This document discusses advanced membrane separation processes including dialysis, electrodialysis, reverse osmosis, and pervaporation. Dialysis uses a semipermeable membrane to separate solutes like acids from contaminating ions. Electrodialysis uses an electric current to drive the separation of ions through ion-selective membranes. Reverse osmosis uses pressure to drive the separation of water from dissolved solutes like salts. Pervaporation combines membrane separation with evaporation to remove components from liquid mixtures.
wholw Content is covered in this presentation .it will give u a basic idea and types about leaching and it will also provide u information via Diagrams .
In most chemical engineering curriculums, distillation and liquid-liquid extraction (LLE) do not receive equal billing. Yet, this powerful separations technology is in place across the CPI, pharmaceutical and oil/gas industries. Discover how to design an LLE column with industry experts Don Glatz and Brendan Cross as they discuss specific examples and separations challenges.
Koch Modular Process Systems, LLC. (KMPS) Extraction Technology Group specializes in the design and supply of liquid-liquid extraction equipment engineered to fulfill the chemical, pharmaceutical, petrochemical, biotech and flavor & fragrance industries’ increasingly challenging purification requirements. Our extractor design expertise includes SCHEIBEL® Columns, KARR® Columns, rotating disc contactor (RDC) columns, pulsed, packed (SMVP) and sieve tray.
At KMPS, we don’t just sell extraction equipment; we supply solutions to your difficult separation applications.
KMPS also provides replacements parts, repair services and troubleshooting assistance for all types of extraction columns. A qualified technician or engineer can be provided on-site for both mechanical and process related support.
The presentation gives the basic information regarding the extraction in food matrix. It includes basics of extraction, principles of extraction and the theory behind the solvent extraction. It also involves terms and terminologies involved in the extraction process, Factors affecting extraction efficiency and Types of Extractors. Mixer-Settlers for extraction, Spray extraction towers, Plate towers contactors, etc.
Slides for the eLearning course Separation and purification processes in biorefineries (https://open-learn.xamk.fi) in IMPRESS project (https://www.spire2030.eu/impress).
Section: Crystallization
Subject: 1.4 Supersaturation
wholw Content is covered in this presentation .it will give u a basic idea and types about leaching and it will also provide u information via Diagrams .
In most chemical engineering curriculums, distillation and liquid-liquid extraction (LLE) do not receive equal billing. Yet, this powerful separations technology is in place across the CPI, pharmaceutical and oil/gas industries. Discover how to design an LLE column with industry experts Don Glatz and Brendan Cross as they discuss specific examples and separations challenges.
Koch Modular Process Systems, LLC. (KMPS) Extraction Technology Group specializes in the design and supply of liquid-liquid extraction equipment engineered to fulfill the chemical, pharmaceutical, petrochemical, biotech and flavor & fragrance industries’ increasingly challenging purification requirements. Our extractor design expertise includes SCHEIBEL® Columns, KARR® Columns, rotating disc contactor (RDC) columns, pulsed, packed (SMVP) and sieve tray.
At KMPS, we don’t just sell extraction equipment; we supply solutions to your difficult separation applications.
KMPS also provides replacements parts, repair services and troubleshooting assistance for all types of extraction columns. A qualified technician or engineer can be provided on-site for both mechanical and process related support.
The presentation gives the basic information regarding the extraction in food matrix. It includes basics of extraction, principles of extraction and the theory behind the solvent extraction. It also involves terms and terminologies involved in the extraction process, Factors affecting extraction efficiency and Types of Extractors. Mixer-Settlers for extraction, Spray extraction towers, Plate towers contactors, etc.
Slides for the eLearning course Separation and purification processes in biorefineries (https://open-learn.xamk.fi) in IMPRESS project (https://www.spire2030.eu/impress).
Section: Crystallization
Subject: 1.4 Supersaturation
Treatment of Effluents from Petroleum RefineriesAsheesh Padiyar
A brief power point presentation on the Effluent treatment from Petroleum Refineries for a Chemical Engineer.Chemical Engineers are also involved in the water treatment , and is of huge concern with the amount of water needed / contaminated during the refinery mass transfer operations.
Problem on Fluidization - Fluid Mechanics & Mechanical Operations (FMMO). Please refer same.
