To investigate the motion patterns of flexible fibers inside a sewage pump and their impact on internal flow characteristics, visualization experiments were conducted to compare the pump flow when transporting water—0.3% CMC solution and 0.3% CMC solution containing flexible fibers under different operating conditions. The results showed that changes in the rheological properties of the 0.3% CMC solution primarily affected fluid viscous dissipation. Under the same rotational speed, the flow rate increased by only 2.4%, but power consumption decreased by 9.1%, resulting in a 6.4% improvement in efficiency. The curvature and distribution of fibers within the impeller flow channel remained stable. Their impact on the flow was characterized by an overall reduction in velocity within the impeller region, with the peak velocity decreasing by up to 26.3%. The primary cause of pump failure due to fibers was their tendency to repeatedly accumulate and detach at the tongue, leading to blockages. Fiber length had a more significant impact on the blockage rate than mass concentration.
{"title":"Experimental Visualization Study on Flow Characteristics Inside a Self-Priming Sewage Pump","authors":"Mingjie Xu, Shuihua Zheng, Yiliang Li, Qing Xue Huang, Zenan Sun, Jianlin Hu","doi":"10.3390/w17050735","DOIUrl":"https://doi.org/10.3390/w17050735","url":null,"abstract":"To investigate the motion patterns of flexible fibers inside a sewage pump and their impact on internal flow characteristics, visualization experiments were conducted to compare the pump flow when transporting water—0.3% CMC solution and 0.3% CMC solution containing flexible fibers under different operating conditions. The results showed that changes in the rheological properties of the 0.3% CMC solution primarily affected fluid viscous dissipation. Under the same rotational speed, the flow rate increased by only 2.4%, but power consumption decreased by 9.1%, resulting in a 6.4% improvement in efficiency. The curvature and distribution of fibers within the impeller flow channel remained stable. Their impact on the flow was characterized by an overall reduction in velocity within the impeller region, with the peak velocity decreasing by up to 26.3%. The primary cause of pump failure due to fibers was their tendency to repeatedly accumulate and detach at the tongue, leading to blockages. Fiber length had a more significant impact on the blockage rate than mass concentration.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"17 5","pages":"735-735"},"PeriodicalIF":0.0,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.mdpi.com/2073-4441/17/5/735/pdf?version=1740996350","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147330869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yixiong Pang, Yu Pan, Lingjun Kong, Zeng-Hui Diao, Bin Li
In this study, a millimeter-scale N/P-doped carbonaceous catalyst was synthesized via facile carbonization of the N/P-doped resin at 800 °C (NPCR-800). This work aimed to investigate the performance of the NPCR-800 catalyst in heterogeneous catalytic ozonation and the mechanism of reactive oxygen species (ROS) generation. The NPCR-800 achieved the highest oxalic acid (OA) degradation efficiency of 91% within 40 min. The first-order kinetics of OA degradation in the NPCR-800/O3 system was approximately twelve and three times higher than that in the O3 and O3/GAC system, respectively. In addition to excellent catalytic ozonation performance, the NPCR catalyst also exhibited good reusability and salt tolerance. The dominant ROS were identified by the electronic spin response and free radical quantitative experiments, being responsible for oxalic acid degradation in NPCR-800/O3 system. The effect of the doped N and P elements on enhancing the catalytic activity was understood, what was ascribed to the efficient reaction of the O3 molecule with the active site of the graphitic N, defect site and carbonyl/carboxyl groups of NPCR to generate the hydroxyl radical and singlet oxygen. A type of metal-free catalytic ozonation strategy was developed in this work, which is promising in the practical treatment of the refractory organic pollutants.
