hg in aquatic systems (after [<a href="#B17-water-15-00199" class="html-bibr">17</a>]).</p> Full article ">Figure 2
<p>Examples of rate constants of aquatic Hg photoreduction calculated using a mass balance box model for (<b>a</b>) the warm season and (<b>b</b>) the cold season (model parameters in the model Equation (6) used for calculations: <span class="html-italic">F</span> (flux) and DGM = real field data, [Hg(II)]<sub>0</sub> = 150 pg L<sup>−1</sup>, <span class="html-italic">d</span> = 200 cm, <span class="html-italic">d</span><sub>1</sub> = 10 cm).</p> Full article ">Figure 3
<p>An Arrhenius relationship between the model-calculated rate constants of aquatic DGM photoproduction and water temperatures to investigate the impact of thermal energy on the Hg reduction. The model-calculated rate constants plotted include the entire calculated rate constants covering both warm and cold seasons.</p> Full article ">Figure 4
<p>The relationship between the model-calculated rate constants of aquatic Hg photoreduction and solar radiation parameter (global radiation). The model-calculated rate constants plotted include the entire calculated rate constants covering both warm and cold seasons.</p> Full article ">Figure 5
<p>Results of the model sensitivity study for the model parameters of water column depth (<span class="html-italic">d</span>), the depth of the surface photic zone (<span class="html-italic">d</span><sub>1</sub>), initial Hg(II) concentration [Hg(II)]<sub>0</sub>, and Hg(0) emiss-ion flux (<span class="html-italic">F</span>).</p> Full article ">
17 pages, 4663 KiB  
Article
Degradability of Polylactide in Natural Aqueous Environments
by Katarzyna Krasowska and Aleksandra Heimowska
Water 2023, 15(1), 198; https://doi.org/10.3390/w15010198 - 3 Jan 2023
Cited by 7 | Viewed by 2747
Abstract
This study aims to estimate the degradation process of polylactide (PLA) in natural aqueous environments. The biological degradation of PLA took place in the Baltic Sea and in the natural pond over a period of 1 to 16 months. The characteristic abiotic parameters [...] Read more.
This study aims to estimate the degradation process of polylactide (PLA) in natural aqueous environments. The biological degradation of PLA took place in the Baltic Sea and in the natural pond over a period of 1 to 16 months. The characteristic abiotic parameters of both environments were monitored during incubation time, and their influence on the PLA degradation was discussed. The changes in weight, chemical structure, mechanical properties and surface morphology of investigated samples were also tested during incubation. The obtained results indicate that polylactide is not very susceptible to an enzymatic attack of microorganisms present in natural aqueous environments. Full article
(This article belongs to the Special Issue Seas under Anthropopressure)
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<p>Macrographs of PLA samples before and after incubation in different aqueous environments: (<b>a</b>) before degradation; (<b>b</b>) 3 months in the pond; (<b>c</b>) 3 months in sea; (<b>d</b>) 6 months in the pond water; (<b>e</b>) 6 months in the seawater; (<b>f</b>) 12 months in the pond; (<b>g</b>) 16 months in the seawater; (<b>h</b>) 12 months in pond water + NaN<sub>3</sub>; (<b>i</b>) 16 months in the seawater + NaN<sub>3</sub>. Source: Own research.</p> Full article ">Figure 1 Cont.
<p>Macrographs of PLA samples before and after incubation in different aqueous environments: (<b>a</b>) before degradation; (<b>b</b>) 3 months in the pond; (<b>c</b>) 3 months in sea; (<b>d</b>) 6 months in the pond water; (<b>e</b>) 6 months in the seawater; (<b>f</b>) 12 months in the pond; (<b>g</b>) 16 months in the seawater; (<b>h</b>) 12 months in pond water + NaN<sub>3</sub>; (<b>i</b>) 16 months in the seawater + NaN<sub>3</sub>. Source: Own research.</p> Full article ">Figure 2
<p>Weight changes [%] of PLA samples after incubation in different aqueous environments. Source: Own research.</p> Full article ">Figure 3
<p>ATR-FTIR spectra of the PLA sample in the wavenumber of 600–4000 cm<sup>−1</sup>: (<b>a</b>) before degradation; (<b>b</b>) after 12 months of degradation in aqueous environments. Source: Own research.</p> Full article ">Figure 3 Cont.
<p>ATR-FTIR spectra of the PLA sample in the wavenumber of 600–4000 cm<sup>−1</sup>: (<b>a</b>) before degradation; (<b>b</b>) after 12 months of degradation in aqueous environments. Source: Own research.</p> Full article ">Figure 4
<p>ATR-FTIR spectra of the PLA sample before degradation and after 12 months incubation in pond and seawater with NaN<sub>3</sub> as the wavenumber of 2800–3800 cm<sup>−1</sup>. Source: Own research.</p> Full article ">Figure 5
<p>The intensity ratio of the band at about 1750 cm<sup>−1</sup> to band approximately 1450 cm<sup>−1</sup> for PLA before and after 12 months of incubation in aqueous environments. Source: Own research.</p> Full article ">Figure 6
<p>Tensile strength [MPa] of PLA samples after incubation in different aqueous environments. Source: Own research.</p> Full article ">Figure 7
<p>Elongation [%] of the PLA samples after incubation in different aqueous environments. Source: Own research.</p> Full article ">Figure 8
<p>Micrographs of PLA samples before and after incubation in natural aqueous environments: (<b>a</b>) before degradation; (<b>b</b>) 3 months in pond water; (<b>c</b>) 3 months in seawater; (<b>d</b>) 6 months in pond water; (<b>e</b>) 6 months in seawater; (<b>f</b>) 12 months in pond water; (<b>g</b>) 12 months in seawater; (<b>h</b>) 16 months in seawater. Source: Own research.</p> Full article ">Figure 9
<p>Micrographs of PLA samples before and after incubation in aqueous environments with sodium azide: (<b>a</b>) before degradation; (<b>b</b>) 12 months in pond water; (<b>c</b>) 16 months in seawater. Source: Own research.</p> Full article ">
21 pages, 5513 KiB  
Article
Trend Analysis of Precipitation, Runoff and Major Ions for the Russian Part of the Selenga River Basin
by Tcogto Zh. Bazarzhapov, Valentina G. Shiretorova, Larisa D. Radnaeva, Elena P. Nikitina, Bator V. Sodnomov, Bair Z. Tsydypov, Valentin S. Batomunkuev, Vasilii V. Taraskin, Suocheng Dong, Zehong Li and Ping Wang
Water 2023, 15(1), 197; https://doi.org/10.3390/w15010197 - 3 Jan 2023
Cited by 4 | Viewed by 1979
Abstract
At present, the problem of climate change is becoming increasingly acute. This is especially pressing for Lake Baikal, a World Natural Heritage site. The Russian part of the Selenga watershed is a suitable site for climate change research. The study of changes in [...] Read more.
