The influence of chlorine on marine bacterial communities was examined in this study. A non-chlorine-adapted marine bacterial community (NCAM) and a chlorine-adapted bacterial community (CAM, bacterial community treated with 0.2 mg-Cl2/L chlorine) were cultivated for 1 month. A distinct difference was observed between the NCAM and CAM, which shared only eight operational taxonomic units (OTUs), corresponding to 13.1% of the total number of identified OTUs. This result suggested that chlorine was responsible for the changes in the marine bacterial communities. Kordiimonas aquimaris was found to be a chlorine-resistant marine bacterium. The effect of intermittent chlorination on the two marine biofilm communities formed on the reverse osmosis (RO) membrane surface was investigated using various chlorine concentrations (0, 0.2, 0.4, 0.6 and 0.8 mg Cl2/L). Although the average number of adherent marine bacteria on the RO membrane over a period of 7 weeks decreased with increasing chlorine concentration, disinfection efficiencies showed substantial fluctuations throughout the experiment. This is due to chlorine depletion that occurs during intermittent chlorination. These results suggest that intermittent chlorination is not an effective disinfection strategy to control biofilm formation.
{"title":"Intermittent chlorination shifts the marine biofilm population on reverse osmosis membranes","authors":"Dawoon Jeong, Chang-Ha Lee, Seockheon Lee, Hyokwan Bae","doi":"10.12989/MWT.2019.10.6.395","DOIUrl":"https://doi.org/10.12989/MWT.2019.10.6.395","url":null,"abstract":"The influence of chlorine on marine bacterial communities was examined in this study. A non-chlorine-adapted marine bacterial community (NCAM) and a chlorine-adapted bacterial community (CAM, bacterial community treated with 0.2 mg-Cl2/L chlorine) were cultivated for 1 month. A distinct difference was observed between the NCAM and CAM, which shared only eight operational taxonomic units (OTUs), corresponding to 13.1% of the total number of identified OTUs. This result suggested that chlorine was responsible for the changes in the marine bacterial communities. Kordiimonas aquimaris was found to be a chlorine-resistant marine bacterium. The effect of intermittent chlorination on the two marine biofilm communities formed on the reverse osmosis (RO) membrane surface was investigated using various chlorine concentrations (0, 0.2, 0.4, 0.6 and 0.8 mg Cl2/L). Although the average number of adherent marine bacteria on the RO membrane over a period of 7 weeks decreased with increasing chlorine concentration, disinfection efficiencies showed substantial fluctuations throughout the experiment. This is due to chlorine depletion that occurs during intermittent chlorination. These results suggest that intermittent chlorination is not an effective disinfection strategy to control biofilm formation.","PeriodicalId":18416,"journal":{"name":"Membrane Water Treatment","volume":"10 1","pages":"395-404"},"PeriodicalIF":1.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46051952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-01DOI: 10.12989/MWT.2019.10.6.405
Rita E. Ampiaw, M. Yaqub, Wontae Lee
Microcystins (MCs) are toxins produced by cyanobacteria causing a major environmental threat to water resources worldwide. Although several MCs have been reported in previous studies, microcystin-LR (m-LR) has been extensively studied as it is highly toxic. Among the several techniques employed for the removal of this toxin, adsorption with AC has been extensively studied. AC has gained wide attention as an effective adsorbent of m-LR due to its ubiquity, high sorption capacity, cost effectiveness and renewability. In this review, the adsorption of m-LR onto AC was evaluated using the information available in existing scientific literature. The effects of the pore volume and surface chemistry of AC on the adsorption of m-LR considering the structural and chemical properties of ACs were also discussed. Furthermore, we identified the parameters that influence adsorption, including natural organic matter (NOM), pH, and ionic strength during the m-LR adsorption process. The effect of these parameters on MCs adsorption onto AC from previous studied is compiled and highlighted. This review may provide new insights into future activated carbon-m-LR adsorption research, and broaden its application prospects.