If you wish to be part of detailed understanding of concepts through an interactive sessions, please register to ATTEMPT Batch#02 Course (April to October 2021).
Write us at attempttosucceed@gmail.com or comment below so that we can revert back to you.
Super Critical Fluid Separation ProcessAbhimanyu Pal
Hello Guys here is a presentation for you named super critical fluid separation process. It may be useful for third year undergraduate of chemical engg. stream. so have a look ,i hope it may be helpful for your project
Presentaion consits of basic idea about the treatment process of the w//w, mainly come from fertilizer industris. Introduction,m types of fertilizers, layout and procees of synthesis includerelevant information about topic.On every unique as well as efficient process for effective reducton of C.O.D and NH3-N. Details of pre as well as post procees effect on every stream is giveing the importance to process importance.
Episode 65 : Membrane separation processes
Membrane separation consists of different process operating on a variety of physical
principles and applicable to a wide range of separations of miscible components
These methods yield only a more concentrated liquid stream than feed. Membrane
separation processes have several advantages. These include :
Low energy alternative to evaporation in concentrating a dilute feed, particularly when the desired material is thermally labile or when the desired component is a clear liquid
The chemical and mechanical stresses on the product are minimal and since no phase change is involve the energy requirement is modest
Product concentration and purification can be achieved in a single step and the
selectivity towards the desired product is good
The method can easily be scaled up
In bioprocess industry, membrane separation is widely used because of the mild operating conditions and low energy requirements in the recovery of lactose from whey, separation of immiscible components such extracellular products (
e.g. proteins, enzymes etc) and biomass.
Membrane separation process cannot be used for feeds containing a high concentration of low molecular weight components because of high osmotic pressure or when the feed has high solid content(>25% w/v) because of pumping problems
SAJJAD KHUDHUR ABBAS
Ceo , Founder & Head of SHacademy
Chemical Engineering , Al-Muthanna University, Iraq
Oil & Gas Safety and Health Professional – OSHACADEMY
Trainer of Trainers (TOT) - Canadian Center of Human
Development
Treatment of Effluents from Petroleum RefineriesAsheesh Padiyar
A brief power point presentation on the Effluent treatment from Petroleum Refineries for a Chemical Engineer.Chemical Engineers are also involved in the water treatment , and is of huge concern with the amount of water needed / contaminated during the refinery mass transfer operations.
Problem on Fluidization - Fluid Mechanics & Mechanical Operations (FMMO). Please refer same.
If you wish to be part of detailed understanding of concepts through an interactive sessions, please register to ATTEMPT Batch#02 Course (April to October 2021).
Write us at attempttosucceed@gmail.com or comment below so that we can revert back to you.
Super Critical Fluid Separation ProcessAbhimanyu Pal
Hello Guys here is a presentation for you named super critical fluid separation process. It may be useful for third year undergraduate of chemical engg. stream. so have a look ,i hope it may be helpful for your project
Presentaion consits of basic idea about the treatment process of the w//w, mainly come from fertilizer industris. Introduction,m types of fertilizers, layout and procees of synthesis includerelevant information about topic.On every unique as well as efficient process for effective reducton of C.O.D and NH3-N. Details of pre as well as post procees effect on every stream is giveing the importance to process importance.
Episode 65 : Membrane separation processes
Membrane separation consists of different process operating on a variety of physical
principles and applicable to a wide range of separations of miscible components
These methods yield only a more concentrated liquid stream than feed. Membrane
separation processes have several advantages. These include :
Low energy alternative to evaporation in concentrating a dilute feed, particularly when the desired material is thermally labile or when the desired component is a clear liquid
The chemical and mechanical stresses on the product are minimal and since no phase change is involve the energy requirement is modest
Product concentration and purification can be achieved in a single step and the
selectivity towards the desired product is good
The method can easily be scaled up
In bioprocess industry, membrane separation is widely used because of the mild operating conditions and low energy requirements in the recovery of lactose from whey, separation of immiscible components such extracellular products (
e.g. proteins, enzymes etc) and biomass.
