sewerage system civil engineering fifth sem ppt download

collection of sewerage system, sewerage collection

1. Department of Civil Engineering
Assignment for CE (PC) 505
[Environmental Engineering-II]
Topics: Sewerage System

•Student Name: Raki Mondal
•Reg. No. : 232570120076 of 2023-24
•Roll No. : 25701323071 Semester: 5
th
•Year: 2024-25



Camellia Institute of Technology
& Management

2. Sewerage System: Sewerage
system refers to the infrastructure which
conveys sewage or surface runoff using
sewers. Some of the components of the
sewerage system includes inlets, catch
basins, clean outs, manholes, lamp
holes, flushing tanks, grease and oil
traps, inverted syphon's and storm
regulators.

4. •What is Sewerage System?
A network of pipes, pumping stations, and
other interconnected components constitute
the sewerage system, also known as sewage
system, which is designed to transfer
wastewater including sewage and storm
water runoff. The infrastructure collects
wastewater from various sources such as
homes, industries, and commercial areas,
and moves it through sewers. The system
primarily utilizes gravity to facilitate the
movement of wastewater and often employs
natural storm water drainage as well.

5. •Sewerage System Types:
Depending upon the mode of collection of sewage the
sewerage system can be classified into following three
categories:-

Combined Sewerage System: Storm run-off and
domestic sewage are carried through the same sewerage
system conduit in a combined system. In a country such as
India, where actual rainy days are sparse, this sewerage
system will have difficulty in maintaining the self-cleansing
velocity of the sewers in the dry season as the sewage
discharge in the dry season would be far less than the
design discharge after including storm water. Due to this
problem, the sewers might get choked, which could
decrease the discharge-carrying capacity of the sewers.

6. Some of the advantages of combined
sewerage system:-
•There is no need to flush sewers in areas
where rainfall occurs throughout the year
because self-cleaning velocity will be
developed due to increased quantity because
of storm water addition.
•For house plumbing, only one set of pipes will
be required.
•In congested areas, it is simple to lay only
one pipe rather than the two required by
other systems.

7. some of the disadvantages of combined
sewerage system are:-
•Not suitable for areas with a short period of
rainfall per year, because dry weather flow will be
low, preventing self-cleaning velocity from
developing in sewers and resulting in silting.
•Large flows must be treated at sewage treatment
plants before disposal, resulting in higher capital
and operating costs for the treatment plant.
•This system is uneconomical when pumping is
required.
•Sewer overflows will contaminate public hygiene
during rainstorms.

8. Separate Sewerage System: Separate
conduits are used in a separate system, one
for sewage and the other for storm water run-
off. Because storm water is not as foul as
sewage and no treatment is generally
provided, it can be discharged directly into
the water body. To meet desired standards,
sewage collected from the city is adequately
treated before it is discharged into a water
body or used for irrigation. For large cities, a
separate system is advantageous and cost-
effective.

9. The advantages of separate sewerage
system are:-
•As sewage and storm water flow in separate
pipes, the amount of sewage to be treated at
the sewage treatment plant is small, resulting
in treatment cost savings.
•Only sanitary sewage is transported in a
closed conduit. This system may be less
expensive because storm water can be
collected and conveyed through open drains.
•Due to lower flow, this method is more cost-
effective when pumping is required during
disposal.

10. The disadvantages of separate sewer
system are:-
•In congested or low-space areas, laying
separate pipes for sewage and storm water
might be difficult.
•Flushing of sewers may be required at some
locations if self-cleansing velocity is not
developed. And maintenance cost of this
sewerage system is high because the
authorities have to spend more money on
maintaining separate sewers.

11. Partially Separate Sewerage System: In this
system, storm water, particularly collected from
building roofs and paved courtyards, is admitted into
the same drain as sewage from residences and
institutions, etc. Storm water from other locations is
collected separately via separate storm water
conduits.
Some advantages of this sewerage system
are:-
•Sewers of reasonable size and cost are required.
•As rainwater from roofs, sullage from bathrooms and
kitchens, etc., are combined with discharge from water
closets, the work of house plumbing is reduced.
•Flushing sewers may not be necessary because a
small amount of storm water can enter sanitary
sewage.

12. Some disadvantages of this
sewerage system are:-
•In dry weather, self-cleansing velocity
in sewers may not develop.
•The cost of pumping at the treatment
plant increases when this sewerage
system is adopted as compared to the
separate sewerage system.

13. Wastewater Types in Sewerage Systems:
Mixture of water and liquid waste generated
due to different activities in the community is
termed as sewage. It includes the water from
urinals, toilets, discharge from residential
areas, commercial areas, institutional
buildings, and storm water or groundwater
entering the sewers. Its decomposition
produces a considerable amount of foul-
smelling fumes, and it contains numerous
pathogenic or disease-causing germs, as well
as a high concentration of organic materials
and suspended particles.

14. The wastewater or the sewage can be
classified on the basis of its origin and
composition. Some of the types of
wastewater are:-

Domestic Sewage: If the sewage is generated
due to various domestic activities such as
washing, bathing etc. from residential buildings,
restaurants, public buildings etc. and carries lots
of waterborne wastes, then this type of sewage is
termed as domestic sewage. Domestic sewage is
free from the wastes generated from the industrial
effluents. Domestic sewage can also be referred
to as sanitary sewage.

15. Industrial Sewage: Industrial sewage refers to
the wastewater generated from various industrial
activities in the form of effluents. Its
decomposition produces a considerable amount
of foul-smelling fumes, and it contains numerous
pathogenic or disease-causing germs, as well as
a high concentration of organic materials and
suspended particles.
Storm water Sewage : Storm water is sewage
runoff from the atmosphere that collects as water
particles in open channels. Rain, drizzle, snow,
and other types of precipitation are examples of
this.

16. Some Other Important Terms in Sewerage
System:-
Night Soil- Human and animal excreta can be
described by a term called the Night Soil.
Subsoil Water- When the groundwater enters the
sewers through any leakages then it is termed as
subsoil water.
Sullage- When waste from the bathroom and kitchen
are taken together then it is termed as sullage. It
includes the wastewater generated from bathrooms,
kitchens, washing places and wash basins, etc. The
sullage contains less organic matter and requires a
lesser degree of treatment.

17. Sewage Treatment Plant- A sewage treatment plant
is a facility that receives waste from residential,
commercial, and industrial sources and removes
contaminants that harm water quality and endanger
public health and safety when discharged into receiving
systems or on land. It is a collection of unit operations
and unit procedures designed to treat sewage to
desirable standards in accordance with regulating
authority effluent requirements.
Low-cost treatment devices such as oxidation ditches,
aerated lagoons, and waste stabilization ponds can be
used to replace the activated sludge or trickling filter
processes. Some unit operations and processes, such
as primary sedimentation and anaerobic digestion, are
eliminated by such treatment devices.

18. Thank you