The document describes the processes involved in an effluent treatment plant (ETP). An ETP treats industrial wastewater through primary, secondary, and tertiary treatments to remove solids, chemicals, and organic substances before reuse or safe disposal. The major treatment stages include physio-chemical processes like oil separation, biological treatment using activated sludge and biotowers, and tertiary treatments like hardness removal. Sludge generated is thickened for volume reduction through sedimentation tanks and centrifuges. The overall ETP process aims to safely treat industrial wastewater for environmental and public health purposes.

1. 1
Under The Guidance of
Prof. (Dr.) Dwaipayan Sen
Presented By Hritwik Ghosh
Department Of Chemical Engineering
Roll No: 2055082

2.  Content
• Introduction
• Classification of the Treatment Process
• Physio Chemical Process
• Biological treatment
• Tertiary Treatment
• Sludge Thickening and centrifuge
• Process Flow Diagram (PFD)
• Treated Effluent Characteristics
• Conclusion
• Reference
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3. 3
 Introduction
What is ETP ?
• ETP(Effluent Treatment Plant) is a process designed for removing solid, chemical, and
organic substances from the wastewater for its reuse or safe disposal to the Environment safely.
• Influent: Untreated industrial wastewater.
• Effluent: Treated industrial wastewater.
• Sludge: Solid part separated from wastewater
by ETP.

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Classification Of Treatment Process :
Physio
Chemical
Biological
Tertiary
Sludge Thickening and
centrifuge
Based on treatment process : The major operations in the
processing scheme are:
A. Free Oil Removal
B. Emulsified Oil Removal
C. Sulphide Treatment
D. Biological Treatment
E. Removal of Hardness

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 Physio Chemical Process :
Fig : TPI OIL SEPARATOR
TPI: Tilted Plate Interceptor
 This is a primary process.
 Separates oil globules from water by
gravity differential.
 Parallel plate assembly at 45°angle.
 This tilted plate interceptor traps
the oil from the water.
 This is a primary separation process
of the oil-water mixture.

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 Physio Chemical process (contd.)
 Then it comes into the equalization pond where oil is removed by a belt oil skimmer from the
surface of the water.
 Effluent from Equalization Pond is pumped into the Flash mixing Tank.
 The Alum, Caustic Acid and Hydrogen Peroxide are dosed in the flash mixer.
 Acid and caustic are added to adjust the pH.
 H₂0₂ is dosed according to the concentration of the sulfides present.
 Alum is added for breaking the oil emulsions and removal of solids and in the Dissolved Air
Flotation unit we can remove the emulsified oil.
Alum,
Caustic
Reaction:
In the acidic range and neutral
conditions, sulphides in the effluent are
mostly present in the form of H2S. The
H2O2 reacts with H2S to give products of
oxidation – water and elemental sulphur
as shown below:
H2O2 + H2S 2 H2O + S

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 Biological Treatment
• The objective of biological treatment is to remove oxygen-consuming matter from wastewater and reduce,
oxidize or stabilize it to the desired degree for safe disposal of the effluent into the receiving stream.
 BIO TOWER :
• A population of micro-organisms attached to the media degrades the organic material present in the
wastewater.
• The organic matter from the liquid is adsorbed onto the biological film.
• In the outer portions of this biological film layer, the organic material is degraded by aerobic micro-
organisms.
• The biomass in the bio tower requires
phosphorous and nitrogen for biological cell
synthesis. H2SO4 and NaOH solution is added
into the pH Adjustment Tank to serve as a
source of P & N respectively.
• The stabilized wastewater from the bio tower
outlet is recirculated back to the bio tower
feed sump by gravity to achieve further
stabilization. The effluent from the bio tower
outlet is fed directly to the Aeration Tank