微囊藻毒素(MCs)是由蓝藻产生的毒素，对全球水资源造成重大环境威胁。虽然在以前的研究中已经报道了几种MCs，但微囊藻毒素- lr (m-LR)因其剧毒而被广泛研究。在几种用于去除该毒素的技术中，活性炭吸附法已得到广泛研究。交流电由于其普遍存在、高吸附量、低成本和可再生等优点，作为一种有效的m-LR吸附剂受到了广泛的关注。在这篇综述中，利用现有的科学文献资料对m-LR在AC上的吸附进行了评价。结合活性炭的结构和化学性质，讨论了活性炭的孔体积和表面化学性质对m-LR吸附的影响。此外，我们确定了影响吸附的参数，包括m-LR吸附过程中的天然有机质(NOM)、pH和离子强度。综述了前人研究中这些参数对MCs在AC上吸附的影响。本文综述为今后活性炭-m- lr吸附研究提供了新的思路，并拓宽了其应用前景。
{"title":"Adsorption of microcystin onto activated carbon: A review","authors":"Rita E. Ampiaw, M. Yaqub, Wontae Lee","doi":"10.12989/MWT.2019.10.6.405","DOIUrl":"https://doi.org/10.12989/MWT.2019.10.6.405","url":null,"abstract":"Microcystins (MCs) are toxins produced by cyanobacteria causing a major environmental threat to water resources worldwide. Although several MCs have been reported in previous studies, microcystin-LR (m-LR) has been extensively studied as it is highly toxic. Among the several techniques employed for the removal of this toxin, adsorption with AC has been extensively studied. AC has gained wide attention as an effective adsorbent of m-LR due to its ubiquity, high sorption capacity, cost effectiveness and renewability. In this review, the adsorption of m-LR onto AC was evaluated using the information available in existing scientific literature. The effects of the pore volume and surface chemistry of AC on the adsorption of m-LR considering the structural and chemical properties of ACs were also discussed. Furthermore, we identified the parameters that influence adsorption, including natural organic matter (NOM), pH, and ionic strength during the m-LR adsorption process. The effect of these parameters on MCs adsorption onto AC from previous studied is compiled and highlighted. This review may provide new insights into future activated carbon-m-LR adsorption research, and broaden its application prospects.","PeriodicalId":18416,"journal":{"name":"Membrane Water Treatment","volume":"10 1","pages":"405-415"},"PeriodicalIF":1.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48794335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-01DOI: 10.12989/MWT.2019.10.6.461
X. Yang, Lifang Liu, Shuai Jiang
In the present work, we present a new effective hydrophilicity modifier for polysulfone (PSf) membrane. Firstly, amphiphilic nanocellulose (ANC) with different substitution degrees (SD) was synthesized by esterification reaction with nanocellulose (NC) and dodecyl succinic anhydride (DDSA). The SD and morphology of ANC were characterized by titration method and transmission electron microscopy (TEM). Then, the polysulfone (PSf)/ANC blend membranes were prepared via an immersion phase inversion method. The influence of SD on the morphology, structure and performances of PSf/ANC blend membrane were carefully investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), mechanical property test, contact angle measuring instrument and filtration experiment. The results showed that the mechanical property, hydrophilicity and anti-fouling property of all the PSf/ANC blend membranes were higher than those of pure PSf membrane and PSf/NC membrane, and the membrane properties were increased with the increasing of SD values. As ANC-4 has the highest SD value, PSf/ANC-4 membrane exhibited the optimal membrane properties. In conclusion, the prepared ANC can be used as an additive to improve the hydrophilicity and anti-fouling properties of polysulfone (PSf) membrane.
