Waste water treatment methods, Waste water treatment plant, Objectives of sewage treatment.

1. BY: Sheama Farheen
Savanur
WASTE WATER TREATMENT

2.  Introduction
 Definition and classes
 Characteristics
 Hazards
 Treatment
 Single dwelling unit
 Municipal treatment process

3. Definition:
 Sewage is the waste water of community.
 It also consists of:
 Domestic water borne wastes: human excrement,
wash waters.
 Industrial water borne wastes: acids, oils, greases.
 Ground, surface and atmospheric waters that
enter the sewage system.

4.  There are two classes of sewage
1) Domestic sewage: Human wastes, laundry,
food preparation etc.,
Grey, turbid liquid with earthy odour
2) Industrial sewage: organic and inorganic
compounds.
type of product produced and nature of
process involved.

5.  Reduce the spread of pathogenic micro
organisms.
 Prevent the pollution of ground and surface water.
 Maintain the oxygen balance.
 Avoid health and aesthetic hazards.
 Prevent development of objectionable conditions.
 Prevent damage to concrete structures.

6.  Due to Biological agents:
contamination of food and water, vector
mediated disease.
 Due to chemicals present in wastes:
solids, liquids or gases which are relatively
toxic or non toxic can pose a serious danger to life

7. Waste water is carried through pipes known as
sewers from its place of production to place of
treatment and disposal.
Types of sewers
• Sanitary sewers: domestic and industrial sewage.
• Storm sewers: dumping storm and surface waters.
• Combined sewers: carry all the sewage

9. • Adequate treatment is necessary to prevent
contamination of receiving waters.
• Wastewater treatment consists of applying known
technology to improve or upgrade the quality of a
wastewater.
Factors :
•Quality and nature
•Cost of the plant
•Sanitary requirements
•circumstances

10.  Wastewater treatment is categorized by the nature
of the treatment process being used as physical,
chemical and biological.
 Physical process involve Degasification and
Equalization
 Chemical process involve chlorination, ozonation,
neutralization, coagulation, adsorption and ion
exchange.
 Biological methods are activated sludge process,
trickling filter and oxidation ponds.

13. 1. Single dwelling units
It is a method of treatment of sewage of
individual or unit structures. EX: septic tank
 They are small rectangular chambers sited below
ground level.
 It is designed to retain the solids of the sewage
entering the tank.
 Sedimentation and the biological degradation is
involved.
 Anaerobic digestion of sewage by the micro
organisms.

15. 1. Primary treatment: to remove coarse solid
particles.
2. Secondary treatment: oxidation of organic
compounds
3. Advanced treatment: removes objectionable
substances .
4. Final treatment: disinfection and disposing.
5. Sludge processing: stabilize the sludge.

16.  Sedimentation :
 most of the settle able solids are separated or
removed from the wastewater by the physical
process of sedimentation
 physical phenomena relating to the settling of
solids by gravity are allowed to operate.
 To remove larger entrained objects .
 Concentration and collection of particulate matter
referred to as sludge.

17. • Secondary treatment depends primarily upon
aerobic organisms which biochemically
decompose the organic solids to inorganic or
stable organic solids
• The devices used in secondary treatment may be
divided into four groups:
 Trickling filters with secondary settling tanks
 Activated sludge and modifications with final
settling tanks
 Intermittent sand filters
 Stabilization ponds

18. • It consists of a bed of coarse pieces of stone
,gravel and slag.
• The depth is 1 to 3 inches. The tank is equipped
with drains underneath.
• The surface of the filter is applied with mixed
population of micro organisms.
• Passage of wastewater through the filter causes
the development of a gelatinous coating of
bacteria, protozoa and other organisms on the
media.

21.  In the absence of oxygen, anaerobic
decomposition becomes active near the surface of
the media.
◦ Settled waste+o2=oxidized fluid+ new cells
 The new cells exert high BOD and must be
removed before effluent is discharged tp a natural
water body.
 For greater efficiency biofilters recirculation of
sewage, plastic media etc., are employed.

22. Activated sludge process
•It is based on vigorous aeration
of sewage resulting in
formation of floccules.
•The floc particles i.e activated
sludge contain large number of
microbes .
•These carry out oxidation of
organic matter and thus BOD is
reduced.
•Due to the growth of
filamentous micro organisms
flocs settle poorely and effects
performance of sewage
treatment.

23. Activated sludge plant

24. Advantages :
Requires a small land area
Has a low BOD & therefore doesn’t require
dilution.
Reduction of suspended solids.
Disadvantages:
Detergents possess a major problem.
Foam formation takes place

26.  They are also known as oxidative ponds or stabilizing
ponds
 It is most important method of sewage treatment in hot
climates where sufficient land is normally available
 The sewage effluent are been dumped into large pond
of depth 2- 4feet
 It is natural process of sewage purification because
oxidation of matters occur through symbiotic action of
algae and aerobic bacteria

27. Aerated lagoon Treatment plant

28. • The putrecible matter is stabilized and thus BOD
is reduced.
• 6CO2+12H2O=C6H12O6+6H20+6O2.
ADVANTAGES:
1. Any degree of purification at lowest cost.
2. Removal of pathogens is greater.
3. Wide variety of industrial waste.
4. The algae produced are potential source of high
protein food.
5. They can be easily designed.

29.  DISADVANTAGES
 Large land space.
 Inefficient for removing fecal bacteria
 Algae may die, & if not removed may become
organic matter of sewage effluent.

31. • The solids accumulated during sedimentation are
pumped into separate tank for digestion of sludge
under controlled condition.
• The microbial action on sludge is known as sludge
digestion.
• Anaerobic and facultative bacteria degrade the
solids to methane and co2 and traces of nitrogen
and hydrogen.
• This gas mixture is used as fuel for heating and
for operating power

32. Sludge digestion Energy consumption

33. Composting:
• It is a process where dewatered sludge undergoes
decomposition within thermophilic temperature
range.
• The dewatered sludge is mixed with a bulking agent
such as wood chips and kept in aerated piles.
• The mixture is allowed to cure for a period of
time(21 days)
• It is finally transformed to humus type material and
used soil conditioner.

34. Thank you