At present, the problem of climate change is becoming increasingly acute. This is especially pressing for Lake Baikal, a World Natural Heritage site. The Russian part of the Selenga watershed is a suitable site for climate change research. The study of changes in precipitation, runoff, and chemical runoff is important for sustainable water resources management. This study presents a trend analysis of precipitation and runoff at hydrological stations and weather stations in the Russian part of the Selenga River basin. A comparative analysis of the concentrations of major ions in the surface water of the Selenga River depending on water levels was also carried out. Analysis of the data series on precipitation revealed a slight negative trend at the Novoselenginsk, Ulan-Ude, and Kabansk stations, and a weak positive trend—at the Kyakhta station. Runoff analysis revealed negative trends at the two used stations (Novoselenginsk and Mostovoi). The hydrochemical regime of the Selenga River is characterized by an increase in major ions and salinity during winter low-water periods, and a decrease during high-water periods. Mineralization and major ion content are lower in the high-water period (2019–2021) than in the low-water period (2015–2017). Full article
(This article belongs to the Section Hydrology)
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<p>Location of the Selenga River basin, water gauge stations, meteorological stations, and sampling points on the territory of Russia.</p> Full article ">Figure 2
<p>Rainfall trend at the Kyakhta station for the period of 1936–2021.</p> Full article ">Figure 3
<p>Rainfall trend at the Novoselenginsk station for the period of 1936–2021.</p> Full article ">Figure 4
<p>Rainfall trend at the Ulan-Ude station for the period of 1936–2021.</p> Full article ">Figure 5
<p>Rainfall trend at the Kabansk station for the period of 1936–2021.</p> Full article ">Figure 6
<p>Runoff trend at the Novoselenginsk station for the period of 1990–2017.</p> Full article ">Figure 7
<p>Runoff trend at the Mostovoi station for the period 1990–2017.</p> Full article ">Figure 8
<p>Summary of rainfall and runoff trends.</p> Full article ">Figure 9
<p>Spatiotemporal (<b>a</b>) and seasonal (<b>b</b>) changes in water salinity in the Selenga.</p> Full article ">Figure 10
<p>Spatiotemporal changes in the content of major ions in the Selenga water ((<b>a</b>)—Cl<sup>−</sup>, (<b>b</b>)—SO<sub>4</sub><sup>2−</sup>, (<b>c</b>)—Na<sup>+</sup>). (Data on Na<sup>+</sup> ion content for 2017 are not available).</p> Full article ">Figure 11
<p>Seasonal changes in the content of major ions in the Selenga water ((<b>a</b>)—Cl<sup>−</sup>, (<b>b</b>)—SO<sub>4</sub><sup>2−</sup>, (<b>c</b>)—Na<sup>+</sup>).</p> Full article ">Figure 12
<p>Changes in air temperature for the period of 1936–2020.</p> Full article ">Figure 13
<p>Spearman rank correlation coefficient for the rainfall and the runoff average annual data: (<b>a</b>)—Novoselenginsk station, and (<b>b</b>)—Mostovoi station.</p> Full article ">Figure 14
<p>Spearman rank correlation coefficient for the air temperature and the rainfall average annual data: (<b>a</b>)—the Novoselenginsk station, and (<b>b</b>)—the Ulan-Ude station.</p> Full article ">
31 pages, 10058 KiB  
Review
Process Water Management and Seepage Control in Tailings Storage Facilities: Engineered Environmental Solutions Applied in Chile and Peru
by Carlos Cacciuttolo, Alvar Pastor, Patricio Valderrama and Edison Atencio
Water 2023, 15(1), 196; https://doi.org/10.3390/w15010196 - 3 Jan 2023
Cited by 14 | Viewed by 8924
Abstract
In the past thirty years many mining projects in Chile and Peru have used: (i) polymeric geomembranes and (ii) design-and-build cutoff trenches, plastic concrete slurry walls, and grout curtain systems to control seepage at tailings storage facilities (TSFs). Geosynthetics are a viable alternative [...] Read more.
In the past thirty years many mining projects in Chile and Peru have used: (i) polymeric geomembranes and (ii) design-and-build cutoff trenches, plastic concrete slurry walls, and grout curtain systems to control seepage at tailings storage facilities (TSFs). Geosynthetics are a viable alternative at a TSF dam for clay cores or impermeable materials, mainly because of their marked advantages in cost, installation, and construction time. This article describes the use of geosynthetics liners and cutoff trench–plastic concrete slurry walls–grout curtain systems in TSF dams in Chile and Peru mining, with the objective to decrease seepage to the environment, considering different dam material cases such as: cycloned tailings sand dams, borrow dams, and mine waste rock dams. Finally, this article discusses aspects of geosynthetic technology acceptance in the local regulatory frameworks, lessons learned, and advances. It focuses on the use and implementation of geosynthetics in TSFs in Chile and Peru, which have some of the highest TSF dams in the world, as well as a wet environment, dry environment, extreme topography, and severe seismic conditions. These conditions constitute a challenge for manufacturers, engineers, and contractors, who must achieve optimal technical solutions, while being environmentally aware and economic. Full article
(This article belongs to the Special Issue Prevention of Groundwater-related Hazards in Geotechnical Engineering and Mining Engineering)
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<p>Schematic view of process water (water in contact with mine tailings) management and seepage control in TSF.</p> Full article ">Figure 2
<p>Typical process water management and seepage control in a TSF.</p> Full article ">Figure 3
<p>Typical sulphide gold ore flowsheet process—gold mine tailings management [<a href="#B4-water-15-00196" class="html-bibr">4</a>].</p> Full article ">Figure 4
<p>Gold mine tailings management—fully lined TSF—Tambomayo TSF, Peru [<a href="#B7-water-15-00196" class="html-bibr">7</a>].</p> Full article ">Figure 5
<p>Typical sulphide copper ore flowsheet process—copper mine tailings management [<a href="#B4-water-15-00196" class="html-bibr">4</a>].</p> Full article ">Figure 6
<p>Copper mine tailings management–partially lined TSF—Los Quillayes TSF, Chile.</p> Full article ">Figure 7
<p>Example of cutoff trench and grout curtain system construction in a TSF.</p> Full article ">Figure 8
<p>Example of plastic concrete slurry wall–grout curtain system in TSF dam.</p> Full article ">Figure 9
<p>Example of detail of plastic concrete slurry wall with cement–bentonite grout curtain in TSF.</p> Full article ">Figure 10
<p>Examples of a geomembrane liner, cutoff trench, and grout curtain system in a TSF.</p> Full article ">Figure 11
<p>Schematic example of seepage collection system in TSF.</p> Full article ">Figure 12
<p>Seepage collection sumps in a TSF-Chile.</p> Full article ">Figure 13
<p>Geomembrane installation—typical construction activities, 2H:1V dam slope–Peru.</p> Full article ">Figure 14
<p>Geomembrane seams—typical details.</p> Full article ">Figure 15
<p>Schematic view of a starter dam with typical geosynthetics installation.</p> Full article ">Figure 16
<p>Starter dam upstream face geotextile–geomembrane liner installation first stage finished—TSF Starter Dam, Chile [<a href="#B42-water-15-00196" class="html-bibr">42</a>,<a href="#B43-water-15-00196" class="html-bibr">43</a>].</p> Full article ">Figure 17
<p>Starter dam upstream face geotextile–geomembrane liner installation second stage finished—TSF Starter Dam, Chile [<a href="#B42-water-15-00196" class="html-bibr">42</a>,<a href="#B43-water-15-00196" class="html-bibr">43</a>].</p> Full article ">Figure 18
<p>Schematic view of cycloned tailings sand dam construction.</p> Full article ">Figure 19
<p>Panoramic view of TSF starter dam with geomembrane liner and mine tailings hydrocyclone station—TSF, Chile.</p> Full article ">Figure 20
<p>Cycloned tailings sand dam upstream face waterproofing—TSF, Chile [<a href="#B44-water-15-00196" class="html-bibr">44</a>].</p> Full article ">Figure 21
<p>Cycloned tailings sand dam upstream face waterproofing construction detail.</p> Full article ">Figure 22
<p>Cycloned tailings sand dam upstream face waterproofing construction process—TSF, Chile.</p> Full article ">Figure 23
<p>Panoramic view—mine waste rock dam upstream face waterproofing construction detail— TSF, Peru.</p> Full article ">Figure 24
<p>Front view—mine waste rock dam upstream face waterproofing construction detail—TSF, Peru.</p> Full article ">Figure 25
<p>Mine waste rock (rockfill) dam upstream face waterproofing construction detail.</p> Full article ">Figure 26
<p>Mine waste rock dam upstream face waterproofing with bituminous geomembrane—TSF, Peru.</p> Full article ">Figure 27
<p>Mine waste rock dam upstream face waterproofing with bituminous geomembrane—construction details.</p> Full article ">Figure 28
<p>Example of smart geosynthetic with fiber optics technology.</p> Full article ">Figure 29
<p>Example of use of geosynthetic liner in the zone of a TSF in contact with rock–TSF Peru.</p> Full article ">
13 pages, 1994 KiB  
Article
Impact of Biochar and Graphene as Additives on the Treatment Performances of a Green Wall Fed with Greywater
by Elisa Costamagna, Alice Caruso, Ana Galvão, Anacleto Rizzo, Fabio Masi, Silvia Fiore and Fulvio Boano
Water 2023, 15(1), 195; https://doi.org/10.3390/w15010195 - 3 Jan 2023
Cited by 2 | Viewed by 2749
Abstract
The treatment of greywater (GW, wastewater share excluding toilet flush) through green walls can be beneficial for urban areas, favouring the diffusion of urban vegetation and reducing potable water consumption. Multiple challenges hinder the treatment performance of green walls, including the composition of [...] Read more.
