3. Contents
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Concept of ETP
Need to treat effluent
Major treatment units
Preliminary treatment
Primary treatment
Secondary treatment
Tertiary treatment
Flowchart of ETP
Summary
References
in ETP
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4. Concept of ETP
Effluent treatment Plant covers the mechanisms and processes used to
treat such waters that have been contaminated in some way by
anthropogenic industrial or commercial activities prior to its release into
the environment or its re-use.
This effluent contains several pollutants, which can be removed with the
help of an effluent treatment plant.
ETP treat water and make free from all objectionable impurities present
in suspension, colloidal or dissolved form.
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5. Need to treat Effluent
To prevent
To prevent
To prevent
To prevent
Protection
groundwater pollution
sea shore
soil
marine life
of public health
To reuse the treated effluent
For agriculture
For groundwater recharge
For industrial recycle
Solving social problems caused by the accumulation of wastewater
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6. MajorTreatment units in ETP
1.Preliminary Treatment
Screens
Detritor/scrapers
Grit Chamber
Skimming Tanks
Aeration
3.Secondary Treatment
Activated Sludge Process (ASP)
Trickling Filter
Multiple Evaporator (ME) Plant
Rotating Biological Contactors (RBC)
4.Tertiary Treatment
Sand/ Membrane Filters
Activated Carbon Filters
Disinfection
Ion-exchange/ESP
Nutrient Removal
2.Primary Treatment
Sedimentation/ Settling tank
Clarifloculator
Equalization Tank
Neutralization Tank
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7. 1.PreliminaryTreatment
Preliminary treatment removes gross solids and materials that can be
easily collected from the effluent and can damage or clog the pumps and
skimmers of primary treatment clarifiers.
These are in-organic materials and insoluble organic pollutants (i.e. large
floating and suspended solid matter, grit, oil & grease) which are inert
cause problems to further chemical and biological treatments.
and
The presence and sequence of preliminary treatment units are totally
depend upon the characteristic of effluent that is to be treated.
All preliminary treatment consist of physical separation techniques by
controlling flow rate of effluent.
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8. Mechanical medium screen Fine screen
Corse bar screen Detritor/ Scrapper
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9. Skimming Tank with separated oil & grease at top
Collection of separated
oil & grease at edge
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10. 2.PrimaryTreatment
Primary treatment consists of temporarily holding the sewage in a inert basin
where heavy solids can settle to the bottom while oil, grease and lighter solids
float to the surface.
The settled material go for sludge treatment and floating materials are skimmed
off. The remaining liquid is passed to secondary treatment.
Tanks are usually equipped with mechanically driven scrapers that continually
drive the collected sludge towards a hopper in the base of the tank where
pumped to sludge treatment facilities.
it is
At this stage, over 70% of the suspended solids and 40% of the BOD is
removed from effluent.
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11. Equalization Tank
Some industries produce different types of
wastes, having different characteristics at different
intervals of time.
Hence, equalization tank is used to mixed
different type of effluent thoroughly to produce
homogenous and equalized effluent for uniform
treatment.
This are large holding tanks with aeration or
to
of
mechanical agitation with paddles manually
give better mixing of the different unit volumes
effluents.
The effluent is hold and mixed for specified
period of time.
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12. Neutralization Tank
Neutralization tank is used to provide treatment to highly acidic or
highly alkaline effluent through neutralizing pH by addition of chemicals.
Industry require neutralization of discharged effluent when it has as
highly acidic and/or highly alkaline effluent.
Acidic effluent is usually treated with lime stone or lime-slurry or caustic
soda, depending upon the type and quantity of effluent.
Alkaline effluent is neutralized by sulphuric acid or CO2
flue gas.
or waste boiler
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13. 3.Secondary treatment
Secondary treatment is a biological treatment of effluent which is typically
performed by indigenous, water-borne micro-organisms in a managed habitat.
Secondary treatment removes dissolved and suspended organic (bio-
degradable) matter by consuming it as a food and convert it into new cell
mass, energy and CO2.
The most common micro-organisms are bacteria (aerobic or anaerobic),
protozoa and rotifers; least common are fungi and algae.
After secondary treatment almost 70-90% of BOD and 80-90% of
dissolved solids are removed from effluent.
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14. I)Trickling Filter
In trickling filter
sprayed
treatment,
through
This zoogloeal film consist of millions
of micro-organisms breakdowns
organic material of effluent into simple
and soluble matter. Treated effluent is
drain at bottom from where it is
collected then undergoes for
sedimentation.
wastewater
sprinkling
is
rotating arm on circular
beds consist of 3-10 ft deep coarse
media (of crushed stones, gravels or
synthetic material).
Microorganisms get
grows on the media
attach and
and results in It is simple to operate and give almost
80-90% of BOD
quality effluent.
removal with highformation of film of micro-
called zoogloealorganisms film.
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15. II)Activated Sludge Process(ASP)
This is most versatile biological oxidation method employed for the treatment
of effluent containing of dissolved solids, coarse and colloidal organic matter.
In this method, effluent is aerated in a reaction tank consist of microbial
population in suspension form. Aerobic bacteria degrades effluent into CO2 and
H2O for which oxygen is supplied through mechanical aeration or by diffused
aeration system.
The bacterial flora grows and remains suspended in the form of a floc called
activated sludge. A part of sludge is recycled for the same tank to provide an
effective microbial population for a fresh treatment cycle.
Industrial ww require 6 to 24 hours of aeration through which almost 90- 95%
of BOD can be removed.
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16. ASP combined with filtration
Aeration Tank in ASP
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17. 3.TertiaryTreatment
Tertiary treatment is the final treatment, meant for ‘polishing’the effluent and
removal of pollutants not removed in primary and secondary treatment.
These pollutants may include soluble inorganic compounds such as
phosphorous or nitrogen which may support algal growth in receiving
water.
Also removes organic materials contributing BOD, COD, color, taste, odor;
bacteria, viruses, colloidal solids contributing turbidity; or soluble minerals
which may interfere with subsequent re-use of the wastewater.
Preferred when treated water is need to be reuse or discharge is into a
highly sensitive or fragile ecosystem (estuaries, rivers, coral reefs, etc).
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18. I)Filtration
Filtration is process of removing particulates and bacterial impurities that could
not be removed in earlier treatment, from water by passing it through a porous
medium.
It is used to remove colloidal and other impurities which impart turbidity to
water. Also for disinfection of water by reducing 90% of bacterial load.
It is also used to reduce odor and color by arresting them in filter media.
There are various type of filter available to treat certain type of wastewater.
Selection is totally depend upon characteristics of ww, efficiency of
absorbent, flow rate and pollutant to be removed from ww.
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19. II)Activated Carbon Filters
ACF consist of activated carbon
granules supported by very fine quartz
filter media. Various grades of carbon
are available for specialized treatment
of wastewater.
Most common adsorbents used are
activated carbon, peat moss, brown coal
and other cellulose materials.
This treatment not only improves taste
of water but also protects other water
treatment units such as reverse osmosis
membranes and ion exchange resins
ACF are used to remove free
chlorine, organic residues, toxic
heavy metal ions and color from
ww.
from possible damage due to oxidation
or organic fouling.
Different media used for ACF ACF Tubes or channels
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20. Conclusion
Different types of industrial wastewater is treated by Effluent treatment
plant for environmental and public health safety.
Major Treatment procedures are preliminary , primary , secondary and
tertiary treatments.
After the effluent treatment wastewater should be evaluated with
different paramenters of temperature , pH , total dissolved
(TDS),COD , BOD , ammonical nitrogen .
solids
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