Filter backwashing is a supplemental part of a drinking water treatment (DWT) facility to wash the filter bed at regular intervals using water or air scour/water by fluidizing the filter bed. Suspended sediments that are retained by the filter bed consist of different particles such as sand, anthracite, and granular activated carbon (GAC) that decline the water flow rate of the filter, and hence consequently the filter bed must be cleaned using a backwashing procedure. Biofiltration has been extensively utilized to decrease organic matter and manage the occurrence of disinfection by-products within drinking water sources. Biological rapid sand filters are frequently utilized to eliminate ammonium from groundwater provinces with the purpose of meeting drinking water requirements. Biological activated carbon (BAC) filters require to be backwashed to wash and enhance the treatment capability by detaching both restrained materials and residual biomass. The reclamation of activated carbon-used backwash water (UBW) was managed by exercising an ultrafiltration (UF) procedure.
{"title":"Backwashing of granular media filters and membranes for water treatment: a review","authors":"M. Turan","doi":"10.2166/aqua.2023.207","DOIUrl":"https://doi.org/10.2166/aqua.2023.207","url":null,"abstract":"\u0000 Filter backwashing is a supplemental part of a drinking water treatment (DWT) facility to wash the filter bed at regular intervals using water or air scour/water by fluidizing the filter bed. Suspended sediments that are retained by the filter bed consist of different particles such as sand, anthracite, and granular activated carbon (GAC) that decline the water flow rate of the filter, and hence consequently the filter bed must be cleaned using a backwashing procedure. Biofiltration has been extensively utilized to decrease organic matter and manage the occurrence of disinfection by-products within drinking water sources. Biological rapid sand filters are frequently utilized to eliminate ammonium from groundwater provinces with the purpose of meeting drinking water requirements. Biological activated carbon (BAC) filters require to be backwashed to wash and enhance the treatment capability by detaching both restrained materials and residual biomass. The reclamation of activated carbon-used backwash water (UBW) was managed by exercising an ultrafiltration (UF) procedure.","PeriodicalId":17666,"journal":{"name":"Journal of Water Supply: Research and Technology-Aqua","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73153108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Conventional treatments for antibiotic residues in effluents are inefficient and do not lead to complete removal. Though effective and feasible degradation of antibiotics using nanoparticles has been reported by several scientists, chemically synthesized nanoparticles have their own disadvantages. Thus, in this study, nZVI was biosynthesized using leaf extract of Shorea robusta and precursor FeSO4·7H2O for photocatalytically degrading tetracycline (TC) and ciprofloxacin (CIP). The characterization of nZVI was performed using SEM, TEM, AFM, EDX, FTIR, and XRD to test their properties, which revealed iron-rich, well-dispersed, spherical, crystalline nanoparticles. Photocatalytic degradation of TC and CIP under UV illumination revealed 88 and 84% optimum efficiency at antibiotic concentrations 15 and 25 mg L−1, 0.014 and 0.0175 g L−1 doses of nZVI, respectively in the pH range 4–6 in 70 min. The degradation was further verified using mass spectrometry, which confirmed the degradation of antibiotics into the breakdown products. Toxicity assay of the degraded antibiotic solution proved it non-toxic for bacteria and safe for discharge into water bodies. The cost analysis of antibiotic degradation using nZVI proved very economical, costing around 1.5 USD per 1,000 L of wastewater.