The treatment of greywater (GW, wastewater share excluding toilet flush) through green walls can be beneficial for urban areas, favouring the diffusion of urban vegetation and reducing potable water consumption. Multiple challenges hinder the treatment performance of green walls, including the composition of the filtering material, the number of levels—i.e., rows—and the age of the system. This study investigated graphene as an additive (5%v) to a filtering medium made of coconut fibre, perlite and biochar in an open-air green wall with pots arranged into three levels. The performance of GW treatment was quantified by comparing the physicochemical features of inflow and outflow samples collected weekly over two months. Samples were also collected at each level of the green wall, and the performance of two analogous systems different by age for three months were compared. The results showed that graphene did not significantly improve treatment performance, except for the first level (e.g., 48% vs. 15% for COD, 72% vs. 51% for TSS, with and without graphene respectively). Moreover, GW treatment mostly happened along the first two levels of the green wall, with marginal depletion (e.g., 15% vs. 7% for NH4+-N) after three months of operational time. Full article
(This article belongs to the Special Issue Biological Technology for Wastewater Treatment)
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<p>One of the four tested modules of the green wall system.</p> Full article ">Figure 2
<p>Values of the parameters measured on-site on input (TW and GW) and output samples from all configurations ((<b>a</b>): pH, (<b>b</b>): Temperature, (<b>c</b>): EC, (<b>d</b>): DO). Median value (red line), 25th and 75th percentiles (blue box), range (black whiskers) and outliers (red cross) are shown.</p> Full article ">Figure 3
<p>Values of the parameters measured off-site on input (TW and GW) and output samples from all configurations ((<b>a</b>): BOD<sub>5</sub>, (<b>b</b>): TSS, (<b>c</b>): TKN, (<b>d</b>): NO<sub>3<sup>−</sup></sub>-N). Median value (red line), 25th and 75th percentiles (blue box), range (black whiskers) and outliers (red cross) are shown.</p> Full article ">Figure 4
<p>Values of the parameters measured off-site on input (TW and GW) and output water from all configurations ((<b>a</b>): TP, (<b>b</b>): SO<sub>4</sub><sup>2−</sup>, (<b>c</b>): Cl<sup>−</sup>, (<b>d</b>): MBAS). Median value (red line), 25th and 75th percentiles (blue box), range (black whiskers) and outliers (red cross) are shown.</p> Full article ">Figure 5
<p>Removal efficiency for different treatment levels.</p> Full article ">
15 pages, 1449 KiB  
Article
Potential of Epipremnum aureum and Bacopa monnieri (L.) Wettst for Saline Phytoremediation in Artificial Wetlands
by Marcos Alfonso Lastiri-Hernández, Dioselina Álvarez-Bernal, Gustavo Cruz-Cárdenas, J. Teodoro Silva-García, Eloy Conde-Barajas and Ernesto Oregel-Zamudio
Water 2023, 15(1), 194; https://doi.org/10.3390/w15010194 - 2 Jan 2023
Cited by 2 | Viewed by 2602
Abstract
The aim of this research was to evaluate the phytoremediative potential of Epipremnum aureum and Bacopa monnieri to improve the chemical properties of irrigation water exposed to the following two saline concentrations: highly saline (EC 2000 μS cm−1) and severely saline [...] Read more.
The aim of this research was to evaluate the phytoremediative potential of Epipremnum aureum and Bacopa monnieri to improve the chemical properties of irrigation water exposed to the following two saline concentrations: highly saline (EC 2000 μS cm−1) and severely saline (EC 4000 μS cm−1). The artificial wetlands used in this experiment were of the free water surface type, considering a hydraulic retention time of 42 days. The evaluated treatments were configured as follows: T1 (B. monnieri [control, 300 μS cm−1]), T2 (B. monnieri [2000 μS cm−1]), T3 (B. monnieri [4000 μS cm−1]), T4 (E. aureum [control, 300 μS cm−1]), T5 (E. aureum [2000 μS cm−1]), T6 (E. aureum [4000 μS cm−1]), T7 (B. monnieri + E. aureum [control, 300 μS cm−1]), T8 (B. monnieri + E. aureum [2000 μS cm−1]), and T9 (B. monnieri + E. aureum [4000 μS cm−1]). The results showed that the species B. monnieri and E. aureum (both separately and together) showed a good ability to reduce the salinity of the irrigation water. However, B. monnieri showed a greater ability of phytoremediation, to the point of improving its chemical properties and reducing potential damage to the soil to use this water. In the highly saline group, B. monnieri accumulated 7.992 g per experimental unit and achieved to reduce of the pH from 7.96 to 7.75, EC from 2000 μS cm−1 to 670 μS cm−1, SAR from 13.54 to 3.91 and ESP from 20.17 to 5.83, which allowed it to go from (C3-S3) to (C3-S1). In the severely saline group, B. monnieri accumulated 13.494 g per experimental unit and achieved to reduce the pH from 8.14 to 7.91, EC from 4000 μS cm−1 to 1730 μS cm−1, SAR from 27.35 to 8.73, ESP from 40.35 to 13.01, which allowed it to go from (C4-S4) to (C3-S2). Full article
(This article belongs to the Special Issue The Role of Constructed Wetlands in Wastewater Treatment and Recycling in Agriculture)
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Graphical abstract
Full article ">Figure 1
<p>Establishment of the free water surface CWs for the evaluation of the different proposed treatments (<b>A</b>,<b>B</b>).</p> Full article ">Figure 2
<p>Classification of irrigation water of the different treatments according to USSL [<a href="#B28-water-15-00194" class="html-bibr">28</a>] and Shahid and Mahmoudi [<a href="#B29-water-15-00194" class="html-bibr">29</a>]. CMS: initial chemical characteristics of irrigation water at 2000 μS cm<sup>−1</sup>; CFS: initial chemical characteristics of irrigation water at 4000 μS cm<sup>−1</sup>; T2 (<span class="html-italic">B. monnieri</span> [2000 μS cm<sup>−1</sup>]), T3 (<span class="html-italic">B. monnieri</span> [4000 μS cm<sup>−1</sup>]), T5 (<span class="html-italic">E. aureum</span> [2000 μS cm<sup>−1</sup>]), T6 (<span class="html-italic">E. aureum</span> [4000 μS cm<sup>−1</sup>]), T8 (<span class="html-italic">B. monnieri</span> + <span class="html-italic">E. aureum</span> [2000 μS cm<sup>−1</sup>]), and T9 (<span class="html-italic">B. monnieri</span> + <span class="html-italic">E. aureum</span> [4000 μS cm<sup>−1</sup>]).</p> Full article ">
14 pages, 3486 KiB  
Article
Experimental Analysis of the Annular Velocity of a Capsule When Starting at Different Positions of a Horizontal Bend Pipe
by Cheng Wang and Xihuan Sun
Water 2023, 15(1), 193; https://doi.org/10.3390/w15010193 - 2 Jan 2023
Viewed by 1428
Abstract
The study of the annular slit flow field is important for energy consumption, transport efficiency, and the force on the capsule for hydraulic capsule transportation. A combination of physical experiments and theoretical analysis was used to study the annular flow field around a [...] Read more.
