Tertiary treatment involves additional wastewater treatment processes beyond secondary treatment to further improve water quality before discharge or reuse. It typically includes nutrient removal through nitrification/denitrification or phosphorus precipitation, disinfection through UV, ozone, or chlorine, and filtration through sand filters, membrane filters, or activated carbon to remove remaining solids and chemicals. The goal of tertiary treatment is to remove nearly all organic and inorganic compounds to produce very high quality effluent suitable for sensitive reuse applications or discharge into the environment. Common tertiary treatment processes include nutrient removal, disinfection, ion exchange, membrane filtration, and sand or activated carbon filtration.

1. Tertiary treatment of waste water
Presented by :- Rajat singh
Msc food tech

2. Topics to be covered today
What is tertiary treatment?
Why need of tertiary treatment?
Steps in tertiary treatment
• Nutrients removal
• Disinfection
• Ion- exchange
• Membrane process
• Filters

3. Introduction
• Tertiary treatment is the next wastewater treatment process after the secondary
treatment . Secondary treatment is not able to remove all impurities present in
water.
• Secondary treatment removes 85 to 95% of BOD and TSS and minor portions of
nitrogen, phosphorus and heavy metals
• Tertiary treatment sometimes as called as final or advanced treatment process and
consisting the removing the organic load left after secondary treatment.
• Tertiary treatment is the final cleaning process that improves wastewater quality
before it is reused, recycled or discharged to the environment. The treatment
removes all organic and inorganic compounds, and substances, such as the
nitrogen and phosphorus.

4. Why need of tertiary treatment
• The purpose of tertiary treatment is to provide
a final treatment stage to raise the effluent
quality before it discharged to the receiving
environment such as sea , river, lake, ground
etc.
• To remove total suspended solids are
present in effluents after secondary treatment.
• To remove specific organic and inorganic
constituents from industrial effluent to make it
suitable for reuse.
• To remove pathogens from the secondary
treated effluents.

6. Nutrient removal
1) Ammonia removal :-
Nitrification ( conversion to Nitrate)
Biological oxidation of nitrogen from ammonia to nitrate .
1) Ammonia to nitrate using Nitrosamines
Ammonia ----nitrosamines nitrite
2) Nitrite to Nitrate using Nitrobacteria ssp.
Nitrite ------nitrobacteria nitrate (N03)
 Denitrification ( conversion to N2 gas)
• Nitrate is converted into nitrogen gas and released into air .( pseudomonas Lactobacillus)
Nitrate, N03  Nitrite, N02  Nitric oxide, NO  Nitrous oxide ,N2O  Nitrogen, N2
2) Phosphorus removal :-
• Physical
• Chemical
• Bilogical

7. Disinfection
1) Uv radiaton :- killing bacteria , virus and other pathogens .
by damaging their genetic structure .
• No chemical are used
• More Rapid
2) Ozonation :- Disinfection achieved by formation of free
radicals as oxidizing agents
• more effective against viruses and bacteria then chlorination .
3) Chlorination :- chlorine is used in 2 forms – Cl2 gas form or
hypochlorite tablets.
• Chlorine react with water to form HOCL , which rapidly
dissociate to form hypochlorite ion.
• Chlorine effective against bacteria..

8. Ion- exchange
• Ion exchange can be used in waste water treatment plants to swap one ion for another for the
purpose of demineralization . The widest application of this process is in domestic water
softening.

9. Membrane process
1) Microfiltration
• Pore sizes 0.01 – 12 um
• Capable of removing bacteria , macromolecules ..
2) Ultra filtration:-
• Remove organic molecules, virus, bacteria or a molecules
weight above about 800 daltons
• Pore size 0.002 -0.03um
3) Nanofiltration:- Allow monlovalent ions such as
sodium or potassium to pass but reject a high proportion
of divalent ions such calcium and magnesium .
• Pore sizes are typically 0.001 – 0.01um
• Effective for removal of colour – forming organic
compounds

10. Membrane technology contd..
4) Reverse osmosis :- Rejects monovalent ions and organics of molecular weight > 50
dalton
• Pore sizes <0.002um
• Used for desalination of sea water.

11. Sand filter
• Sand ,either fine or coarse is generally
used as filter media.They consist of
fine sand supported by gravel are
used in water treatment process of
water purification.
• sand filter is an environmental friendly
waste water treatment process.
• simple to use and inexpensive.
• The principle involves percolating
water through a sand bed.

12. Sand filter

13. Types of Sand filter
Rapid or
Gravity
sand filters
Semi rapid
sand filters
Slow sand
filters
Sand
filter

14. Rapid Sand filter
• They consist of larger sand grains supported by
gravel and capture particles thought the bed.
• Rapid sand filter need to be cleaned frequently ,
by back washing which involve reversing the water
direction
• Rapid and semi –rapid sand filter require pumps
and the use of chemical to trap suspend particles.

15. Rapid sand filter counted…
Two types of RSF are typically used:
1) Rapid gravity sand filters
2) Rapid pressure sand filters.,
• RSFs require adequate pre-treatment (usually coagulation-flocculation) and
post-treatment (usually disinfection with chlorine).
• Both construction and operation is cost-intensive.
• It is a relatively sophisticated process usually requiring power-operated
pumps, regular backwashing or cleaning, and flow control of the filter outlet.
.