Membrane separation process cannot be used for feeds containing a high concentration of low molecular weight components because of high osmotic pressure or when the feed has high solid content(>25% w/v) because of pumping problems
SAJJAD KHUDHUR ABBAS
Ceo , Founder & Head of SHacademy
Chemical Engineering , Al-Muthanna University, Iraq
Oil & Gas Safety and Health Professional – OSHACADEMY
Trainer of Trainers (TOT) - Canadian Center of Human
Development
The various stages of processing that occur after the completion of the fermentation or bioconversion stage, including separation, purification, and packaging of the product
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
Water billing management system project report.pdfKamal Acharya
Our project entitled “Water Billing Management System” aims is to generate Water bill with all the charges and penalty. Manual system that is employed is extremely laborious and quite inadequate. It only makes the process more difficult and hard.
The aim of our project is to develop a system that is meant to partially computerize the work performed in the Water Board like generating monthly Water bill, record of consuming unit of water, store record of the customer and previous unpaid record.
We used HTML/PHP as front end and MYSQL as back end for developing our project. HTML is primarily a visual design environment. We can create a android application by designing the form and that make up the user interface. Adding android application code to the form and the objects such as buttons and text boxes on them and adding any required support code in additional modular.
MySQL is free open source database that facilitates the effective management of the databases by connecting them to the software. It is a stable ,reliable and the powerful solution with the advanced features and advantages which are as follows: Data Security.MySQL is free open source database that facilitates the effective management of the databases by connecting them to the software.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
An Approach to Detecting Writing Styles Based on Clustering Techniquesambekarshweta25
An Approach to Detecting Writing Styles Based on Clustering Techniques
Authors:
-Devkinandan Jagtap
-Shweta Ambekar
-Harshit Singh
-Nakul Sharma (Assistant Professor)
Institution:
VIIT Pune, India
Abstract:
This paper proposes a system to differentiate between human-generated and AI-generated texts using stylometric analysis. The system analyzes text files and classifies writing styles by employing various clustering algorithms, such as k-means, k-means++, hierarchical, and DBSCAN. The effectiveness of these algorithms is measured using silhouette scores. The system successfully identifies distinct writing styles within documents, demonstrating its potential for plagiarism detection.
Introduction:
Stylometry, the study of linguistic and structural features in texts, is used for tasks like plagiarism detection, genre separation, and author verification. This paper leverages stylometric analysis to identify different writing styles and improve plagiarism detection methods.
Methodology:
The system includes data collection, preprocessing, feature extraction, dimensional reduction, machine learning models for clustering, and performance comparison using silhouette scores. Feature extraction focuses on lexical features, vocabulary richness, and readability scores. The study uses a small dataset of texts from various authors and employs algorithms like k-means, k-means++, hierarchical clustering, and DBSCAN for clustering.
Results:
Experiments show that the system effectively identifies writing styles, with silhouette scores indicating reasonable to strong clustering when k=2. As the number of clusters increases, the silhouette scores decrease, indicating a drop in accuracy. K-means and k-means++ perform similarly, while hierarchical clustering is less optimized.
Conclusion and Future Work:
The system works well for distinguishing writing styles with two clusters but becomes less accurate as the number of clusters increases. Future research could focus on adding more parameters and optimizing the methodology to improve accuracy with higher cluster values. This system can enhance existing plagiarism detection tools, especially in academic settings.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Online aptitude test management system project report.pdfKamal Acharya
The purpose of on-line aptitude test system is to take online test in an efficient manner and no time wasting for checking the paper. The main objective of on-line aptitude test system is to efficiently evaluate the candidate thoroughly through a fully automated system that not only saves lot of time but also gives fast results. For students they give papers according to their convenience and time and there is no need of using extra thing like paper, pen etc. This can be used in educational institutions as well as in corporate world. Can be used anywhere any time as it is a web based application (user Location doesn’t matter). No restriction that examiner has to be present when the candidate takes the test.
Every time when lecturers/professors need to conduct examinations they have to sit down think about the questions and then create a whole new set of questions for each and every exam. In some cases the professor may want to give an open book online exam that is the student can take the exam any time anywhere, but the student might have to answer the questions in a limited time period. The professor may want to change the sequence of questions for every student. The problem that a student has is whenever a date for the exam is declared the student has to take it and there is no way he can take it at some other time. This project will create an interface for the examiner to create and store questions in a repository. It will also create an interface for the student to take examinations at his convenience and the questions and/or exams may be timed. Thereby creating an application which can be used by examiners and examinee’s simultaneously.