{"title":"Carbonization of N/P Co-Doped Resin for Metal-Free Catalytic Ozonation of Oxalic Acid","authors":"Yixiong Pang, Yu Pan, Lingjun Kong, Zeng-Hui Diao, Bin Li","doi":"10.3390/w17050710","DOIUrl":"https://doi.org/10.3390/w17050710","url":null,"abstract":"In this study, a millimeter-scale N/P-doped carbonaceous catalyst was synthesized via facile carbonization of the N/P-doped resin at 800 °C (NPCR-800). This work aimed to investigate the performance of the NPCR-800 catalyst in heterogeneous catalytic ozonation and the mechanism of reactive oxygen species (ROS) generation. The NPCR-800 achieved the highest oxalic acid (OA) degradation efficiency of 91% within 40 min. The first-order kinetics of OA degradation in the NPCR-800/O3 system was approximately twelve and three times higher than that in the O3 and O3/GAC system, respectively. In addition to excellent catalytic ozonation performance, the NPCR catalyst also exhibited good reusability and salt tolerance. The dominant ROS were identified by the electronic spin response and free radical quantitative experiments, being responsible for oxalic acid degradation in NPCR-800/O3 system. The effect of the doped N and P elements on enhancing the catalytic activity was understood, what was ascribed to the efficient reaction of the O3 molecule with the active site of the graphitic N, defect site and carbonyl/carboxyl groups of NPCR to generate the hydroxyl radical and singlet oxygen. A type of metal-free catalytic ozonation strategy was developed in this work, which is promising in the practical treatment of the refractory organic pollutants.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"17 5","pages":"710-710"},"PeriodicalIF":0.0,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.mdpi.com/2073-4441/17/5/710/pdf?version=1740737304","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147330531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Treating contamination plumes in relatively lower-permeability zones (LPZs) presents a significant challenge for injection-based remediation due to aquifer heterogeneity. Currently, xanthan gum, as a co-remediation agent, has been confirmed to enhance the removal efficiency of contaminants in these zones. However, its associated effects on plume migration remain to be clarified. This study revealed the mechanisms by which xanthan addition enhances the removal rate of perchloroethylene (PCE), as well as its effects on plume migration. The results demonstrated that the injection of xanthan induces adverse migration of contamination plumes. A nonlinear relationship was observed between xanthan concentration, injection rate, and remediation performance. Within the studied range (0 g/L–0.8 g/L; 10 mL/min–40 mL/min), an optimal xanthan concentration (0.8 g/L) and injection rate (25 mL/min) were identified, at which the PCE removal efficiency was significantly improved, and the contamination plume migration was effectively inhibited. For combinations of porous media with a lower permeability contrast, adding xanthan led to better performance. To provide a comprehensive assessment of the remediation performance, four key indicators were proposed: remediation measurement factor, PCE removal rate, sweeping uniformity, and injection pressure. The results identified the optimal remediation conditions: M-F combination with the lowest permeability contrast (4.9), 0.4 g/L xanthan, and an injection rate of 25 mL/min. These findings contribute valuable insights for the formulation of more efficient remediation strategies.
{"title":"The Effects of Xanthan Gum as a Synergistic Delivery Reagent on Perchloroethylene Remediation in Lower-Permeability Zones of Aquifers","authors":"Qi Xu, Zhijuan Jia, Xiao-Gang Wen, Yanping Xiao, Haobin Zhong, Jiajun Chen","doi":"10.3390/w17050682","DOIUrl":"https://doi.org/10.3390/w17050682","url":null,"abstract":"Treating contamination plumes in relatively lower-permeability zones (LPZs) presents a significant challenge for injection-based remediation due to aquifer heterogeneity. Currently, xanthan gum, as a co-remediation agent, has been confirmed to enhance the removal efficiency of contaminants in these zones. However, its associated effects on plume migration remain to be clarified. This study revealed the mechanisms by which xanthan addition enhances the removal rate of perchloroethylene (PCE), as well as its effects on plume migration. The results demonstrated that the injection of xanthan induces adverse migration of contamination plumes. A nonlinear relationship was observed between xanthan concentration, injection rate, and remediation performance. Within the studied range (0 g/L–0.8 g/L; 10 mL/min–40 mL/min), an optimal xanthan concentration (0.8 g/L) and injection rate (25 mL/min) were identified, at which the PCE removal efficiency was significantly improved, and the contamination plume migration was effectively inhibited. For combinations of porous media with a lower permeability contrast, adding xanthan led to better performance. To provide a comprehensive assessment of the remediation performance, four key indicators were proposed: remediation measurement factor, PCE removal rate, sweeping uniformity, and injection pressure. The results identified the optimal remediation conditions: M-F combination with the lowest permeability contrast (4.9), 0.4 g/L xanthan, and an injection rate of 25 mL/min. These findings contribute valuable insights for the formulation of more efficient remediation strategies.