A presentation on l.jpg
This presentation is the property of its rightful owner.
Sponsored Links
1 / 56

A Presentation on PowerPoint PPT Presentation


  • 51 Views
  • Uploaded on
  • Presentation posted in: General

A Presentation on. Dr.S. Kanmani Phone:044 – 22359027 Professor in Civil Engineering [email protected] Centre for Environmental Studies Anna University Chennai, Chennai – 600 025. Reverse Osmosis. TDS. TDS Ranges. TDS Concentrations. History of Membrane Treatment.

Download Presentation

A Presentation on

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


A presentation on l.jpg

A Presentation on

Dr.S. KanmaniPhone:044 – 22359027

Professor in Civil Engineering [email protected]

Centre for Environmental Studies

Anna University Chennai, Chennai – 600 025


Slide3 l.jpg

Reverse Osmosis


Slide4 l.jpg

TDS


Slide5 l.jpg

TDS Ranges


Slide6 l.jpg

TDS Concentrations


Slide7 l.jpg

History of Membrane Treatment

  • 1748, Osmosis

  • 1948, Reverse Osmosis (RO)

  • Membrane classification MF, UF, NF & RO.


Ro removes l.jpg

RO Removes

Ionic

Non ionic

Particulate

Microbiological


Slide9 l.jpg

Osmosis

Reverse Osmosis


Osmosis its reverse l.jpg

OSMOSIS & its REVERSE

Po= P

--

Po<P

--

--

Po>P

--


Reverse osmosis l.jpg

Reverse Osmosis

Water Flow

Product

Feed

Concentrate

Ions


Types of membranes l.jpg

TYPES OF MEMBRANES

  • Cellulose acetate

  • Polyamide hydrocarbon (PAH)

  • Sulfonated polysulfone (SPS)

    • Hollow fibre

    • Spiral bound

    • Tubular

  • RO membranes degraded by chlorine.

  • SPS membranes are resistant to Cl2 attack.

  • Chlorine-resistant membranes would eliminate the

  • need for de-chlorination of the RO feed and re-

  • chlorination of permeate.

  • Reducing the overall cost of RO.


  • Membranes l.jpg

    MEMBRANES

    They are made of different materials

    - Cellulose acetate/triacetate

    - Cellulose acetate blends

    - Poly amides

    - Ceramics etc

    They are in different forms

    - Hollow fibre

    - Thin film composite spiral wound

    They have different characteristics -capabilities to remove impurities and operating pressures


    Slide14 l.jpg

    Hollow fibre Configuration


    Slide15 l.jpg

    Hollow-fiber membranes


    Ro element l.jpg

    RO ELEMENT


    Ro element18 l.jpg

    RO ELEMENT


    Ro element19 l.jpg

    RO ELEMENT


    Ro membrane sizes l.jpg

    RO Membrane Sizes

    Recent Advancement:Extra large RO Membranes: 18 in dia x 60 in long


    Reverse osmosis what it cannot do l.jpg

    Reverse Osmosis:What It Cannot Do

    Cannot concentrate to 100%

    Cannot separate to 100%

    Not always the most cost effective method


    Typical operating pressures pressure driven membrane processes l.jpg

    Typical Operating PressuresPressure Driven Membrane Processes

    1 bar = 1 atm = 100 kPa = 100 kN/m2 = 1 kg/m.s2 = 10 m H2O = 760 mm Hg=14.5 psi


    Rule of thumb l.jpg

    Rule of Thumb

    100 mg/L TDS » 1 psi (0.07 atm) osmotic pressure

    1,000 mg/L TDS » 10 psi (0.7 atm) osmotic pressure

    35,000 mg/L TDS » 350 psi (25 atm)osmotic pressure


    Single module ro l.jpg

    SINGLE MODULE RO

    Module : Pressure vessel containing 1 -10 RO elements


    Modules in single array l.jpg

    MODULES IN SINGLE ARRAY

    M-1

    Pre-

    Treatment

    M-2

    Permeate

    P

    M-3

    Reject


    Modules in multiple array l.jpg

    MODULES IN MULTIPLE ARRAY

    M-1

    Permeate

    Pre-

    Treatment

    M-3

    P

    M-2

    Reject


    Modules in multiple stage l.jpg

    MODULES IN MULTIPLE STAGE

    M-1

    Permeate

    Pre-

    Treatment

    M-2

    P

    Reject


    Slide28 l.jpg

    Membrane Operational

    Terminology

    • Influent/Feed Water

    • Effluent/Permeate

    • Concentrate/Retentate/Reject

    • Flux – Volume of water that passes through a membrane per unit of time & per unit of surface area of the membrane (L/h/m2)