Examination System is very useful for Teachers/Professors. As in the teaching profession, you are responsible for writing question papers. In the conventional method, you write the question paper on paper, keep question papers separate from answers and all this information you have to keep in a locker to avoid unauthorized access. Using the Examination System you can create a question paper and everything will be written to a single exam file in encrypted format. You can set the General and Administrator password to avoid unauthorized access to your question paper. Every time you start the examination, the program shuffles all the questions and selects them randomly from the database, which reduces the chances of memorizing the questions.
4. Introduction
• In a dialysis membrane-separation process, the feed is a liquid,
at pressure P1, containing solvent, solutes of type A, and solutes
of type B and/or insoluble, but dispersed, colloidal matter.
• A sweep liquid or wash of the same solvent is fed at pressure P2
to the other side of the membrane.
• The membrane is thin with micropores of a size such that solutes
of type A can pass through by a concentration driving force.
• Solutes of type B are larger in molecular size than those of type
A and pass through the membrane only with difficulty or not at
all.
5. Introduction
• Colloids do not pass through the membrane.
• With pressure P1 = P2, the solvent may also pass through
the membrane, but by a concentration-driving force
acting in the opposite direction.
• The transport of the solvent is called osmosis.
• By elevating P1 above P2, solvent osmosis can be
reduced or eliminated if the difference is higher than the
osmotic pressure.
6. Contd…
• The products of a dialysis unit (dialyzer) are a liquid
diffusate (permeate) containing solvent, solutes of
type A, and little or none of type B solutes; and a
dialysate (retentate) of solvent, type B solutes,
remaining type A solutes, and colloidal matter.
• Ideally, the dialysis unit would enable a perfect
separation between solutes of type A and solutes of
type B and any colloidal matter
7.
8. Example
• When dialysis is used to recover sulfuric acid (type A
solute) from an aqueous stream containing sulfate salts
(type B solutes), the following results are obtained
• Thus, about 64% of the H2SO4 is recovered in the
diffusate, accompanied by only 6% of the CuSO4, and no
NiSO4.
9. Applications
• Recovery of chromic, hydrochloric, and hydrofluoric acids from
contaminating metal ions.
• Removal of alcohol from beer to produce a low-alcohol beer.
• Recovery of nitric and hydrofluoric acids from spent stainless steel pickle
liquor.
• Removal of mineral acids from organic compounds.
• Removal of low-molecular-weight contaminants from polymers.
• Hemodialysis, in which urea, creatine, uric acid, phosphates, and chlorides
are removed from blood without removing essential higher-molecular
weight compounds and blood cells in a device called an artificial kidney
10. Membrane Types & Modules
• Typical microporous-membrane materials used in dialysis are
hydrophilic, including cellulose, cellulose acetate, various acid-
resistant polyvinyl copolymers, polysulfones, and
polymethylmethacrylate.
• Typically less than 50 mm thick and with pore diameters of 15
to 100 Ȧ
• The most common membrane modules are plate-and-frame
and hollow-fiber.
• Dialysis membranes can be thin because pressures on either
side of the membrane are essentially equal.
11. Contd…
• A common dialyzer is the plate-and-frame type. For
dialysis, the frames are vertical and a unit might
contain 100 square frames, each 0.75 m 0.75 m on
0.6-cm spacing, equivalent to 56 m2 of membrane
surface.
• Recent dialysis units utilize hollow fibers of 200-mm
inside diameter, 16-mm wall thickness, and 28-cm
length, packed into a heat exchanger- like module to
give 22.5 m2 of membrane area.
12. Contd…
• In a plate-and-frame dialyzer, the flow pattern is nearly
countercurrent.
• Because total flow rates change little and solute
concentrations are small, it is common to estimate solute
transport rate by assuming a constant overall mass-
transfer coefficient with a log-mean concentration-
driving force
13. Rate Equation
• The differential rate of solute mass transfer across
the membrane is
• where Ki is the overall mass-transfer coefficient, in terms of
the three coefficients
• where kiF and kiP are mass-transfer coefficients for the feed-
side and permeate-side boundary layers (or films)
14. Contd…
• If a solute does not interact with the membrane material,
effective diffusivity De , is the ordinary molecular-diffusion
coefficient, which depends only on solute and solvent
properties.
