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Water, Volume 13, Issue 20 (October-2 2021) – 143 articles

Cover Story (view full-size image): In Algeria, studies and analyses of the current situation of the water distribution networks indicate that the type of material and the aging of pipes are among the reasons that lead to an increase in leakage, which can create problems related to the deterioration of the quality of the distributed water to the consumer, spreading a series of waterborne disease epidemics. Groundwater is one of the main resources for water consumption in the region, and consumers resort to the use of underground water through the exploration of springs, either filling bottles directly from the spring or filling them from mineral water tanks of street vendors licensed by the Ministry of Health. View this paper
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Article
Assessment of the Continuous Extreme Drought Events in Namibia during the Last Decade
Water 2021, 13(20), 2942; https://doi.org/10.3390/w13202942 - 19 Oct 2021
Cited by 4 | Viewed by 911
Abstract
In the context of climate change, the intensity, frequency, and duration of drought events have increased significantly, resulting in a profound impact on both natural ecosystems and socio-economic systems. In arid and semi-arid regions, precipitation is the main limiting factor for vegetation growth, [...] Read more.
In the context of climate change, the intensity, frequency, and duration of drought events have increased significantly, resulting in a profound impact on both natural ecosystems and socio-economic systems. In arid and semi-arid regions, precipitation is the main limiting factor for vegetation growth, and the ecosystems are very sensitive to climate change. Over the past 10 years, the Namibian government has declared national emergencies in 2013, 2016, and 2019 due to extreme drought events. The continued extreme drought has posed serious threat to the country’s food security. Accurately monitoring the continuous drought events in Namibia and assessing their impact on the ecosystem is essential for drought risk management in the region. Based on long-term satellite observation of vegetation index and precipitation, we have evaluated the spatiotemporal dynamics of the three drought events, the vegetation–precipitation relationship across biomes, and the impact of continuous drought events on regional ecosystems. The results suggest that: (1) According to affected area and severity, the drought in 2019 was the most severe one, followed by the drought in 2013; the 2015–2016 drought spread over smaller spatial area, although it continued for two years; (2) Both the accumulated NDVI and precipitation in the growing season in Namibia increased from 2001 to 2010 while showing a significant decreasing trend during 2011–2020; (3) In Namibia, there is a significant correlation between the current season’s accumulated precipitation and the current season’s accumulated NDVI (r = 0.90, p < 0.01). The current season’s accumulated precipitation is also well correlated with the next season’s accumulated NDVI (r = 0.87, p < 0.01), and the correlation between the current season’s accumulated precipitation and the next season’s accumulated NDVI in a wet year is even stronger (r = 0.96, p < 0.01). This indicates that part of the precipitation in the current season may be stored in the soil for the next season’s plant growth, which is more obvious in the northern plains with deep-rooted woody plants; (4) In 2013, the drought event suddenly changed from a long-term relatively humid state to an extremely dry state. During the ecological recovery stage, the NDVI during the growing season could not return to the state before the drought, causing irreversible damage to the Namibian ecosystem. In summary, the continuous extreme drought events during the last decade have caused profound impacts on the regional ecosystem. Much more attention should be paid to whether the extreme drought events will continue into the next decade and how the ecosystem can sustain a new equilibrium under a warmer and drier climate. Full article
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Article
Resilience Assessment and Critical Point Identification for Urban Water Supply Systems under Uncertain Scenarios
Water 2021, 13(20), 2939; https://doi.org/10.3390/w13202939 - 19 Oct 2021
Cited by 2 | Viewed by 825
Abstract
The urban water supply system environment is becoming more complicated and unpredictable than ever before in the context of global climate change and expanding urbanization. Existing studies have adopted either static or dynamic approaches to assess the resilience of water supply systems without [...] Read more.
The urban water supply system environment is becoming more complicated and unpredictable than ever before in the context of global climate change and expanding urbanization. Existing studies have adopted either static or dynamic approaches to assess the resilience of water supply systems without combining the two. Previous literature mostly establishes rigid quantitative metrics for resilience assessment, often without depicting the dynamics and adaptability of system resilience. For example, these studies usually fail to provide a critical point for identifying system resilience. To accurately describe the dynamics and adaptability of water supply system resilience under uncertain scenarios, in this study, we constructed a comprehensive framework based on the qualitative assessment of the input parameters, combining static and dynamic assessment, with the latter playing a dominant role based on the system perspective of pressure–state–influence–response. Taking Qingdao as a case study, we combined this framework with the system resilience theory, and statically assessed the five types of capitals and three attributes of resilience with the capital portfolio approach (CPA). Then, we dynamically assessed the resilience of urban water supply systems and identified critical points with the dynamic socio-technical model coupled with system resilience and the fitting analysis method. The results are as follows: (1) the static assessment results demonstrate an imbalanced development in the levels of the five types of capitals (financial capital, management efficiency, infrastructure, available water resources, and adaptation) and three attributes (robustness, recoverability, and adaptability) in the water supply systems of Qingdao. (2) The dynamic assessment results show that the current resilience trajectory of the water supply systems in Qingdao is that of a city in transition. (3) The fitting analysis shows that robustness (RB) has a linear relationship with resilience, recoverability (RE) has a non-linear relationship with resilience, and the critical points are RB = 0.70 and RE = 1.20. The research findings provide a reference for studying resilience mechanisms, internal attribute relationships, and resilience enhancement measures of urban water supply systems. Full article
(This article belongs to the Section Urban Water Management)
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Article
Removal Performance of Faecal Indicators by Natural and Silver-Modified Zeolites of Various Particle Sizes under Dynamic Batch Experiments: Preliminary Results
Water 2021, 13(20), 2938; https://doi.org/10.3390/w13202938 - 19 Oct 2021
Cited by 1 | Viewed by 616
Abstract
One of the oldest and most promising applications of natural zeolites (NZs) is in water and wastewater treatment processes. Modified zeolites (MZs), with improved ion exchange and adsorption capacities, have been extensively applied to the removal of pollutants from aqueous solutions. However, the [...] Read more.
One of the oldest and most promising applications of natural zeolites (NZs) is in water and wastewater treatment processes. Modified zeolites (MZs), with improved ion exchange and adsorption capacities, have been extensively applied to the removal of pollutants from aqueous solutions. However, the application of MZs in pathogens or indicator organisms has not been extensively explored. This study examines the effect of both natural Greek zeolite (NZ), with a clinoptilolite content of up to 85% (OLYMPUS SA-INDUSTRIAL MINERALS), and modified Greek zeolite through incorporation with silver ions (Ag-MNZ), on the survival of two selected faecal indicator bacteria (Escherichia coli and Enterococcus faecalis). A series of dynamic batch experiments with a slow agitation of 12 rpm were conducted at a constant ambient temperature (22°C) in order to examine the inactivation of the above bacteria by NZ and Ag-MNZ. It was found that the Ag-MNZ resulted in a much higher reduction in the bacterial numbers when compared to the NZ and the control (absence of zeolites). Moreover, the reduction in bacterial numbers was affected by NZ particle size, with higher removal rates observed for coarse (1–3 mm) than for fine (0–1 mm) NZ. Finally, the E. faecalis was found to be more resistant than E. coli to Ag-MNZ. Full article
(This article belongs to the Special Issue Water Quality and the Public Health)
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Article
Matrix Suction Evaluation of Soil-Rock Mixture Based on Electrical Resistivity
Water 2021, 13(20), 2937; https://doi.org/10.3390/w13202937 - 19 Oct 2021
Cited by 2 | Viewed by 688
Abstract
The soil-rock mixture is an important construction material in practical engineering. Its physical properties, especially soil-water properties, are particularly important for on-site construction, while both matrix suction and electrical resistivity in unsaturated soils depend on the magnitude of moisture content, and a certain [...] Read more.