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"17 5","pages":"682-682"},"PeriodicalIF":0.0,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.mdpi.com/2073-4441/17/5/682/pdf?version=1740583152","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147333109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel composite biomass aerogel adsorbent (HSA) was prepared by dual physical and chemical cross-linking using sodium alginate (SA) as an organic biomass template and hydroxyapatite nanowires (HAPNWs) as an inorganic biomass skeleton. The structure of the HSA was characterized by scanning electron microscopy (SEM), X-ray powder diffractometry (XRD), Fourier transformed infrared spectroscopy (FTIR), and stress testing. One-factor experiments were conducted focusing on adsorption conditions at a Pb ion concentration of 300 mg/L, and the adsorption conditions were optimized using the response surface method. The optimal conditions obtained by numerical optimization using Design-Expert 13 were as follows: pH of 7.23, adsorption temperature of 35.42 °C, and adsorption time of 1050.73 min; the optimal adsorption capacity was 278.874 mg/g. To further reveal the adsorption mechanism of HSA, its adsorption model and kinetics were analyzed. Adsorption was most consistent with the Langmuir isothermal adsorption model, while the kinetics were most consistent with the pseudo-secondary kinetic model. R2 reached 0.9986, indicating a mono-molecular layer of adsorption by heat, while the main adsorption mechanism was chemisorption.
{"title":"Pb2+ Adsorption, Performance, and Response Surface Optimization of Hydroxyapatite Nanowire Sodium Alginate Aerogel (HSA)","authors":"Weiyuan Cao, Zixuan Yang, Ren Liu, Zilin Zhang, Guokuan Chen, Zilin Zhou, Liwei Xu","doi":"10.3390/w17050631","DOIUrl":"https://doi.org/10.3390/w17050631","url":null,"abstract":"A novel composite biomass aerogel adsorbent (HSA) was prepared by dual physical and chemical cross-linking using sodium alginate (SA) as an organic biomass template and hydroxyapatite nanowires (HAPNWs) as an inorganic biomass skeleton. The structure of the HSA was characterized by scanning electron microscopy (SEM), X-ray powder diffractometry (XRD), Fourier transformed infrared spectroscopy (FTIR), and stress testing. One-factor experiments were conducted focusing on adsorption conditions at a Pb ion concentration of 300 mg/L, and the adsorption conditions were optimized using the response surface method. The optimal conditions obtained by numerical optimization using Design-Expert 13 were as follows: pH of 7.23, adsorption temperature of 35.42 °C, and adsorption time of 1050.73 min; the optimal adsorption capacity was 278.874 mg/g. To further reveal the adsorption mechanism of HSA, its adsorption model and kinetics were analyzed. Adsorption was most consistent with the Langmuir isothermal adsorption model, while the kinetics were most consistent with the pseudo-secondary kinetic model. R2 reached 0.9986, indicating a mono-molecular layer of adsorption by heat, while the main adsorption mechanism was chemisorption.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"17 5","pages":"631-631"},"PeriodicalIF":0.0,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147332147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dialdehyde cellulose fabric (DACF) membranes with varying degrees of oxidation were fabricated using periodate oxidation and were employed for the chemical adsorption of amino-groups containing dyes from wastewater. The aldehyde group contents of DACF membranes were adjusted by altering oxidation time, which was confirmed by titration experiments. The chemical structure and morphology of DACF membranes were characterized using ATR-FTIR, TGA, SCA, SEM, XPS, and XRD measurements. The optimized DACF membrane, which was treated for an oxidation time of 24 h and has an aldehyde content of 2.97 mmol/g, was used for the chemical adsorption of amino-containing dye molecules. This process relies on the Schiff base reaction between the amino groups of the target dye molecule and the aldehyde groups of the membrane. Two typical cationic dyes, fuchsin basic and chrysoidine, containing aromatic amino groups, were chosen to determine the adsorption capacity of the DACF membrane. The adsorption kinetics, isotherms, and thermal dynamics of the DACF membrane were investigated comprehensively, while both pseudo-first- and pseudo-second-order kinetics models fit well, indicating the complicated chemical/diffusion adsorption process, where the hydrophobic properties of the DACF membrane retarded the adsorption rate. The maximum adsorption capacities of the DACF membrane against fuchsin basic and chrysoidine were 108.69 and 46.29 mg/g, respectively, as determined by Langmuir isotherm simulations. Various competing ions such as Na+, Ca2+, Cl−, and SO42− at high concentrations of 10,000 ppm were used to challenge the adsorption capability of the DACF membrane, with negligible effects observed. A new adsorption mechanism based on chemical/diffusion interaction was proposed. Bovine serum albumin (BSA), fuchsin basic, and chrysoidine were mixed to simulate the multicomponent wastewater containing dissolved organic nitrogen (DON) and demonstrated the adsorption process; the direct adsorption capacity of the DACF membrane was up to 63.0%. This work offers a new method for the highly efficient removal of organic pollutants by a chemical reaction approach.