The study of the annular slit flow field is important for energy consumption, transport efficiency, and the force on the capsule for hydraulic capsule transportation. A combination of physical experiments and theoretical analysis was used to study the annular flow field around a capsule that was set in motion at different positions of a horizontal bend pipe. We study the flow velocity distribution of the gap flow field at different bend positions of the capsule by changing the position of the capsule at the bend. We found that the distribution of the flow field remained similar for different starting positions of the capsule, but the flow velocity increased suddenly and dramatically at the inflow section of the ring gap. We recorded different velocity distributions of the annular gap on the concave and convex sides of the pipe; on the convex side, the streamline of the gap was smooth, and the change in velocity was relatively small. The flow velocity of the slit flow varied more notably on the concave side of the pipe, and there was a greater fluctuation in the flow velocity distribution. Because the effects of the capsule and the pipe on water flow were not the same, we found large fluctuations in gap flow velocity at different measuring points on the concave side. Gap flow velocity was most influenced by axial flow velocity. We found that the axial flow velocity was about one order of magnitude greater than the radial flow velocity or circumferential flow velocity. In this paper, we analyze the changes in the ring gap flow field of the capsule at different bending positions and analyze the reasons for the flow field changes and the flow velocity distribution law. This is of great significance to the study of the transport efficiency and energy consumption of the capsule. The results of this paper complement the study of capsule initiation at different positions in the bend and provide a reference point in terms of transport efficiency, energy consumption, and capsule stress. The results of this study promote the development of hydraulic capsule transportation. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
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<p>Layout of the test system: (<b>a</b>) schematic diagram, 1. centrifugal pumps, 2. gate valve, 3. electromagnetic flowmeter, 4. trapezoidal water jacket, 5. PIV, 6. workbench, 7. steel water tank; (<b>b</b>) PIV measuring; (<b>c</b>) bend pipe; (<b>d</b>) PIV schematic sketch.</p> Full article ">Figure 2
<p>Structure schematic of the capsule. (<b>a</b>) Capsule geometry model; (<b>b</b>) Capsule physical model.</p> Full article ">Figure 3
<p>Schematic diagram of capsule at different positions of elbow.</p> Full article ">Figure 4
<p>Schematic diagram of measuring point layout.</p> Full article ">Figure 5
<p>Cloud chart of the time-averaged distribution of overall capsule velocity. (<b>a</b>) Position 1; (<b>b</b>) position 2; (<b>c</b>) position 3; (<b>d</b>) position 4.</p> Full article ">Figure 6
<p>Variation curve of annular slit flow axial velocity at the same measuring point along the flow. (<b>a</b>) Position 1; (<b>b</b>) position 2; (<b>c</b>) position 3; (<b>d</b>) position 4.</p> Full article ">Figure 6 Cont.
<p>Variation curve of annular slit flow axial velocity at the same measuring point along the flow. (<b>a</b>) Position 1; (<b>b</b>) position 2; (<b>c</b>) position 3; (<b>d</b>) position 4.</p> Full article ">Figure 7
<p>Variation curve of circumferential flow velocity at horizontal measuring points of annular slit flow. (<b>a</b>) Position 1; (<b>b</b>) position 2; (<b>c</b>) position 3; (<b>d</b>) position 4.</p> Full article ">Figure 7 Cont.
<p>Variation curve of circumferential flow velocity at horizontal measuring points of annular slit flow. (<b>a</b>) Position 1; (<b>b</b>) position 2; (<b>c</b>) position 3; (<b>d</b>) position 4.</p> Full article ">Figure 8
<p>Variation curve of radial velocity of annular slit flow at the same measuring point along the flow. (<b>a</b>) Position 1; (<b>b</b>) position 2; (<b>c</b>) position 3; (<b>d</b>) position 4.</p> Full article ">
19 pages, 7353 KiB  
Article
Flood Simulation and Flood Risk Reduction Strategy in Irrigated Areas
by Zhenyang Liu, Yujiang Xiong and Junzeng Xu
Water 2023, 15(1), 192; https://doi.org/10.3390/w15010192 - 2 Jan 2023
Cited by 4 | Viewed by 2043
Abstract
The potential risk of flood or waterlogging in irrigation districts has increased due to global climate change and intensive human activities. This paper employed a waterlogging process simulation model for flat irrigation districts in the paddy fields to simulate floods under different scenarios. [...] Read more.
The potential risk of flood or waterlogging in irrigation districts has increased due to global climate change and intensive human activities. This paper employed a waterlogging process simulation model for flat irrigation districts in the paddy fields to simulate floods under different scenarios. The scenarios of the rainfall conditions, initial storage depths, and work scales are designed, respectively. The risk of flood damage increases as rainfall increases, with a maximum increase of 62.8%, comparing the extreme scenario with the current scenario. A moderate rise in pumping station flow and using pre-rain drainage measures in the paddy fields can effectively reduce waterlogging loss. The total regional flood damage was reduced by up to 10.9%, 15.8%, and 35.9% when the pump station flow in the study area was increased by 10%, 20%, and 30%. The insights from this study of the possible future extreme flood events may help flood control planning. Full article
(This article belongs to the Section Water, Agriculture and Aquaculture)
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<p>Study area map and drainage system generalization.</p> Full article ">Figure 2
<p>Framework and internal relationships between the modules of the Waterlogging Process Model.</p> Full article ">Figure 3
<p>The structure and meaning of the two-layer tank model.</p> Full article ">Figure 4
<p>Time distribution diagram of a typical rainfall process.</p> Full article ">Figure 5
<p>Variation and distribution of submerged depth under different rainfall return periods of the current scenario ((<b>a</b>). P5% (<b>b</b>). P2% (<b>c</b>). P1%, unit: m).</p> Full article ">Figure 6
<p>Waterlogging loss under different rainfall return periods of the current scenario ((<b>a</b>). P2% (<b>b</b>). P1%).</p> Full article ">Figure 7
<p>Distribution of waterlogging loss under different rainfall return periods of extreme scenario.</p> Full article ">Figure 8
<p>Scheduling schemes under different frequency rainfall conditions in the current and extreme climate scenario. Black represents the gate and red represents the pump. Serial number of pump Station: P0: Heping, P1: Zhongxinhe, P2: Nijia, P3: Hongqi, P4: Jiangmahe, P5: Zhongshihe, P6: Lvyanghe. C: current scenario, E: extreme scenario.</p> Full article ">Figure 9
<p>Variation of waterlogging depth and yield reduction rate of paddy fields with different initial storage depths under a 50-year rainfall of the current scenario.</p> Full article ">Figure 10
<p>Waterlogging loss of paddy fields with an initial storage depth of 0 cm under different rainfall frequencies.</p> Full article ">Figure 11
<p>Scheduling schemes under different frequency rainfall conditions in the current and extreme climate scenario (initial storage depth of 0 cm).</p> Full article ">Figure 12
<p>Scheduling schemes under different frequency rainfall conditions and work scale in the extreme climate scenario. (a–c, a: rainfall frequency, b: initial water level, c-work scale increased).</p> Full article ">Figure 13
<p>Distribution of averaged waterlogging loss with different initial storage depths and work scales under 2% frequency.</p> Full article ">Figure 14
<p>Distribution of averaged waterlogging loss with different initial storage depths and work scales under 1% frequency.</p> Full article ">
27 pages, 7628 KiB  
Article
Evaluation of the Influence of Catchment Parameters on the Required Size of a Stormwater Infiltration Facility
by Sabina Kordana-Obuch, Mariusz Starzec and Daniel Słyś
Water 2023, 15(1), 191; https://doi.org/10.3390/w15010191 - 2 Jan 2023
Cited by 6 | Viewed by 2580
Abstract
One sustainable method of stormwater management is surface infiltration with retention. Proper design of stormwater infiltration facilities ensures a reduction in flood risk within urban catchments. However, this is not possible without considering the key design parameters of such facilities. The aim of [...] Read more.