    • Recovery-%of feed that is converted to permeate

    • Contaminant removal – % of a contaminant removed from the feed stream.


    Slide29 l.jpg

    Membrane Operational

    Terminology (Contd.)

    • 7.Size exclusion – Removal of PM by sieving

    • 8. Molecular Weight Cutoff (MWCO), measured in Daltons – A Dalton is a non-SI unit of mass equal to 1/2th of mass of a carbon – 12 atom.

    • Membrane Fouling : Reduction of flux through a membrane caused by the build-up of contaminants (Macro (i.e surface) & Micro (pore) fouling, Reversible/Irreversible Fouling).

    • Transmembrane Pressure – (Average feed pr. - Permeate pr.)


    Slide30 l.jpg

    Membrane Classifications


    Slide31 l.jpg

    Terminology

    • Membrane Module : A complete unit consisting of membranes, support frame & ports (feed inlet, reject, outlet permeate)

    • Array/Train : Assembly of catridges in pressurised systems

    • Catridge: A manufactured canister of membranes with feed, permeate & reject connections.

    • Module: A collection of membranes intended to be mounted & replaced as a unit.


    Slide32 l.jpg

    Membrane Materials & Configurations

    • Physical structure of membrane – Microporous or Asymmetric

    • Pore size – uniform (isotropic), Varied (anisotropic)

    • Membrane materials – Organic (cellulose- based) & Inorganic (metals/ceramics)

    • Types of membranes – Flat sheet, Hollow fibres, Tubes, spiral-wound cylinders & Rotating flat plates


    Slide33 l.jpg

    NF & RO for Advanced Treatment

    • Fouling potential may be estimated based on SDI (<5), turbidity (<NTU).

    • Pretreatments steps for RO include

      • MF/UF

      • SMBS addition

      • Chloramination

      • H2SO4addition

      • Scale inhibitor chemical addition

      • Catridge filtration.


    Slide34 l.jpg

    Design Criteria


    Slide35 l.jpg

    RO Feed Water Quality


    Pre treatment l.jpg

    PRE-TREATMENT

    Pretreatment; TDS < 10,000

    No microorganisms

    No oil

    Turbidity < 1 NTU

    Particle size < 25 micron

    pH = 4.5 prevents scale formation


    Pre treatment37 l.jpg

    PRE-TREATMENT

    • Screening of solids: prevent fouling of the membranes by fine particle or biological growth, and damage to pump.

    • Cartridge filtration : polypropylene filters to remove 1 - 5 µm particles.

    • Biocidal Treatment: biocides such as chlorine to kill bacteria.

    • De-chlorination: bisulfite dosing to remove the chlorine which can oxidize membrane.


    Factors which affect performance of membranes l.jpg

    Factors Which Affect Performance of Membranes

    Feedwater Pressure

    Feedwater Temperature

    Feedwater Concentration

    Increased Recovery


    Slide39 l.jpg

    Fouling

    • Biological or colloidal fouling

    • Sulphate salts (CaSO4)

    • Silica fouling can be more difficult to predicted & control than other types of fouling.

    • Soluble silica is concentrated to insoluble levels in RO process

    • Effluent organics can adsorb onto membrane element surface, causing pore clogging & even a change in membrane surface charge.


    Slide40 l.jpg

    THANK YOU

    Dr.S. Kanmani, B.E., M.E.,Ph.D.

    Professor in Environmental Engineering

    Centre For Environmental Studies, Anna University

    Phone: 044-22359027

    email : [email protected]


    Slide41 l.jpg

    Membrane Technology

    • Desalination Technologies (Membrane Processes / Distillation Technologies / Chemical Processes (IX)).

