Effluent Treatment Plant or ETP is one type of waste water treatment method which is particularly designed to purify industrial wastewater for its reuse and its aim is to release safe water to the environment from the harmful effect caused by the effluent. Helping achieve a greener society.

1. Industrial Effluent Treatment by
Modern Techniques

2. Introduction
• The Effluent treatment plants (ETP) are used for the removal
of high amounts of organic compounds, debris, dirt, grit,
pollution, toxic, non-toxic materials and polymers etc. from
industrial effluent.
• Any Industrial Effluent Treatment Plant (ETP) must be
studied for the possibility of the ” 3 R” principle, they are
Reduce, Recycle and Reuse.

3. What is an ETP
• ETP (Effluent Treatment Plant) is a process design for treating the industrial waste water for its
reuse or safe disposal to the environment
• Influent: Untreated industrial waste water.
• Effluent: Treated industrial waste water.
• Sludge: Solid part separated from waste water by ETP.

4. Chemical Unit Processes:
• Those processes used for the treatment of waste water in which
change is brought about by means of or through chemical reaction
are known as “Chemical unit processes”.
• Various chemical unit processes:
Chemical precipitation
Adsorption
Disinfection
Dechlorination
Other chemical applications

5. Biological Unit Processes:
• Those processes used for the treatment of waste water in which Reduction
or Removal of impurities is brought by microorganisms is called “Biological
unit processes”.
• Classification of biological process for waste water treatment :
• Processes according to Operational Conditions
• Aerobic Process
• Anaerobic Process
• Facultative Process
• Anoxic Process
• Processes according to Microbial Maintenance in the system
• Suspended growth process
• Attached growth or fixed film Process

6. These are the Common methods of
treatment of Industrial Wastes
• Neutralization cum Equalization
• COD/BOD Ratio
• Chemical Coagulation and Precipitation
• Settling Treatment
• Segregation
• Monitoring of ET P
• Oxidation and Reduction
• Disinfection
• Adsorption by Activated Carbon
• Stripping
• Thermal Processes
• Tertiary Treatment of Sewage
• Removal of Color
• Disposal of Solid Wastes

7. Neutralization cum Equalization
• Acidic effluents of one process and alkaline effluents of another
process can be combined for Neutralization. By neutralization
the pH of the effluent will be brought in the range of 6 to
9.Neutralization may be achieved in the same Equalization
tank.
• pH must be in the range of 6 to 8.5 for most of the biological
treatment processes to function efficiently.
Acid + Base = Salt +Water
Bases employed are: Slaked lime, Caustic Soda, NaOH
Soda Ash Na2C03
Acids employed are: H2S04, HCI or CO2.

8. COD/BOD Ratio
• If COD/BOD Ratio is 2 or less i.e more than about 0.5,
Biological treatment methods Will be economical.
• If COD/BOD ratio is very high, Biological treatment is suitable
only if the Chemical Precipitation methods are first employed.
• Once the non-biodegradables (COD) are removed, the
COD/BOD ratio decreases and if it is < 2, Biological treatment
methods like Trickling Filters, Activated Sludge Process,
Oxidation ponds etc. may be employed.

9. Chemical Coagulation and Precipitation
• Coagulation are used to separate the suspended solids portion
from the water. Suspended particles vary in source, charge,
particle size, shape, and density.... Coagulation occurs in
successive steps, allowing particle collision and growth of floc.
• Chemical precipitation in water and wastewater treatment is
the change in form of materials dissolved in water into solid
particles. Chemical precipitation is used to remove ionic
constituents from water by the addition of counter-ions to
reduce the solubility.

10. Settling Treatment
• The goal of settling process is the expulsion of settleable
organic and inorganic solids by sedimentation, and the removal
of materials that will float (scum or rubbish) by skimming.
• The sewage should first be subjected to settling process for
removal of Screenings like wood, paper and plastic squanders
and skimmings to oil and grease.
• Evacuation of toxic substances like Chromium, Cadmium,
Cyanide, Arsenic etc., is essential before sending the
wastewater for biological treatment.
• Almost all toxic substances like Arsenic, Selenium, Cadmium,
Nickel etc., can be removed by Alkaline Chlorination (i.e.
Chlorination at pH > 10) or Activated Carbon.