One sustainable method of stormwater management is surface infiltration with retention. Proper design of stormwater infiltration facilities ensures a reduction in flood risk within urban catchments. However, this is not possible without considering the key design parameters of such facilities. The aim of this paper is to determine the influence of the parameters characterizing the catchment area on the size of the stormwater infiltration facilities. The research used SWMM 5.1 and Statistica software. It was carried out on the example of model catchments and a real urban catchment. The analysis showed that it is of key importance in the design of stormwater infiltration facilities to accurately determine the total catchment area, the type of soil within it, and the proportion of impervious surfaces. The relevance of the other parameters that characterize the catchment area is clearly lesser. However, they cannot be completely ignored, and their values should be determined as accurately as possible. These research results can guide stakeholders in the decision-making process during investment planning and implementation. Full article
(This article belongs to the Special Issue Feature Papers of Water-Energy Nexus)
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Figure 1

Figure 1
<p>Research plan.</p> Full article ">Figure 2
<p>Computational model.</p> Full article ">Figure 3
<p>The analyzed catchments, consisting of sixteen subcatchments (J1–J16—junctions; S1–S16—subcatchments; S.INF—subcatchment simulating rainfall over an infiltration facility; INF—infiltration facility; R1—rain gage; O1—outlet from the overflow).</p> Full article ">Figure 4
<p>The maximum level of fill in an infiltration tank (<span class="html-italic">h<sub>ijmax</sub></span>) as a function of the duration of rainfall (<span class="html-italic">t</span>) and the bottom area of the facility (<span class="html-italic">S<sub>ij</sub></span>), determined for a randomly selected catchment (<span class="html-italic">h<sub>ijmax</sub></span>—maximum level of fill in the tank at a given area of its bottom; <span class="html-italic">S<sub>i</sub></span>—required area of the tank; <span class="html-italic">t<sub>o</sub></span>—critical rainfall duration).</p> Full article ">Figure 5
<p>Infiltration tank fill level (<span class="html-italic">h<sub>ij</sub></span>) in time (<span class="html-italic">t<sub>i</sub></span>) depending on the duration of the rainfall (<span class="html-italic">t</span>), determined for its bottom area of <span class="html-italic">S<sub>i</sub></span> = 563.30 m<sup>2</sup> (<span class="html-italic">h<sub>ijmax</sub></span>—maximum fill level in the tank at a given area of its bottom; <span class="html-italic">t<sub>o</sub></span>—critical rainfall duration).</p> Full article ">Figure 6
<p>Location of the study area.</p> Full article ">Figure 7
<p>Soil samples from an example borehole.</p> Full article ">Figure 8
<p>Hydrodynamic model of the study catchment area.</p> Full article ">Figure 9
<p>Rainfall depth at the KOLBUSZOWA 250210220 meteorological station with a 10 min time step (based on [<a href="#B62-water-15-00191" class="html-bibr">62</a>]).</p> Full article ">Figure 10
<p>Depth of the analyzed rainfall: (<b>a</b>) 19 June 2020—<span class="html-italic">p</span> = 0.00098; (<b>b</b>) 19 May 2019—<span class="html-italic">p</span> = 0.065; (<b>c</b>) 8 August 2019—<span class="html-italic">p</span> = 0.53.</p> Full article ">Figure 10 Cont.
<p>Depth of the analyzed rainfall: (<b>a</b>) 19 June 2020—<span class="html-italic">p</span> = 0.00098; (<b>b</b>) 19 May 2019—<span class="html-italic">p</span> = 0.065; (<b>c</b>) 8 August 2019—<span class="html-italic">p</span> = 0.53.</p> Full article ">Figure 11
<p>Results of the simulations carried out for the infiltration basin (<span class="html-italic">A<sub>z</sub></span>—reduced catchment area; <span class="html-italic">A<sub>c</sub></span>—total catchment area; C—runoff coefficient).</p> Full article ">Figure 12
<p>Results of the simulations carried out for the infiltration tank (<span class="html-italic">A<sub>z</sub></span>—reduced catchment area; <span class="html-italic">A<sub>c</sub></span>—total catchment area; C—runoff coefficient).</p> Full article ">Figure 13
<p>Comparison of the required area of the stormwater infiltration facility (<span class="html-italic">S<sub>i</sub></span>) generated from the artificial neural network (ANN) and obtained from hydrodynamic simulations (HM): (<b>a</b>) infiltration basin, fully water saturated; (<b>b</b>) infiltration basin, completely drained; (<b>c</b>) infiltration tank, fully water saturated; (<b>d</b>) infiltration tank, completely drained.</p> Full article ">Figure 14
<p>Stormwater fill level in the infiltration facility (blue line—actual fill level; red line—designed fill level).</p> Full article ">Figure 15
<p>The length of fill of the infiltration facility above the value of <span class="html-italic">h<sub>imax</sub></span> = 0.3 m in the period from 1 January 2011 to 30 June 2022 (designations as in <a href="#water-15-00191-f002" class="html-fig">Figure 2</a>).</p> Full article ">Figure 16
<p>Maximum level of fill in the stormwater infiltration facility: (<b>a</b>) 19 June, 2020—<span class="html-italic">p</span> = 0.00098; (<b>b</b>) 19 May, 2019—<span class="html-italic">p</span> = 0.065; (<b>c</b>) 8 August, 2019—<span class="html-italic">p</span> = 0.53 (designations as in <a href="#water-15-00191-f002" class="html-fig">Figure 2</a>).</p> Full article ">
14 pages, 2790 KiB  
Article
Synthesis and Characterization of Silver Nanoparticles for the Preparation of Chitosan Pellets and Their Application in Industrial Wastewater Disinfection
by Paula Sartori, Ana Paula Longaray Delamare, Giovanna Machado, Declan M. Devine, Janaina S. Crespo and Marcelo Giovanela
Water 2023, 15(1), 190; https://doi.org/10.3390/w15010190 - 2 Jan 2023
Cited by 3 | Viewed by 2805
Abstract
The use of silver nanoparticles (AgNPs) has become popular in several applications due to their bactericidal properties. In this sense, it is ideal that the AgNPs are incorporated into a matrix in order to minimize their release to the environment and to maintain [...] Read more.
