Chapter 3. Fundamental physical-chemical engineering processes applicable to water treatment (214 pages)

1.Coagulation-flocculation
1.1.General comments
1.1.1.Suspended solids and colloïds
1.1.2.Colloidal suspensions - The need for coagulation
1.1.3.Aggregations stages
1.1.4.Coagulants
1.1.5.Flocculation additives (or flocculants)
1.1.6.Effect of pre-oxidation
1.2.Typical reagents
1.2.1.Mineral coagulants
1.2.2.«Natural» flocculation additives
1.2.3.Synthetic organic coagulants
1.2.4.Synthetic organic flocculants
1.3.Flocculation with sludge contact
1.4.Special case of emulsions
2.Chemical precipitations
2.1.Removing hardness (calcium and magnesium)
2.1.1.Main methods
2.1.2.Precipitation calculation and control (obtaining a minimum M- alk.)
2.1.3.Special case of partial carbonate removal
2.2.Precipitating silica
2.2.1.Silica removal using Mg²⁺
2.2.2.Silica removal using sodium aluminate
2.2.3.Colloidal silica
2.3.Metal precipitation
2.4.Other precipitations (case of anions)
2.4.1.Sulphates
2.4.2.Fluorides
2.4.3.Phosphates
2.5.Sludge produced
2.6.Precipitation inhibiton
2.6.1.Spontaneous inhibition: examples
2.6.2.Induced inhibition
3.Sedimentation
3.1.Different types of sedimentation
3.1.1.Granular particle sedimentation
3.1.2.Flocculent settling of flocculated particles
3.1.3.Hindered settling of flocculated particles
3.2.Designing settling tanks
3.2.1.Influence of the hydraulic surface loading
3.2.2.Influence of solids loading
3.2.3.Settling tank structure
3.3.Lamellar sedimentation
3.3.1.Principle
3.3.2.Utilisation
3.3.3.Choosing the type of lamella packs
3.3.4.Conclusion
3.4.Sludge contact clarification
3.4.1.Sludge recirculation clarifier
3.4.2.Sludge blanket clarifier
3.4.3.Combination with lamellar settling
3.5.Ballasted floc sedimentation
4.Flotation
4.1.Flotability and rising velocity
4.1.1.General, terminology
4.1.2.Relationship between size and bubble velocity
4.1.3.Particle-bubble composite
4.2.Natural flotation and aided flotation
4.2.1.Natural flotation
4.2.2.Aided flotation (medium or fine bubbles)
4.3.Microbubble flotation (DAF or FAD)
4.3.1.Microbubble production using pressurisation in DAF
4.3.2.Technology
4.3.3.Uses for DAF
5.Filtration
5.1.Fundamental equations
5.1.1.In-depth filtration
5.1.2.Filtration of a liquid suspension accompanied by the formation of a cake
5.2.General filtration principles
5.2.1.Filtration mechanisms
5.2.2.Filtering matter fouling and washing
5.2.3.Selecting the filtration mode
5.3.Filtration through a mechanical support
5.3.1.Screening and Micro-screening
5.3.2.Filtration through cartridges and candles
5.3.3.Pre-coat filtration
5.4.Filtration through a granular bed
5.4.1.Porous media
5.4.2.Control and optimisation
5.4.3.Choosing a filter bed
5.4.4.Washing the filter medium
5.4.5.Applications
6.Centrifugation
6.1.Centrifugal separation basics
6.2.Centrifugal force
6.3.Water treatment applications
6.3.1.Separating oily suspensions with low suspended solids content
6.3.2.Separating sludge-laden suspensions that have a high oil content
6.3.3.Cycloning used to separate out high granulometry, heavy particles

7.Fluidisation
8.Electrolysis
8.1.Basic principles - definitions
8.1.1.Nernst equation
8.1.2.Electrolysis voltage
8.1.3.Faraday's law