16. •Pressure sand filter•Gravity Sand filter

17. Parts of gravity sand filter
• The major parts of a gravity rapid sand filter are:
• Chamber: filter tank or filter box made from concreate.
• Depth of tank 2.5 to 3.5 m and surface area 10 to 80 sqm
• Filter media (sand) :- size 0.35 to 0.55mm
• Gravel support :- size of gravel varies from 2.5 mm at bottom to 0.5 at the
top.
• Under drain system :- Embeded in 60cm to 70 cm thick gravel

18. Steps of Rapid sand filter
impure water
1) Coagulation
• Addition of alum ( 5-40mg/l)
2) Rapid mixing
• Violent mixing of alum
3) Flocculation
• Slow stirring of water by paddles ( 30)
• Flocculent ppt. of aluminum hydroxide entangles all particulate suspended matter along with bacteria
4) sedimentation:-
• Flocculent ppt, settle down
• Clear water above goes for filtration
5) filtration:- Remaining Alum flocculent layer over sand bed , hold back bacteria & oxidizes organic
matter

19. Advantages of rapid sand filter
1) Rapid sand filter can deal with raw water directly . No preliminary storage is needed.
2) Filter is 40-50 times rapid then slow sand filter.
3) The washing of filter is easy.
4) The filter beds occupy less space.

20. Slow sand filter
• Slow sand filters are used in water
purification for removing bacteria and
suspended solids.
• Remove 98- 99% of bacteria.
• They are typically 1 to 2 meters deep,
can be rectangular or cylindrical.
• They reduce turbidity and pathogenic
microorganism organisms through
various biological agents, (bacteria,
viruses, microbes etc) physical and
chemical processes in the presence of
microorganism

21. Elements of Slow sand filter
1) Filter box
a) Supernatant water
• Depth 1 to 1.5m
• Promotes downward flow of water through the same bed
• Waiting time 3-12 hours for raw water to undergo partial purification by sedimentation and
oxidation
b) Sand bed :- Depth 1m ( sand of diameter 0.2 -0.3mm ) , gravel with 0.2 -1cm diameter.
c) Under drainage system :- depth 0.15m
• At the bottom of filter bed
Porous pipes :- outlet for filtered water as well as support to the filter media above

22. Elements of Slow sand filter Counted..
d) Filter control valves :-
• To regulate the flow of water in and out
e) Filter cleaning :-
• Increasing bed resistance
• Necessary to open the regulatory vales fully
• Scrapping top portion of sand bed up to 2cm depth.
• After 3-4 year new bed constructed

23. Advantages of slow sand filter
1) Simple to construct and operate .
2) Construction is cheaper then rapid sand filter.
3) Quality of filtered water is high.

24. Rapid and Closed Sand filter

25. Activated carbon filters
Activated carbon filters are generally employed in the process of removing
organic compounds and or extracting free chlorine from water there by
making the water suitable for discharge or use in manufacturing processes.
Activated Carbon (AC) filtration, is not capable of removing all type of
contaminant. For example, sodium, microbes, fluoride, and nitrates cannot
be removed with AC filtration. Water softening also cannot be achieved with
AC filters. In addition, heavy metals, such as lead, can only be removed
with a very specific kind of activated carbon water treatment, which is
typically used only in residential point-of-use filters.

26. Principle of activated carbon filter
• There are two principal mechanisms by which activated
carbon removes contaminants from water;
1)Adsorption,
2) Catalytic reduction. .
• Organic compounds are removed by adsorption and
residual disinfectants such as chlorine and chloramines
are removed by catalytic reduction.
• The contaminant is attracted t and held (adsorbed) on
the surface of the carbon particles.
• the efficiency of adsorption depends upon particle and
pore size, surface area, surface chemistry, density of
filter media.

27. Material for manufacturing ACF
Coal
Coconut shells
Wood
Peat nut shell
Petroleum coke

28. Properties:
• Pore size and distribution have the greatest impact on the
effectiveness of AC filtration. The best filtration occurs when carbon
pores are barely large enough to allow for the adsorption of
contaminants .
• Water Temperature and pH: The rate of adsorption will usually be
higher at lower temperatures and pH level.
• Length of Exposure: The length of time in which the contaminant is in
contact with the AC filter also influences the adsorption process – the
longer the length of contact, the greater the number of contaminants
that will be removed.
• Concentration: The adsorption process can be affected by the
concentration of organic contaminants. For example, with chloroform
removal one AC filter may be more effective than another at filtering
high concentrations of contaminants, and less effective at filtering low
concentration of contaminants.

29. Types of activated carbon filter
1)Granular activated
carbon filter :-
• GAC is basically used carbon in a
granular form , they exclude particles
by size.
2)powdered activated /
adsorptive carbon filter :-
• filter contains a material that either
adsorbs or react with a contaminant in
water.

30. References
• Wastewater Engineering by Dr. B.C PUNIA
• Waste- water Engineering by S.C Bhatia
• WHO (Editor) (1996): Rapid Sand Filtration. (= Fact Sheets on Environmental Sanitation,
2/14). Geneva: World Health Organization (WHO). URL [Accessed: 15.02.2012]. PDF
• HUISMAN, L.; WOOD, W.E. (1974): Slow Sand Filtration. Geneva: World Health Organisation
(WHO). URL [Accessed: 06.02.2012]. PDF

31. Thank you