The use of silver nanoparticles (AgNPs) has become popular in several applications due to their bactericidal properties. In this sense, it is ideal that the AgNPs are incorporated into a matrix in order to minimize their release to the environment and to maintain their high reactivity. In view of these facts, the main goal of this work was to synthesize and characterize AgNPs, evaluating the influence of pH on the synthesis, for later incorporation into a chitosan polymeric matrix that will be used in the form of pellets for the disinfection of industrial wastewater. For this purpose, AgNPs were initially synthesized by a chemical route using silver nitrate, sodium borohydride and sodium citrate and then characterized by ultraviolet-visible spectroscopy, transmission electron microscopy and as a function of bacterial growth inhibition against Escherichia coli and Enterococcus faecalis. At the end of this procedure, AgNPs were incorporated in chitosan and the pellets formed were employed in the disinfection process, while assessing their bactericidal activity as well as the amount of silver leached. In general, the results showed that AgNPs synthesized at pH 10.0 were smaller (3.14 ± 0.54 nm) and presented greater dispersion than the AgNPs synthesized at other pH values. Furthermore, it was possible to observe a synergistic effect between chitosan and AgNPs and the chitosan pellets containing AgNPs proved to be effective in wastewater treatment, destroying Escherichia coli after 60 min of treatment. Finally, by considering the ease of application, the low environmental impact and the bactericidal action, it is concluded that the hybrid pellets developed in this work have great potential to be used as auxiliaries in wastewater treatment. Full article
(This article belongs to the Special Issue Application of Nanomaterials in Water Treatment)
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<p>Schematic diagram of the methodology of the study.</p> Full article ">Figure 2
<p>Visual aspect of AgNPs synthesized as a function of the pH of the sodium citrate solution.</p> Full article ">Figure 3
<p>UV-Vis spectra of AgNPs synthesized at different pH values of sodium citrate solution.</p> Full article ">Figure 4
<p>TEM images obtained from dilute solutions of AgNPs synthesized at the pH range 2.0–13.0. All images are scaled to 100 nm.</p> Full article ">Figure 5
<p>Histograms of AgNPs synthesized at pH range 5.0–13.0.</p> Full article ">Figure 6
<p>Contact angle with the surface of (<b>a</b>) chitosan and (<b>b</b>) chitosan with AgNPs pellets.</p> Full article ">Figure 7
<p>Evaluation of the bactericidal activity of chitosan pellets containing AgNPs against <span class="html-italic">Escherichia coli</span>: (<b>a</b>) control; (<b>b</b>) 60 min of treatment; (<b>c</b>) 120 min of treatment; (<b>d</b>) 180 min of treatment.</p> Full article ">
15 pages, 2863 KiB  
Article
Physicochemical and Sorption Characteristics of Carbon Biochars Based on Lignin and Industrial Waste Magnetic Iron Dust
by Mariia Galaburda, Alicja Bosacka, Dariusz Sternik, Olena Oranska, Mykola Borysenko, Volodymyr Gun’ko and Anna Derylo-Marczewska
Water 2023, 15(1), 189; https://doi.org/10.3390/w15010189 - 2 Jan 2023
Cited by 3 | Viewed by 2545
Abstract
Magnetosensitive biochars were prepared with mechanochemical ball-milling of lignin and blast furnace dust with further pyrolysis at 800 °C under an inert gas atmosphere. The physicochemical and sorption characteristics of the materials were analyzed using several techniques: low-temperature nitrogen adsorption–desorption, X-ray powder diffraction, [...] Read more.
Magnetosensitive biochars were prepared with mechanochemical ball-milling of lignin and blast furnace dust with further pyrolysis at 800 °C under an inert gas atmosphere. The physicochemical and sorption characteristics of the materials were analyzed using several techniques: low-temperature nitrogen adsorption–desorption, X-ray powder diffraction, Raman spectroscopy, elemental analysis, potentiometric titration, and thermal analysis. All the synthesized biocarbons were characterized by their specific surface areas (SBET) in the range of 290–330 m2/g and microporous structures with certain contribution of mesopores in the total porosity. Equilibrium adsorption studies revealed the potential applicability of the materials in water remediation from hazardous organic substances modelled with methylene blue (MB) dye. Generally, this study illustrates the effective conversion of sustainable waste into a functional carbon material. Full article
(This article belongs to the Special Issue Application of Nanomaterials in Water Treatment)
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<p>(<b>a</b>) Nitrogen adsorption–desorption isotherms and (<b>b</b>) pore size distributions of 1: STInd–1; 2: STInd–2; 3: STInd–3; 4: STInd–4; and 5: indulin/carbon.</p> Full article ">Figure 2
<p>(<b>a</b>) XRD patterns and (<b>b</b>) Raman spectra of carbonized materials and furnace dust. 1: indulin/carbon; 2: STInd–1; 3: STInd–2; 4: STInd–3; 5: STInd–4; and 6: DustST.</p> Full article ">Figure 3
<p>TG (<b>a</b>) and DTG and DTA (<b>b</b>) curves of biochars.</p> Full article ">Figure 4
<p>Surface charge density as a function of pH (Qs vs. pH) of carbonized indulin-based biochars.</p> Full article ">Figure 5
<p>The effect of (<b>a</b>) pH (C<sub>0</sub> = 12.8 mg/L, pH = 2, 4, 7), (<b>b</b>) contact time C<sub>0</sub> = 12.8 mg/L, pH = 7), (<b>c</b>) the percent of methylene blue removal (C<sub>0</sub> = 12.8 mg/L, pH ~7) and (<b>d</b>) maximum adsorption (a<sub>m</sub>) (mg/g) for the investigated adsorbents.</p> Full article ">Figure 6
<p>The scheme of biochars synthesis with the possible mechanism of methylene blue adsorption.</p> Full article ">
13 pages, 6356 KiB  
Article
Impact of the Boreholes on the Surrounding Ground
by Sudip Shakya, Koki Nakao, Shuichi Kuwahara and Shinya Inazumi
Water 2023, 15(1), 188; https://doi.org/10.3390/w15010188 - 2 Jan 2023
Cited by 3 | Viewed by 2778
Abstract
The infrastructures that were constructed decades ago do not meet the present structural benchmark, and they need to be demolished. In order to reclaim these lands, the existing pile foundations must be removed; otherwise, the land will lose its value. Since the piles [...] Read more.
The infrastructures that were constructed decades ago do not meet the present structural benchmark, and they need to be demolished. In order to reclaim these lands, the existing pile foundations must be removed; otherwise, the land will lose its value. Since the piles are pulled out, vacant spaces are created in the ground. This causes the surrounding ground to experience settlement, jeopardizing its stability. The degree of influence depends upon the number of boreholes, the saturated condition of the ground, the time period of the vacant condition, the presence of loading, etc. It is important to understand the scope of the probable settlement under various situations. This study focused on determining the amount of displacement and its range for three different saturated soil types under loaded and unloaded conditions using the finite element method (FEM) analysis. It was observed that stiff ground underwent maximum deformation, while soft ground experienced the maximum influence from external factors. Moreover, the presence of loading not only increased the displacement amount and range, but it also caused a change in the location of the maximum displacement. Full article
(This article belongs to the Special Issue Risk Management Technologies for Deep Excavations in Water-Rich Areas)
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<p>Analytical ground models for single and double boreholes.</p> Full article ">Figure 2
<p>Top views of displacement contour for single boreholes left vacant.</p> Full article ">Figure 3
<p>Rates of change in maximum displacement vectors for single boreholes left vacant.</p> Full article ">Figure 4
<p>Top views of displacement contour for double boreholes left vacant.</p> Full article ">Figure 5
<p>Rates of change in maximum displacement vectors for double boreholes left vacant.</p> Full article ">Figure 6
<p>Rates of change in total stress for double boreholes left vacant.</p> Full article ">Figure 7
<p>Rates of change in pore water pressure for double boreholes left vacant.</p> Full article ">Figure 8
<p>Comparison of frontal cross sectional total stress contour for vacant and filled cases of double boreholes.</p> Full article ">Figure 9
<p>Comparison of sinking amounts for vacant and filled cases of double boreholes.</p> Full article ">Figure 10
<p>Comparison of porewater pressure for vacant and filled cases of double boreholes.</p> Full article ">Figure 11
<p>Analytical ground models for single and double boreholes under the loading condition.</p> Full article ">Figure 12
<p>Top views of the displacement contour for single boreholes under the loading condition.</p> Full article ">Figure 13
<p>Rates of change in maximum displacement vectors for single boreholes under the loading condition.</p> Full article ">Figure 14
<p>Top views of displacement contour for double boreholes under the loading condition.</p> Full article ">Figure 15
<p>Rates of change in maximum displacement vectors for double boreholes under the loading condition.</p> Full article ">
19 pages, 2683 KiB  
Article
Tuning the Photocatalytic Performance of Ni-Zn Ferrite Catalyst Using Nd Doping for Solar Light-Driven Catalytic Degradation of Methylene Blue
by Pooja Dhiman, Garima Rana, Elmuez A. Dawi, Amit Kumar, Gaurav Sharma, Arun Kumar and Jayati Sharma
Water 2023, 15(1), 187; https://doi.org/10.3390/w15010187 - 2 Jan 2023
Cited by 19 | Viewed by 2669
Abstract
In this paper, we describe the creation of a moderate band gap Nd-substituted Ni-Zn ferrite as a nano photo catalyst via a simple and cost-effective process of solution combustion. Nd substitution alters the crystallite size, shape, band gap, and magnetic characteristics of Ni-Zn [...] Read more.
