in this presentation describe what is sewage, sludge and polluted water and also the treatment of sewage, sludge and water pollution.

1. Mobeen Arshad
Roll no 20
MSc 4th Semester
GC Women University, Sialkot
Treatments of sewage, sludge and
polluted water

2. Contents
i. Sewage
ii. What is sewage treatment?
iii. Process of sewage treatment
iv. Sludge
v. Sludge treatment process
vi. Polluted water
vii. Polluted water treatment

3. Sewage
 Produced by a community of people
 Characterized by
volume or rate of flow,
physical condition,
chemical and toxic constituents,
Bacteriologic status (which organisms it contains and in
what quantities)
 consists mostly of grey water, black water, detergents,
soaps and toilet paper.

4. What is sewage Treatment?
 Process of converting sewage water that is no
longer needed or is no longer suitable for use into
bilge water that can be discharged back into
the environment
Sewage water Bilge water
(back into environment)

5. PROCESS OF SEWAGE
TREATMENT
I. SCREENING
 removes large objects like, diapers, nappies, sanitary
items, cotton buds, face wipes and even broken bottles,
bottle tops, plastics and rags that may block or damage
equipment.
 Special equipment is used to remove grit that gets
washed into the sewer.
II. PRIMARY TREATMENT
 separation of organic solid matter (or human waste) from
the wastewater
 putting the wastewater into large settlement tanks for the
solids to sink to the bottom of the tank

6. PROCESS OF SEWAGE
TREATMENT
 At bottom, large scrappers continuously scrape the
floor of the tank and push the sludge towards the
center.
III. SECONDARY TREATMENT
 Put water into large rectangular tanks. called
aeration lanes.
 Air pumped into the water to encourage bacteria to
break down the tiny bits of sludge that escaped the
sludge scrapping process.

7. PROCESS OF SEWAGE
TREATMENT
IV. FINAL TREATMENT
 treated wastewater is passed through a
settlement tank
 Sludge formed at the bottom of the tank from the
settling of the bacteria action
 Again sludge scrapped and collected
 Free from any harmful substances
 Than filtered with a bad of sand

8. PROCESS OF SEWAGE
TREATMENT

9. SLUDGE
 Semi-solid slurry that can be produced from a range of
industrial processes, from water treatment, wastewater
treatment or on site sanitation systems
 Settled suspension obtained from conventional
drinking water treatment
 Solids separated from suspension in a liquid

10. Sludge treatment Process
 Stabilization
 Also called mass reduction or degistion
 Result in reduction of organic content
 Improved drain ability
 Reduces odor of the polluted matter
 Reduce the volume of sludge
 Two units
Anaerobic
aerobic

11. Sludge treatment Process
 Aerobic digestion
Organic part decomposes in the presence of
oxygen by micro organism.
Bacteria convert organic matter into carbon dioxide.
• Advantage
 Operation is relatively easy
 Lower capital cost
Lower BOD concentrations in supernatant liquor
End product odorless and stable

12. Sludge treatment Process
 Disadvantage
 A high power cost is associated with supplying
the required O2
 A digested sludge is produced with poor
mechanical dewatering characteristics
 A useful by-product such as methane is not
recovered

13. Sludge treatment Process
 Anaerobic digestion
 A biological process that uses bacteria in an
oxygen free environment.
 These bacteria converts volatile solids into
carbon dioxide, methane and ammonia.
 Sludge held without aeration for 10-90 days
 Process can be accelerated by heating to 35-
40oC
 These are called High Rate Digesters (10-20
days)

14. Sludge treatment Process
 Advantages
 low solids production
 useable methane gas produced
 Disadvantages
 high capital costs
 susceptibility to shocks and overloads

15. Sludge treatment Process
 Sludge dewatering
 Dewatering aims to reduce the water content
further.
 The sludge can then be handled like a solid.
 Dewatering can be done mechanically using a
filter
 press (employing pressure or vacuum), or a
centrifuge.
 Also be done using drying beds.

16. Sludge treatment Process
 Drying beds
 Most popular methods.
 A drying bed consists of a 30 cm bed of sand
with an under-drainage .
 Sludge is applied on the sand bed and is allowed
to dry by evaporation and drainage of excess
water over a period of several weeks depending
on climatic conditions.
 Bacterial decomposition of the sludge takes place
during the drying process while moisture content
is sufficiently high.
 During the rainy season the process may take a
longer time to complete

17. Sludge treatment Process

18. POLLUTED WATER
 Water pollution is the contamination of water
bodies (like oceans, seas, lakes, rivers, aquifers
and groundwater) usually caused due to human
activities.
 Water pollution is any change in the physical,
chemical or biological properties of water that will
have a detrimental consequence any living
organism.

19. POLLUTED WATER TREATMENT
PROCESS
I. Industrial water treatment
 Primary phase
 Suspended, solid particles and inorganic material is
removed by the use of filters
 Secondary phase
 Use biological filters to naturally degrade the organic
waste material
 Tertiary phase
 All solid particles remove and chemical additives are
supplied to get rid of any left-over impurities

20. POLLUTED WATER TREATMENT
PROCESS
II. De-nitrification
 Prevent leaching of nitrates in soil
 Fertilizers contain nitrogen, bacteria in the soil
convert the nitrogen in the fertilizer to nitrates,
make easier for plants to absorb
 Immobilization is a process where the nitrates
become part of the soil organic matter
 Oxygen levels low, another form of bacteria then
turns the nitrates into gases such as nitrogen,
nitrous oxide and nitrogen dioxide
 This conversation process called de-nitrification.

21. POLLUTED WATER TREATMENT
PROCESS
III. Septic tanks and sewage treatment
 Septic tanks treat sewage at the place where it is
located
 Used to treat sewage from an individual building
 Untreated sewage from a property flows into the
septic tank
 Solids are separated from the liquid, depending
on their density
 Heavier particles settle at the bottom of the tank
whereas lighter particles at the top.
 Biological process use to degrade solid particles, than
liquid flow in land drainage and solid filttered.

22. POLLUTED WATER TREATMENT
PROCESS
IV. Ozone wastewater treatment
 Ozone generator is used to break down
pollutants in the water source
 Generators convert oxygen into ozone by using
ultraviolet radiation or by an electric discharge
field
 Ozone is a very reactive gas that can oxidise
bacteria, moulds, organic material and other
pollutants found in water

23. POLLUTED WATER TREATMENT
PROCESS
Ozone wastewater treatment benefits:
I. Kills bacteria effectively
II. Oxidises substances such as iron and sulphur
so that they can be filtered out of the solution
III. no nasty odours or residues produced from the
treatment
IV. Ozone converts back into oxygen quickly, and
leaves no trace once it has been used.

24. POLLUTED WATER TREATMENT
PROCESS
Ozone wastewater treatment disadvantage:
I. The treatment requires energy in the form of
electricity; this can cost money and cannot work
when the power is lost.
II. Treatment cannot remove dissolved minerals
and salts.
III. Produce by-products such as bromate that can
harm human health.