{"title":"Dialdehyde Cellulose Fabric Membranes Enable Chemical Adsorption of Amino-Containing Dyes for Wastewater Treatment","authors":"Zhaoju Zhang, Hongyang Ma, Benjamin S. Hsiao","doi":"10.3390/w17020281","DOIUrl":"https://doi.org/10.3390/w17020281","url":null,"abstract":"Dialdehyde cellulose fabric (DACF) membranes with varying degrees of oxidation were fabricated using periodate oxidation and were employed for the chemical adsorption of amino-groups containing dyes from wastewater. The aldehyde group contents of DACF membranes were adjusted by altering oxidation time, which was confirmed by titration experiments. The chemical structure and morphology of DACF membranes were characterized using ATR-FTIR, TGA, SCA, SEM, XPS, and XRD measurements. The optimized DACF membrane, which was treated for an oxidation time of 24 h and has an aldehyde content of 2.97 mmol/g, was used for the chemical adsorption of amino-containing dye molecules. This process relies on the Schiff base reaction between the amino groups of the target dye molecule and the aldehyde groups of the membrane. Two typical cationic dyes, fuchsin basic and chrysoidine, containing aromatic amino groups, were chosen to determine the adsorption capacity of the DACF membrane. The adsorption kinetics, isotherms, and thermal dynamics of the DACF membrane were investigated comprehensively, while both pseudo-first- and pseudo-second-order kinetics models fit well, indicating the complicated chemical/diffusion adsorption process, where the hydrophobic properties of the DACF membrane retarded the adsorption rate. The maximum adsorption capacities of the DACF membrane against fuchsin basic and chrysoidine were 108.69 and 46.29 mg/g, respectively, as determined by Langmuir isotherm simulations. Various competing ions such as Na+, Ca2+, Cl−, and SO42− at high concentrations of 10,000 ppm were used to challenge the adsorption capability of the DACF membrane, with negligible effects observed. A new adsorption mechanism based on chemical/diffusion interaction was proposed. Bovine serum albumin (BSA), fuchsin basic, and chrysoidine were mixed to simulate the multicomponent wastewater containing dissolved organic nitrogen (DON) and demonstrated the adsorption process; the direct adsorption capacity of the DACF membrane was up to 63.0%. This work offers a new method for the highly efficient removal of organic pollutants by a chemical reaction approach.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"17 2","pages":"281-281"},"PeriodicalIF":0.0,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.mdpi.com/2073-4441/17/2/281/pdf?version=1737363442","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147333094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jing Yuan, Lin Zhao, Yanting Li, Guangnan Xing, Danning Chen, Yongkui Yang
The environmental treatment of endocrine-disrupting compounds (EDCs) has attracted significant attention. Nonylphenol (NP), a highly toxic EDC with widespread distribution, presents an urgent challenge requiring effective removal strategies. Although microalgae-based treatments offer environmentally friendly and cost-effective solutions, the high toxicity level of NP impedes this process. Analysis was conducted on cell biomass, cell morphology, extracellular polymeric substances (EPSs), and the degradation of nonylphenol in Chlorella pyrenoidosa treated with nonylphenol and glucose. Glucose restored the algal biomass to 2.23 times its original level, reduced cellular damage, and maintained normal physiological activities. Glucose also stimulated algal metabolism and promoted the secretion of EPSs. The polysaccharide content of soluble EPSs (S-EPSs) increased by 32.7%, whereas that of the bound EPSs (B-EPSs) increased by 55.5%. The three-dimensional excitation–emission matrix fluorescence spectroscopy of B-EPS indicated that glucose enhanced tryptophan secretion. Glucose showed great potential as a biostimulant to enhance NP bioremediation efficiency in aquatic ecosystems. This finding indicates that the nonylphenol remediation of wastewater can be integrated with microalgal biomass recovery, creating opportunities for revenue generation.