对废水中抗生素残留的常规处理效率低下，不能完全去除。虽然一些科学家已经报道了利用纳米颗粒有效和可行地降解抗生素，但化学合成的纳米颗粒有其自身的缺点。因此，本研究以赤芍叶提取物和前体FeSO4·7H2O合成nZVI光催化降解四环素(TC)和环丙沙星(CIP)。通过SEM、TEM、AFM、EDX、FTIR和XRD等测试手段对nZVI进行了表征，发现其具有富铁、分散良好的球形晶体纳米颗粒。紫外光催化降解TC和CIP的结果表明，在抗生素浓度为15和25 mg L−1、0.014和0.0175 g L−1、pH范围为4-6时，70 min内，TC和CIP的最佳降解效率分别为88%和84%。通过质谱进一步验证了降解效果，证实了抗生素降解为分解产物。对降解后的抗生素溶液进行毒性试验，证明其对细菌无毒，可安全排放到水体中。使用nZVI降解抗生素的成本分析证明是非常经济的，每1000升废水成本约为1.5美元。
{"title":"Photocatalytic degradation of tetracycline and ciprofloxacin antibiotic residues in aqueous phase by biosynthesized nZVI using Sal (Shorea robusta) leaf extract","authors":"Aditya Kumar Jha, S. Chakraborty","doi":"10.2166/aqua.2023.113","DOIUrl":"https://doi.org/10.2166/aqua.2023.113","url":null,"abstract":"\u0000 Conventional treatments for antibiotic residues in effluents are inefficient and do not lead to complete removal. Though effective and feasible degradation of antibiotics using nanoparticles has been reported by several scientists, chemically synthesized nanoparticles have their own disadvantages. Thus, in this study, nZVI was biosynthesized using leaf extract of Shorea robusta and precursor FeSO4·7H2O for photocatalytically degrading tetracycline (TC) and ciprofloxacin (CIP). The characterization of nZVI was performed using SEM, TEM, AFM, EDX, FTIR, and XRD to test their properties, which revealed iron-rich, well-dispersed, spherical, crystalline nanoparticles. Photocatalytic degradation of TC and CIP under UV illumination revealed 88 and 84% optimum efficiency at antibiotic concentrations 15 and 25 mg L−1, 0.014 and 0.0175 g L−1 doses of nZVI, respectively in the pH range 4–6 in 70 min. The degradation was further verified using mass spectrometry, which confirmed the degradation of antibiotics into the breakdown products. Toxicity assay of the degraded antibiotic solution proved it non-toxic for bacteria and safe for discharge into water bodies. The cost analysis of antibiotic degradation using nZVI proved very economical, costing around 1.5 USD per 1,000 L of wastewater.","PeriodicalId":17666,"journal":{"name":"Journal of Water Supply: Research and Technology-Aqua","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88105600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Surface waterbodies, on which the growing population of Kashmir Valley is reliant in a variety of ways, are increasingly deteriorated due to anthropogenic pollution from the rapid economic development. This research aims to assess the water quality of the surface waterbodies in the north-eastern region of Kashmir Valley. Standard analytical procedures were used to analyze the water samples taken from 11 distinct sampling stations for 14 physiochemical parameters. The results were compared with the standard permissible levels which showed that the water quality of rivers and lakes in the north-east Himalayan region has steadily declined. Furthermore, multivariate statistical techniques were used with the goal to identify key variables that influence seasonal and sectional water quality variations. The analysis of variance (ANOVA) analysis revealed that there is substantial spatio-temporal variability in the water quality parameters. According to principal component analysis (PCA) results, four primary components, which together accounted for 79.23% of the total variance, could be used to evaluate all data. Chemical, organic, and conventional pollutants were found to be significant latent factors influencing the water quality of rivers in the study region. The results indicate that PCA and ANOVA may be used as vital tools to identify crucial surface water quality indices and the most contaminated river sections.
{"title":"Application of multivariate statistical methods to enhance the water quality monitoring system of Kashmir Valley with special emphasis to side-stream pollution","authors":"Sarvat Gull, Shagoofta Rasool Shah, A. M. Dar","doi":"10.2166/aqua.2023.230","DOIUrl":"https://doi.org/10.2166/aqua.2023.230","url":null,"abstract":"\u0000 Surface waterbodies, on which the growing population of Kashmir Valley is reliant in a variety of ways, are increasingly deteriorated due to anthropogenic pollution from the rapid economic development. This research aims to assess the water quality of the surface waterbodies in the north-eastern region of Kashmir Valley. Standard analytical procedures were used to analyze the water samples taken from 11 distinct sampling stations for 14 physiochemical parameters. The results were compared with the standard permissible levels which showed that the water quality of rivers and lakes in the north-east Himalayan region has steadily declined. Furthermore, multivariate statistical techniques were used with the goal to identify key variables that influence seasonal and sectional water quality variations. The analysis of variance (ANOVA) analysis revealed that there is substantial spatio-temporal variability in the water quality parameters. According to principal component analysis (PCA) results, four primary components, which together accounted for 79.23% of the total variance, could be used to evaluate all data. Chemical, organic, and conventional pollutants were found to be significant latent factors influencing the water quality of rivers in the study region. The results indicate that PCA and ANOVA may be used as vital tools to identify crucial surface water quality indices and the most contaminated river sections.","PeriodicalId":17666,"journal":{"name":"Journal of Water Supply: Research and Technology-Aqua","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81673669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Cai, Yi-mei Tian, Xiuli Wu, Yuanna Zhang, Yong-Wen Ke, Yan Wang, Wenjun Sun
Membrane filtration technology is widely applied in conventional surface water treatment plants because of its low power load and high filtration accuracy. This study follows the transition from a power-driven to a gravity-driven siphon-submerged ultrafiltration membrane system in a drinking water treatment plant in Shandong Province, China. The proportion of space membrane areas in the tank was further developed, by increasing the membrane areas of a single tank to 1.6 times of that before the transformation, the design production capacity of a single tank is increased from 10,000 m3/d before the transformation to 16,700 m3/d. The recovery rate of a single tank was also increased from 96.28 to 97.77%. The energy consumption per ton of water decreased from 0.06 to 0.017 MJ. The annual carbon emissions reduction reached 197.13 tons per tank. In terms of the water quality, the algae removal rate from surface water by the ultrafiltration membrane reached 100%. Further, the removal rates of 2 μm particles, turbidity, and chlorophyll were above 99%. Our results suggest that gravity-driven siphon-submerged ultrafiltration promotes environmental protection, energy conservation, and emissions reduction. This technology introduces a new development direction for membrane filtering in drinking water treatment plants.