• In practice, the membrane may have a profound effect on
solute diffusivity if membrane–solute interactions such as
covalent, ionic, and hydrogen bonding; physical adsorption
and chemisorption; and increases in membrane polymer
flexibility occur.
• Thus, it is best to measure PMi experimentally using process
fluids.
15. • Transport of solvents such as water, usually in a direction
opposite to the solute, can be described in terms of Fick’s law
• It is common to measure the solvent flux and report a so-
called water-transport number, which is the ratio of the
water flux to the solute flux, with a negative value indicating
transport of solvent in the solute direction
• Design parameters for dialyzers are best measured in the
laboratory using a batch cell with a variable-speed stirring
mechanism on both sides of the membrane so that external
mass-transfer resistances, 1/kiF and 1/kiP are made negligible
16. Electrodialysis
• Electrodialysis is an electrically driven membrane
separation process.
• Electrodialysis refers to an electrolytic process for
separating an aqueous, electrolyte feed into
concentrate and dilute or desalted water by an
electric field and ion-selective membranes.
17. • In Electrodialysis, cation exchange membranes are
alternated with anion exchange membranes in a
parallel array to form solution compartments of
thickness ∼1 mm.
• The cation-selective membranes (C) carry a negative
charge, and thus attract and pass positively charged
ions (cations), while retarding negative ions (anions).
• The anion-selective membranes (A) carry a positive
charge that attracts and permits passage of anions.
Both types of membranes are impervious to water.
18. • The net result is that both anions and cations are concentrated in
compartments 1, 3 and 5, from which concentrate is withdrawn,
and ions are depleted in compartments 2 and 4, from which the
demineralized solution is withdrawn.
19. • A direct-current voltage causes current to flow through the
cell by ionic conduction from the cathode to the anode.
• A cell pair or unit cell contains one cation-selective
membrane and one anion-selective membrane.
• A commercial electrodialysis system consists of a large
stack of membranes in a plate-and-frame configuration,
contains 100 to 600 cell pairs.
• In a stack, membranes of 0.4 to 1.5 m2 surface area are
separated by 0.5 to 2 mm with spacer gaskets
20. • The total voltage or electrical potential applied
across the cell includes
1. The electrode potentials
2. Over voltages due to gas formation at the two electrodes
3. The voltage required to overcome the ohmic resistance of
the electrolyte in each compartment
4. The voltage required to overcome the resistance in each
membrane,
5. The voltage required to overcome concentration polarization
effects in the electrolyte solutions adjacent to the
membrane surface.
21. Applications
• Production of drinking water by the desalination of sea-water or
brackish water.
• Production of sodium chloride for table salt
• Recovery of nickel and copper from electroplating rinse water
• deionization of cheese whey, fruit juices, wine, milk, and sugar
molasses
• Separation of salts, acids, and bases from organic compounds
• Recovery of organic compounds from their salts
23. Introduction
• When miscible solutions of different concentration are
separated by a membrane that is permeable to the
solvent but nearly impermeable to the solute, diffusion
of the solvent occurs from less concentrated to the more
concentrated solution, where solvent activity is lower.
• The diffusion of solvent is called Osmosis.
• Osmotic transfer of water occurs in many plant and
animal cells
24.
25. Introduction
• The transfer of solvent can be stopped by increasing the
pressure of the concentrated solution until the activity of
solvent is same on both sides of the membrane.
• If pure solvent is on one side of the membrane, the
pressure required to equalize solvent activities is the
osmotic pressure of the solution.
• If pressure higher than the osmotic pressure is applied,
solvent will diffuse from concentrated solution to dilute
solution. This Phenomenon is called Reverse Osmosis
27. Basic Terminology
• Feed water: Supply water that is fed into the RO system to be
treated
• Permeate: A portion of the feed water that passes through a series
of membranes and is returned as purified water.
• Concentrate: A portion of the feed water that is rejected by the
membrane and contains the solution of impurities that have been
filtered out of the permeate.
• Water flux: The rate of permeate production typically expressed as
the rate of water flow per unit area of membrane (e.g., gallons per
square foot per day)
• Recovery rate: The ratio of permeate flow to feed water flow, which
indicates the overall water efficiency of the system
29. RO Membrane Properties
• More than 50% of RO modules use cellulose acetate
membrane.