{"title":"Glucose as a Metabolic Enhancer: Promoting Nonylphenol Detoxification by Chlorella pyrenoidosa","authors":"Jing Yuan, Lin Zhao, Yanting Li, Guangnan Xing, Danning Chen, Yongkui Yang","doi":"10.3390/w17020244","DOIUrl":"https://doi.org/10.3390/w17020244","url":null,"abstract":"The environmental treatment of endocrine-disrupting compounds (EDCs) has attracted significant attention. Nonylphenol (NP), a highly toxic EDC with widespread distribution, presents an urgent challenge requiring effective removal strategies. Although microalgae-based treatments offer environmentally friendly and cost-effective solutions, the high toxicity level of NP impedes this process. Analysis was conducted on cell biomass, cell morphology, extracellular polymeric substances (EPSs), and the degradation of nonylphenol in Chlorella pyrenoidosa treated with nonylphenol and glucose. Glucose restored the algal biomass to 2.23 times its original level, reduced cellular damage, and maintained normal physiological activities. Glucose also stimulated algal metabolism and promoted the secretion of EPSs. The polysaccharide content of soluble EPSs (S-EPSs) increased by 32.7%, whereas that of the bound EPSs (B-EPSs) increased by 55.5%. The three-dimensional excitation–emission matrix fluorescence spectroscopy of B-EPS indicated that glucose enhanced tryptophan secretion. Glucose showed great potential as a biostimulant to enhance NP bioremediation efficiency in aquatic ecosystems. This finding indicates that the nonylphenol remediation of wastewater can be integrated with microalgal biomass recovery, creating opportunities for revenue generation.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"17 2","pages":"244-244"},"PeriodicalIF":0.0,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.mdpi.com/2073-4441/17/2/244/pdf?version=1737096016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147332249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guanghua Wang, Tongyu Li, Wenxuan Yin, Jianhua Zhou, Dongwei Lu
With the widespread use of plastic products, microplastic (MP) pollution has become an important factor threatening the water environment and human health. Ultrafiltration (UF) technology, based on organic polymer membranes, is a common method to remove MPs in water treatment processes, offering high removal efficiency and scalability. However, in water treatment plants (WTPs), oxidation pretreatment is often applied before UF, and the presence of oxidants can affect membrane performance. In this study, we constructed a polyvinylidene fluoride (PVDF) ultrafiltration membrane for a gravity filtration system to investigate the impact of sodium hypochlorite oxidation pretreatment on the removal of polystyrene (PS) MPs under gravity filtration. As a result, pre-chlorination reduced PS microplastic deposition on membranes by improving flux stability (15.1%) but significantly decreased the removal rate (from 36.6% to 22.6%). Pre-oxidation facilitated a shift in fouling behavior toward intermediate blocking while reducing standard blocking and enhancing irreversible fouling recovery. However, continuous chlorine exposure increased membrane porosity and pore size, substituted fluorine with chlorine, and led to organic carbon leaching, indicating pre-oxidation jeopardizes membrane stability and separation performance. These findings provide insights into the development of novel strategies aimed at enhancing the efficiency and sustainability of membrane treatment processes in WTPs.