{"title":"Efficiency of a gravity-driven membrane in a water treatment plant","authors":"C. Cai, Yi-mei Tian, Xiuli Wu, Yuanna Zhang, Yong-Wen Ke, Yan Wang, Wenjun Sun","doi":"10.2166/aqua.2023.198","DOIUrl":"https://doi.org/10.2166/aqua.2023.198","url":null,"abstract":"\u0000 Membrane filtration technology is widely applied in conventional surface water treatment plants because of its low power load and high filtration accuracy. This study follows the transition from a power-driven to a gravity-driven siphon-submerged ultrafiltration membrane system in a drinking water treatment plant in Shandong Province, China. The proportion of space membrane areas in the tank was further developed, by increasing the membrane areas of a single tank to 1.6 times of that before the transformation, the design production capacity of a single tank is increased from 10,000 m3/d before the transformation to 16,700 m3/d. The recovery rate of a single tank was also increased from 96.28 to 97.77%. The energy consumption per ton of water decreased from 0.06 to 0.017 MJ. The annual carbon emissions reduction reached 197.13 tons per tank. In terms of the water quality, the algae removal rate from surface water by the ultrafiltration membrane reached 100%. Further, the removal rates of 2 μm particles, turbidity, and chlorophyll were above 99%. Our results suggest that gravity-driven siphon-submerged ultrafiltration promotes environmental protection, energy conservation, and emissions reduction. This technology introduces a new development direction for membrane filtering in drinking water treatment plants.","PeriodicalId":17666,"journal":{"name":"Journal of Water Supply: Research and Technology-Aqua","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76442674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. López-Felices, J. F. Velasco-Muñoz, J. A. Aznar-Sánchez, I. M. Román-Sánchez
The availability and quality of water resources for agricultural irrigation are being increasingly compromised by different factors. In this context, the installation of rainwater harvesting (RWH) systems for use in agricultural holdings can contribute to mitigating this problem. However, the use of these systems by farmers continues to be very low. This paper analyses the factors that influence a farmer's decision to adopt these systems to take advantage of rainwater. Greenhouse agriculture in southeast Spain is the case studied. For this, a binary logistic regression model based on a survey administered to farmers was used. Among the variables found to be significant, the most important variables are the quantity of water in the pond, the pond capacity and environmental awareness. The variables that least affect the adoption decision are age, education level and income. These results have allowed the development of the main lines of action for policy-makers to intervene in order to promote the adoption of these systems. These measures focus on enhancing the training of farmers, providing them with financial support and boosting their environmental awareness. The results of this study lead to improved research on farmers’ behaviour and sustainable management of water resources in agriculture.