• It has high permeability for water and low permeability for
dissolved salts.
• Its limitation are:
I. Smaller allowable pH range of 4.5-7.5 (beyond this range, cellulose
acetate becomes prone to hydrolysis)
II. Susceptibility to biological attack (degradation due to growth of
microbes)
III. Reduction of solvent flux because of compaction or mechanical
compression of membrane at high pressure difference
30. RO Membrane Properties
• Another common membrane materials in RO systems
are thin film composite (TFC) membranes.
• TFC membranes are not chlorine-tolerant but can
tolerate harsh chemical environments and wide ranges in
water temperature and pH, and are less vulnerable to
compaction than CA membranes.
• TFC membranes generally have higher water flux than CA
membranes because the layers are extremely thin, which
creates more water transport through the membrane
material.
31. Applications
• Potable water from sea or brackish water
• Ultra pure water for food processing and
electronic industries
• Pharmaceutical grade water
• Water for chemical, pulp & paper industry
• Wastewater treatment
• Municipal and industrial waste treatment
32. Mechanism
• The mechanism of water and salt transport in
reverse osmosis is not completely understood.
• One theory is that water and solutes diffuse
separately through the polymer by a solution-
diffusion mechanism.
• In this mechanism concentration of water in dense
polymer is assumed to be proportional to the activity
of water in the solution
33. Mechanism
• On the low-pressure side of the dense layer, activity is
essentially unity if nearly pure water is produced at 1 atm.
• On the high-pressure side, activity would be
slightly less than 1.0 at atmospheric pressure
1.0 at atmospheric pressure
slightly greater than 1.0 at higher pressures
• The upstream pressure is generally set at 20 to 50 atm above
the osmotic pressure of the feed solution.
• At these pressures, activity of water “aW“ is only a few percent
greater than for pure water at 1 atm and change in activity
and concentration across the membrane are small
34. • The Driving force for water transport is the difference
in activity, which is proportional to pressure
difference in osmotic pressures of feed and product.
• The equation for water flux is
Dw is the diffusivity in the membrane
Cw is the average water concentration (g/cm3)
Vw is the partial molar volume of water (cm3/gmol)
35. • The flux of solute is assumed proportional to the
difference in solution concentration, the diffusivity
and a solubility or distribution coefficient.
36. Concentration Polarization
• Nearly complete rejection of solute by the membrane
leads to a higher concentration at the membrane surface
than in bulk solution and this effect is called
Concentration polarization.
• Concentration polarization reduces the flux of water
because the increase in osmotic pressure reduces the
driving force for water transport.
• The solute rejection decreases both because of the lower
water flux and the greater salt concentration at the
surface increases the flux of solute
37. Concentration Polarization
• Equations for concentration polarization have been derived for simple
cases such as laminar flow of feed solution inside hollow fibres.
• Consider a membrane with a water flux Jw when the bulk solute
concentration is cs and f is the fraction of solute rejected.
Diffusion of solute away from membrane surface is characterized by mass
transfer Coefficient kc and driving force csi – cs .
At steady state, diffusional flux equals the amount of solute rejected per
unit area
Jw cs f = kc (csi – cs)
• Polarization factor is defined as
Г =
Jw f
kc
=
(csi – cs)
cs
38. Factors that impact on RO performance
Basic effects of:
• Temperature
• Pressure
• Recovery rate
39. Temperature Effects
• RO permeate flow is strongly dependent on the
temperature of the feed water.
• The higher the temperature the higher the permeate
flow rate.
• Why? Lower viscosity makes it easier for the water to
permeate through the membrane barrier
• RULE OF THUMB – for every 1˚C the permeate flow
will increase ~ 3%
40. Temperature Variation on Salt flux
• Solute rejection declines with a temperature rise because
of the osmotic pressure increase with temperature.
• Increasing temperature increases salt passage more than
water passage
• Generally you will get better rejections at lower
temperatures
• RULE OF THUMB – salt flux increases 6% for 1˚C increase
41. Pressure Effects
• Water passage increases with pressure. Solute
rejection rises with pressure, since solvent flux
increases and solute diffusion does not.
• Higher flow of water through the membrane will tend
to promote more rapid fouling, the single greatest
cause of membrane failure.
