all about process done to clarify water

1. A PRESENTATION
ON...
TREATMENT OF URBAN
SEWAGE
SUBMITTED TO:-
HOD KAMAL SANGURI
PRESENTED BY
:-
SAURABH NEGI
DEPARTMENT OF MECHANICAL ENGG
GRAPHIC ERA HILL UNIVERSITY

2. THE SEWAGE WATER TREATMENT
PROCESS

4. 1.Taking the wastewater away
• The wastewater goes down the drain and into a
pipe, which takes it to a larger sewer pipe
under the road.
• The sewer then joins our network of other
sewers and takes the wastewater to a sewage
treatment works.

5. 2.SCREENING
• The first stage of cleaning the
wastewater is to remove large
objects that may block or damage
equipment. This includes items
that should never have been put
down the drain in the first place
- such as nappies, face wipes,
sanitary items and cotton buds -
but often can be things like
bricks, bottles and rags!
• The wastewater often contains a
lot of grit that gets washed into
the sewer, so special equipment
are used.

6. 3.Primary treatment
• The wastewater still contains
organic solid matter - or human
waste. The next stage is to
seperate this from the water, and
to do this, we put the
wastewater into large settlement
tanks, which causes the solids to
sink to the bottom of the tank.
We call these settled solids
‘sludge’.
• About 70% of solids settle out at
this stage.

7. 4.Secondary treatment
• Although the visible bits of sludge
have been removed, we have to
ensure that the smaller and
sometimes invisible nasty bugs are
also taken out.
• Utilizes biological treatment
processes
• removes dissolved colloidal and
organic matter from waste water.
• microorganisms convert nonsettleable
solids to settleable solids.
• Ex….
• Bacteria and protozoa

8. Secondary Treatment: Aeration Tank
– Biological Treatment
– Activated sludge: contains bacteria/protozoa that eat organics in the liquid
wastes
– Air bubbles pumped in to aid bacteria in digesting

9. Secondary Treatment: Final Clarifiers
– Microbes fall to
bottom and most get
recycled back into
aeration tank to
work on more waste
– Any excess microbes
are removed and
sent to solids
treatment.

10. 5.Tertiary treatment
• Treatment levels beyond secondary are called advanced or Tertiary treatment.
• This step removes stubborn contaminants that secondary treatment was not able
to clean up. (Di
• Dsinfection-
• PURPOSE: Destruction of harmful (pathogenic) microorganisms i.e. disease causing
germs.
• Done through:
1. Chlorination
2. Ozone:more powerful but unstable to store.
3. Ultraviolet light
4. Hydrogen peroxide:similar to ozone but activators such as formic acid is
required to improve its working.

11. • the Tertiary Wastewater Treatment process consists of flocculation
basins, clarifiers, filters, and chlorine basins or ozone or ultraviolet
radiation processes.

12. 6.SLUDGE TREATMENT AND DISPOSAL

13. CONT,
• The residue that accumulates in sewage
treatment plants is called sludge (or biosolids).
• Treatment and disposal of sewage sludge are
major factors in the design and operation of all
wastewater treatment plants.
• Two basic goals of treating sludge before final
disposal are to reduce its volume and to stabilize
the organic materials.

14. Treatment methods
• Treatment of sewage
sludge may include a
combination of
• thickening,
• digestion, and
• dewatering
processes.

15. Treatment methods
• Thickening-
• Thickening is usually the first step in sludge treatment because it is
impractical to handle thin sludge, a slurry of solids suspended in
water.
• Digestion-
• Sludge digestion is a biological process in which organic solids are
decomposed into stable substances. Digestion reduces the total mass
of solids, destroys pathogens, and makes it easier to dewater or dry
the sludge.
• Dewatering-
• Digested sewage sludge is usually dewatered before disposal.
Dewatered sludge still contains a significant amount of water—often
as much as 70 percent—but, even with that moisture content, sludge
no longer behaves as a liquid and can be handled as a solid material.

16. 7. Back to the rivers

17. summary

18. Why to treat sewage wastewater?

19. Key Sector Overview-india
• India, home to 16% of the world’s population, has only 2.5% of the world’s
land area and only 4% of the world’s water resources at its disposal.
• The current consumption in country is approximately 581 trillion litres with
irrigation requirements accounting for a staggering 89% of national usage
followed by domestic use at 7% and industrial use at 4%.
• Experts project India’s water demand to grow by 20% in the next decade,
with industrial requirements to double from 23.2 to 47 trillion litres,
domestic requirements to grow by 40% from 41 to 55 trillion litres, while
irrigation to grow by 14% from 517 to 592 trillion litres.
Source : Google