water treatment 1
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Particles of the greatest public health significance are___________ in size.
Conventional filters are NOT effective at removing particles of what size.
Suspended Particles are easily and effectively removed by ___________________
Sedimentation and Filtration
What war the three particle size categories
Suspended, colloidal and Dissolved
What characteristic causes colloidal particles to remain stable in water?
Negative Surface charge
3 Primary Coagulants used
- Aluminum Sulfate: Al+++
- Ferric Chloride: Fe+++
- Ferric Sulfate: Fe+++
- only last for about one second in the water
Conventional Treatment 4 steps
Apply positive charges to neutralize negative charges
When a primary coagulant dissolves in water, it forms
- Uses the same Primary Coagulants as charge neutralization.
- Forms sticky inorganic polymers that will physically adhere to colloids
React with alkalinity to form inorganic polymers - a chemical equivalent to biological mucus
Sweep Coagulation requires and produces
- Ten times more coagulant
- Ten times more sludge
What is the purpose of the coagulation process?
Destabilization of Colloids
What are the 2 mechanisms of coagulation?
Charge Neutralization and Sweep Coagulation
What is the most common chemical used for coagulation?
aluminum Sulfate (Alum)
Ability to resist decrease in pH
Total Alkalinity =
Hydroxide + Carbonate + Bicarbonate
Ability to resist change in ph
0-14 7 is neutral
Primary coagulants produce
Hydrogen ions thus decreasing the ph of the water
Primary coagulants combine with
hydroxides, forming into inorganic polymers (floc)
ph change is moderated by
alkalinity which neutralizes hydrogen ions
Do primary coagulants act as acids bases, or neutral substances?
what is the final chemical product in sweep coagulation with alum?
What are the three ions that make up total alkalinity in water?
- Potassium Permanganate
- Chlorine dioxide
Preoxidation can yeild
Long organic molecules that can link many colloidal particles together
Most common Coagulant [polymer] Aid?
The mechanism by which polymers work is called?
what is the most commonly applied chemical prior to coagulation?
Coagulation process components
- Reaction chamber
- Mixing system Chemical feeders
charge neutralization must be completed
- very quickly about one second
- in-pipe section
Sweep Coagulation time frame
about one minute in a small mixing chamber
chemical feeders are
- positive displacement pumps
- very accurate and controllable
- Needed to match positive charges with negative colloids
most effective way to add coagulation chemicals
the most common chemical feeder for primary coagulation chemicals
Positive Displacement pumps
what is the term for the laboratory measurement of colloidal surface charge?
Laboratory procedure used to determine the optimum coagulant
Once colloids are destabilized what is the next treatment step?
Increasing particle size with Clocculation
What would you like to do?
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