SCI1306.pdf - SCHOOL OF BUILDING AND ENVIRONMENT DEPARTMENT...

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SCHOOL OF BUILDING AND ENVIRONMENT
DEPARTMENT OF CIVIL ENGINEERING
UNIT – I – SEWERAGE SYSTEM – SCI 1306

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INTRODUCTION
SANITARY ENGINEERING:
It is defined as the branch of public health engineering deals with the collection, conveyance,
treatment and safe disposal of wastes for preventing the communicable diseases.
STAGES OF SANITARY ENGINEERING:
Conveyance of sewage
Collection of sewage
Treatment of sewage
Disposal of sewage
OBJECTIVES OF SANITARY ENGINEERING:
To maintain the environment and to prevent the effect of sewage to public health in general.
To prevent the effect of disposal of sewage on land or nearby water bodies from pollution.
To prevent the environment from mosquitoes, flies, bacteria etc.
To dispose the human excreta to a safe place before it starts decomposition.
SEWAGE:
It is a dilute mixture of the wastes of various types from the residential, public and industrial
places.
It includes sullage water and foul discharge from the water closets, urinals, hospitals, stables
etc.
STORM WATER:
It is the surface runoff obtained during and after the rainfall which enters sewers through
inlet.
Storm water is not foul as sewage and hence it can be carried in the open drains and can be
disposed off in the natural rivers without any difficulty.
SANITARY SEWAGE:
It is the sewage obtained from the residential buildings & industrial
effluents Establishments.
Being extremely foul it should be carried through underground conduits.
DOMESTIC SEWAGE:
It is the sewage obtained from the lavatory basins, urinals & water closets of houses, offices
& institutions.
It is highly foul on account of night soil and urine contained in it.
Night soil starts putrefying & gives offensive smell.

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It may contain large number of bacteria due to the excremental wastes of patients.
This sewage requires great handling &disposal.
INDUSTRIAL SEWAGE:
It consists of spent water from industries and commercial areas.
The degree of foulness depends on the nature of the industry concerned and processes
involved.
SEWERAGE SYSTEM:
The entire system of collection of sewage and conveyance of sewage to treatment units by
using sewers is called sewerage system.
The sewerage system carries two types of flow.
DRY WEATHER FLOW (DWF):
Domestic sewage and industrial sewage collectively, is called as DWF.
It does not contain storm water.
It indicates the normal flow during dry season.
WET WEATHER FLOW (WWF):
The flow of storm water is called WWF.
SULLAGE:
It is defined as the waste water from domestic buildings especially from bathrooms, kitchens
etc.
It is merely waste water and does not create any bad smell or odour.
SLUDGE:
It is the organic matter deposited in the sedimentation tank during treatment.
SEWERAGE:
The entire system of collecting, carrying & disposal of sewage through sewers is known as
sewerage.