{"title":"Effect of Sodium Hypochlorite Disinfection on Polyvinylidene Fluoride Membranes in Microplastic Ultrafiltration","authors":"Guanghua Wang, Tongyu Li, Wenxuan Yin, Jianhua Zhou, Dongwei Lu","doi":"10.3390/w17010099","DOIUrl":"https://doi.org/10.3390/w17010099","url":null,"abstract":"With the widespread use of plastic products, microplastic (MP) pollution has become an important factor threatening the water environment and human health. Ultrafiltration (UF) technology, based on organic polymer membranes, is a common method to remove MPs in water treatment processes, offering high removal efficiency and scalability. However, in water treatment plants (WTPs), oxidation pretreatment is often applied before UF, and the presence of oxidants can affect membrane performance. In this study, we constructed a polyvinylidene fluoride (PVDF) ultrafiltration membrane for a gravity filtration system to investigate the impact of sodium hypochlorite oxidation pretreatment on the removal of polystyrene (PS) MPs under gravity filtration. As a result, pre-chlorination reduced PS microplastic deposition on membranes by improving flux stability (15.1%) but significantly decreased the removal rate (from 36.6% to 22.6%). Pre-oxidation facilitated a shift in fouling behavior toward intermediate blocking while reducing standard blocking and enhancing irreversible fouling recovery. However, continuous chlorine exposure increased membrane porosity and pore size, substituted fluorine with chlorine, and led to organic carbon leaching, indicating pre-oxidation jeopardizes membrane stability and separation performance. These findings provide insights into the development of novel strategies aimed at enhancing the efficiency and sustainability of membrane treatment processes in WTPs.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"17 1","pages":"99-99"},"PeriodicalIF":0.0,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.mdpi.com/2073-4441/17/1/99/pdf?version=1735800015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147330683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-27DOI: 10.17159/wsa/2023.v49.i4.4002
None JK Turpie, None GK Letley
The City of Cape Town experienced a serious drought between 2016 and 2018 which led to severe water shortages and concerns for the environment. This study took advantage of a period of unprecedented levels of awareness about water security in order to investigate households’ willingness to pay (WTP) for reliable water supply and their WTP to avoid environmental damages in securing this supply. Increasing the supply of water from dams and groundwater will ultimately impact on aquatic ecosystems, but alternatives are more expensive. We surveyed 248 households from 105 suburbs and used contingent valuation methods to investigate WTP for both secure and less damaging or ‘greener’ ways of supplying water. Depending on income level, households were willing to pay 63–127% more for their normal levels of consumption in order to have security of supply, and a further 35–68% more to ensure its environmental sustainability. Based on the relationship between WTP for 7 income categories, the overall WTP for secure water supply under non-drought conditions amounted to some 2.8 billion ZAR/year, which is about 90% higher than pre-drought revenues. Aggregate WTP for securing this supply using options that ensured the protection of the region’s rivers and estuaries was 3.3 billion ZAR. These results have an important bearing on water investment and pricing decisions over the longer term.
{"title":"Cape Town residents’ willingness to pay for a secure and ‘green’ water supply","authors":"None JK Turpie, None GK Letley","doi":"10.17159/wsa/2023.v49.i4.4002","DOIUrl":"https://doi.org/10.17159/wsa/2023.v49.i4.4002","url":null,"abstract":"The City of Cape Town experienced a serious drought between 2016 and 2018 which led to severe water shortages and concerns for the environment. This study took advantage of a period of unprecedented levels of awareness about water security in order to investigate households’ willingness to pay (WTP) for reliable water supply and their WTP to avoid environmental damages in securing this supply. Increasing the supply of water from dams and groundwater will ultimately impact on aquatic ecosystems, but alternatives are more expensive. We surveyed 248 households from 105 suburbs and used contingent valuation methods to investigate WTP for both secure and less damaging or ‘greener’ ways of supplying water. Depending on income level, households were willing to pay 63–127% more for their normal levels of consumption in order to have security of supply, and a further 35–68% more to ensure its environmental sustainability. Based on the relationship between WTP for 7 income categories, the overall WTP for secure water supply under non-drought conditions amounted to some 2.8 billion ZAR/year, which is about 90% higher than pre-drought revenues. Aggregate WTP for securing this supply using options that ensured the protection of the region’s rivers and estuaries was 3.3 billion ZAR. These results have an important bearing on water investment and pricing decisions over the longer term.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"120 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136312499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-27DOI: 10.17159/wsa/2023.v49.i4.4036