The soil-rock mixture is an important construction material in practical engineering. Its physical properties, especially soil-water properties, are particularly important for on-site construction, while both matrix suction and electrical resistivity in unsaturated soils depend on the magnitude of moisture content, and a certain relationship can be established between the two physical quantities. Therefore, in this paper, we designed a matrix suction–electrical resistivity synergistic test device and conducted indoor physical tests on common soil-rock mixtures in the Chongqing area to investigate the correlation between matrix suction and electrical resistivity in soil-rock mixtures. The electrical resistivity comprehensive parameter was used to represent the electrical resistivity characteristics of rock and soil. Based on the experimental results, a matrix suction–electrical resistivity comprehensive parameter model applicable to soil-rock mixtures was established, and the sensitivity analysis of the model parameters was carried out. The results show that the soil-water characteristic curve of the soil-rock mixture has a double-step shape, and the shape of the curve under different compaction degrees is similar. The matrix suction and mass moisture content of the soil-rock mixture were positively correlated with the compaction degree. There was good consistency between the experimentally measured matrix suction and the matrix suction reflected by the electrical resistivity in the model. Moreover, the model curve was able to reflect the drainage process of pores in the soil for soil–stone mixtures with a bimodal pore size distribution, thus providing a new way to measure the matrix suction of unsaturated soil–stone mixtures in practical engineering. Full article
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Article
Kinetics, Thermodynamics, and Isotherms of Methylene Blue Adsorption Study onto Cassava Stem Activated Carbon
Water 2021, 13(20), 2936; https://doi.org/10.3390/w13202936 - 19 Oct 2021
Cited by 4 | Viewed by 748
Abstract
Water treatment using activated carbon is widely accepted, despite its high production cost. Therefore, this study was aimed to investigate the potential of cassava stem in activated carbon form for methylene blue (MB) dye uptake from water. Raw cassava stem (RCS) was also [...] Read more.
Water treatment using activated carbon is widely accepted, despite its high production cost. Therefore, this study was aimed to investigate the potential of cassava stem in activated carbon form for methylene blue (MB) dye uptake from water. Raw cassava stem (RCS) was also utilized to evaluate the difference between cassava stem in its raw form and after being converted to the activated carbon (ACS). The MB adsorption from water using the RCS and ACS was done in this study. The batch adsorption study showed fast MB uptake by ACS at 60 min contact time, while higher adsorbent dosage and higher pH contributed to higher adsorption percentage. The thermodynamic study showed positive values of ∆H° of ACS, indicating that the adsorption process of MB was endothermic. Meanwhile, the negative value of ∆G° showed that the adsorption processes of MB were spontaneous. The thermodynamic study showed higher fitting to Langmuir isotherm, with data from the kinetic study showing better pseudo-second-order equation fitting, which suggests the chemisorption process had happened. The highest adsorption recorded by ACS was 384.61 mg/g, indicating the possibility of cassava stem as the lower cost raw material for activated carbon production with excellent adsorption characteristics. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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Article
Investigation of Metal and Trace Elements of Cenospheres from Lignite High-Calcium Fly Ash (Thailand)
Water 2021, 13(20), 2935; https://doi.org/10.3390/w13202935 - 19 Oct 2021
Viewed by 678
Abstract
High-calcium fly ashes contain a large content of small particles including cenospheres of chemical constituents known to be similar to fly ash and the parent coal. Coal fly ash contains metal and trace elements that may leach out during disposal or utilization. This [...] Read more.
High-calcium fly ashes contain a large content of small particles including cenospheres of chemical constituents known to be similar to fly ash and the parent coal. Coal fly ash contains metal and trace elements that may leach out during disposal or utilization. This work aimed to understand an overview of cenosphere characteristics relating to fly ash and leaching study. To our knowledge, this is the first report on metal and trace element leaching of cenospheres separated from high-calcium (28.9 wt.%) class C fly ash produced from the Mae Moh coal-fired thermal power plant in Thailand. In this study, the cenospheres were separated from fly ash by a wet separation process (sink-float method) using water as medium. Physical properties, morphology, chemical composition, the mineral phases of cenospheres and fly ash have been characterized. Extraction was carried out by acid digestion; the selected metal and trace elements in this study are Mg, Al, Zn, Pb, Cd, Cr, and Cu; the obtained environmentally available concentrations of cenospheres were analyzed in comparison to those of fly ash. The concentrations of Cu, Cr, Pb, and Cd elements of interest in the leachates obtained from the toxicity characteristic leaching procedure (TCLP) showed the tendency to decrease in that order. All the elements were found below the permissible limit values regarding Thailand soil quality standards. Association of the heavy metal trace elements in cenospheres and fly ash was discussed in in terms of physico-chemical-geochemistry correlating with the leaching concentrations. Full article
(This article belongs to the Section Water Quality and Contamination)
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Brief Report
Effect of the Presence of Virus-like Particles on Bacterial Growth in Sunlit Surface and Dark Deep Ocean Environments in the Southern East China Sea
Water 2021, 13(20), 2934; https://doi.org/10.3390/w13202934 - 19 Oct 2021
Viewed by 572
Abstract
Virus-like particles (VLPs) are thought to increase the dissolved organic carbon by releasing the contents of the host cell, which, in turn, can affect bacterial growth in natural aquatic environments. Yet, experimental tests have shown that the effect of VLPs on the bacterial [...] Read more.