{"title":"Factors influencing the use of rainwater for agricultural irrigation: the case of greenhouse agriculture in southeast Spain","authors":"B. López-Felices, J. F. Velasco-Muñoz, J. A. Aznar-Sánchez, I. M. Román-Sánchez","doi":"10.2166/aqua.2023.205","DOIUrl":"https://doi.org/10.2166/aqua.2023.205","url":null,"abstract":"\u0000 The availability and quality of water resources for agricultural irrigation are being increasingly compromised by different factors. In this context, the installation of rainwater harvesting (RWH) systems for use in agricultural holdings can contribute to mitigating this problem. However, the use of these systems by farmers continues to be very low. This paper analyses the factors that influence a farmer's decision to adopt these systems to take advantage of rainwater. Greenhouse agriculture in southeast Spain is the case studied. For this, a binary logistic regression model based on a survey administered to farmers was used. Among the variables found to be significant, the most important variables are the quantity of water in the pond, the pond capacity and environmental awareness. The variables that least affect the adoption decision are age, education level and income. These results have allowed the development of the main lines of action for policy-makers to intervene in order to promote the adoption of these systems. These measures focus on enhancing the training of farmers, providing them with financial support and boosting their environmental awareness. The results of this study lead to improved research on farmers’ behaviour and sustainable management of water resources in agriculture.","PeriodicalId":17666,"journal":{"name":"Journal of Water Supply: Research and Technology-Aqua","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90429921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Herein, we report a facile approach for constructing a calixarene-based electrochemical heavy metal sensor (Calix/MPA/Au) via a one-pot reaction for the detection of Ni(II) and Zn(II) ions. The surface elemental properties and analytical performance of the Calix/MPA/Au sensor were characterized by X-ray photoelectron spectroscopy (XPS) and differential pulse voltammetry (DPV). Under optimum conditions, the sensor exhibited detection limits of 1.5 and 0.34 mg/L at linear ranges of 2.85–6.65 and 0.13–1.68 mg/L for the Zn(II) and Ni(II) ions, respectively. The developed sensor exhibited a better electrochemical performance in the detection of Zn(II) and Ni(II) ions owing to the favourable host–guest interactions between the hydroxyl groups-functionalized lower rim of dicarboxyl-calix[4]arene and the metal ions. The RSD of the five independent Calix/MPA/Au electrode for Zn(II) and Ni(II) ions was calculated to be 16.3 and 16.1%, respectively. Despite the lower sensitivity of the modified electrode towards Ni(II) ions, this finding proves the high selectivity of the calixarene as a detection probe towards the fitted size of guest ion, hence promising to be assembled and explored as a solid-state based-supramolecular host molecule for tracing metal ions.
{"title":"Electrochemical detection of nickel(II) and zinc(II) ions by a dicarboxyl-Calix[4]arene-based sensor (Calix/MPA/Au) through differential pulse voltammetry analysis","authors":"Siti Nur Farhana Abdul Aziz, S. A. Alang Ahmad","doi":"10.2166/aqua.2023.179","DOIUrl":"https://doi.org/10.2166/aqua.2023.179","url":null,"abstract":"\u0000 Herein, we report a facile approach for constructing a calixarene-based electrochemical heavy metal sensor (Calix/MPA/Au) via a one-pot reaction for the detection of Ni(II) and Zn(II) ions. The surface elemental properties and analytical performance of the Calix/MPA/Au sensor were characterized by X-ray photoelectron spectroscopy (XPS) and differential pulse voltammetry (DPV). Under optimum conditions, the sensor exhibited detection limits of 1.5 and 0.34 mg/L at linear ranges of 2.85–6.65 and 0.13–1.68 mg/L for the Zn(II) and Ni(II) ions, respectively. The developed sensor exhibited a better electrochemical performance in the detection of Zn(II) and Ni(II) ions owing to the favourable host–guest interactions between the hydroxyl groups-functionalized lower rim of dicarboxyl-calix[4]arene and the metal ions. The RSD of the five independent Calix/MPA/Au electrode for Zn(II) and Ni(II) ions was calculated to be 16.3 and 16.1%, respectively. Despite the lower sensitivity of the modified electrode towards Ni(II) ions, this finding proves the high selectivity of the calixarene as a detection probe towards the fitted size of guest ion, hence promising to be assembled and explored as a solid-state based-supramolecular host molecule for tracing metal ions.","PeriodicalId":17666,"journal":{"name":"Journal of Water Supply: Research and Technology-Aqua","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76881417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. S. Rautela, D. Kumar, B. G. R. Gandhi, Ajay Kumar, A. Dubey
A large population depends on water resources generated due to runoff from Himalayan River basins. They provide enough water for drinking, domestic, industrial, and irrigation. Also, these rivers have a high hydropower potential. A lack of in-depth studies has made it difficult to understand how these rivers respond hydrologically to climate change (CC) and, thus, impact the environment. In this paper, modelling the Alaknanda River Basin (ARB) using the Soil and Water Assessment Tool (SWAT) has been conducted to understand the hydrological response and assess its water balance components. The result shows that the basin's water yield and Evapotranspiration (ET) vary from 58 to 63% and 34 to 39% of precipitation, respectively. The average annual contribution of snowmelt to the total riverine flow will range from 20 to 24% throughout the simulation period. SFTMP, TLAPS, SMTMP, CN2, SMFMX, and GW_DELAY is found to be most sensitive at the significance level of less than 0.05, showing the contribution of the snowmelt is significant in streamflow, while delay in the groundwater will affect the contribution of surface runoff and groundwater in the streamflow. Based on the results, it is highly recommended that the spatial and temporal hydro-meteorological should be investigated in-depth.