8.2.Water treatment applications
8.2.1.Electrochlorination
8.2.2.Metal recovery
8.2.3.Electrocoagulation
8.2.4.Other applications
9.Membrane separation
9.1.General
9.1.1.Membrane structure
9.1.2.Transfer mechanisms across membranes
9.1.3.Desalination and clarification membranes
9.2.Desalination membranes
9.2.1.Transfer through the membrane
9.2.2.Utilisation and membrane water balance
9.2.3.Reverse osmosis
9.2.4.Nanofiltration
9.3.Clarification membranes
9.3.1.Ultrafiltration (UF) membranes
9.3.2.Microfiltration (MF) membranes
9.3.3.Clarification membranes: definitions
9.3.4.Irreversible fouling causes and mechanisms
9.3.5.Utilisation: dead-end or tangential operation
9.4.Permeation processes
9.4.1.Gas permeation
9.4.2.Degassing membranes (de-oxygenation)
9.4.3.Pervaporation
9.4.4.Distillation through a membrane
9.5.Dialysis membranes
9.5.1.Piezodialysis (pressure gradient and amphoterous membranes)
9.5.2.Simple dialysis (concentration gradient)
9.5.3.Electrodialysis (electrical field gradient)
9.5.4.Water electro-deionisation
10.Adsorption
10.1.Mechanism
10.2.Main adsorbents
10.2.1.Activated carbon
10.3.Applied activated carbon principles
10.3.1.Activated carbon (PAC)
10.3.2.Granular carbon (GAC)
11.Ion exchange
11.1.General
11.1.1.Principle
11.1.2.Ion exchange mechanism
11.1.3.Regeneration methods
11.1.4.Ion exchange vocabulary
11.2.Main types of ion exchangers
11.2.1.Ion exchanger characteristics
11.2.2.Cation exchangers
11.2.3.Anion exchangers
11.2.4.A few values
11.2.5.Adsorbant resins and special resins
11.3.Classic schemes used
11.3.1.Co-current line
11.3.2.Countercurrent line
11.3.3.Water softening
11.3.4.Carbonate removal
11.3.5.Demineralisation
11.4.Various line options
11.5.Demineralisation line calculation principle
11.6.Operation and maintenance of a total demineralisation unit
11.6.1.Treatment verification
11.6.2.Resin disinfection
11.6.3.Resin storage
12.Oxidation and reduction
12.1.Purpose of oxidation-reduction treatments
12.2.Fundamental concepts on the oxidation-reduction chemical reaction
12.3.Basic concepts on disinfection
12.4.The oxidants and disinfectants
12.4.1.Oxygen
12.4.2.Chlorine and hypochlorite
12.4.3.Chlorine dioxide
12.4.4.Ozone
12.4.5.Permanganate
12.4.6.Hydrogen peroxide
12.4.7.Paracetic acid
12.4.8.UV radiation
12.4.9.Advanced oxidation systems
12.5.Oxidising agent selection guide
12.6.Reducing agents
12.6.1.Chemical reduction of oxygen
12.6.2.Reduction of hexavalent chromium
12.6.3.Reduction of normal oxidising agents
13.Neutralisation-remineralisation
13.1.Introduction: applications and stakes
13.2.The calcium-carbonate balance
13.2.1.General: natural water
13.2.2.Soft water/hard water
13.2.3.Aggressive water/scaling water
13.3.Treatment objectives
13.4.Methods used to determine pH
13.4.1.Ions present
13.4.2.The equilibriums and their thermodynamic constants
13.4.3.pHS approximation through calculation
13.4.4.Approximation of pHS using graphs
13.4.5.Correction options applicable to aggressive water - Indexes
13.5.Reagents and treatments that can be used
13.5.1.Neutralisation or soft water remineralisation
13.5.2.For neutralising hard water
14.Gas-liquid exchange
14.1.Theoretical bases for gas/liquid exchanges
14.2.Gas dissolution (absorption)
14.3.Stripping (desorption)