Virus-like particles (VLPs) are thought to increase the dissolved organic carbon by releasing the contents of the host cell, which, in turn, can affect bacterial growth in natural aquatic environments. Yet, experimental tests have shown that the effect of VLPs on the bacterial growth rate at different depths has seldom been studied. Bacteria–VLP interaction and the effect of VLPs on bacterial growth rate in the sunlit surface (3 m) and dark, deep ocean (130 m) environments were first explored at a test site in the southern East China Sea of the northwest Pacific. Our experimental results indicated that bacterial and virus-like particle (VLP) abundance decreased with depth from 0.8 ± 0.3 × 105 cells mL−1 and 1.8 ± 0.4 × 106 VLPs mL−1 at 3 m to 0.4 ± 0.1 × 105 cells mL−1 and 1.4 ± 0.3 × 106 VLPs mL−1 at 130 m. We found that the abundance of VLPs to Bacteria Ratio (VBR) in the dark deep ocean (VBR = 35.0 ± 5.6) was higher than in the sunlit surface environment (VBR = 22.5 ± 2.1). The most interesting finding is that in the dark, deep ocean region the bacterial growth rate in the presence of VLPs was higher (0.05 h−1) than that in virus-diluted treatments (0.01 h−1). However, there was no significant difference in the bacterial growth rates between the treatments in the sunlit surface ocean region. Deep-sea ecosystems are dark and extreme environments that lack primary photosynthetic production, and our estimates imply that the contribution of recycled carbon by viral lysis is highly significant for bacterial growth in the dark, deep ocean environment. Further work for more study sites is needed to identify the relationship of VLPs and their hosts to enable us to understand the role of VLPs at different depths in the East China Sea. Full article
(This article belongs to the Special Issue Microbial Communities in Water Environments: Dynamics and Interaction)
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Article
Transient Process of Pumped Storage System Coupling Gas–Liquid Interface: Novel Mathematical Model and Experimental Verification
Water 2021, 13(20), 2933; https://doi.org/10.3390/w13202933 - 19 Oct 2021
Viewed by 637
Abstract
The traditional calculation method for a transient process has high accuracy when the pipeline only contains liquid, but when the pipeline contains both gas and liquid the accuracy is greatly reduced. The coupling characteristics of gas–liquid interface movement in hydraulic transient processes are [...] Read more.
The traditional calculation method for a transient process has high accuracy when the pipeline only contains liquid, but when the pipeline contains both gas and liquid the accuracy is greatly reduced. The coupling characteristics of gas–liquid interface movement in hydraulic transient processes are not clear due to the lack of high-precision mathematical model and experimental verification. This paper proposes a novel mathematical model of a gas–liquid pipeline system in a hydropower station based on Preissman’s implicit difference scheme and the method of characteristics. The solving mechanism of the transient process of gas–liquid movement was developed on the gas–liquid interface tracking method. Subsequently, the models proposed in this paper were applied in two typical scenarios of a gas–liquid transient process in a hydropower system, and their accuracy were verified in a field experiment. The comparison results showed that the novel model could accurately capture the movement of the gas–liquid interface, and the average relative error of the characteristic parameter was about 7.2%. Under the load rejection condition, the change speed of characteristic parameters was positively correlated with the pipeline slope. Under the pump failure after low-head startup condition, the maximum pumping discharge was negatively correlated with startup water level and the maximum reversal discharge and speed were positively correlated with the pump failure water level. Compared with the conventional method, the proposed model has advantages in solving the complex transient process coupling gas–liquid. It has potential value in applications such as the safe operation of hydropower stations, the transient process of water diversion projects and in urban pipe network operation. Full article
(This article belongs to the Section Hydrogeology)
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Article
An Assessment of Hydroacoustic and Electric Fishing Data to Evaluate Long Term Spatial and Temporal Fish Population Change in the River Thames, UK
Water 2021, 13(20), 2932; https://doi.org/10.3390/w13202932 - 19 Oct 2021
Viewed by 927
Abstract
This paper reports the results from mobile hydroacoustic surveys carried out between 1994 and 2018, to assess the fish stocks in four impounded reaches, covering 19.8 km of the River Thames, England. The data are complemented with electric fishing boom boat results, collected [...] Read more.
This paper reports the results from mobile hydroacoustic surveys carried out between 1994 and 2018, to assess the fish stocks in four impounded reaches, covering 19.8 km of the River Thames, England. The data are complemented with electric fishing boom boat results, collected at the same study reaches and time periods. Hydroacoustic surveys used inter-calibrated dual and split-beam scientific echosounders, with the transducers beaming horizontally across the river to provide fish abundance and distribution estimates. Electric fishing surveys provided catch per unit effort estimates and information on size structure and species composition. Catch data from the margins of the study reaches were dominated by roach (Rutilus rutilus), with bleak (Alburnus alburnus) dominant in mid-river. Hydroacoustic data demonstrated patchy spatial distribution, often associated with natural and anthropogenic habitat features. Cyclical peaks and troughs in both hydroacoustic and electric fishing abundance were found. There were periods of correspondence with electric fishing abundance estimates, but also periods of significant divergence. The concept of ‘Shifting Baseline Syndrome’ is discussed with reference to these data, illustrating the importance of viewing long term quantitative information when using meaningful reference points. The potential impact of river temperature and flow on the fish population data are discussed. Full article
(This article belongs to the Special Issue Hydroacoustics in Marine, Transitional and Freshwaters)
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Article
A Characterization of the Hydrochemistry and Main Controlling Factors of Lakes in the Badain Jaran Desert, China
Water 2021, 13(20), 2931; https://doi.org/10.3390/w13202931 - 19 Oct 2021
Cited by 4 | Viewed by 681
Abstract
Badain Jaran Desert, the coexistence of dunes and lakes, and the presence of the world’s tallest dunes, has attracted worldwide attention among hydrologists. Freshwater, brackish, and saline lakes coexistence in the Badain Jaran Desert under extremely arid environmental conditions. This raises the question [...] Read more.
Badain Jaran Desert, the coexistence of dunes and lakes, and the presence of the world’s tallest dunes, has attracted worldwide attention among hydrologists. Freshwater, brackish, and saline lakes coexistence in the Badain Jaran Desert under extremely arid environmental conditions. This raises the question of why diverse lake water types exist under the same climatic conditions. Answering this question requires the characterization of lake hydrochemistry and the main controlling factors. The purpose of the presented research was to systematically analyzed samples from 80 lakes using statistical analysis, correlation analysis and hydrogeochemical methods to investigate the hydrochemical status and evolution of lakes in the Badain Jaran Desert. The results showed that the lake water in Badain Jaran Desert is generally alkaline, with the average pH and TDS were 9.31 and 165.12 g L−1, respectively. The main cations to be Na+ and K+, whereas the main anions are Cl and SO42−. HCO3 and CO32− decreased and SO42− and Cl increased from southeast to northwest, whereas lake hydrochemistry changed from the SO42−-Cl-HCO3 type to the SO42−-Cl type and lakes transitioned from freshwater to saline. The freshwater and slightly brackish lakes are mainly distributed in the piedmont area at a high altitude near the Yabulai Moutains, whereas saline lakes are mainly distributed in the desert hinterland at a low altitude, and there is a roughly increasing trend of ions from the Yabulai Mountains. The evaporation-crystallization reactions are the dominant in the study region. Moreover, some saline mineral deposits, are extensive in these regions caused by intense evaporation-crystallization. Full article
(This article belongs to the Special Issue Soil Hydrological Processes in Desert Regions)
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Article
Variability of δ2H and δ18O in Soil Water and Its Linkage to Precipitation in an East Asian Monsoon Subtropical Forest Plantation
Water 2021, 13(20), 2930; https://doi.org/10.3390/w13202930 - 19 Oct 2021
Cited by 1 | Viewed by 794
Abstract
The linkage between δ2H and δ18O of soil water and precipitation provides a way of understanding precipitation infiltration, residence time, and soil water source. Soil water at 0–5, 15–20, and 40–45 cm depths and event-based precipitation were collected in [...] Read more.