{"title":"Enhancement of hydrophilicity and anti-fouling property of polysulfone membrane using amphiphilic nanocellulose as hydrophilic modifier","authors":"X. Yang, Lifang Liu, Shuai Jiang","doi":"10.12989/MWT.2019.10.6.461","DOIUrl":"https://doi.org/10.12989/MWT.2019.10.6.461","url":null,"abstract":"In the present work, we present a new effective hydrophilicity modifier for polysulfone (PSf) membrane. Firstly, amphiphilic nanocellulose (ANC) with different substitution degrees (SD) was synthesized by esterification reaction with nanocellulose (NC) and dodecyl succinic anhydride (DDSA). The SD and morphology of ANC were characterized by titration method and transmission electron microscopy (TEM). Then, the polysulfone (PSf)/ANC blend membranes were prepared via an immersion phase inversion method. The influence of SD on the morphology, structure and performances of PSf/ANC blend membrane were carefully investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), mechanical property test, contact angle measuring instrument and filtration experiment. The results showed that the mechanical property, hydrophilicity and anti-fouling property of all the PSf/ANC blend membranes were higher than those of pure PSf membrane and PSf/NC membrane, and the membrane properties were increased with the increasing of SD values. As ANC-4 has the highest SD value, PSf/ANC-4 membrane exhibited the optimal membrane properties. In conclusion, the prepared ANC can be used as an additive to improve the hydrophilicity and anti-fouling properties of polysulfone (PSf) membrane.","PeriodicalId":18416,"journal":{"name":"Membrane Water Treatment","volume":"10 1","pages":"461-469"},"PeriodicalIF":1.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48892418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-01DOI: 10.12989/MWT.2019.10.6.471
Mayzonee Ligaray, Minjeong Kim, J. Shim, Jongkwan Park, K. Cho
The complex combination of organic contaminants in the wastewater made water treatment challenging; hence, organic matter in water bodies is usually measured in terms of organic carbon. Since it is important to identify the types of compounds when deciding suitable treatment methods, this study implemented a quantitative and qualitative analysis of the organic matter content in an actual graywater sample from Ulsan, Republic of Korea using mass spectroscopy (MS). The graywater was treated using adsorption to remove the organic contaminants. Using orbitrap MS, the organic matter content between an untreated graywater and the treated effluent were compared which yielded a significant formula count difference for the samples. It was revealed that CHON formula has the highest removal count. Isotherm studies found that the Freundlich equation was the best fit with a coefficient of determination (R2) of 0.9705 indicating a heterogenous GAC surface with a multilayer characteristic. Kinetics experiments fit the pseudo-second order equation with an R2 of 0.9998 implying that chemisorption is the rate-determining step between the organic compounds and GAC at rate constant of 52.53 g/mg•h. At low temperatures, the reaction between GAC and organic compounds were found to be spontaneous and exothermic. The conditions for optimization were set to achieve a maximum DOC and TN removal which yielded removal percentages of 94.59% and 80.75% for the DOC and TN, respectively. The optimum parameter values are the following: pH 6.3, 2.46 g of GAC for every 30 mL of graywater sample, 23.39 hrs contact time and 38.6 Celcius degree.
{"title":"Performance evaluation of organic matter adsorption from actual graywater using GAC: Orbitrap","authors":"Mayzonee Ligaray, Minjeong Kim, J. Shim, Jongkwan Park, K. Cho","doi":"10.12989/MWT.2019.10.6.471","DOIUrl":"https://doi.org/10.12989/MWT.2019.10.6.471","url":null,"abstract":"The complex combination of organic contaminants in the wastewater made water treatment challenging; hence, organic matter in water bodies is usually measured in terms of organic carbon. Since it is important to identify the types of compounds when deciding suitable treatment methods, this study implemented a quantitative and qualitative analysis of the organic matter content in an actual graywater sample from Ulsan, Republic of Korea using mass spectroscopy (MS). The graywater was treated using adsorption to remove the organic contaminants. Using orbitrap MS, the organic matter content between an untreated graywater and the treated effluent were compared which yielded a significant formula count difference for the samples. It was revealed that CHON formula has the highest removal count. Isotherm studies found that the Freundlich equation was the best fit with a coefficient of determination (R2) of 0.9705 indicating a heterogenous GAC surface with a multilayer characteristic. Kinetics experiments fit the pseudo-second order equation with an R2 of 0.9998 implying that chemisorption is the rate-determining step between the organic compounds and GAC at rate constant of 52.53 g/mg•h. At low temperatures, the reaction between GAC and organic compounds were found to be spontaneous and exothermic. The conditions for optimization were set to achieve a maximum DOC and TN removal which yielded removal percentages of 94.59% and 80.75% for the DOC and TN, respectively. The optimum parameter values are the following: pH 6.3, 2.46 g of GAC for every 30 mL of graywater sample, 23.39 hrs contact time and 38.6 Celcius degree.","PeriodicalId":18416,"journal":{"name":"Membrane Water Treatment","volume":"10 1","pages":"471-484"},"PeriodicalIF":1.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44088933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-01DOI: 10.12989/MWT.2019.10.6.441
A. Kazemzadeh, S. Mousavi, J. Mehrzad, A. Motavalizadehkakhky, M. Hosseiny
In this study, cellulose acetate (CA) / nylon66 (NYL66) (95/5) blend membranes with different thicknesses were prepared by a solvent evaporation method. The effects of membrane thickness (almost 7-25 micrometre), feed concentration (70- 95 wt.% isopropanol), and feed temperature (30-60 C) were investigated on the performance of membrane in the separation of isopropanol-water mixtures. With regard to the results of sorption experiments, it was found that the increase of feed temperature enhanced the overall sorption while by increasing feed concentration, the overall sorption passed through a maximum value at 70 wt. % isopropanol (IPA) . The best separation factor 3080.51 was gained at high isopropanol concentration 95 wt.%, low feed temperature 30 C, and high membrane thickness 24.62 micrometre. Regarding the pervaporation separation index, the obtained results showed that proper values for the thickness of membrane, feed temperature, and isopropanol concentration in feed were 24.62 micrometre, 40 C, and 70 wt.%, respectively.
