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I. Caltran
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4 records found
1
Ceramic Nanofiltration Setup
Design and Upscale
The ceramic Nanofiltration membranes are studied in TU Delft to treat the brine. It has abilities to concentrate NOM and separate it from salts, and chemical precipitation to recover a clean solution with regeneration salt (i.e., NaCl) from the membrane permeate.For achieving this, the first step should build up the Setup. Therefore, this additional thesis aims to upscale a previous ceramic nanofiltration setup, which should run overnight without supervision. This thesis is divided into two parts: (1) design and building, and (2) experiment. The results show that although the recirculation pump limits the potential of the setup, it can still provide high recovery and stable permeability.
...
The ceramic Nanofiltration membranes are studied in TU Delft to treat the brine. It has abilities to concentrate NOM and separate it from salts, and chemical precipitation to recover a clean solution with regeneration salt (i.e., NaCl) from the membrane permeate.For achieving this, the first step should build up the Setup. Therefore, this additional thesis aims to upscale a previous ceramic nanofiltration setup, which should run overnight without supervision. This thesis is divided into two parts: (1) design and building, and (2) experiment. The results show that although the recirculation pump limits the potential of the setup, it can still provide high recovery and stable permeability.
Master thesis
(2019)
-
Pooja Halvawala, Luuk Rietveld, Sebastiaan Heijman, Ralph Lindeboom, Irene Caltran
The presence of organic and inorganic contaminants in aquatic ecosystem has been threat to public health and environment. To produce drinking water, removal of natural organic matter has been of importance due to formation of DBPs. Of the many available treatments, ion exchange (IEX) has the potential to remove natural organic matter (NOM). However, IEX resins need to be regenerated upon saturation with NOM, which generates brine. Usually, NaCl is used to regenerate the resins, hence the desorbed NOM ends in the brine with sodium chloride and other ions like sulphate and nitrate which are present in surface or ground water. The disposal of high saline brine is complex due to aftereffects on the environment and the associated costs. Therefore, an interesting physical alternative is to separate the NOM from brine that can be further reprocessed as fertilisers for agriculture. Ceramic nanofiltration (NF) appears to be an alternative to treat the brine. This type of membrane is chemically and mechanically robust, can be operated at extreme pH conditions, withstands backwashing and chemical cleaning. Besides, ceramic nanofiltration membranes have the capability to separate multivalent ions which makes it suitable to treat the brine. However, NOM possess a complex matrix and relies on various factors for its high removal. In this research, it was interesting to recognize the NOM fractions and the behaviour alleviating NOM retention. Various IEX brines from water treatment plants were studied. For this, NOM was characterised using two different methods i.e., LC-OCD and NSM. The LC-OCD characterization done by Het Waterlaboratorium characterized NOM fraction based on the size of fractions into Humic substances, building blocks, Low molecular weight neutrals and low molecular weight acids. Characterisation of NSM was done by Udine University, Italy wherein the characterization of humics was done on the principle of the selective resin adsorption and precipitation. The characterisation of NOM by LC-OCD predicted the NOM rejection on membrane quite accurately. The effect of ionic strength was investigated to reflect NOM removal. NOM rejection for same NOM source and membrane pore size remained unaffected by the ionic strength of the brine. However, when different membrane pore sizes (600Da and 900Da) for different NOM source, NOM removal by ceramic nanofiltration was governed a combination of steric exclusion, electrostatic repulsion and hydrophobic nature of the humic content and. In longer duration, ceramic NF membranes may foul due to filtration process. To reflect the same, fouling test was conducted. Fouling test was conducted with the high ionic strength brine because during the filtration experiments, it showed highest permeability drop. The sudden drop in permeate flux was due to osmotic pressure difference. However, during NOM filtration period, the flux and permeability were quite steady which suggested no major fouling in that phase. Irreversible fouling did not affect the membrane pore size.
...
The presence of organic and inorganic contaminants in aquatic ecosystem has been threat to public health and environment. To produce drinking water, removal of natural organic matter has been of importance due to formation of DBPs. Of the many available treatments, ion exchange (IEX) has the potential to remove natural organic matter (NOM). However, IEX resins need to be regenerated upon saturation with NOM, which generates brine. Usually, NaCl is used to regenerate the resins, hence the desorbed NOM ends in the brine with sodium chloride and other ions like sulphate and nitrate which are present in surface or ground water. The disposal of high saline brine is complex due to aftereffects on the environment and the associated costs. Therefore, an interesting physical alternative is to separate the NOM from brine that can be further reprocessed as fertilisers for agriculture. Ceramic nanofiltration (NF) appears to be an alternative to treat the brine. This type of membrane is chemically and mechanically robust, can be operated at extreme pH conditions, withstands backwashing and chemical cleaning. Besides, ceramic nanofiltration membranes have the capability to separate multivalent ions which makes it suitable to treat the brine. However, NOM possess a complex matrix and relies on various factors for its high removal. In this research, it was interesting to recognize the NOM fractions and the behaviour alleviating NOM retention. Various IEX brines from water treatment plants were studied. For this, NOM was characterised using two different methods i.e., LC-OCD and NSM. The LC-OCD characterization done by Het Waterlaboratorium characterized NOM fraction based on the size of fractions into Humic substances, building blocks, Low molecular weight neutrals and low molecular weight acids. Characterisation of NSM was done by Udine University, Italy wherein the characterization of humics was done on the principle of the selective resin adsorption and precipitation. The characterisation of NOM by LC-OCD predicted the NOM rejection on membrane quite accurately. The effect of ionic strength was investigated to reflect NOM removal. NOM rejection for same NOM source and membrane pore size remained unaffected by the ionic strength of the brine. However, when different membrane pore sizes (600Da and 900Da) for different NOM source, NOM removal by ceramic nanofiltration was governed a combination of steric exclusion, electrostatic repulsion and hydrophobic nature of the humic content and. In longer duration, ceramic NF membranes may foul due to filtration process. To reflect the same, fouling test was conducted. Fouling test was conducted with the high ionic strength brine because during the filtration experiments, it showed highest permeability drop. The sudden drop in permeate flux was due to osmotic pressure difference. However, during NOM filtration period, the flux and permeability were quite steady which suggested no major fouling in that phase. Irreversible fouling did not affect the membrane pore size.