    • Most common desalination technology – Membrane Processes

    • A membrane is a thin porous material that allows water molecules to pass through it, but rejects viruses, bacteria, metals, salts , etc.

    • Wide variety of polymeric materials : Cellulose, Acetate, Nylon.

    • Non – polymeric materials: Ceramics, Metals, Composites.


    Slide42 l.jpg

    • Two types of Membrane processes:

      • Pressure Driven (RO, NF, UF, MF)

      • Electrical – Driven (Electrodialysis)


    Slide43 l.jpg

    Application of Pressure – Driven Membrane Processes


    Slide44 l.jpg

    Application of Membrane Processes


    Slide45 l.jpg

    Reverse Osmosis

    • A physical process.

    • Osmotic pressure difference bt. Salt water & pure water is used.

    • A pressure greater than osmotic pressure is applied on feed water.

    • A con. Salt soln is rejected.

    • TDS upto 45,000 mg/L could be treated.

    • Pump is used to raise the pressure applied to sea water.


    Slide46 l.jpg

    • For brackish water, pump pressure ( 140 – 400 psi)

    • For sea water , pump pressure ( upto 1200 psi)

    • Two common Membrane Types (Cellulose Acetake, CA & Non – CA Membranes)

    • CA membranes are used in desalination process. They have smooth surface that is resistant to fouling.

    • Non – CA members, Thin – film Composite Membranes ( eg. Polyamide & Composite Membranes) use Organic materials (eg Polysulphone)


    Slide47 l.jpg

    • They have high Flux – Rate (Volume of fresh water per membrane surface area).

    • Non – CA membranes are stable over wide pH range than CA membranes, but susceptible to Cl2.

    • In order to meet RO feed water quality requirements , pretreatment is needed (for removal of large particles, Organics & adding Chemicals to prevent Formation of precipitates & scales).

    • CO2 & soda ash are added to increase alkalinity of treated water.

    • Recovery is the vol. of fresh water produced as a % of vol. feed water processed.

    • Typical recovery rates (30 – 80 %)


    Slide48 l.jpg

    General Membrane Operation

    & Maintenance Procedures

    • Back washing of the membrane is a common technique used with low-pressure, hollow-fiber membranes to maintain the design operating flux of the system.

    • Standard solutions of acids, bases & detergents are used to clean most membrane.

    • Cl2 in the form of sodium hypochlorite is used to remove biological foulants.

    • Critic acid (C6H8O7) is a common acid used to clean membrane is effective in removing iron scales & mineral scales (CaCO3, CaSO4, MgSO4) resulting from hard water

    • Caustic could be used to remove biological fouling when Cl2 cannot be applied

    • Other chemicals used to clean low-pressure membranes include H2O2, HCl & EDTA.


    Slide49 l.jpg

    Membrane Post Treatment System

    • Degasification to remove H2S, CO2 from permeate.

    • NaOH is used to increase pH.


    Slide50 l.jpg

    Scale Prevention

    • To prevent formation of CaCO3, pH of RO feed water is lowered by adding mineral acid.

    • Solubility of CaCO3 salt depends on pH & bicarbonate ion, thus converting bicarbonate ion to CO2 & lowering pH will increase its solubility.

    • Mineral acid can be used to control biofouling (i.e HCl, H2SO4)

    • Antiscalants are required when con. of salt exceeds its solubility.

    • Polymeric scale inhibitors (polyacrylates or poly acrylic acid) have been developed.


    Slide51 l.jpg

    Post Treatment

    • Degasification, stabilisation, Alkalinity recovery & disinfection

    • Degasification (addition of PO) to remove gases from permeate

    • NaOH or hydrated line is added to raise pH.


    Slide52 l.jpg

    Membrane Classifications


    Slide53 l.jpg

    Membranes


    Slide54 l.jpg

    Membrane Materials


    Slide55 l.jpg

    Packing Modules

    • Plate & Frame

    • Spiral Wound

    • Tubular

    • Hollow - Fiber


    Slide56 l.jpg

    RO


  • Login