{"title":"Effect of different conditions on pervaporation dehydration in CA/NYL66 blend membrane","authors":"A. Kazemzadeh, S. Mousavi, J. Mehrzad, A. Motavalizadehkakhky, M. Hosseiny","doi":"10.12989/MWT.2019.10.6.441","DOIUrl":"https://doi.org/10.12989/MWT.2019.10.6.441","url":null,"abstract":"In this study, cellulose acetate (CA) / nylon66 (NYL66) (95/5) blend membranes with different thicknesses were prepared by a solvent evaporation method. The effects of membrane thickness (almost 7-25 micrometre), feed concentration (70- 95 wt.% isopropanol), and feed temperature (30-60 C) were investigated on the performance of membrane in the separation of isopropanol-water mixtures. With regard to the results of sorption experiments, it was found that the increase of feed temperature enhanced the overall sorption while by increasing feed concentration, the overall sorption passed through a maximum value at 70 wt. % isopropanol (IPA) . The best separation factor 3080.51 was gained at high isopropanol concentration 95 wt.%, low feed temperature 30 C, and high membrane thickness 24.62 micrometre. Regarding the pervaporation separation index, the obtained results showed that proper values for the thickness of membrane, feed temperature, and isopropanol concentration in feed were 24.62 micrometre, 40 C, and 70 wt.%, respectively.","PeriodicalId":18416,"journal":{"name":"Membrane Water Treatment","volume":"10 1","pages":"441-449"},"PeriodicalIF":1.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46702483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.12989/MWT.2019.10.5.339
K. Jung, J. Ahn, Sohyun Cho, Y. Lee, K. Han, Dong-seok Shin, Kyunghyun Kim
Long term water quality change was analyzed to evaluate the effect of the Total Maximum Daily Load (TMDL) policy. A trend analysis was performed for biochemical oxygen demand (BOD) and total phosphorus (TP) concentrations data monitored at the outlets of the total 41 TMDL unit watersheds of the Nakdong River in the Republic of Korea. Because water quality data do not usually follow a normal distribution, a nonparametric statistical trend analysis method was used. The monthly mean values of BOD and TP for the period between 2004 and 2015 were analyzed by the seasonal Mann-Kendall test and the locally weighted scatterplot smoother (LOWESS). The TMDL policy effect on the water quality change of each unit watershed was analyzed together with the results of the trend analysis. From the seasonal Mann-Kendall test results, it was found that for BOD, 7.8 % of the 41 points showed downward trends, 26.8 % and the rest 65.9% showed upward and no trends. For TP, 51.2% showed no trends and the rest 48.8% showed downward trends. From the LOWESS analysis results, TP began to decrease in most of the unit watersheds from mid-2010s when intensive chemical treatment processes were introduced to existing wastewater treatment plants. Overall, for BOD, relatively more points were improved in the main stream compared to the points of the tributaries although overall trends were mostly no trend or upward. For TP, about half of the points were improved and the rest showed no trends.