In this paper, we describe the creation of a moderate band gap Nd-substituted Ni-Zn ferrite as a nano photo catalyst via a simple and cost-effective process of solution combustion. Nd substitution alters the crystallite size, shape, band gap, and magnetic characteristics of Ni-Zn ferrite significantly. Investigations using X-ray diffraction revealed that all samples display a pure phase. The average crystallite size was determined to be between 31.34 and 38.67 nm. On Nd doping, morphology investigations indicated that the shape of nanoparticles changed from approximately spherical to stacked grains. Band gap experiments confirmed the red shift in optical band gap on Nd doping. The synthesized catalysts Ni0.5Zn0.5Fe2O4 (Nd0), Ni0.5Zn0.45Nd0.05Fe2O4 (Nd1), and Ni0.5Zn0.5Nd0.05Fe1.95O4 (Nd2) have been effectively used for the degradation of methylene blue dye under the solar light irradiation. The sample with Nd substitution on Fe sites had the highest methylene blue degradation efficiency. Nd2 photo catalyst degrades the methylene blue dye with a degradation efficiency of 98% in 90 min of solar light irradiation. The photocatalytic activity is triggered by the existence of oxygen vacancies and a mixed valence state of Ni, Fe, and Nd, as confirmed by the XPS investigation. In addition, the investigations on scavenging reveal that the hydroxyl radical is a reactive component in the degradation process. The degradation route has been investigated in relation to the many potential reactions and discovered reactive substances. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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<p>(<b>a</b>) X-ray diffraction pattern for synthesized catalysts, (<b>b</b>) TEM image for Nd2 sample, and (<b>c</b>) corresponding SAED pattern.</p> Full article ">Figure 2
<p>Rietveld refined XRD pattern of Nd0, Nd1, and Nd2 samples.</p> Full article ">Figure 3
<p>SEM images for (<b>a</b>–<b>c</b>) Nd0, Nd1, and Nd2 samples. (<b>d</b>–<b>i</b>) Elemental mapping for Nd2 sample.</p> Full article ">Figure 4
<p>(<b>a</b>–<b>c</b>) Tauc’s plot for Nd0, Nd1, and Nd2 samples, (<b>d</b>) EIS spectra for Nd1 and Nd2 catalysts.</p> Full article ">Figure 5
<p>De-convoluted core level spectra for (<b>a</b>) Fe2p, (<b>b</b>) Ni 2p, (<b>c</b>) O1s, and (<b>d</b>) Zn 2p state.</p> Full article ">Figure 6
<p>Core level de-convoluted spectra for Nd 3d state.</p> Full article ">Figure 7
<p>Magnetization versus applied field curves for Nd0, Nd1, and Nd2 samples.</p> Full article ">Figure 8
<p>(<b>a</b>) <span class="html-italic">C<sub>t</sub></span>/<span class="html-italic">C</span><sub>0</sub> vs. time curve for photo degradation of methylene blue. (<b>b</b>) Pseudo first order kinetics of photo degradation process. (<b>c</b>) Effect of pH of the medium on the degradation of methylene blue. (<b>d</b>) Effect of catalyst dose on the photo degradation of methylene blue (reaction parameter, pH-12, methylene blue concentration-0.20 mg/L). (<b>e</b>) Photo degradation of methylene blue with/without presence of H<sub>2</sub>O<sub>2</sub> (pH-7: H<sub>2</sub>O<sub>2.</sub> volume-5 mL: methylene blue concentration-0.20 mg/L, catalyst dose: 25 mg). (<b>f</b>) Scavenging experiment for the determination of reactive species.</p> Full article ">Figure 9
<p>(<b>a</b>) Proposed mechanism for solar driven degradation of methylene blue using Nd2 catalyst, (<b>b</b>) Reusability of Nd2 catalyst over five successive cycles.</p> Full article ">Scheme 1
<p>Redox reactions involved in degradation of methylene blue.</p> Full article ">Scheme 2
<p>Feasible reactions for photo degradation of MB involving H<sub>2</sub>O<sub>2</sub> using Nd2 catalyst.</p> Full article ">
21 pages, 12355 KiB  
Article
Capacity Optimization of Rainwater Harvesting Systems Based on a Cost–Benefit Analysis: A Financial Support Program Review and Parametric Sensitivity Analysis
by Youngkyu Jin, Sangho Lee, Taeuk Kang, Jongpyo Park and Yeulwoo Kim
Water 2023, 15(1), 186; https://doi.org/10.3390/w15010186 - 2 Jan 2023
Cited by 8 | Viewed by 3404
Abstract
Water risk has been continuously rising due to climate change and ownership disputes of water resources. Dam construction to secure water resources may lead to environmental problems and upstream immersion. On the other hand, rainwater harvesting systems can effectively supply water at a [...] Read more.