• Membrane element manufacturers usually provide
limits with regard to the maximum applied pressure to
be used, as a function of feed water quality.
42. Recovery rate Effects
• As recovery is increased, concentration of solute in the
concentrate stream increases, resulting in increased
osmotic pressure which must be overcome.
• Membrane flux declines with increasing solute
concentration at high recovery rate.
• Large systems typically have recovery rates between
40% and 60%. In other words, for every 10 gallons of
feed water entering the system, 4 to 6 gallons of
purified permeate water are produced
45. Introduction
• Pervaporation is a separation process in which one or
more components of a liquid mixture diffuse through
a selective membrane, evaporate under low pressure
on downstream side and are removed by a vacuum
pump or a chilled condenser.
• The process differs from other membrane processes
in that there is a phase change from liquid to vapor
in the permeate.
46.
47. Introduction
• The driving force in the membrane is achieved by
lowering the activity of the permeating components at
the permeate side.
• Components in the mixture permeate through the
membrane and evaporate as a result of the partial
pressure on the permeate side being held lower than the
saturation vapor pressures.
• The driving force is controlled by applying a vacuum on
the permeate side
49. • Composite membranes are used with dense layer in
contact with the liquid and the porous supporting layer
exposed to the vapor.
• Pervaporation is favored when the feed solution is dilute
in the main permeant because sensible heat of the feed
mixture provides the permeant enthalpy of vaporization
• The phase change occurs in the membrane and the heat
of vaporization is supplied by the sensible heat of the
liquid conducted through the thin dense layer.
50. • The decrease in temperature of the liquid as it
passes through the separator lowers the rate of
permeation and this usually limits the application
of pervaporation to removal of small amounts of
feed.
• Commercial units generally use flat-sheet
membranes stacked in filter press arrangement.
Spiral-wound membranes could also be used.
51. Applications
• Dehydration of ethanol or the production of high purity
ethanol by a hybrid process which also incorporates
distillation.
• Such separations use cellulose-acetate-based composite-
membranes, with an active layer of polyvinyl alcohol.
• Membranes used for ethanol purification are also suitable for
dehydration of many other organic solvents including
methanol, isopropanol, butanol, MEK, acetone and
chlorinated solvents.
52. Applications
• Removal of volatile organic contaminants from water
using silicone rubber or organophilic polymers for the
membrane.
• The separation of close-boiling organic mixtures like
benzene–cyclohexane is receiving much attention.
• Separating benzene from cyclohexane consisting of a
cellulose acetate support matrix and incorporating
polyphosphonates to improve the preferential
permeability of benzene.
58. Mechanism
• The flux of each component is proportional to the concentration
gradient and the diffusivity in the dense layer.
• However, the concentration gradient is often non-linear because
the membrane swells appreciably as it absorbs liquid.
• Diffusion coefficient in the fully swollen polymer may be 10 to 100
times the value in unswollen polymer.
• When the polymer is swollen mainly by absorption of one
component, the diffusivity of other components is increased also.
• This interaction makes it difficult to develop correlations for
membrane permeability and selectivity.
59. Mechanism
• Models for transport of permeant through a membrane by
pervaporation have been proposed, based on solution-
diffusion.
• They assume equilibrium between the upstream liquid and
the upstream membrane surface & between the
downstream vapor and its membrane side.
• Membrane transport follows Fick’s law, with a permeant
concentration gradient as the driving force.
• However, because of phase change and non ideal-solution
feed, simple equations do not apply.
Editor's Notes
The liquid feed, which is DCE saturated with water (0.2 wt%), is preheated to 90C at 0.7 atm and sent to a PVA membrane system, which produces a retentate of almost pure DCE (<10 ppm H2O) and a permeate vapor of 50 wt% DCE. Following condensation, the two resulting liquid phases are separated, with the DCE-rich phase recycled and the water-rich phase sent to an air stripper, steam stripper, adsorption unit, or hydrophobic, pervaporation membrane system for residual DCE removal.
For removal of VOCs (e.g., toluene and trichloroethylene) from wastewater, pervaporation with hollow-fiber modules of silicone rubber can be used, as shown in Figure 14.23c. The retentate is almost pure water (<5 ppb of VOCs) and the permeate, after condensation, is (1) a water-rich phase that is recycled to the membrane system and (2) a nearly pure VOC phase.