Nanofiltration - 1st Edition - ISBN: , Nanofiltration: Principles and Applications ' is edited by three well-known specialists from. Fill Nanofiltration Principles And Applications Pdf, download blank or editable online. Sign, fax and printable from PC, iPad, tablet or mobile with PDFfiller. Nanofiltration and reverse osmosis. Page 2. 1. Introduction. 2. Theory. 3. Membrane modules. 4. Applications. 5. Principle slow sand filtration.
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PDF | According to Koros et al.  fouling is “the process resulting in loss of performance of a membrane due to deposition of suspended or. PDF | A I Schäfer and others published Nanofiltration: Principles and Applications / Ed. de A.I. Schäfer, A.G. Fane, T.D. Waite ; pról. de Robert J. Petersen. Request PDF on ResearchGate | On Jan 1, , A.I. Schäfer and others published Nanofiltration: Principles and Applications.
Continuous recovery of homogeneous catalysts Natural Essential Oils and similar products Fractionation of crude extracts Enrichment of natural compounds Gentle Separations Medicine Able to extract amino acids and lipids from blood and other cell culture. Advantages and disadvantages[ edit ] One of the main advantages of nanofiltration as a method of softening water is that during the process of retaining calcium and magnesium ions while passing smaller hydrated monovalent ions, filtration is performed without adding extra sodium ions, as used in ion exchangers. Performing gentle molecular separation is linked with nanofiltration that is often not included with other forms of separation processes centrifugation. These are two of the main benefits that are associated with nanofiltration. Nanofiltration has a very favorable benefit of being able to process large volumes and continuously produce streams of products.
Continuous recovery of homogeneous catalysts Natural Essential Oils and similar products Fractionation of crude extracts Enrichment of natural compounds Gentle Separations Medicine Able to extract amino acids and lipids from blood and other cell culture. Advantages and disadvantages[ edit ] One of the main advantages of nanofiltration as a method of softening water is that during the process of retaining calcium and magnesium ions while passing smaller hydrated monovalent ions, filtration is performed without adding extra sodium ions, as used in ion exchangers.
Performing gentle molecular separation is linked with nanofiltration that is often not included with other forms of separation processes centrifugation. These are two of the main benefits that are associated with nanofiltration.
Nanofiltration has a very favorable benefit of being able to process large volumes and continuously produce streams of products. Still, Nanofiltration is the least used method of membrane filtration in industry as the membrane pores sizes are limited to only a few nanometers. Anything smaller, reverse osmosis is used and anything larger is used for ultrafiltration.
Ultrafiltration can also be used in cases where nanofiltration can be used, due to it being more conventional. A main disadvantage associated with nanotechnology, as with all membrane filter technology, is the cost and maintenance of the membranes used.
Repairs and replacement of membranes is dependent on total dissolved solids, flow rate and components of the feed. With nanofiltration being used across various industries, only an estimation of replacement frequency can be used. This causes nanofilters to be replaced a short time before or after their prime usage is complete.
Design and operation[ edit ] Industrial applications of membranes require hundreds to thousands of square meters of membranes and therefore an efficient way to reduce the footprint by packing them is required. Membranes first became commercially viable when low cost methods of housing in 'modules' were achieved.
They need to be stayed by a porous support that can withstand the pressures required to operate the NF membrane without hindering the performance of the membrane. To do this effectively, the module needs to provide a channel to remove the membrane permeation and provide appropriate flow condition that reduces the phenomena of concentration polarisation.
A good design minimises pressure losses on both the feed side and permeate side and thus energy requirements. Leakage of the feed into the permeate stream must also be prevented. This can be done through either the use of permanent seals such as glue or replaceable seals such as O-rings.
It occurs because the particles are convected towards the membrane with the solvent and its magnitude is the balance between this convection caused by solvent flux and the particle transport away from the membrane due to the concentration gradient predominantly caused by diffusion. Although concentration polarisation is easily reversible, it can lead to fouling of the membrane.
