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WORKING OF W TER

TRE TMENT PL NT

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NEED OF WATER

TREATMENT

Untreated Water:

is unhealthy for humans, pets, and wildlife.

allows bacteria, viruses, and other disease-causing

pathogens to enter groundwater and surface water.

hepatitis, dysentery, and other diseases may result from

bacteria and viruses in drinking water.

can raise the nitrate levels in groundwater which affects

the ability of an infant's blood to carry oxygen, a condition

called methemoglobinemia (blue-baby syndrome).

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WATER TREATMENT PROCESSES:

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1 Waste Water

2 Screening

3 Coagulation/Flocculation

4 Sedimentation

5 Softening

6 pH Adjustment

7 Stabilization

8 Filtration

9 Disinfection

10 Aeration

11 Supply

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Screening

The process of removal of large debris such as

sticks, leaves, trash and other large particles

which may interfere with subsequent

purification steps.

It removes debris which may clog the pumps

and may cause problems in water treatment.

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Coagulation/Flocculation

Coagulation means a reduction in the forceswhich tend to keep suspended particles apart.

The joining together of small particles into larger,settleable and filterable particles isflocculation.

The coagulants may include: Aluminum sulphate or Alum

Aluminum Hydroxide

Iron salts, etc.

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Floc Formation

http://en.wikipedia.org/wiki/File:Usine_Bret_MG_1643.jphttp://en.wikipedia.org/wiki/File:Usine_Bret_MG_1643.jp

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Sedimentation

It occurs in sedimentation basin or clarifier which

is a large tank, allowing flocs to settle to the

bottom.

Sedimentation basins may be rectangular, where

water flows from end to end, or

circular where flow is from the centre outward.

The minimum clarifier retention time is normally

2- 4 hours.

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Sedimentation Tank

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Filtration

It is the removal of particulate impurities and

floc from the water being treated.

It considerably reduces presence of bacteria in

water.

The most common type of filter is

Rapid Sand Filter

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Rapid Sand Filtration

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Disinfection

It is the treatment by which disease producing bacteria

and other micro-organisms present in water are killed.

Disinfectants cause:

Damage to cell wall of micro-organisms which leads to celllysis and death.

Alteration of cell permeability which causes outflow of

vital nutrients such as nitrogen and phosphorus.

The various forms of disinfectants include:

Chlorine

Chloramine

Chlorine dioxide

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Aeration

It is the process in which water is broughtinto contact with air.

It transfers volatile substances like oxygen,

carbon dioxide,etc to or from water.

It reduces the concentration of taste-odor

producing substances like sulphides.

It causes removal of volatile organic

compounds which are suspected carcinogens.

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