The linkage between δ2H and δ18O of soil water and precipitation provides a way of understanding precipitation infiltration, residence time, and soil water source. Soil water at 0–5, 15–20, and 40–45 cm depths and event-based precipitation were collected in a subtropical forest plantation. Correlations between the δ18O of soil water and precipitation on the same day were used to determine the critical threshold of precipitation infiltration. Residence time of precipitation in soil was determined with correlations between the δ18O of soil water and cumulative precipitation before sampling. Soil water source was determined by the intersection points of Soil Water Evaporation Lines (SEL) and local meteoric water lines. The results showed that precipitation >5–6 mm could pass through canopy and litter, and infiltrate into soil. Residence times varied from a few days to several months, and increased with soil depth. The model-based approach for SEL estimation were more robust than the regression-based approach due to the inverse variability in the δ2H and δ18O of soil water source and soil evaporative fractionation. Soil water at a 0–5 cm depth originated mainly from precipitation in the current season, while those at 15–20 and 40–45 cm depths originated mainly from precipitation in the previous season. Full article
(This article belongs to the Special Issue Use of Water Isotopes in Hydrological Processes II)
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Review
An Overview of Crop and Crop Residue Management Impacts on Crop Water Use and Runoff in the Canadian Prairies
Water 2021, 13(20), 2929; https://doi.org/10.3390/w13202929 - 19 Oct 2021
Cited by 4 | Viewed by 773
Abstract
Although crop and crop residue management practices are mainly used for increasing crop yield, they and the resulting changes in crop growth affect one or more hydrological components, including runoff. Based on published research in the Canadian Prairies, this paper reviews the effects [...] Read more.
Although crop and crop residue management practices are mainly used for increasing crop yield, they and the resulting changes in crop growth affect one or more hydrological components, including runoff. Based on published research in the Canadian Prairies, this paper reviews the effects of crop type, quantity of crops and crop residues, crop variability within landscapes, tillage, and stubble management practices on crop water use (termed including evaporation, transpiration and interception), snow trapping, and water infiltration, with the aim to discuss major impacts of crop and residue management on runoff. Rainfall runoff is influenced by rain interception and crop water use, and it can be reduced by choosing appropriate crop types, increasing above-ground biomass, or increasing coverage on the soil surface, activities which coincide with the farmer’s efforts of increasing crop productivity. However, although high stubble and reduced tillage for maintaining good residue cover help conserve soil moisture and improve soil health, they increase snowmelt runoff potential. The review emphasizes the need of future research to assess the agronomic and environmental trade-offs of crop residue management, the linkage between crop water use and runoff, and the impacts of crop and residue management on runoff across various temporal and spatial scales. Full article
(This article belongs to the Special Issue Research on Cold Regions Hydrology)
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Review
Engineering Microbial Consortia towards Bioremediation
Water 2021, 13(20), 2928; https://doi.org/10.3390/w13202928 - 19 Oct 2021
Cited by 5 | Viewed by 833
Abstract
Bioremediation is a sustainable remediation technology as it utilizes microorganisms to convert hazardous compounds into their less toxic or non-toxic constituent elements. This technology has achieved some success in the past decades; however, factors involving microbial consortia, such as microbial assembly, functional interactions, [...] Read more.
Bioremediation is a sustainable remediation technology as it utilizes microorganisms to convert hazardous compounds into their less toxic or non-toxic constituent elements. This technology has achieved some success in the past decades; however, factors involving microbial consortia, such as microbial assembly, functional interactions, and the role of member species, hinder its development. Microbial consortia may be engineered to reconfigure metabolic pathways and reprogram social interactions to get the desired function, thereby providing solutions to its inherent problems. The engineering of microbial consortia is commonly applied for the commercial production of biomolecules. However, in the field of bioremediation, the engineering of microbial consortia needs to be emphasized. In this review, we will discuss the molecular and ecological mechanisms of engineering microbial consortia with a particular focus on metabolic cross-feeding within species and the transfer of metabolites. We also discuss the advantages and limitations of top-down and bottom-up approaches of engineering microbial consortia and their applications in bioremediation. Full article
(This article belongs to the Special Issue Carbon Neutrality and Wastewater Treatment)
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Article
Water Quality, Availability, and Uses in Rural Communities in the Kurdistan Region, Iraq
Water 2021, 13(20), 2927; https://doi.org/10.3390/w13202927 - 18 Oct 2021
Cited by 1 | Viewed by 1109
Abstract
Water resource management and the investigation of the quality and quantity of groundwater and surface water is important in the Kurdistan Region of Iraq. The growing population, as well as agricultural and industrial projects, consume huge amounts of water, especially groundwater. A total [...] Read more.
Water resource management and the investigation of the quality and quantity of groundwater and surface water is important in the Kurdistan Region of Iraq. The growing population, as well as agricultural and industrial projects, consume huge amounts of water, especially groundwater. A total of 572 ground and surface water samples were collected for physicochemical analysis to determine the availability and quality of the water in the Kurdistan region. The physicochemical parameters such as pH, electrical conductivity, and total dissolved solids were analyzed to evaluate the suitability of the water for different purposes like livestock, irrigation, and agriculture. GIS-based multi-criteria decision analysis (MCDA) was used to determine the suitability map of water for irrigation purposes. Most of the groundwater samples were suitable for irrigation except for some samples from Erbil City, especially those taken in the Makhmur district, and samples from some small areas in the cities of Sulaymania and Duhok. All groundwater samples were acceptable for all types of agricultural crops, except for 15 well samples that were determined not to be usable for fruit crops. However, this water was acceptable for livestock and poultry. Most of the water wells provided freshwater except for 36 deep wells, which supplied slightly brackish to brackish water. Water samples were found to have low to medium salinity levels except for 26 well samples and one spring sample that had high salinity levels, and 2 well samples with very high salinity levels. Most of the samples had an excellent to good water classification except for 85 samples classified as permissible, 8 classified as doubtful, and 4 classified as unsuitable for irrigation according to the Todd classification. According to the Rhoades classification, all water samples were non-saline to slightly saline except for 11 samples that were moderately saline. Full article
(This article belongs to the Special Issue Water Management for Climate Smart Agriculture)
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Article
Integrated Geospatial Analysis and Hydrological Modeling for Peak Flow and Volume Simulation in Rwanda
Water 2021, 13(20), 2926; https://doi.org/10.3390/w13202926 - 18 Oct 2021
Cited by 2 | Viewed by 1117
Abstract
The ability to adequately and continually assess the hydrological catchment response to extreme rainfall events in a timely manner is a prerequisite component in flood-forecasting and mitigation initiatives. Owing to the scarcity of data, this particular subject has captured less attention in Rwanda. [...] Read more.