None Hilary Takawira, None Joshua Mbanga
Wastewater treatment plants (WWTPs) have been identified as point sources of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARG). Due to variations in antibiotic use and prescribing patterns in different countries, it is imperative to establish the presence of ARB and ARGs in water environments on a country-by-country basis. This study investigated the occurrence of 11 antibiotic-resistance genes (QNRB, DFR14, CTX-M, KPC, Sul1, QNRA, Sul2, ERMB, ERMA, SHV, NDM), and antibiotic-resistant Escherichia coli in a WWTP and its associated river water in Harare, Zimbabwe. 24 water samples were collected across 3 sites: upstream and downstream of the WWTP; final effluent of the WWTP. The samples were collected weekly for 8 weeks. Pure cultures of the E. coli isolates were obtained by membrane filtration (0.45 µm) and repeated streaking on Tryptone Bile X-glucuronide followed by biochemical tests (indole test; citrate test; motility, indole, and ornithine). Antibiotic resistance profiling was done for 12 antibiotics using the disc diffusion method. Total genomic DNA was extracted from the 21 water samples and the occurrence of 11 antibiotic-resistant genes investigated using conventional PCR. 86 E. coli isolates were obtained from the sampled sites: 28 from the upstream site, 26 from the WWTP effluent, and 32 from the downstream site. The results from chi-squared analysis showed a significant association (p < 0.05) between the sampling site and the percentage of antibiotic-resistant E. coli for all 12 antibiotics investigated. The percentage of E. coli isolates resistant to the tested antibiotics varied from 29% (ertapenem) to 80.2% (ciprofloxacin). 81 (94.2%) E. coli isolates were resistant to antibiotics from ≥3 classes. Eight (8/11, 72.7%) ARGs were detected in the WWTP effluent and river water samples. Results indicate that the investigated WWTP and associated river water are reservoirs of ARGs and antibiotic-resistant E. coli, which is a public health concern.
污水处理厂(WWTPs)已被确定为耐药细菌(ARB)和耐药基因(ARG)的点源。由于不同国家的抗生素使用和处方模式存在差异，必须在各国的基础上确定水环境中是否存在ARB和ARGs。本研究对津巴布韦哈拉雷某污水处理厂及其相关河水中11个耐药基因(QNRB、DFR14、CTX-M、KPC、Sul1、QNRA、Sul2、ERMB、ERMA、SHV、NDM)和耐药大肠杆菌的发生情况进行了调查。污水处理厂的最终排出物。每周采集样本，连续8周。通过膜过滤(0.45µm)获得大肠杆菌分离物的纯培养物，并在Tryptone Bile X-glucuronide上反复染色，然后进行生化试验(吲哚试验;柠檬酸测试;运动性、吲哚和鸟氨酸)。采用圆盘扩散法对12种抗生素进行耐药性分析。从21份水样中提取总基因组DNA，并采用常规PCR方法调查11个耐药基因的发生情况。从采样地点分离出86株大肠杆菌:28株来自上游地点，26株来自污水处理厂排放物，32株来自下游地点。卡方分析结果显示显著相关(p <对所有12种抗生素的耐药大肠杆菌百分比与采样点之间的差异为0.05)。大肠杆菌分离株对所测抗生素耐药的百分比从29%(厄他培南)到80.2%(环丙沙星)不等。81株(94.2%)大肠杆菌对≥3类抗生素耐药。污水处理厂出水和河流水样共检出8种ARGs(8/11, 72.7%)。结果表明，所调查的污水处理厂及其相关河水是ARGs和耐药大肠杆菌的宿主，是一个公共卫生问题。
{"title":"Occurrence of multidrug-resistant Escherichia coli and antibiotic resistance genes in a wastewater treatment plant and its associated river water in Harare, Zimbabwe","authors":"None Hilary Takawira, None Joshua Mbanga","doi":"10.17159/wsa/2023.v49.i4.4036","DOIUrl":"https://doi.org/10.17159/wsa/2023.v49.i4.4036","url":null,"abstract":"Wastewater treatment plants (WWTPs) have been identified as point sources of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARG). Due to variations in antibiotic use and prescribing patterns in different countries, it is imperative to establish the presence of ARB and ARGs in water environments on a country-by-country basis. This study investigated the occurrence of 11 antibiotic-resistance genes (QNRB, DFR14, CTX-M, KPC, Sul1, QNRA, Sul2, ERMB, ERMA, SHV, NDM), and antibiotic-resistant Escherichia coli in a WWTP and its associated river water in Harare, Zimbabwe. 24 water samples were collected across 3 sites: upstream and downstream of the WWTP; final effluent of the WWTP. The samples were collected weekly for 8 weeks. Pure cultures of the E. coli isolates were obtained by membrane filtration (0.45 µm) and repeated streaking on Tryptone Bile X-glucuronide followed by biochemical tests (indole test; citrate test; motility, indole, and ornithine). Antibiotic resistance profiling was done for 12 antibiotics using the disc diffusion method. Total genomic DNA was extracted from the 21 water samples and the occurrence of 11 antibiotic-resistant genes investigated using conventional PCR. 86 E. coli isolates were obtained from the sampled sites: 28 from the upstream site, 26 from the WWTP effluent, and 32 from the downstream site. The results from chi-squared analysis showed a significant association (p < 0.05) between the sampling site and the percentage of antibiotic-resistant E. coli for all 12 antibiotics investigated. The percentage of E. coli isolates resistant to the tested antibiotics varied from 29% (ertapenem) to 80.2% (ciprofloxacin). 