{"title":"Evaluation of long-term water quality management policy effect using nonparametric statistical methods","authors":"K. Jung, J. Ahn, Sohyun Cho, Y. Lee, K. Han, Dong-seok Shin, Kyunghyun Kim","doi":"10.12989/MWT.2019.10.5.339","DOIUrl":"https://doi.org/10.12989/MWT.2019.10.5.339","url":null,"abstract":"Long term water quality change was analyzed to evaluate the effect of the Total Maximum Daily Load (TMDL) policy. A trend analysis was performed for biochemical oxygen demand (BOD) and total phosphorus (TP) concentrations data monitored at the outlets of the total 41 TMDL unit watersheds of the Nakdong River in the Republic of Korea. Because water quality data do not usually follow a normal distribution, a nonparametric statistical trend analysis method was used. The monthly mean values of BOD and TP for the period between 2004 and 2015 were analyzed by the seasonal Mann-Kendall test and the locally weighted scatterplot smoother (LOWESS). The TMDL policy effect on the water quality change of each unit watershed was analyzed together with the results of the trend analysis. From the seasonal Mann-Kendall test results, it was found that for BOD, 7.8 % of the 41 points showed downward trends, 26.8 % and the rest 65.9% showed upward and no trends. For TP, 51.2% showed no trends and the rest 48.8% showed downward trends. From the LOWESS analysis results, TP began to decrease in most of the unit watersheds from mid-2010s when intensive chemical treatment processes were introduced to existing wastewater treatment plants. Overall, for BOD, relatively more points were improved in the main stream compared to the points of the tributaries although overall trends were mostly no trend or upward. For TP, about half of the points were improved and the rest showed no trends.","PeriodicalId":18416,"journal":{"name":"Membrane Water Treatment","volume":"10 1","pages":"339-352"},"PeriodicalIF":1.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48500205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.12989/MWT.2019.10.5.331
Yuan Yuan, Jianqiao Zhang
This study aimed to investigate the membrane fouling and sludge characteristics in a pilot-scale submerged membrane bioreactor (MBR) operated under low temperature (7 degree Celcius) To elucidate the mechanisms of membrane fouling at low temperature, we studied the correlation between MBR performances and physicochemical properties of sludge including extracellular polymeric substance (EPS), relative hydrophobicity (RH) and floc size during long-term operation. The MBR was shown able to remove chemical oxygen demand (COD) stably and efficiently (>90 %) in the case of overgrowth of filamentous bacteria (bulking sludge) at low temperature. On the other hand, the occurrence of filamentous bulking greatly accelerated membrane fouling, as indicated by membrane filtration period of 14 days for filamentous bulking at 7 degree Celcius, in comparison with that of 27 days for non-bulking sludge at 24 degree Celcius. The overgrowth of filamentous bacteria resulting from low-temperature condition led to an increased release of EPS, higher RH, smaller floc size and lower fractal dimension of sludge. These factors accelerated the formation of compact cake layer on membrane surface in association with performance diminution in terms of increase in transmembrane pressure (TMP) of the membrane and thus the decrease in membrane permeability.
{"title":"Membrane fouling and sludge characteristics in submerged membrane bioreactor under low temperature","authors":"Yuan Yuan, Jianqiao Zhang","doi":"10.12989/MWT.2019.10.5.331","DOIUrl":"https://doi.org/10.12989/MWT.2019.10.5.331","url":null,"abstract":"This study aimed to investigate the membrane fouling and sludge characteristics in a pilot-scale submerged membrane bioreactor (MBR) operated under low temperature (7 degree Celcius) To elucidate the mechanisms of membrane fouling at low temperature, we studied the correlation between MBR performances and physicochemical properties of sludge including extracellular polymeric substance (EPS), relative hydrophobicity (RH) and floc size during long-term operation. The MBR was shown able to remove chemical oxygen demand (COD) stably and efficiently (>90 %) in the case of overgrowth of filamentous bacteria (bulking sludge) at low temperature. On the other hand, the occurrence of filamentous bulking greatly accelerated membrane fouling, as indicated by membrane filtration period of 14 days for filamentous bulking at 7 degree Celcius, in comparison with that of 27 days for non-bulking sludge at 24 degree Celcius. The overgrowth of filamentous bacteria resulting from low-temperature condition led to an increased release of EPS, higher RH, smaller floc size and lower fractal dimension of sludge. These factors accelerated the formation of compact cake layer on membrane surface in association with performance diminution in terms of increase in transmembrane pressure (TMP) of the membrane and thus the decrease in membrane permeability.","PeriodicalId":18416,"journal":{"name":"Membrane Water Treatment","volume":"10 1","pages":"331-338"},"PeriodicalIF":1.