The ability to adequately and continually assess the hydrological catchment response to extreme rainfall events in a timely manner is a prerequisite component in flood-forecasting and mitigation initiatives. Owing to the scarcity of data, this particular subject has captured less attention in Rwanda. However, semi-distributed hydrological models have become standard tools used to investigate hydrological processes in data-scarce regions. Thus, this study aimed to develop a hydrological modeling system for the Nyabarongo River catchment in Rwanda, and assess its hydrological response to rainfall events through discharged flow and volume simulation. Initially, the terrain Digital Elevation Model (DEM) was pre-processed using a geospatial tool (HEC-GeoHMS) for catchment delineation and the generation of input physiographic parameters was applied for hydrological modeling system (HEC-HMS) setup. The model was then calibrated and validated at the outlet using sixteen events extracted from daily hydro-meteorological data (rainfall and flow) for the rainy seasons of the country. More than in other events, the 15th, 9th, 13th and 5th events showed high peak flows with simulated values of 177.7 m3s−1, 171.7 m3s−1, 169.9 m3s−1, and 166.9 m3s−1, respectively. The flow fluctuations exhibited a notable relation to rainfall variations following long and short rainy seasons. Comparing the observed and simulated hydrographs, the findings also unveiled the ability of the model to simulate the discharged flow and volume of the Nyabarongo catchment very well. The evaluated model’s performance exposed a high mean Nash Sutcliffe Efficiency (NSE) of 81.4% and 84.6%, with correlation coefficients (R2) of 88.4% and 89.8% in calibration and validation, respectively. The relative errors for the peak flow (5.5% and 7.7%) and volume (3.8% and 4.6%) were within the acceptable range for calibration and validation, respectively. Generally, HEC-HMS findings provided a satisfactory computing proficiency and necessitated fewer data inputs for hydrological simulation under changing rainfall patterns in the Nyabarongo River catchment. This study provides an understanding and deepening of the knowledge of river flow mechanisms, which can assist in establishing systems for river monitoring and early flood warning in Rwanda. Full article
(This article belongs to the Special Issue Hydrological Response to Climate Change)
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Review
Planning and Management of Coastal Buffer Zones in Taiwan
Water 2021, 13(20), 2925; https://doi.org/10.3390/w13202925 - 18 Oct 2021
Viewed by 841
Abstract
Overuse of coastal regions may lead to coastal erosion and shoreline retreat, threatening the inherent life and property of the coast. This is because typhoon waves with storm surges frequently attack overdeveloped coasts and related structures. In the present study, coastal buffer and [...] Read more.
Overuse of coastal regions may lead to coastal erosion and shoreline retreat, threatening the inherent life and property of the coast. This is because typhoon waves with storm surges frequently attack overdeveloped coasts and related structures. In the present study, coastal buffer and protection zones were defined for the management of coastal disasters. The coastal buffer zone may offer remarkable advantages to avoid improper coastal use and limit the impact of extreme events by reducing erosion, mitigating coastal disasters, improving water quality, expanding habitats, and minimizing coastal degradation. Further, factors affecting the establishment of coastal buffer zones were classified according to natural and anthropogenic characteristics. Moreover, regarding the direction of research into coastal buffer zones, themes and countermeasures for coastal buffer zone management were discussed from the perspectives of technology, planning, and management policies. Finally, the application of numerical models to assess the impact factors in coastal buffer zones are proposed. Full article
(This article belongs to the Special Issue Research on Water Resources Planning and Management in Coastal Areas)
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Article
A Leak Zone Location Approach in Water Distribution Networks Combining Data-Driven and Model-Based Methods
Water 2021, 13(20), 2924; https://doi.org/10.3390/w13202924 - 18 Oct 2021
Cited by 4 | Viewed by 1034
Abstract
Model-based and data-driven methods are commonly used in leak location strategies in water distribution networks. This paper formulates a hybrid methodology in two stages that complements the advantages and disadvantages of data-driven and model-based strategies. In the first stage, a support vector machine [...] Read more.
Model-based and data-driven methods are commonly used in leak location strategies in water distribution networks. This paper formulates a hybrid methodology in two stages that complements the advantages and disadvantages of data-driven and model-based strategies. In the first stage, a support vector machine multiclass classifier is used to reduce the search space for the leak location task. In the second stage, leak location task is formulated as an inverse problem, and solved using a variation of the differential evolution algorithm called topological differential evolution. The robustness of the method is tested considering measurement and varying demand uncertainty conditions ranging from 5 to 15% of node nominal demands. The performance of the hybrid method is compared to the support vector machine classifier and topological differential evolution approaches as standalone methods of leak location. The hybrid proposal shows higher performance in terms of location accuracy, zone size, and computational load. Full article
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Article
The Impact of Rainfall Movement Direction on Urban Runoff Cannot Be Ignored in Urban Hydrologic Management
Water 2021, 13(20), 2923; https://doi.org/10.3390/w13202923 - 17 Oct 2021
Cited by 1 | Viewed by 683
Abstract
Urban floods have been exacerbated globally, associated with increasing spatial-temporal variations in rainfall. However, compared with rainfall variabilities of intensity and duration, the effect of rainfall movement direction is always ignored. Based on 1313 rainfall scenarios with different combinations of rainfall intensity and [...] Read more.
Urban floods have been exacerbated globally, associated with increasing spatial-temporal variations in rainfall. However, compared with rainfall variabilities of intensity and duration, the effect of rainfall movement direction is always ignored. Based on 1313 rainfall scenarios with different combinations of rainfall intensity and rainfall movement direction in the typically rainy city of Shenzhen in China, we find that the effect of rainfall movement direction on the peak runoff may reach up to 20%, which will decrease to less than 5% under heavy rainfall intensity conditions. In addition, our results show that the impact of rainfall movement direction is almost symmetrical and is associated with the direction of the river. The closer rainfall movement direction is to the Linear Directional Mean of rivers, the larger is the peak runoff of section. Our results reveal that rainfall movement direction is significant to urban peak runoff in the downstream reaches, which should be considered in urban hydrological analysis. Full article
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Article
Study on the Bathroom Space and the Application of Same-Floor Drainage in Congregate Housing
Water 2021, 13(20), 2922; https://doi.org/10.3390/w13202922 - 17 Oct 2021
Viewed by 881
Abstract
There are no regulations in Taiwan that clearly forbid the current practice of configuring a pipeline that passes through the floor of a condo to reach the ceiling of another condo downstairs with different ownership, giving rise to potential disputes during pipeline maintenance. [...] Read more.
