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Effluent Treatment Plant
Prepared by-
1.Mashuk Rahman Khan
2.Logic Karmaker
3.Lamia Mahpara
4.Fahim Ahamed
5.Saifur Rahman
Prepared for-
Md. Monirul Islam (MrL)

An Effluent Treatment Plant is a physical plant which is generally used to
alter the properties of wastewater.
 Also known as Wastewater treatment.
 Several physical, chemical and biological processes are used to remove
any toxic materials present in the wastewater.
 After the properties of the wastewater are changed, the remaining water
is known as Effluent.
 The Effluent can be discharged into the environment for re-use.
 Common by-products of the process are screenings, grit, sewage, sludge
and odorous gases.
 The by-products are also treated in the plant.

Common sources of Wastewater-
Iron and Steel Industry
Food Industry
Pulp and paper industry
Nuclear Industry
Organic Chemicals Industry
 Residential Wastewater

Steps used in wastewater treatment-
Pre-Treatment
Primary Treatment
Secondary Treatment
Tertiary Treatment
Disinfection
Odor Control

 Pre-Treatment
Pre-Treatment removes all materials that can be easily collected from
the raw sewage before they damage or clog the pumps and sewage lines
of primary treatment clarifiers.
Commonly removed objects during Pre-Treatment-
trash
tree limbs
leaves
branches
other large objects.

Screening
During Pre-treatment, the influent in sewage water passes through a bar
screen to remove all large objects like cans, rags, sticks, plastic packets
etc. carried in the sewage stream.
Grit Removal
Pre-treatment may include a sand or grit channel or chamber, where the
velocity of the incoming sewage is adjusted to allow the settlement of
sand, grit, stones, and broken glass.

 Primary Treatment
In the primary sedimentation stage, sewage flow through large tanks
known as Primary Sedimentation tanks.
The tanks are used to settle sludge while grease and oil rise to the
surface and are skimmed off.
The design of the tank should be such that it removes a high percentage
of the floatables and sludge.
Primary treatment can reduce the biodegradable organics of the
incoming wastewater by 20-30% and the total suspended solids by some
50-60%.

Secondary (biological) treatment
The dissolved organic matter that escapes primary treatment, are
removed.
Microbes present in the plant, consume the organic matter as food, and
convert it to carbon dioxide, water, and energy for their own growth and
reproduction.
Secondary treatment degrade the biological content of the sewage
derived from human waste or food waste.
Aerobic biological processes are used.

Secondary treatment technologies include-
The basic activated sludge process
the variants of pond and constructed wetland systems
trickling filters
 other forms of treatment which use biological activity to break down
organic matter.

Two types of Secondary sedimentation-
Fixed-film systems include trickling filters, bio-towers, and rotating
biological contactors where the biomass grows on media and the sewage
passes over its surface.
Suspended-growth systems include activated sludge, where the
biomass is mixed with the sewage and can be operated in a smaller
space than trickling filters that treat the same amount of water.

 Tertiary Treatment
Removes the pollutants that were not sufficiently removed in the
secondary treatment-
Solids
Nitrogen
Phosphorus
Metals
Tertiary Treatment provides a final treatment stage to the effluent
before it is discharged into the sea or oceans or land.

Nitrogen Removal-
Nitrogen is removed through the biological oxidation of nitrogen
from ammonia to nitrate (nitrification), followed by denitrification, the
reduction of nitrate to nitrogen gas.
Phosphorus Removal achieved by-
Chemical Precipitation (with the help of salt or aluminium)
The help of bacteria (with a process known as enhanced biological
phosphorus removal)

 Disinfection
Disinfection is done to reduce the number of micro-organisms present in
the water that is to be reduced back into the environment.
Disinfection is done by-
 Chlorination
 Using UV rays
 Ozone disinfection (Ozone oxidizes most organic material it comes in
contact with, thereby destroying many pathogenic microorganisms)

 Odor Control
The odor of the water is controlled by-
Carbon Reactors
Contact Media with bio-slimes
Small doses of chlorine
Circulating fluids to biologically capture and metabolize the noxious
gases.
Addition of iron salts, hydrogen peroxide or calcium nitrate.

Other treatments that can be present in industrial wastewater
treatment plants-
An API oil-water separator for removing separate phase oil from
wastewater.
A clarifier for removing solids from wastewater.
A roughing filter to reduce the biochemical oxygen demand of
wastewater.
A carbon filtration plant, to remove toxic dissolved organic compounds
from wastewater.

Conclusion
Some global estimates by United Nations Development
Programme(UNDP) and UN-Habitat –
•90 % of all wastewater are released into the environment.
•In many developing countries the bulk of domestic and industrial
wastewater is discharged without any treatment.
•In Latin America about 15 percent of collected wastewater passes
through treatment plants.
•In Venezuela, 97 percent of the country’s sewage is discharged raw into
the environment.
•Only few cities in sub-Saharan Africa have sewer-based sanitation
systems, let alone wastewater treatment plants.

•Developing countries should plan on investing in more of wastewater
treatment plants.
•Countries all around the world should start planning to build Effluent
Treatment plants.

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