Sewage and wastewater treatment

1. Department of MICROBIOLOGY
Seminar topic On :-
MASTER OF SCIENCE IN MICROBIOLOGY
ACADEMIC YEAR 2020-21
SUBMITTED BY:
ABHIJITH JIGALI
M.Sc IV SEMESTER
UNDER THE GUIDANCE OF
Dr. Naveen Kumar K J
P.G. DEPARTMENT OF STUDIES IN MICROBIOLOGY DAVANGERE UNIVERSITY
SHIVAGANGOTHRI DAVANGERE-577007

2. CONTENTS
1. Introduction.
2. Sources of water pollution.
3. Sewage characteristics and pollutes.
4. Wastewater and sewage treatments.
• Primary treatment.
• Second treatment.
• Tertiary treatment.
5. Emerging technologies of wastewater and sewage
treatment.
6. Sludge treatment and disposal.
7. Summary.
8. Conclusion.
9. Reference.

3. INTRODUCTION
 Wastewater and sewage treatment is the removal of
impurities from wastewater or sewage before it
reaches aquifers or natural bodies of water such as
rivers, lakes, estuaries, and oceans.
 In broad terms, water is said to be polluted when it
contains enough impurities to make it unfit for a
particular use such as drinking, swimming, fishing etc.
 Although water quality is affected by natural
conditions, which implies human activity as the source
of contamination and also caused by the drainage of
contaminated wastewater into surface water.
 So wastewater treatment is a major element of water
pollution control.

4. SOURCES OF WATER POLLUTION
Two kinds water pollution sources may originated.
1). Point source.
2). Dispersed source.
1). Point sources: Is one that reaches water from a single
identifiable source such as pipe or ditch.
For example: Discharged pipes, Drainage ditches.
2). Dispersed source: Dispersed sources are broad, unconfined
areas from which pollutants enter a body of water.
For example: Caring animal waste, fertilizers, pesticides, urban
storm water drainage, petroleum residues from automobiles are
considered a dispersed source because of the many locations at
which it enters local stream or lakes.

5. SEWAGE CHARACTERISTICS AND
POLLUTANTS
• Types of sewage.
1. Domestic sewage.
2. Industrial sewage.
3. Storm sewage.
• Pollutants:
Organic material.
 Plant nutrients.
 Microbes.
 Suspended solids.

6. WASTEWATER AND SEWAGE
TREATMENTS
Sewage treatment generally involves three main
stages, called Primary , secondary, and tertiary
treatment and also include intermediate stages and
final polishing processes.
1). Primary treatment: Primary treatment is also
called physical treatment, It removes about 60% of
total suspended solids and 35% of BOD.
Primary treatment removes material that will float
on sewage.
It includes the physical processes of screening,
comminution, grit removal, and sedimentation.

7. • Screening: It is made up of long, closely spaced,
narrow metal bars. They block floating debris
such as wood, rags, and other bulky objects.
• Comminution: In this process, it is used to grind
and shred debris that passes through the screens.
• Grit removal: Grit chambers are long narrow
tanks that are slow down the flow, So that solids,
coffee grounds and egg shells will settle out of
the water.
• Sedimentation: In this the shredded material and
sedimentation solids are removed by
sedimentation processes.

9. 2). Secondary treatment:
Secondary treatment is also as biological
treatment, It removes the soluble organic matter
that escapes from primary treatment.
 It also removes suspended solids by biological
processes in which microbes consume the
organic impurities as food, converting into Co2,
water, and energy for their own growth and
reproduction.
 Removal of soluble organic matter at the
treatment plant helps to protect the dissolved
oxygen balance of a receiving stream, river, or
lake.

10. There are three basic biological secondary treatment
methods:
The trickling filter, Activated sludge process, And
oxidation pond.
Trickling filter:
Trickling filter is simply tank filled with a deep bed of
stones. Settled sewage is sprayed continuously over the
top of the stones and trickles to the bottom.
 In this process microbes to absorb the dissolved
organics, thus lowering the biochemical oxygen
demand of the sewage.
 Air circulating upward through the spaces among the
stones provides sufficient oxygen for the metabolic
processes.

11. Trickling filter

12. Activated sludge treatment:
This is most versatile biological oxidation process
employed for the treatment of wastewater contain
dissolve solids and organic matter.
 Sewage from sedimentation tank enter into
aeration tank.
 The compressed air is then injected into the
mixture through porous diffusers located at the
bottom of tank.
Under such oxygenated conditions,
microorganisms thrive, forming an active, healthy
suspension of biological solids called activated
sludge. This gives the microbes enough time to
absorb dissolved organics from the sewage.

14. Oxidation pond treatment:
Oxidation ponds are also stabilization ponds,
designed to treat wastewater through the
interaction of sunlight, bacteria, and algae.
 Algae grow using energy from the sun light,
carbon dioxide and inorganic components
released by bacteria in water.
 Sludge deposits in the pond must eventually
be removed by dredging. The remaining algae
can be removed by filtration or by
combination of chemical treatment and
settling.

