water treatment 1

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Particles of the greatest public health significance are___________ in size.

Colloidal
Conventional filters are NOT effective at removing particles of what size.

Colloidal
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
- Coagulation
- Flocculation
- Sedimentation
- Filtration
Charge Neutralization

Apply positive charges to neutralize negative charges
When a primary coagulant dissolves in water, it forms

trivalent cations
Sweep Coagulation
- Uses the same Primary Coagulants as charge neutralization.
- Forms sticky inorganic polymers that will physically adhere to colloids
Sweep Coagulation
reaction

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)
Alkalinity

Ability to resist decrease in pH
Total Alkalinity =

Hydroxide + Carbonate + Bicarbonate
buffering capacity

Ability to resist change in ph
Alkalinity neutralizes

Hydrogen ions
pH Scale

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?

Acids
what is the final chemical product in sweep coagulation with alum?

Aluminum Hydroxide
What are the three ions that make up total alkalinity in water?
- Carbonate
- bicarbonate
- hydroxide
common preoxidant
- Chlorine
- Ozone
- Potassium Permanganate
- Chlorine dioxide
Preoxidation can yeild

Microflocculation
Polymers

Long organic molecules that can link many colloidal particles together
Most common Coagulant [polymer] Aid?

Cationic polymer
The mechanism by which polymers work is called?

Polymer Bridging
what is the most commonly applied chemical prior to coagulation?

Chlorine
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

Pumped injection
the most common chemical feeder for primary coagulation chemicals

Positive Displacement pumps
what is the term for the laboratory measurement of colloidal surface charge?

zeta potential
Laboratory procedure used to determine the optimum coagulant

jar test
Once colloids are destabilized what is the next treatment step?

Increasing particle size with Clocculation

Author

Hazard

282856

Card Set

water treatment 1

Description

water treatment terms and information

Updated

9/12/2014, 11:49:09 PM

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