Ceramic nanofiltration membranes
Rejection of salts and NOM at high ionic strength and modification of pore size by atomic layer deposition
Master thesis
(2018)
-
Liying Feng, Luuk Rietveld, Sebastiaan Heijman, Irene Caltran, Ran Shang, Frank Dirne
Natural Organic Matter (NOM) is always present in the drinking water sources such as rivers, lakes and reservoirs. It causes several problems, including the unfavourable colour and odour of water, formation of disinfectant by-products and harmful microbial growth. In drinking water treatment, anion exchange (anion-IEX) is used for NOM removal. However, the regeneration of anion-IEX produces a brine, which is a high saline waste stream containing the desorbed NOM and anions (i.e. sulphate) as well as the residual sodium chloride added during the regeneration process.
One possible approach to manage the waste brine is to recover the valuable compounds from the brine, and consequently, reduce the brine volume that has to be disposed. The separation could be done by ceramic nanofiltration (NF) membranes. However, the separation performance of ceramic NF membranes at high salinity conditions is still not fully understood. Therefore, the use of ceramic NF membranes to treat the brine-like wastes that contain NOM and high salt concentrations were investigated.
Commercial 500 Dalton(Da) ceramic NF membranes were used in the salt experiments. Several experimental conditions such as pH and ionic strength were investigated to understand their influence on the rejection of sulphate (SO42-) and chloride (Cl-). The results show that the salt rejection was governed by charge effect, and it changed depending on pH and ionic strength. When ionic strength was 0.1M, the mitigated charge effect led to a low rejection of SO42- (<20%) and Cl- (<5%) by the 500Da membranes. On the other hand, the 560Da membrane used in salt&NOM experiments exhibited more than 95% rejection of NOM but less than 25% rejection of both SO42- and Cl- when ionic strength was 1M.
Since the 500Da membranes were unable to reject divalent ions at high ionic strength, it is suggested to decrease the membrane pore size to achieve the separation of SO42- and Cl-. The size of pores in ceramic membranes can be narrowed down by an approach called Atomic Layer Deposition (ALD) (Shang et al., 2017). In this study, the vacuum TiO2 ALD was applied to coat thin films on the commercial ceramic NF membranes that have Molecular weight cut-off (MWCO) ranging from 600Da to 900Da. After the first coating, the water permeability of the membranes decreased dramatically while the MWCO of the membranes decreased slightly. After the second coating, an increased MWCO was observed, which might be attributed to the plugging of small pores. In addition, the flux distribution and pore size distribution were theoretically analysed to investigate the change of the membrane pores before and after ALD.
...
Natural Organic Matter (NOM) is always present in the drinking water sources such as rivers, lakes and reservoirs. It causes several problems, including the unfavourable colour and odour of water, formation of disinfectant by-products and harmful microbial growth. In drinking water treatment, anion exchange (anion-IEX) is used for NOM removal. However, the regeneration of anion-IEX produces a brine, which is a high saline waste stream containing the desorbed NOM and anions (i.e. sulphate) as well as the residual sodium chloride added during the regeneration process.
One possible approach to manage the waste brine is to recover the valuable compounds from the brine, and consequently, reduce the brine volume that has to be disposed. The separation could be done by ceramic nanofiltration (NF) membranes. However, the separation performance of ceramic NF membranes at high salinity conditions is still not fully understood. Therefore, the use of ceramic NF membranes to treat the brine-like wastes that contain NOM and high salt concentrations were investigated.
Commercial 500 Dalton(Da) ceramic NF membranes were used in the salt experiments. Several experimental conditions such as pH and ionic strength were investigated to understand their influence on the rejection of sulphate (SO42-) and chloride (Cl-). The results show that the salt rejection was governed by charge effect, and it changed depending on pH and ionic strength. When ionic strength was 0.1M, the mitigated charge effect led to a low rejection of SO42- (<20%) and Cl- (<5%) by the 500Da membranes. On the other hand, the 560Da membrane used in salt&NOM experiments exhibited more than 95% rejection of NOM but less than 25% rejection of both SO42- and Cl- when ionic strength was 1M.
Since the 500Da membranes were unable to reject divalent ions at high ionic strength, it is suggested to decrease the membrane pore size to achieve the separation of SO42- and Cl-. The size of pores in ceramic membranes can be narrowed down by an approach called Atomic Layer Deposition (ALD) (Shang et al., 2017). In this study, the vacuum TiO2 ALD was applied to coat thin films on the commercial ceramic NF membranes that have Molecular weight cut-off (MWCO) ranging from 600Da to 900Da. After the first coating, the water permeability of the membranes decreased dramatically while the MWCO of the membranes decreased slightly. After the second coating, an increased MWCO was observed, which might be attributed to the plugging of small pores. In addition, the flux distribution and pore size distribution were theoretically analysed to investigate the change of the membrane pores before and after ALD.