16. 3). Tertiary treatment:
The tertiary treatment provide a final treatment
stage to further improve the effluent quality before
it is discharged to the receiving environment.
In tertiary treatment includes effluent polishing,
biological nutrient removal, and disinfection.
• Effluent polishing:
In this process the removal of additional
suspended solids and BOD from secondary effluent.
It is most effective treatment and using granular
media filters to purify drinking water and also be
achieved using microstrainers for treatment of
wastewater.

17. • Biological nutrient removal:
The wastewater may contain high levels of nutrients nitrogen and
phosphorous. Excessive release to the environment can lead to a buildup of
nutrients called eutrophication, which can in turn encourage the overgrowth
of weeds, algae, and cyanobacteria. This may cause the algal bloom and high
amount organic matter are settled down.
So different treatment processes are required to remove nitrogen and
phosphorous;
 Nitrogen removal: Nitrogen is removed through the biological oxidation of
nitrogen from ammonia to nitrate(Nitrification), followed by
denitrification(reduction of nitrate to nitrogen). Later nitrogen gas is
released to atmosphere.
 Phosphorous removal: Phosphorus can be removed biologically by
specific bacteria called polyphosphate accumulating organisms( PAOs) are
selectively enriched and accumulate large quantities of phosphorous with
in their cells. Phosphorous removal can also removed by precipitation,
usually with salts of iron and aluminum.

18. Disinfection:
In this process of treatment of wastewater is to
substantially reduce the number of microorganisms in the
water to be discharged back into the environment for the
later use.
• The effectiveness of disinfection depends on the
quality of the water.
Common methods of disinfection treatment
include ozone, chlorine, ultraviolet light treatments.
 Chlorination treatment: Chlorination is the process of
adding chlorine to sewage treatment to kill the harm
full microorganisms. Its common type of wastewater
disinfection treatment and long term effectiveness.

19. Ultraviolet treatment:
In this process UV radiation can be used to target
harmful pathogens. UV radiation cause damage to
the genetic structure of bacteria, virus, and other
pathogens making them to incapable of
reproduction in wastewater treatment.
Ozonation treatment:
Ozone is very unstable and reactive oxidizes the
most of organic material, thereby destroying many
pathogenic microorganisms in wastewater
treatment.

20. EMERGING TECNOLOGIES OF
WASTEWATER AND SEWAGE TREATMENT
Improved treatment technologies:
Wastewater treatment sector have been
working to implement established technologies
and to improve rules and regulations to meet
quality and human health protection.
These include the membrane bioreactor process,
The ballasted floc reactor, and integrated fixed
film activated sludge (IFAS) process.

21. Automation:
Advanced wastewater purification process involves
biological treatments that are sensitive to processing
parameters to the environment.
To ensure stable and reliable operation treatment plants
quite often need to implement sophisticated
technologies includes, Use of online analytical
instruments, programmable logic controllers(PLC),
supervisory control and data acquisition(SCADA) systems,
human machine interface(HMI), Such innovations
improve system operations significantly, thus minimize
supervision needs.

22. SLUDGE TEATMENT AND DISPOSAL
The residue that accumulates in sewage treatment
plants is called sludge. Which is produced as a by product
of wastewater treatment processes.
The two main basic goals of treating sludge before final
disposal are to reduce its volume and to stabilize the
organic materials.
Treatment of sewage sludge may include a combination
of thickening, digestion, and dewatering processes.
The final destination of treated sewage sludge can be
disposed buried underground in a sanitary landfill.

23. SUMMARY.
• Wastewater and sewage treatment is the removal of
impurities from wastewater or sewage before it
reaches to natural bodies.
• Which contains organic material, suspended solids,
plant nutrients and microbes.
• The sewage treatment which involves primary,
secondary, and tertiary treatments. In primary
treatment, which removes floating and suspended
particles. In secondary and tertiary, removes total
organic material and improves the effluent quality.
• Finally treated sewage sludge can be disposed buried
underground in a sanitary landfill

24. CONCLUSION.
• The major aim of waste water treatment is
remove as much of suspended solids and the
remaining effluents before it is discharged to the
environment.
• If wastewater is not properly treated, then
environment and human health can be negatively
impacted.
• The advanced and improved technologies must
be used to treat wastewater in order to recover
energy, nutrients and other chemicals. Which
helps to reduce nutrient pollution and less cost.

25. References.
 Viswanath Buddolla.,Environmental
Biotechnology., Alpha science international ltd
(2017).,pp- 544.
 Bernard R. Glick, Jack J.Pasternak, Cheryl L,
Patten., Molecular Biotechnology., 4th edition.,
ASM Press Washington, DC(2010).