coag_lecture_updated_Fall_f06

coag_lecture_updated_Fall_f06 -...

Info iconThis preview shows pages 1–14. Sign up to view the full content.

View Full Document Right Arrow Icon
    EVEG 3110 October 16 th 2006
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
    Problem removal of Colloidal particles  Size Stability Double Layer Coagulation Reduce repulsive forces = particle destabilization DLVO Theory (not DLOV – typo) 10 -4 10 -3 1 10 -1 10 -2 100 10 Dissolved Colloidal Suspended
Background image of page 2
    City of New Orleans – Carrollton Plant Sewerage and Water Board of New Orleans M i s s i s s i p p i   R i v e r Sedimentation Chlorine Contact Screen Coagulation Basin Flocculation Basin Polyelectrolyte Ferric Sulfate Lime Rapid Sand Filters (44) Sodium Hexametaphosphate Fluorosilicic Acid Free Chlorine Anhydrous Ammonia Finished Product Water (125 MGD)
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
   
Background image of page 4
Common Chemical Precipitants Chemical Formula Molecular Weight (gm/mol) Dry Liquid Alum Al 2 (SO 4 ) 3 18H 2 O a 666.7 60-75 78-80 (49%) Ferric Chloride FeCl 3 162.1 83-85 Ferric Sulfate Fe 2 (SO 4 ) 3 b 400 70-72 Ferrous Sulfate FeSO 4 7H 2 O 278 62-66 Lime Ca(OH) 2 56 as CaO 35-50 a Number of bound water molecules varies from 13 - 18. b May also have bound water molecules From Metcalf and Eddy Density (lb/ft 3 )
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Simple coagulants are selected because they release cations FE +++ AL +++ CA ++ (Softening) Triple charge is are so much more effective That only FE +++ or AL +++ are used unless Softening is required
Background image of page 6
Double Layer and Zeta Potential Fixed Layer (Stern Layer) Diffuse layer of counter ions Particle Zeta potential The electric potential measured at The surface of the shear plane
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 8
Zeta Potential Distance Potential ψ 0 ψ s ζ Nernst potential Stern potential Zeta potential At plane of shear At surface of particle At static ion interface
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
    Coagulation and Flocculation - - - - - - - - - - + + + + + + + + + + + + + - - - - - - - - - - + + + + + + + + + + + + + + + + + + - - - - - - + Typical conditions, repulsive forces exceed the forces of attraction. - + - - - + - + + + - + - - - + - + + + - + - - - + - + + + - + - - - + - + + + - + - - - + - + + + Coagulants alter the surface charge of the colloids. This reduces the repulsive forces and results in destabilization. Floc: 1 – 100 microns + + + + - - - - + + + - + + - - - + + + - - - + + + - - - + - + - + - + - + - + - + - + - + - + - + - - - - -
Background image of page 10
   
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
    Coagulation and Flocculation Goal: To alter the surface charge of colloidal particles so that the particles adhere to each other (destabilization) and are capable of settling by gravity.
Background image of page 12
    Simple  Coagulant Properties
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 14
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/20/2010 for the course EVEG 3110 taught by Professor Malone during the Spring '10 term at LSU.

Page1 / 42

coag_lecture_updated_Fall_f06 -...

This preview shows document pages 1 - 14. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online