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44905199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-01DOI: 10.12989/MWT.2019.10.4.259
F. Kashaninia, H. Rezaie, H. Sarpoolaky
Cost effective clay adsorptive microfiltration membranes were synthesized to remove Cr (III) from high polluted water. Raw and calcined bentonite were mixed in order to decrease the shrinkage and also increase the porosity; then, 20 wt% of carbonate was added and the samples, named B (without carbonate) and B-Ca20 (with 20 wt% calcium carbonate) were uniaxially pressed and after sufficient drying, fired at 1100 degree(C) for 3 hours. Then, physical and mechanical properties of the samples, their phase analyses and microstructure and also their ability for Cr(III) removal from high polluted water (including 1000 ppm Cr (III) ions) were studied. Results showed that the addition of calcium carbonate lead the porosity to increase to 33.5% while contrary to organic pore formers like starch, due to the formation of wollastonite, the mechanical strength not only didn't collapse but also improved to 36.77 MPa. Besides, sample B-Ca20, due to the presence of wollastonite and anorthite, could remove 99.97% of Cr (III) ions. Hence, a very economic and cost effective combination of membrane filtration and adsorption technology was achieved for water treatment which made microfiltration membranes act even better than nanofiltration ones without using any adsorptive nano particles.
{"title":"Clay adsorptive membranes for chromium removal from water","authors":"F. Kashaninia, H. Rezaie, H. Sarpoolaky","doi":"10.12989/MWT.2019.10.4.259","DOIUrl":"https://doi.org/10.12989/MWT.2019.10.4.259","url":null,"abstract":"Cost effective clay adsorptive microfiltration membranes were synthesized to remove Cr (III) from high polluted water. Raw and calcined bentonite were mixed in order to decrease the shrinkage and also increase the porosity; then, 20 wt% of carbonate was added and the samples, named B (without carbonate) and B-Ca20 (with 20 wt% calcium carbonate) were uniaxially pressed and after sufficient drying, fired at 1100 degree(C) for 3 hours. Then, physical and mechanical properties of the samples, their phase analyses and microstructure and also their ability for Cr(III) removal from high polluted water (including 1000 ppm Cr (III) ions) were studied. Results showed that the addition of calcium carbonate lead the porosity to increase to 33.5% while contrary to organic pore formers like starch, due to the formation of wollastonite, the mechanical strength not only didn't collapse but also improved to 36.77 MPa. Besides, sample B-Ca20, due to the presence of wollastonite and anorthite, could remove 99.97% of Cr (III) ions. Hence, a very economic and cost effective combination of membrane filtration and adsorption technology was achieved for water treatment which made microfiltration membranes act even better than nanofiltration ones without using any adsorptive nano particles.","PeriodicalId":18416,"journal":{"name":"Membrane Water Treatment","volume":"10 1","pages":"259-264"},"PeriodicalIF":1.0,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49356013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-01DOI: 10.12989/MWT.2019.10.4.251
Z. Cui, Daqing Tong, Xue Li, Xiaozu Wang, Zhaohui Wang
Fabricating hydrophobic porous membrane is important for exploring the applications of membrane distillation (MD). In the present paper, poly(vinylidene fluoride) (PVDF) hollow fiber membrane was modified by coating polydimethylsiloxane (PDMS) on its surface. The effects of PDMS concentration, cross-linking temperature and cross-linking time on the performance of the composite membranes in a vacuum membrane distillation (VMD) process were investigated. It was found that the hydrophobicity and the VMD performance of the PVDF hollow fiber membrane were obviously improved by coating PDMS. The optimal PDMS concentration, cross-linking temperature and cross-linking time were 0.5 wt%, 80 degree(c), and 9 hr, respectively.