11. Segregation
• segregation is the separating and sorting of waste to facilitate
recycling. ... For example, a company who sorts its cardboard
packaging, glass containers, metal waste and wood waste will save
a considerable amount of waste then sending a mixed material skip
for recycling.
• Streams with toxic substances and high concentrations of a
particular pollutant like Cyanide and Chromium. BOD and pH should
be treated separately. Separation of wastewater streams of different
qualities is known as ‘Segregation’ or Separation’. Cooling Tower
blow downs that are large in quantity and have no major pollutants in
them should be treated separately, they are segregated from others.
Similarly, small stream with high concentration of a pollutant should
not be mixed with others.

12. Monitoring of ETP
• The Effluent Treatment Plant needs a constant monitoring.
Constant watch on the Operation of Biological treatment
process is essential. Before starting any biological method, the
wastewater must be made free from toxic substances like As,
Hg, Chlorine etc. pH must be in the range of 6.5 to 8.5 by
adding suitable neutralizing agents.

13. Oxidation and Reduction
• Hazardous subsatnces are converted to harmless or less toxic /
hazardous forms.

14. Disinfection
• Boiling, KMnO4, UV Rays, Bromine and Iodine, Excess lime are
a portion of the disinfectants utilized while Chlorination is the
most utilized technique for sterillization. Disinfection regularly
includes the injection of a chlorine solution at the head end of a
chlorine contact basin. The chlorine dosage depends upon the
of the wastewater and different factors, but dosages of 5 to 15
mg/l are common.

15. Adsorption by Activated Carbon
• Adsorption is a surface phenomenon in which the pollutants to
be removed or taken onto the surface of the adsorbent.
Efficiency of adsorbent increases with availability of surface
area per gram of adsorbent. Normal Carbon has a surface are
of 0.001 m2/gram while Activated carbon has a surface area of
more than 1000m2/gram. Molecular Sieves also are possible
alternatives to treatment of effluents with toxic substances but
the efficiency is more only if the effluent is free from primary
pollutants like clay, MLSS and TDS.

16. Advance Demineralization Techniques
• It is like
Evaporation and Distillation
Ion Exchange
Reverse Osmosis
Freezing.

17. Stripping
• Gases dissolved in effluent can be removed by stripping or
desorption. Effluent, if sprinkled or sprayed into atmosphere in
the form of droplets through nozzles, gases are deabsorbed
and temperature of effluent also decreases due to escape of
steam.

18. Thermal Processes
• Thermal processes i.e. by Incineration at temperatures of 8000C
or above of C, H, O, S, N, Heavy Metals for thermal destruction
of hazardous wastes- organic as well as inorganic.

19. Tertiary Treatment of Sewage:
• After the Secondary Clarifier, an Oxidation Pond is always
recommended as it gives a tertiary treatment to the wastewater
and gives it a polishing nature. A Stabilization Pond using Algae
is a very low cost treatment method and is very efficient also in
the removal of BOD. Design Organic loadings as high as 300 kg
BOD/ha/day and detention periods of 10 to 15 days, gives up to
90% of removal of BOD, if properly maintained. Anaerobic
Ponds may be used if BOD is > 2000 mg/ l. Anaerobic Pond
with 3 months detention time and 5m depth removes 60% of
BOD/ COD. Also this has no maintenance costs at all.

20. Removal of Color
• Iron imparts red or reddish brown color to Water while Manganese
imparts black color to water. Zinc gives Opalescence, a whitish color
to water while some dissolved organics etc., cause other colors and
odors to water. Most of Iron’ Manganese and associated color and
odor can be removed by Chlorination, in the final stages. Further
removal of color and odor, as a tertiary treatment is done by using
Activated Carbon, Activated Silica or Molecular Sieves. Activated
Carbon at a pH Of 3 removes 90% of color, which is the main trouble
shooting parameter in a Tannery . Textile or Paper and Pulp Industry.
Consumer acceptance will be more and public uproar will be less
once the color is removed effectively as color is a common man’s
index of-pollution. Coagulation, Flocculation, Carbon adsorption and
Chlorination are the common ruethods adopted for removal of color.

21. Disposal of Solid Wastes
• Most of the toxic substances are present in the Precipitates or
the solid wastes, which are considered hazardous and hence
are taken away by the local Pollution Control Board once in a
year. The solid wastes are to be stored in water tight storage
tanks during this period and need not be further treated