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Biological Treatment (contd.)
 Activated Sludge Process(ASP) :
• It is a type of suspended growth process.
• This process relies on a dense microbial population, which is in suspension in the wastewater.
• Under aerobic conditions, the organics in the waste are consumed by the microbes as a source of energy,
producing oxidized end products (CO2 and H2O) and for cell synthesis i.e. new micro-organisms.
BOD(Food) + N + P + O2 + Bacteria CO2 + H2O+ Energy + New bacterial cells
• This process occurs when there is insufficient food for bacteria to grow. The microbes utilize organic
matter released from dead cells. This is known as Endogenous respiration and can be represented as:
Dead bacterial cells + O2 CO2 + H2O + N + P
• Physically, activated sludge is in the form of large-size flocs, which have good settling properties, leaving
a clear supernatant on settling. The formation of flocs is not unconditionally needed for the efficient
removal of soluble organic substances from wastewater. It is, however necessary for obtaining a clear
effluent and sufficiently thickened recalculated activated sludge.
• Bacteria are the most important types of micro-organisms concerned with organics removal.

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 Tertiary Treatment
 The removal of hardness and reduction in reactive silica from treated effluent is achieved by the
addition of lime, soda ash, dolomite and alum in the reaction zone of the High Rate Solid Contact
Clarifier (HRSCC).
 Purpose of dosing alum, lime and soda ash is for the removal of temporary as well as permanent
hardness & to increase the pH of effluent to a desired level suitable for silica removal.
 Dolomite comprises of CaO & MgO. The MgO present in the dolomite precipitates as Mg(OH)2 and the
silica is adsorbed in the Mg(OH)2 as sludge.
High Rate Solid Contact Clarifier
Storages

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 Tertiary Treatment
The reaction takes place as follows:
 Alum Reaction:
AI2(SO4)3.18 H2O + 3Ca (HCO3)2 ---> 3CaSO4 + 2AI (OH)3 + 6 CO2 + 18 H2O
 Lime Reactions:
Ca (OH)2 + Ca (HCO3)2 ---------> 2CaCO3 + 2H2O
 Soda Ash Reaction:
Permanent Hardness is removed with sodium carbonate (also called soda ash or soda) as per the
following reactions :
CaSO4 + Na2CO3 -----------> Na2SO4 + CaCO3
CaCl2 + Na2CO3 ----------> 2NaCl + CaCO3

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 SLUDGE THICKENING AND CENTRIFUGE OPERATION
Biological sludge generated from Activated Sludge
Process (ASP) is thickened for volume reduction.
Thickening is done by gravity separation in a
sedimentation tank called thickener.
Similarly, oily sludge from TPI & DAF and chemical
sludge from HRSCC is thickened for volume reduction.

12.  ETP Process Flow Diagram (PFD):
Storages
Dissolved Air Flotation unit
Alum,
Caustic
Alum High Rate Solid Contact Clarifier

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 Conclusion
Industrial wastewater is treated by an Effluent treatment plant for
environmental and public health safety.
Major Treatment procedures are Pre-treatment, primary, secondary,
and tertiary treatments.
After the effluent treatment wastewater should be evaluated
through different parameters.
By maintaining the concentration of these parameters we get the
treated water that can be further used as process water.

15.  References
1. https://www.slideshare.net/asheeshpadiyar/treatment-of-effluents-from-
petroleum-refineries
2. https://www.slideshare.net/ImranBokhari/oil-refinery-waste-water-treatment-
plant
3. https://www.slideshare.net/arunstkmce/waste-water-treatment-refineries
4. https://www.slideshare.net/JaidevSingh/effluent-treatment-plant-design-
operation-and-analysis-of-waste-water-16567872
5. https://www.slideshare.net/akashtk/introduction-of-effluent-treatment-plant
6. Effluent Treatment — Vikaspedia
7. Working of an Effluent Treatment Plant (ETP) (pharmaceuticalsky.com)
8. Effluent Treatment Plant (ETP) Process and Flow Diagram (kelvinindia.in)
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16. Thank You
Hritwik Ghosh
hritwik.ghosh.che24@heritageit.edu.in
Student (Che 3rd)
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