{"title":"Long-term hydrological simulation for the estimation of snowmelt contribution of Alaknanda River Basin, Uttarakhand using SWAT","authors":"K. S. Rautela, D. Kumar, B. G. R. Gandhi, Ajay Kumar, A. Dubey","doi":"10.2166/aqua.2023.176","DOIUrl":"https://doi.org/10.2166/aqua.2023.176","url":null,"abstract":"\u0000 A large population depends on water resources generated due to runoff from Himalayan River basins. They provide enough water for drinking, domestic, industrial, and irrigation. Also, these rivers have a high hydropower potential. A lack of in-depth studies has made it difficult to understand how these rivers respond hydrologically to climate change (CC) and, thus, impact the environment. In this paper, modelling the Alaknanda River Basin (ARB) using the Soil and Water Assessment Tool (SWAT) has been conducted to understand the hydrological response and assess its water balance components. The result shows that the basin's water yield and Evapotranspiration (ET) vary from 58 to 63% and 34 to 39% of precipitation, respectively. The average annual contribution of snowmelt to the total riverine flow will range from 20 to 24% throughout the simulation period. SFTMP, TLAPS, SMTMP, CN2, SMFMX, and GW_DELAY is found to be most sensitive at the significance level of less than 0.05, showing the contribution of the snowmelt is significant in streamflow, while delay in the groundwater will affect the contribution of surface runoff and groundwater in the streamflow. Based on the results, it is highly recommended that the spatial and temporal hydro-meteorological should be investigated in-depth.","PeriodicalId":17666,"journal":{"name":"Journal of Water Supply: Research and Technology-Aqua","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87763365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To determine the response between the onshore sediment transport capacity (Tc) and various hydraulic parameters, a variable-slope, fixed-bed flume experiment was conducted to investigate Tc for five slopes and six flow rates by comparing five levels of sediment, and a total of 150 experiments were conducted. The results show that among the response relationships between each hydraulic parameter and Tc, the relationships between flow power, unit flow power, and average flow velocity and Tc is significant. In predicting Tc under different soil conditions, the shear stress produced divergence, which should be further explored. The reliability of using slope and flow rate as a single parameter to predict Tc is questionable. As a kinetic index, flow power can be used to predict Tc. The average flow velocity and unit flow power can predict Tc well and are closely related to the soil used in the experiments. The shear stress of water flow can express the evolution of Tc, which is mainly influenced by the median particle size of sediment particles in predicting Tc. The results of the study provide a new method for establishing a prediction model for soil erosion in the loess hilly gully area.
{"title":"Numerical calculation of sediment transport capacity of land flow on slopes: method investigation and improvement","authors":"Yan Li, Weijun Yuan, Kuandi Zhang, Ziyan Li","doi":"10.2166/aqua.2022.054","DOIUrl":"https://doi.org/10.2166/aqua.2022.054","url":null,"abstract":"\u0000 To determine the response between the onshore sediment transport capacity (Tc) and various hydraulic parameters, a variable-slope, fixed-bed flume experiment was conducted to investigate Tc for five slopes and six flow rates by comparing five levels of sediment, and a total of 150 experiments were conducted. The results show that among the response relationships between each hydraulic parameter and Tc, the relationships between flow power, unit flow power, and average flow velocity and Tc is significant. In predicting Tc under different soil conditions, the shear stress produced divergence, which should be further explored. The reliability of using slope and flow rate as a single parameter to predict Tc is questionable. As a kinetic index, flow power can be used to predict Tc. The average flow velocity and unit flow power can predict Tc well and are closely related to the soil used in the experiments. The shear stress of water flow can express the evolution of Tc, which is mainly influenced by the median particle size of sediment particles in predicting Tc. The results of the study provide a new method for establishing a prediction model for soil erosion in the loess hilly gully area.","PeriodicalId":17666,"journal":{"name":"Journal of Water Supply: Research and Technology-Aqua","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80287746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Geometrical changes and high flow velocity cause flow separation and cavitation in the transition regions of hydraulic structures. A few studies have been conducted on the flow pressure and cavitation index in these regions, and the results need to be still improved. The present study examined the flow pressure and cavitation index variations for expansion angles between 0° and 10° and Froude numbers up to 20.1. Several relevant equations were also suggested to predict permissible angles in the transition regions. The results showed that negative pressure occurred at all lateral expansion angles except 0° when the Froude number was equal to or greater than ≥6.5. The cavitation phenomenon did not occur on the side walls for Froude number up to 4.49. However, the values of the cavitation index were reduced to less than the critical value for the Froude number of 14 when expansion angle was greater than 6°. The results also revealed that the side walls should not be expanded when Froude number was equal to or greater than 17.5. The occurrence of the cavitation on these walls substantially increased for Froude number of 20.1 even as expansion angle equals 0°.