The module uses flat sheets wrapped around a central tube. The membranes are glued along three edges over a permeate spacer to form 'leaves'.
The permeate spacer supports the membrane and conducts the permeate to the central permeate tube. Between each leaf, a mesh like feed spacer is inserted.
Once the leaves have been wound around the central tube, the module is wrapped in a casing layer and caps placed on the end of the cylinder to prevent 'telescoping' that can occur in high flow rate and pressure conditions.
Tubular module[ edit ] Tubular modules look similar to shell and tube heat exchangers with bundles of tubes with the active surface of the membrane on the inside. Flow through the tubes is normally turbulent , ensuring low concentration polarisation but also increasing energy costs. The tubes can either be self-supporting or supported by insertion into perforated metal tubes.
This module design is limited for nanofiltration by the pressure they can withstand before bursting, limiting the maximum flux possible. The membranes can be easily cleaned through a ' pigging ' technique with foam balls are squeezed through the tubes, scouring the caked deposits. There is a range of techniques available however the most common is feed channel spacers as described in spiral wound modules. All of the strategies work by increasing eddies and generating a high shear in the flow near the membrane surface.
Some of these strategies include vibrating the membrane, rotating the membrane, having a rotor disk above the membrane, pulsing the feed flow rate and introducing gas bubbling close to the surface of the membrane.
Two important parameters should be investigated during preliminary calculations, performance and morphology parameters. In order to maintain electroneutrality, the anions, sulphate and chloride, were also more rejected at pH 2. These results are in accordance with the Feed pH Tests conducted with the same membranes and similar feeds.
The higher transmission of Na through NF also explains the low and negative rejections of Cl in order to maintain electroneutrality. The analytical error associated with the measurement of ion concentrations in the feed and permeate samples was propagated to the calculation of ion rejection and transmission through the membranes.
The precision associated with rejection data varied between 0.
The analytical error was therefore well below the difference in ion rejections at the two pH values Table 4 , confirming the difference in pH as being the main explanation of the observed changes in ion rejections.
To the best of our knowledge, few studies have tested TS 80 on mine waters. The authors reported a feed pH close to neutral and stated that TS 80 was negatively charged, i.
A comparison between the results of MacNaughton et al. A general consideration for all ions in solution is that lower rejections were achieved when the feed pH was higher than the membrane IEP. Discharge criteria for mine waters are site-specific, and the industry must comply with increasingly stringent environmental targets.
The application of NF as an end-of-pipe membrane treatment process to meet discharge criteria is quite well established in the literature [ 11 , 31 ].
General discharge criteria for water, as suggested by Rieger et al. Lower metal ion concentrations were observed in the composite permeate at pH 2. Sulphate concentrations in the composite permeate exceeded the guideline limit at both pH values for NF and at pH 4.
In order to meet discharge criteria for all ions, a two-pass system, where the permeate from the first pass is re-filtered through a membrane, might be necessary. The concentration of ions in the permeate after a second pass was estimated assuming ion rejections remained constant for the second pass Table 4.
With a two-pass system, discharge criteria were met for sulphate at both pH values and by both membranes. However, the general discharge criteria for copper and manganese were met for TS 80 at pH 2. These results demonstrate that two factors need to be considered when treating mine influenced water by nanofiltration to meet discharge criteria. First, a membrane with appropriate ion rejection selectivity needs to be chosen; it was demonstrated that TS 80 offers higher rejections overall compared to NF and would, therefore, be a more appropriate membrane when the ultimate treatment requirement is to meet environmental guidelines.
Second, once the fit for purpose membrane is chosen, understanding the interaction between the membrane IEP and mine water pH is also important to meet discharge criteria. The guiding factor in designing a treatment for MIW is the nature of the stream to be treated, particularly the pH, the identity of the metals contained in the stream and their particular discharge criteria.
It has been demonstrated that NF is a viable technology in mining processes for acid and metal recovery applications [ 29 , 32 , 33 ]. NF has also been applied to the treatment of MIW [ 6 , 9 , 11 ]; however, to the best of our knowledge, few studies focused on the use of NF with the final purpose of recovering commodity metals from mine influenced water streams.