There are no regulations in Taiwan that clearly forbid the current practice of configuring a pipeline that passes through the floor of a condo to reach the ceiling of another condo downstairs with different ownership, giving rise to potential disputes during pipeline maintenance. In Japan and China, the regulations for water supply and the drainage system strictly forbid the installation of drainage pipes that pass through the floor of a condo to reach the ceiling of another condo downstairs. In this study, life cycle cost analysis was adopted to investigate the traditional piping system as well as the same-floor drainage system, including the descended floor piping system, the raised floor piping system and a pre-wall piping system. According to the results of the life cycle cost and benefit analysis for pipeline renewal and maintenance, and taking into account the overall pipeline construction cost, although adoption of the same-floor drainage system increases the total cost by about 0.3–2.7%, it shows benefits in terms of pipeline maintenance and construction time. From the perspective of property management, if the same-floor drainage system can be implemented in the initial design stage, operation and management related issues can be minimized to reduce both pipeline maintenance and management costs, achieving the best performance in sustainable construction and maintenance. Full article
(This article belongs to the Section Urban Water Management)
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Article
Network Model Analysis of Residual Chlorine to Reduce Disinfection Byproducts in Water Supply Systems in Yangon City, Myanmar
Water 2021, 13(20), 2921; https://doi.org/10.3390/w13202921 - 17 Oct 2021
Cited by 2 | Viewed by 1039
Abstract
In Yangon City, chlorination commenced in January 2020 to supply drinkable water; therefore, there is as yet no information on chlorine decay and DBP formation in the water supply system. This study aimed to find methods to optimize chlorine dosage in Yangon City. [...] Read more.
In Yangon City, chlorination commenced in January 2020 to supply drinkable water; therefore, there is as yet no information on chlorine decay and DBP formation in the water supply system. This study aimed to find methods to optimize chlorine dosage in Yangon City. Onsite sampling and laboratory analyses of residual chlorine and trihalomethane (THM) formation, as well as water quality simulations, were conducted to find the chlorine decay and THM formation kinetics. Due to a high chlorine dose of 2 mg/L for both pre- and post-chlorination, disinfection was effective despite the low removal efficiency of turbidity. However, THMs were found in high levels in both treated and tap water due to the high THM formation potential of raw water. The re-contamination and/or transformation of dissolved organic matter were found in the distribution network by increases in specific ultraviolet absorption (SUVA) values and excitation-emission matrix (EEM) fluorophores, which brought about variations of THMs in the networks. The EPANET models were run assuming there to be no water leakages; it was found that the chlorine dose could be decreased to 0.8 mg/L to meet the guidelines for THMs and residual chlorine. The methods employed in this study could be also applied in other water supply systems in tropical developing countries with limited water quality monitoring data. Full article
(This article belongs to the Special Issue Water Pollution and Sanitation)
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Article
Improving Household Agriculture with Roof-Harvested Rainwater: A Case Study in Sydney and Nairobi
Water 2021, 13(20), 2920; https://doi.org/10.3390/w13202920 - 17 Oct 2021
Cited by 1 | Viewed by 991
Abstract
The production and distribution of a sufficient quantity of food and water of satisfactory quality is at the heart of sustainable development. At the small domestic scale, roof-harvested rainwater can make a significant contribution to food supply and distribution systems (production, handling, storage, [...] Read more.
The production and distribution of a sufficient quantity of food and water of satisfactory quality is at the heart of sustainable development. At the small domestic scale, roof-harvested rainwater can make a significant contribution to food supply and distribution systems (production, handling, storage, and transportation). In this paper, we compare the potential crop production of a small garden plot using three methods of watering: (1) rainfed only with no irrigation; (2) irrigated with the ideal amount of water; and (3) rainwater tanks of various sizes installed and used to irrigate the plot. Yield was determined on the basis of the yield calculation method presented in FAO 33. It was found that yields can be increased considerably by installing a correctly managed rainwater storage system (RSS). A 3 kL RSS connected to a 120 m2 roof can increase yields in Nairobi from 40 kg to 96 kg. In Sydney, a larger roof of 200 m2 can increase yields from 66 kg to 143 kg. This study makes an important contribution to water and food security-related sustainable development goals. Full article
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Article
Discharge and Temperature Controls of Dissolved Organic Matter (DOM) in a Forested Coastal Plain Stream
Water 2021, 13(20), 2919; https://doi.org/10.3390/w13202919 - 17 Oct 2021
Cited by 2 | Viewed by 753
Abstract
Streams in the southeastern United States Coastal Plains serve as an essential source of energy and nutrients for important estuarine ecosystems, and dissolved organic matter (DOM) exported from these streams can have profound impacts on the biogeochemical and ecological functions of fluvial networks. [...] Read more.
Streams in the southeastern United States Coastal Plains serve as an essential source of energy and nutrients for important estuarine ecosystems, and dissolved organic matter (DOM) exported from these streams can have profound impacts on the biogeochemical and ecological functions of fluvial networks. Here, we examined hydrological and temperature controls of DOM during low-flow periods from a forested stream located within the Coastal Plain physiographic region of Alabama, USA. We analyzed DOM via combining dissolved organic carbon (DOC) analysis, fluorescence excitation–emission matrix combined with parallel factor analysis (EEM-PARAFAC), and microbial degradation experiments. Four fluorescence components were identified: terrestrial humic-like DOM, microbial humic-like DOM, tyrosine-like DOM, and tryptophan-like DOM. Humic-like DOM accounted for ~70% of total fluorescence, and biodegradation experiments showed that it was less bioreactive than protein-like DOM that accounted for ~30% of total fluorescence. This observation indicates fluorescent DOM (FDOM) was controlled primarily by soil inputs and not substantially influenced by instream production and processing, suggesting that the bulk of FDOM in these streams is transported to downstream environments with limited in situ modification. Linear regression and redundancy analysis models identified that the seasonal variations in DOM were dictated primarily by hydrology and temperature. Overall, high discharge and shallow flow paths led to the enrichment of less-degraded DOM with higher percentages of microbial humic-like and tyrosine-like compounds, whereas high temperatures favored the accumulation of high-aromaticity, high-molecular-weight, terrestrial, humic-like compounds in stream water. The flux of DOC and four fluorescence components was driven primarily by water discharge. Thus, the instantaneous exports of both refractory humic-like DOM and reactive protein-like DOM were higher in wetter seasons (winter and spring). As high temperatures and severe precipitation are projected to become more prominent in the southeastern U.S. due to climate change, our findings have important implications for future changes in the amount, source, and composition of DOM in Coastal Plain streams and the associated impacts on downstream carbon and nutrient supplies and water quality. Full article
(This article belongs to the Section Water Quality and Contamination)
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Review
Drinking Water Standards and Their Implementation—A Critical Assessment
Water 2021, 13(20), 2918; https://doi.org/10.3390/w13202918 - 17 Oct 2021
Cited by 3 | Viewed by 1050
Abstract
Diminishing clean water resources and their pollution (due to human activities and climatic change) are of great concern on a global basis. Under such conditions, the adequacy of drinking water (DW) standards and their meticulous implementation are issues of utmost importance in safeguarding [...] Read more.