81 (94.2%) E. coli isolates were resistant to antibiotics from ≥3 classes. Eight (8/11, 72.7%) ARGs were detected in the WWTP effluent and river water samples. Results indicate that the investigated WWTP and associated river water are reservoirs of ARGs and antibiotic-resistant E. coli, which is a public health concern.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"24 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136311739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-27DOI: 10.17159/wsa/2023.v49.i4.3998
None Annelie Swanepoel, None Hein du Preez, None Henk Bouwman
Due to the worldwide increasing prevalence of microplastics in the aquatic environment, this study aimed to perform a screening of the source and drinking water of South Africa’s largest bulk drinking water supplier to determine the extent to which microplastics occur in the water. Source water samples, samples immediately after treatment, and samples in the distribution network (Johannesburg, Mabopane, Garankua and Pelindaba) were analysed. Microplastics concentrations in the source water ranged from 0.24 to 1.47 particles/L, immediately after treatment from 0.56 to 0.9 particles/L, and in the distribution network from 0.26 to 0.88 particles/L. Most of the microplastics found in the water were classified as ‘fragments’ and a few as ‘fibres’. The control sample (indicating contamination during sample preparation and analysis) showed 0.34 particles/L, which was higher than some of the samples taken, indicating very low microplastics concentrations in these samples. Little evidence was found that the drinking water treatment processes reduced the number of microplastics from the source to the final treated water. No evidence could be found that the pipes in the distribution network contribute to microplastics in the tap water. The most frequently found polymer in the samples was rubber. Based on mass, however, as a function of particle size and polymer density, ethylene-vinyl-acetate (a polymer commonly used as foam in sporting equipment and flip-flops) comprised 54% of the microplastics and polyethylene (standard and chlorinated) 25%.
{"title":"A baseline study on the prevalence of microplastics in South African drinking water: from source to distribution","authors":"None Annelie Swanepoel, None Hein du Preez, None Henk Bouwman","doi":"10.17159/wsa/2023.v49.i4.3998","DOIUrl":"https://doi.org/10.17159/wsa/2023.v49.i4.3998","url":null,"abstract":"Due to the worldwide increasing prevalence of microplastics in the aquatic environment, this study aimed to perform a screening of the source and drinking water of South Africa’s largest bulk drinking water supplier to determine the extent to which microplastics occur in the water. Source water samples, samples immediately after treatment, and samples in the distribution network (Johannesburg, Mabopane, Garankua and Pelindaba) were analysed. Microplastics concentrations in the source water ranged from 0.24 to 1.47 particles/L, immediately after treatment from 0.56 to 0.9 particles/L, and in the distribution network from 0.26 to 0.88 particles/L. Most of the microplastics found in the water were classified as ‘fragments’ and a few as ‘fibres’. The control sample (indicating contamination during sample preparation and analysis) showed 0.34 particles/L, which was higher than some of the samples taken, indicating very low microplastics concentrations in these samples. Little evidence was found that the drinking water treatment processes reduced the number of microplastics from the source to the final treated water. No evidence could be found that the pipes in the distribution network contribute to microplastics in the tap water. The most frequently found polymer in the samples was rubber. Based on mass, however, as a function of particle size and polymer density, ethylene-vinyl-acetate (a polymer commonly used as foam in sporting equipment and flip-flops) comprised 54% of the microplastics and polyethylene (standard and chlorinated) 25%.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"126 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136311740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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