A difference of about 1. This loss could be significant in offsetting capital and operating costs and demonstrates the importance of understanding the interactions between membrane and solution chemistry. The performance of two nanofiltration membranes treating mine influenced water streams was investigated in this study. Particular attention was given to the relationship between feed pH, membrane surface charge and the iso-electric point and how such a relationship impacted on ion rejections.
The results were presented and discussed with the perspective of nanofiltration technology as both an end-of-pipe treatment of mine influenced water, i.
Ion rejection was significantly impacted by membrane charge. Nanofiltration was shown to be successful in achieving metal recovery objectives and meeting discharge criteria; however, understanding the relationship between membrane performance and solution characteristics is essential for an optimal implementation of NF on mine influenced water.
Current research is focused on further validation of the results of this study. Additional tests are being performed with different mine water feeds and nanofiltration membranes, and a detailed cost benefit analysis is planned at the end of the test campaign, which will better quantify the lifecycle cost differences between RO and NF for a specific feed.
The authors are grateful to Hatch Technologies and Peter Snowsill, Director, Process Separations, for funding and support during this series of studies. All three authors significantly contributed to the paper. Mark Mullett developed the hypothesis, designed the test campaign, provided resources and management support for the study, contributed significantly to the test work and reviewed the whole paper.
Roberta Fornarelli contributed to the design of the test campaign, performed the vast majority of the test campaign and wrote the entire paper, including the literature review and the discussion of the results in the context of the existing literature. David Ralph provided funding for the analytical work, consulted on the design of the individual tests throughout the campaign and thoroughly reviewed the paper prior to submission.
National Center for Biotechnology Information , U. Journal List Membranes Basel v. Membranes Basel.
Published online Mar Mark Mullett 1 Hatch Ltd. Roberta Fornarelli 1 Hatch Ltd. D Find articles by David Ralph. Author information Article notes Copyright and License information Disclaimer. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license http: This article has been cited by other articles in PMC.
Abstract Two nanofiltration membranes, a Dow NF polyamide thin film and a TriSep TS 80 polyamide thin film, were investigated for their retention of ionic species when filtering mine influenced water streams at a range of acidic pH values. Introduction The management of water in mining operations is becoming increasingly scrutinized, with water reuse, water treatment and discharge being major issues faced by the industry [ 1 ].
Table 1 Iso-electric point IEP of different commercial nanofiltration NF membranes as measured in the existing literature. Open in a separate window. Experimental Section 2.
Table 2 Composition of mine water MW samples. Methods Three sets of tests were conducted on four mine water samples and on two NF membranes. Table 3 Details of experimental tests conducted on four mine influenced water samples and two nanofiltration membranes. Feed pH Tests A second set of tests, referred to as the Feed pH Tests Table 3 , were carried out to determine the impact of feed pH and membrane charge on ion rejection when filtering mine water through two different NF membranes.
Experimental Set-Up The schematic diagram of the cross-flow flat sheet membrane test unit is shown in Figure 1 a membrane surface area of 0. Figure 1. Results and Discussion 3. Figure 2. Figure 3. Figure 4. Table 4 The results of the Recovery Tests. Nanofiltration of MIW for Environmental Discharge Discharge criteria for mine waters are site-specific, and the industry must comply with increasingly stringent environmental targets.
Nanofiltration of MIW for Metal Recovery It has been demonstrated that NF is a viable technology in mining processes for acid and metal recovery applications [ 29 , 32 , 33 ]. Figure 5. Conclusions The performance of two nanofiltration membranes treating mine influenced water streams was investigated in this study.
Acknowledgments The authors are grateful to Hatch Technologies and Peter Snowsill, Director, Process Separations, for funding and support during this series of studies. Conflicts of Interest The authors declare no conflict of interest. Author Contributions All three authors significantly contributed to the paper. References 1.
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