Diminishing clean water resources and their pollution (due to human activities and climatic change) are of great concern on a global basis. Under such conditions, the adequacy of drinking water (DW) standards and their meticulous implementation are issues of utmost importance in safeguarding human health. Unfortunately, the significant number of disease outbreaks (and of other suspected/potential health effects) related to DW, even in developed countries, attests to the fact that these issues require vigilance and continuous re-appraisal, particularly considering the assorted emerging contaminants and the ever-improving technological tools to cope with them. Therefore, the present comprehensive assessment addresses the main issues and concerns regarding DW standards and implementation thereof. Emphasis is placed on identifying the inherent deficiencies of standards (due to neglect of potential toxic contaminants and to debatable specifications/limit values) and regulations for their implementation and the monitoring of DW quality (due to weaknesses of available analytical/measurement techniques and inadequacies of tools and protocols). Rather serious deficiencies on these aspects are evident regarding the main categories of contaminants, i.e., synthetic chemicals and biological species. In regard to addressing these issues, progress made in recent years at the scientific/technical level and the main challenges are outlined toward the goal of an improvement in standards and their implementation. Full article
(This article belongs to the Section Urban Water Management)
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Article
Has Third-Party Monitoring Improved Water Pollution Data Quality? Evidence from National Surface Water Assessment Sections in China
Water 2021, 13(20), 2917; https://doi.org/10.3390/w13202917 - 17 Oct 2021
Viewed by 693
Abstract
In China, the central government assesses local governments based on data monitored and reported by local agencies, and the accuracy of local statistics has been controversial. In order to further guarantee the authenticity and reliability of surface water monitoring data, the central government [...] Read more.
In China, the central government assesses local governments based on data monitored and reported by local agencies, and the accuracy of local statistics has been controversial. In order to further guarantee the authenticity and reliability of surface water monitoring data, the central government will gradually withdraw the local monitoring powers of the national surface water assessment section and implement third-party monitoring to achieve “national assessment and national monitoring.” This paper is based on the time-point water data of important national water quality automatic monitoring stations from 2015 to 2020, using the McCrary (2008) density test to infer possible data manipulation phenomena, and analyze whether third-party monitoring has improved the accuracy of China’s environmental data. The results of the study show that between 2015 and 2020, the observed 81 monitoring sites had varying degrees of data discontinuity. The discontinuity of the data after third-party monitoring was reduced in dissolved oxygen (DO) measurement, an important indicator in the assessment, implying that third-party monitoring has improved the quality of water environment data and the accuracy of the data. The research in this article provides a reference for third-party participation in environmental governance and proves that the participation of these organizations can reduce data manipulation behaviors of local governments and ensure the effectiveness of environmental data. Full article
(This article belongs to the Section Water Resources Management, Policy and Governance)
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Article
Reduction in Arsenic Exposure by Domestic Water Purification Devices in Shanghai Area and Related Health Risk Assessment
Water 2021, 13(20), 2916; https://doi.org/10.3390/w13202916 - 16 Oct 2021
Viewed by 891
Abstract
Domestic water purification devices (point-of-use) are important choices for people to deal with sudden drinking water contamination. Especially for sudden heavy metal and arsenic contamination, home water purification units can play a key role as a secondary line of defense. Most of the [...] Read more.
Domestic water purification devices (point-of-use) are important choices for people to deal with sudden drinking water contamination. Especially for sudden heavy metal and arsenic contamination, home water purification units can play a key role as a secondary line of defense. Most of the arsenic removal studies are limited to meeting the requirements of local water quality standards and few studies have been conducted on arsenic removal from household water purifiers. In this paper, the distribution characteristics of arsenic in water at the end of the pipeline network in the Shanghai water supply area have been investigated. Three types of household water purifiers, mainly with membrane separation technology, were selected to treat the simulated arsenic contamination in tap water sources. The effects of pH and inorganic salts on arsenic removal were studied in comparison to the results of coexisting ion concentrations in tap water. The results showed that the total arsenic concentrations in different tap water samples range from 0.479–1.195 µg L−1, which is lower than the limit value for arsenic concentration set by China’s drinking water standard GB 5749–2006 (10 µg L−1) and by the World Health Organization (10 µg L−1). It is found that reverse osmosis and nanofiltration water purifiers were more effective in removing As(V), with removal rate above 97.7%, and less effective in removing As(III), the rate ranging from 40.1 to 56.3%. Preliminary validation was provided for the safety of household water purifiers in securing universal and sudden drinking water contamination. Domestic water purifiers are effective in reducing the risk of arsenic exposure in drinking water. Full article
(This article belongs to the Topic Emerging Solutions for Water, Sanitation and Hygiene)
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Article
Influence of Terrestrial Precipitation on the Variability of Extreme Sea Levels along the Coast of Bangladesh
Water 2021, 13(20), 2915; https://doi.org/10.3390/w13202915 - 16 Oct 2021
Cited by 1 | Viewed by 1083
Abstract
The coastal area of Bangladesh is highly vulnerable to extreme sea levels because of high population exposure in the low-lying deltaic coast. Since the area lies in the monsoon region, abundant precipitation and the resultant increase in river discharge have raised a flood [...] Read more.
The coastal area of Bangladesh is highly vulnerable to extreme sea levels because of high population exposure in the low-lying deltaic coast. Since the area lies in the monsoon region, abundant precipitation and the resultant increase in river discharge have raised a flood risk for the coastal area. Although the effects of atmospheric forces have been investigated intensively, the influence of precipitation on extreme sea levels in this area remains unknown. In this study, the influence of precipitation on extreme sea levels for three different stations were investigated by multivariate regression using the meteorological drivers of precipitation, sea level pressure, and wind. The prediction of sea levels considering precipitation effects outperformed predictions without precipitation. The benefit of incorporating precipitation was greater at Cox’s Bazar than at Charchanga and Khepupara, reflecting the hilly landscape at Cox’s Bazar. The improved prediction skill was mainly confirmed during the monsoon season, when strong precipitation events occur. It was also revealed that the precipitation over the Bangladesh area is insensitive to the El Niño-Southern Oscillation and Indian Ocean Dipole mode. The precipitation over northern Bangladesh tended to be high in the year of a high sea surface temperature over the Bay of Bengal, which may have contributed to the variation in sea level. The findings suggest that the effect of precipitation plays an essential role in enhancing sea levels during many extreme events. Therefore, incorporating the effect of terrestrial precipitation is essential for the better prediction of extreme sea levels, which helps coastal management and reduction of hazards. Full article
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Article
Trends of Nitrogen and Phosphorus in Surface Sediments of the Lagoons of the Northern Adriatic Sea
Water 2021, 13(20), 2914; https://doi.org/10.3390/w13202914 - 16 Oct 2021
Cited by 2 | Viewed by 731
Abstract
The analysis of nutrient concentrations in surface sediments is a reliable tool for assessing the trophic status of a water body. Nitrogen and phosphorus concentrations are strongly related to the sediment characteristics but are mainly driven by anthropogenic impacts. The results of the [...] Read more.
