Encyclopedia of Environmental Science and Engineering, Volume I and II

ENVIRONMENTAL HEALTH 351

Screening Sedimentation Oxidation Disinfection

Intermittent

sand filter

Vacuum

filter

Contact

bed

Plain

sedimentation

Septic

tank

Imhoff

tank

Standard

trickling filter

Chemical

conditioning

Secondary

settling

Chlorination

Treated

Sewage

Digestor

High rate

trickling filter

Chemical

precipitation

Activated

sludge

Rapid sand

filtration

Ponds or

irrigation

Incineration

Sludge

drying

Fine

screens

Racks

Grit

chamber

Skimming

tanks

Comminutors

Raw

Sewage

FIGURE 10 Sewage-treatment processes. From Environmental Sanitation, Joseph A. Salvato, Jr., John Wiley & Sons, Inc., New York,

1958.

Sludge

digester

Sludge

drying

bed

Primary

Settling

Ta n k

Comminutor,bar screen and grit Dosing chamber

chamber

Raw

Sewage

Supernatant

Pump and sludge heater

Trickling

Filter

By-pass

Secondary

Settling

Tank

Sludge

return

Pump

Treated

effluent

To oxidation

Pond, Sand filter,

irrigation system or

receiving waters.

FIGURE 11 A secondary sewage treatment plant.

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