{"title":"Hydrophobic modification of PVDF hollow fiber membranes using polydimethylsiloxane for VMD process","authors":"Z. Cui, Daqing Tong, Xue Li, Xiaozu Wang, Zhaohui Wang","doi":"10.12989/MWT.2019.10.4.251","DOIUrl":"https://doi.org/10.12989/MWT.2019.10.4.251","url":null,"abstract":"Fabricating hydrophobic porous membrane is important for exploring the applications of membrane distillation (MD). In the present paper, poly(vinylidene fluoride) (PVDF) hollow fiber membrane was modified by coating polydimethylsiloxane (PDMS) on its surface. The effects of PDMS concentration, cross-linking temperature and cross-linking time on the performance of the composite membranes in a vacuum membrane distillation (VMD) process were investigated. It was found that the hydrophobicity and the VMD performance of the PVDF hollow fiber membrane were obviously improved by coating PDMS. The optimal PDMS concentration, cross-linking temperature and cross-linking time were 0.5 wt%, 80 degree(c), and 9 hr, respectively.","PeriodicalId":18416,"journal":{"name":"Membrane Water Treatment","volume":"10 1","pages":"251-257"},"PeriodicalIF":1.0,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48537797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lotus leaf has a special dual micro and nano surface structure which gives its highly hydrophobic surface characteristics and so-called self cleaning effect. In order to endow PVDF hollow fiber membrane with this special structure and improve the hydrophobicity of membrane surface, PVDF hollow fiber composite membranes was obtained through the immersion coating of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) dilute solution on the outside surface of PVDF support membrane. The prepared PVDF composite membranes were used in the vacuum membrane distillation (VMD) for the desalination. The effects of PVDF-HFP dilute solution concentration in the dope solution and coating time on VMD separation performance was studied. Membranes were characterized by SEM, WCA measurement, porosity, and liquid entry pressure of water. VMD test was carried out using 35 g.L-1 NaCl aqueous solution as the feed solution at feed temperature of 30 degree(C) and the permeate pressure of 31.3 kPa. The vapour flux reached a maximum when PVDF-HFP concentration in the dilute solution was 5 wt% and the coating time was kept in the range of 10-60 s. This was attributed to the well configuration of micro-nano rods which was similar with the dual micro-nano structure on the lotus leaf. Compared with the original PVDF membrane, the salt rejection can be well maintained which was greater than 99.99 % meanwhile permeation water conductivity was kept at a low value of 7-9 uS.cm-1 during the continuous testing for 360 h.
{"title":"Preparation of highly hydrophobic PVDF hollow fiber composite membrane with lotus leaf-like surface and its desalination properties","authors":"Hongbin Li, X. Zi, Wenying Shi, Longwei Qin, Haixia Zhang, X. Qin","doi":"10.12989/MWT.2019.10.4.287","DOIUrl":"https://doi.org/10.12989/MWT.2019.10.4.287","url":null,"abstract":"Lotus leaf has a special dual micro and nano surface structure which gives its highly hydrophobic surface characteristics and so-called self cleaning effect. In order to endow PVDF hollow fiber membrane with this special structure and improve the hydrophobicity of membrane surface, PVDF hollow fiber composite membranes was obtained through the immersion coating of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) dilute solution on the outside surface of PVDF support membrane. The prepared PVDF composite membranes were used in the vacuum membrane distillation (VMD) for the desalination. The effects of PVDF-HFP dilute solution concentration in the dope solution and coating time on VMD separation performance was studied. Membranes were characterized by SEM, WCA measurement, porosity, and liquid entry pressure of water. VMD test was carried out using 35 g.L-1 NaCl aqueous solution as the feed solution at feed temperature of 30 degree(C) and the permeate pressure of 31.3 kPa. The vapour flux reached a maximum when PVDF-HFP concentration in the dilute solution was 5 wt% and the coating time was kept in the range of 10-60 s. This was attributed to the well configuration of micro-nano rods which was similar with the dual micro-nano structure on the lotus leaf. Compared with the original PVDF membrane, the salt rejection can be well maintained which was greater than 99.99 % meanwhile permeation water conductivity was kept at a low value of 7-9 uS.cm-1 during the continuous testing for 360 h.","PeriodicalId":18416,"journal":{"name":"Membrane Water Treatment","volume":"10 1","pages":"287-298"},"PeriodicalIF":1.0,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47442614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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