The analysis of nutrient concentrations in surface sediments is a reliable tool for assessing the trophic status of a water body. Nitrogen and phosphorus concentrations are strongly related to the sediment characteristics but are mainly driven by anthropogenic impacts. The results of the determination of total nitrogen and total inorganic and organic phosphorus in surface sediments of the lagoons and ponds of the northwestern Adriatic Sea (Marano-Grado, Venice, Po Delta, Comacchio Valleys, Pialassa della Baiona) show the merit of this approach. Indeed, when previous data are available, the ratio between the actual and background values can provide useful information on the trophic changes that have occurred in the most recent times, and the results can also explain the conditions present in less studied environments. In this context, numerous studies performed in the Venice lagoon since the second half of the 20th century during different environmental scenarios provide mean concentration ranges and propose the main causes of changes. The results of single datasets available for the other lagoons fall into scenarios that occurred in the Venice lagoon. At present, the most eutrophic basins are Pialassa della Baiona, the Po Delta lagoons and ponds and the Comacchio valleys due to industrial effluents, fish farming and clam harvesting, respectively, whereas the Venice lagoon is now experiencing environmental recovery. Full article
(This article belongs to the Section Water Quality and Contamination)
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Article
Nitrate Removal from Actual Wastewater by Coupling Sulfur-Based Autotrophic and Heterotrophic Denitrification under Different Influent Concentrations
Water 2021, 13(20), 2913; https://doi.org/10.3390/w13202913 - 16 Oct 2021
Cited by 3 | Viewed by 1062
Abstract
Contamination of wastewater with organic-limited nitrates has become an urgent problem in wastewater treatment. The cooperating heterotrophic with sulfur autotrophic denitrification is an alternative process and the efficiency has been assessed in many studies treating simulated wastewater under different operating conditions. However, due [...] Read more.
Contamination of wastewater with organic-limited nitrates has become an urgent problem in wastewater treatment. The cooperating heterotrophic with sulfur autotrophic denitrification is an alternative process and the efficiency has been assessed in many studies treating simulated wastewater under different operating conditions. However, due to the complex and diverse nature of actual wastewater, more studies treating actual wastewater are still needed to evaluate the feasibility of collaborative denitrification. In this study, lab-scale experiments were performed with actual nitrate polluted water of two different concentrations, with glucose and sodium thiosulfate introduced as mixed electron donors in the coupling sulfur-based autotrophic and heterotrophic denitrification. Results showed that the optimum denitrification performance was exhibited when the influent substrate mass ratio of C/N/S was 1.3/1/1.9, with a maximum denitrification rate of 3.52 kg NO3-N/(m3 day) and nitrate removal efficiency of 93% in the coupled systems. Illumina high-throughput sequencing analysis revealed that autotrophic, facultative, and heterotrophic bacteria jointly contributed to high nitrogen removal efficiency. The autotrophic denitrification maintained as the predominant process, while the second most prevalent denitrification process gradually changed from heterotrophic to facultative with the increase of influent concentration at optimum C/N/S ratio conditions. Furthermore, the initiation of dissimilatory nitrate reduction to ammonium (DNRA) was very pivotal in promoting the entire denitrification process. These results suggested that sulfur-based autotrophic coupled with heterotrophic denitrifying process is an alternative and promising method to treat nitrate containing wastewater. Full article
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Concept Paper
Evaluation of a Minimum Liquid Discharge (MLD) Desalination Approach for Management of Unconventional Oil and Gas Produced Waters with a Focus on Waste Minimization
Water 2021, 13(20), 2912; https://doi.org/10.3390/w13202912 - 16 Oct 2021
Cited by 1 | Viewed by 973
Abstract
The objective of this research study was to evaluate the feasibility of using a minimum liquid discharge (MLD) desalination approach as an alternate management option for unconventional produced waters (PWs) with a focus on minimizing the generation of solid waste. The feasibility of [...] Read more.
The objective of this research study was to evaluate the feasibility of using a minimum liquid discharge (MLD) desalination approach as an alternate management option for unconventional produced waters (PWs) with a focus on minimizing the generation of solid waste. The feasibility of MLD was evaluated using OLI, a water chemistry software, to model thermal desalination of unconventional PWs from the Delaware Basin in New Mexico (NM). Desalination was theoretically terminated at an evaporation point before halite (NaCl) saturation in the residual brine. Results of this study showed that selectively targeting a subset of higher flow rate and lower TDS wells/centralized tank batteries (CTBs) could yield up to 76% recovery of distillate while generating minimal solid waste. Using a selective MLD approach did reduce the quantity of distillate recovered when compared with ZLD, and left a reduced volume of residual brine which has to be managed as a liquid waste. However, selective MLD also greatly reduced the amount of solid waste. The use of a ZLD approach yielded incrementally greater quantities of distillate but at the cost of large quantities of difficult-to-manage highly soluble waste. Simulation results showed that waste generated before NaCl precipitation was primarily composed of insoluble compounds such as calcite, barite and celestite, which can be disposed in conventional landfills. This study also found a simple empirical linear relationship between TDS and distillate recovery, thus allowing a non-expert to rapidly estimate potential distillate recovery for a given starting PW quality. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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Article
Stem Photosynthesis Affects Hydraulic Resilience in the Deciduous Populusalba but Not in the Evergreen Laurus nobilis
Water 2021, 13(20), 2911; https://doi.org/10.3390/w13202911 - 16 Oct 2021
Viewed by 634
Abstract
Stem photosynthesis has been suggested to play relevant roles to cope with different biotic and abiotic stress factors, including drought. In the present study, we performed measurements of stem hydraulic conductance and non-structural carbohydrate content in the evergreen Laurus nobilis L. and the [...] Read more.
Stem photosynthesis has been suggested to play relevant roles to cope with different biotic and abiotic stress factors, including drought. In the present study, we performed measurements of stem hydraulic conductance and non-structural carbohydrate content in the evergreen Laurus nobilis L. and the deciduous Populusalba L., subjected to inhibition of stem photosynthesis and successive exposure to a drought-recovery cycle in order to check if stem photosynthesis may be involved in allowing hydraulic recovery after drought stress relief. Stem shading affected the growth of L. nobilis but not of P. alba saplings. By contrast, inhibition of stem photosynthesis was coupled to inhibition of hydraulic recovery following embolism build-up under drought in P. alba but not in L. nobilis. The two study species showed a different content and behavior of nonstructural carbohydrates (NSCs). The differences in NSCs’ trend and embolism reversal ability led to a significant relationship between starch content and the corresponding hydraulic conductance values in L. nobilis but not in P. alba. Our findings suggest that stem photosynthesis plays a key role in the maintenance of hydraulic functioning during drought especially in the deciduous species. This, in turn, may increase their vulnerability under current global climate change scenarios. Full article
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