{"title":"Evolution of pressure and cavitation in transition region walls for supercritical flow","authors":"Tohid Jamali, M. Manafpour, H. Ebrahimnezhadian","doi":"10.2166/aqua.2023.142","DOIUrl":"https://doi.org/10.2166/aqua.2023.142","url":null,"abstract":"\u0000 Geometrical changes and high flow velocity cause flow separation and cavitation in the transition regions of hydraulic structures. A few studies have been conducted on the flow pressure and cavitation index in these regions, and the results need to be still improved. The present study examined the flow pressure and cavitation index variations for expansion angles between 0° and 10° and Froude numbers up to 20.1. Several relevant equations were also suggested to predict permissible angles in the transition regions. The results showed that negative pressure occurred at all lateral expansion angles except 0° when the Froude number was equal to or greater than ≥6.5. The cavitation phenomenon did not occur on the side walls for Froude number up to 4.49. However, the values of the cavitation index were reduced to less than the critical value for the Froude number of 14 when expansion angle was greater than 6°. The results also revealed that the side walls should not be expanded when Froude number was equal to or greater than 17.5. The occurrence of the cavitation on these walls substantially increased for Froude number of 20.1 even as expansion angle equals 0°.","PeriodicalId":17666,"journal":{"name":"Journal of Water Supply: Research and Technology-Aqua","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90640505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Planners are often faced with the challenge to provide crude estimates of water distribution system (WDS) infrastructure capacity and associated costs in the early phases of greenfield developments. This study investigated the relationship between the physical and hydraulic characteristics of a WDS and the corresponding serviced area. Five physical parameters (a) and two hydraulic parameters (b) describing the serviced area were identified for analysis, namely (a) total pipeline length, land area, area shape factor, terrain index, reservoir distance from area centroid and (b) peak flow rate and average static system pressure. Multiple linear regression was performed on the data. A model was compiled linking the total pipeline length of a WDS to the peak flow rate. The model is applicable to predominantly residential service zones larger than 80 hectares with a peak hour flow rate of <450 L/s. The model enables the prediction of the potable water distribution pipe infrastructure required for future development areas in the absence of basic planning information, such as cadastral layouts. Alternatively, the model can estimate the potential maximum peak flow rate that can be supplied, if the total pipeline length is known.
{"title":"A model for evaluating water distribution system capacity as a function of the total pipeline length","authors":"C. Loubser, Frans Grotepass, J. Winter, H. Jacobs","doi":"10.2166/aqua.2022.194","DOIUrl":"https://doi.org/10.2166/aqua.2022.194","url":null,"abstract":"\u0000 Planners are often faced with the challenge to provide crude estimates of water distribution system (WDS) infrastructure capacity and associated costs in the early phases of greenfield developments. This study investigated the relationship between the physical and hydraulic characteristics of a WDS and the corresponding serviced area. Five physical parameters (a) and two hydraulic parameters (b) describing the serviced area were identified for analysis, namely (a) total pipeline length, land area, area shape factor, terrain index, reservoir distance from area centroid and (b) peak flow rate and average static system pressure. Multiple linear regression was performed on the data. A model was compiled linking the total pipeline length of a WDS to the peak flow rate. The model is applicable to predominantly residential service zones larger than 80 hectares with a peak hour flow rate of <450 L/s. The model enables the prediction of the potable water distribution pipe infrastructure required for future development areas in the absence of basic planning information, such as cadastral layouts. Alternatively, the model can estimate the potential maximum peak flow rate that can be supplied, if the total pipeline length is known.","PeriodicalId":17666,"journal":{"name":"Journal of Water Supply: Research and Technology-Aqua","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81121110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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