Water risk has been continuously rising due to climate change and ownership disputes of water resources. Dam construction to secure water resources may lead to environmental problems and upstream immersion. On the other hand, rainwater harvesting systems can effectively supply water at a low cost, although economic efficiency of these systems is still debatable. This study evaluates financial support programs to promote installation of rainwater harvesting systems, increasing economic feasibility. Based on a cost–benefit analysis, capacity optimization methods are further suggested. A sensitivity analysis is performed to determine the relative importance among uncertain parameters such as inflation and discount rates. In doing so, priority factors to consider in the design of rainwater harvesting systems are ultimately identified. A net present value, although it is sensitive to the inflation rate, is shown to be more appropriate to estimate the economic efficiency of rainwater harvesting system, compared to the typical cost–benefit ratio. Because the high future value overestimates the economic feasibility of rainwater harvesting systems, proper inflation rates should be applied. All in all, a funding program to promote rainwater harvesting systems significantly increases the benefits. Thus, national financial support policies are recommended to ensure economic feasibility of rainwater harvesting systems. Full article
(This article belongs to the Special Issue Rainwater Harvesting and Treatment)
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<p>The location of the study area in Cheongna-dong, Incheon, South Korea.</p> Full article ">Figure 2
<p>Rainfall–runoff time series data in the study area (1995–2004): (<b>a</b>) box and whisker plot with monthly distributions of rainfall; (<b>b</b>) result of rainfall–runoff simulation.</p> Full article ">Figure 3
<p>Monthly target draft of the rainwater harvesting system in the study area.</p> Full article ">Figure 4
<p>A conceptual searching scheme of particles in a particle swarm algorithm.</p> Full article ">Figure 5
<p>A schematic diagram of the connection between a rainwater harvesting system simulation model and a particle swarm algorithm.</p> Full article ">Figure 6
<p>The capacity–reliability curves for the considered rainwater harvesting system: (<b>a</b>) the capacity–temporal reliability curve; (<b>b</b>) the capacity–volumetric reliability curve.</p> Full article ">Figure 7
<p>The results of the cost–benefit analysis for the capacity of the considered rainwater harvesting system: (<b>a</b>) the capacity–BCR curve; (<b>b</b>) the capacity–NPV curve.</p> Full article ">Figure 8
<p>The results of the cost–benefit analysis of the considered rainwater harvesting system without financial support programs: (<b>a</b>) the capacity–BCR curve; (<b>b</b>) the capacity–NPV curve.</p> Full article ">Figure 9
<p>Historical records for the inflation rate in South Korea.</p> Full article ">Figure 10
<p>The curves of fitted probability distributions and their 90% confidence intervals: (<b>a</b>) histogram against the five distributions of the inflation rate; (<b>b</b>) the normal distribution with a mean of 3.26 and a variance of 1.06 for the discount rate.</p> Full article ">Figure 11
<p>The results of the uncertainty analysis for the inflation rate: (<b>a</b>) the maximum net present value; (<b>b</b>) the corresponding capacity.</p> Full article ">Figure 12
<p>The results of our sensitivity analysis for the inflation and discount rates: (<b>a</b>) the maximum net present value; (<b>b</b>) the corresponding capacity.</p> Full article ">
22 pages, 2019 KiB  
Review
BioH2 Production Using Microalgae: Highlights on Recent Advancements from a Bibliometric Analysis
by Shirin P. Arimbrathodi, Muhammad Asad Javed, Mohamed A. Hamouda, Ashraf Aly Hassan and Mahmoud E. Ahmed
Water 2023, 15(1), 185; https://doi.org/10.3390/w15010185 - 2 Jan 2023
Cited by 15 | Viewed by 3826
Abstract
Demand for clean energy has increased due to the proliferation of climate change impact from excessive emission of greenhouse gases (GHG) from the combustion of fossil fuels. H2 is a clean energy source since water vapor is the only byproduct after its [...] Read more.
Demand for clean energy has increased due to the proliferation of climate change impact from excessive emission of greenhouse gases (GHG) from the combustion of fossil fuels. H2 is a clean energy source since water vapor is the only byproduct after its combustion. Growing microalgae offers a promising low-energy and low-cost approach for bioH2 production. In this study, a bibliometric analysis was performed for the production of H2 using microalgae to evaluate the conceptual, intellectual, and social structure of the dataset. In addition, a scoping review of articles was conducted to highlight recent advancements and identify future research recommendations. A total of 184 relevant publications over 23 years (2000–2022) were retrieved from the Scopus database for analysis. The results demonstrated an exponential increase in citations from 283 to 996 in the last decade, indicating the interest in bioH2 production from microalgae. Results also revealed that the International Journal of Hydrogen Energy accounted for more than 25% of the published articles, of which China contributed almost 28%. Oxygen sensitivity of the H2ase enzyme and sulfur deprivation were highlighted as the main limiting factors of bioH2 production using microalgae. It was also evident that the most widely studied microalgae species were green algae, especially Chlamydomonas and Chlorella. Effective process modifications, particularly hybridizing microalgae with bacteria consortium and implementing oxygen regulating strategies, were shown to give up to a 10-fold increase in H2 yield. This study also discusses recent developments in technologies, strategies, microalgal species, and optimizing controlling factors affecting bioH2 production. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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<p>Schematic diagram of bioH<sub>2</sub> production through (<b>a</b>) direct biophotolysis and (<b>b</b>) indirect biophotolysis.</p> Full article ">Figure 2
<p>Research methodology flowchart. (<span class="html-italic">n</span>: number of articles).</p> Full article ">Figure 3
<p>Number of articles and number of citations for articles published on the topic of bioH<sub>2</sub> production from microalgae.</p> Full article ">Figure 4
<p>The network map for the top keywords is subdivided into four clusters based on the similarities. Keywords related to bioH<sub>2</sub> were removed. (The size of the node represents the frequency of occurrence, and the curved lines show the co-appearance between the keywords).</p> Full article ">Figure 5
<p>Emerging keywords in the field of biohydrogen production using microalgae.</p> Full article ">Figure 6
<p>Co-authorship and countries (the size of the node represents the volume of publications, and the line thickness illustrates the term recurrence between the countries).</p> Full article ">Figure 7
<p>Co-citation network map. (The node size represents the number of citations, and the curved lines show the co-citation ties between the references).</p> Full article ">
10 pages, 1517 KiB  
Communication
MIMS as a Low-Impact Tool to Identify Pathogens in Water
by Salvia Sajid, Ishika Aryal, Suleman Farooq Chaudhri, Frants Roager Lauritsen, Mikkel Girke Jørgensen, Håvard Jenssen and Bala Krishna Prabhala
Water 2023, 15(1), 184; https://doi.org/10.3390/w15010184 - 2 Jan 2023
Cited by 3 | Viewed by 2944
Abstract
Bacteria produce many kinds of volatile compounds throughout their lifecycle. Identifying these volatile compounds can help to understand bacterial interactions with the host and/or other surrounding pathogens of the same or different species. Some commonly used techniques to detect these volatile compounds are [...] Read more.
Bacteria produce many kinds of volatile compounds throughout their lifecycle. Identifying these volatile compounds can help to understand bacterial interactions with the host and/or other surrounding pathogens of the same or different species. Some commonly used techniques to detect these volatile compounds are GC and/or LC coupled to mass spectrometric techniques. However, these methods can sometimes become challenging owing to tedious sample preparation steps. Thus, identifying an easier method to detect these volatile compounds was investigated in the present study. Here, Membrane-inlet mass spectrometry (MIMS) provided a facile low-impact alternative to the existing strategies. MIMS was able to differentiate between the pathogenic and nonpathogenic bacterial strains, implying that it can be used as a bioprocess monitoring tool to analyze water samples from either water treatment plants or biotechnological industries. Full article
(This article belongs to the Special Issue Pathogen Detection and Identification in Wastewater)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Schematic representation of Membrane-Inlet Mass Spectrometry (MIMS) (Created in <a href="http://BioRender.com" target="_blank">BioRender.com</a> (accessed on 22 December 2022)).</p> Full article ">Figure 2
<p>Representative mass spectra of (<b>A</b>) control (LB media), (<b>B</b>) <span class="html-italic">S. epidermidis</span>, and (<b>C</b>) <span class="html-italic">P. aeruginosa</span> from undiluted overnight cultures.</p> Full article ">Figure 3
<p>(<b>A</b>) Representative heatmap of undiluted overnight cultures from <span class="html-italic">E. coli</span> pathogenic and lab strains (<span class="html-italic">n</span> = 4). (<b>B</b>) Optical density-adjusted cultures harvested 3 h after induction with IPTG (<span class="html-italic">n</span> = 3).</p> Full article ">Figure 4
<p>Representative PCA plot illustrating the ability of MIMS to separate the volatile profiles of different bacterial strains and the uninoculated media (control).</p> Full article ">Figure 5
<p>A representative PCA plot illustrating the ability of MIMS to distinguish between the volatile profiles of uninoculated media, i.e., control and growth media with cells expressing the functional YdgR and cells expressing the dysfunctional protein (YdgR mutant).</p> Full article ">
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