There are six physical methods used to treat wastewater: screening, grit chambers, fat and grease removal, flotation, equalization basins, and clarifiers. Screening removes large solids, grit chambers remove sand and debris, fat and grease removal uses skimmers, flotation removes oils and greases using dissolved air, equalization basins level flows, and clarifiers remove solids through sedimentation.

1. WASTE
WATER
TREATMENT
BY
PHYSICAL
METHODS

2. Physical
methods
There are six
methods in the
treatment of waste
water by means of
physical methods.
Screening
Grit Chamber
Fat and Grease removal
Flotation
Equalization basin
Wastewater Clarifier Sedimentation Tank

3. SCREENING
• First step at any wastewater
treatment
• It involves removal of non-
biodegradable and floating
solids
• Examples for floating solids are
rags, papers, plastics, tins and
wood
• Waste water screening may be
done either as coarse screening
or fine screening

4. GRIT
CHAMBER
• It is a sedimentation basin placed
at the front of waste water
treatment plant.
• It removes sand, egg shells,
coffee grounds and other
materials which may cause clog in
the channels

5. FAT AND
GREASE
REMOVAL
 Fat and grease are removed by
passing the sewage through a small
tank where skimmers collect the fat
floating on the surface.
 Air blowers in tank base
also collect fat as a froth
 Many plants use primary
clarifiers with mechanical surface
skimmers for fat and grease removal.Fat
oil and
grease

6. FLOTATION
• It is widely used in industrial waste
water treatment plants
• It removes fats, oi, grease and
suspended solids from waste water.
• These units are called as Dissolved
Air Flotation (DAF)units.
• These DAF units removes oil from the
wastewater effluents of oil refineries,
petrochemical and chemical
plants,natural gas processing plants.

7. Dissolved Air Flotation (DAF) Unit

8. EQUALIZATION
BASIN
• Flow equalization levels out operation
parameters such as flow, pollutant
levels, and temperature over a time
frame (usually 24 hours).
• It is not a treatment process but a
technique that improves the
effectiveness of secondary and
advanced wastewater
treatment processes.
In rest phase
In working phase

9. WASTEWATER
CLARIFIER
SEDIMENTATION TANK
 This plays an important role in
removing heavier sludge solids by
means of settling and seperation from
liquid phase.
 These types of primary sedimentation
tanks were designed to deal with
higher rate of loading and also having
retention time for the water

10. SOURCE:
CONTENT: NGO International
Company
IMAGES: Google Images