SEWERAGE

Sanitary sewage

Liquid waste coming from residential area is known as

sewerage scheme

The network of underground pipes used for transporting these waste is called

domestic, industrial, infiltration and inflow, storm water

Wastewater classified into:

Dry waste

these are wastes generated from all sorts of activity namely residential, commercial and industrial, which are dry in nature is called

Refuse

If the nature of the waste is mostly inorganic and partly organic, it is known as

sewage

spent water

wastewater system

collect, transmit, treat, and dispose of water supplies used by domestic, industrial, commercial and public users.

Domestic Sewage

discharged from residences, commercial and institutional facilities.

garbage

If the composition of the waste is mostly organic it is called

0\.1 to 0.2 kg capita

Quantity of refuse and garbage varies from ?

Collection

This includes collection of wastewater by plumbing system from lavatories, baths, kitchens, wash basins, sinks, etc.

Conveyance

The above collected wastes is transported through an under-group pipe or pipes to the periphery of a town.

Disposal

At the outskirts, the water is treated to make it harmless and their disposed-off.

sewage

Liquid wastes containing suspended, colloidal and dissolved solids is called

Domestic sewage

Liquid wastes coming from latrines and urinals

Sewer

A pipe or conduit which carries sewege

Sewerage

Network of sewers or pipes used for the purpose of transporting sewage.

Water treatment

This consist of a chain of treatment operations which reduce its volume and strength after which it renders the waste harmless and is suitable for disposal.

Raw waste

Untreated waste which is in fresh state

Sullage

Liquid waste flowing from kitchen and bathrooms

Industrial Sewage

Liquid wastes generated from industrial processing units

Municipal Sewage

all liquid waste namely domestic, industrial and storm water generated within the municipal area.

Combined Sewage

when sanitary sewage and storm water is mixed it is called

Separate Sewer

it is an underground pipe which carries either storm water alone or sanitary sewage alone.

Combined sewer

it is carried by single pipe

Organic matter

living or dead, human, animal and plant matter and their waste discharge, which is highly unstable and decomposes with time.

Inorganic matter

inert matter like sand, grit, ashes, etc. which is stable with time.

Surface drain

Roadside channels meant for collection of sullage and rainwater.

Conservancy system

this system has some disadvantages like (1) health hazards to the personnel handling the sewage (2) nuisance conditions prevail while collecting and transporting (3) it is human practice and social injustice

Water carriage system

In this system the wastes from water-closets are collected by flushing with water this water is used to transport the waste to treatment works by a system of pipes.

Conservancy system, Water carriage system

Method of Sanitation

separate, partially separate, combined system

three types of sewerage system

separate system

two separate sets sewers are installed, one for collection and conveyance of sanitary sewage and other for storm water.

combined system

when both sanitary sewage and storm water are carried in a single sewer, it is called

partially separate system

addition to the sanitary sewage, the initial washings from the drainage are due to rains is included in a common sewer.

perpendicular, intercepter, zone, fan, radial

five types of patterns of sewerage lay out

perpendicular pattern

if storm water drains are laid through shortest route to the existing surface water course, it is called

intercepter sewer pattern

collects the excess sewage from all the mains and conveys it to the treatment plant, it is called

zone pattern

if the area is different elevations, then the entire area is divided into zones of different elevations. sewerage system is provided for each zone separately and separate intercepter are laid to collect the flow. it is called

fan pattern

flow is collected from outward to inward, to a central trunk-sewer.

radial patternq

wastewater is collected from heart of the city to outside periphery by two or three trunk-sewers

liters per day

quantity of sewage is expressed by

dry weather flow

the flow of only sanitary sewage in the absence of storms in dry season is known as

population, type of area, rate of water supply, groundwater infiltration

the dry weather flow depends on:

rational method, empirical formulae

storm water flow is estimated by:

area of drainage

the drainage rea is measured from the topographical map of the city.

intensity of rainfall

the intensity of rainfall for a required frequency can be estimated from the ?

time of concentration

it its the time required for rainfall to flow-over the ground surface from the farthest point in the drainage area to reach the outlet point of the area.

sewer appurtances

various accessories on the sewerage system and are necessary for the efficient operation of the system

man-holes

openings of either circular or rectangular in shape constructed on the alignment of a sewer line to enable a person to enter the sewer for inspection, cleaning and flushing.

inspection, cleaning, maintenance of sewer line

objectives of man-holes

at all junction of two or more sewers, whenever diameter of sewer changes, whenever direction of sewer line changes, when sewers of different elevations join together.

location of man-holes provided:

45

diameter: up to 300 - ___ spacing interval

75

diameter: 301 to 500 - ___ spacing interval

90

diameter: up to 300 - ___ spacing interval

beyond 90

any interval depending upon the local conditions

cover frame, access shaft, steps on ladder, working chamber, bottom shaft

man-hole consist of :

cover and frame

made of cast-iron or reinforced concrete. with size of opening should be 50-55 cm diameter, so that a man can enter comfortably.

access shaft

upper portion of a man-hole is known as

steps or ladder

fixed in the masonary wall, at vertical intervals of 30cm in a zigzag fashion

working chamber

lower portion of man-hole where inspection and cleaning is done.

bottom shaft

manholes is constructed with cement concrete of 15cm x 30cm thick floor over which a semi-circular or U shaped channel.

junction chamber

a masonary or concrete structure constructed at the intersection of two large size sewers is known as

drop man-hole

difference in elevation of the invert levels of the incoming and outgoing sewers of a man-hole is more than 60 cm.

flushing man-hole

located generally at the head of a sewer to flush out the deposits in the sewer with water.

junction chamber, drop man-hole, flushing man-hole

special man-hole :

lamp-holes

openings constructed on straight sewer lines between two man-holes which are far apart and permit the intersection of a lamp into the sewer to find out obstructions if any inside the sewers from the next man-hole.

22\.5-30cm

lamphole consists of vertical stoneware or concrete or cast iron pipe of diameter ________ which connected to sewer line through a T-juntion.

street inlets

openings through which surface run-off is admitted and conveyed to the storm sewer or combined sewer.

curb intlet

vertical openings in the openings in the road curb, with grating at top and curb side through which storm water flows into the sewer and they are preferred where heavy traffic is anticipated.

gutter inlets

horizontal openings in the gutter which are fitted with gratings (bars) through which flow passes.

combined inlet

the curb and gutter act as a single unit to allow the flow.

catch basins

small settling chambers of diameter 60 - 90 cm and 60 - 75 cm deep, which are constructed below the street intets.

grit, sand, debris

interrupt the velocity of storm water entering through inlets and allow _____ __,__ ____ __,__ ______ and so on, to settle in the basin instead of allowing them to enter in to sewers.

60cm

the outlet pipe of catch pipe catch basin which is connected to the storm-sewer is fixed about ____ above the bottom of the basin and usually trapped.

flushing tank

is a device or arrangement which is made to hold and suddenly release sewage into the sewer for the purpose of flushing.

1/10

the capacity of flushing tanks should be about ____ of total cubic capacity of sewer line served it.

storm relief works

combined sewers to permit the excess storm-water to be diverted by another sewer into a nearby water course.

overflow weir, leaping weir, siphon spillway

the storm relief works maybe of three types

inverted siphon

depressed portions of sewer which flow full under pressure. they are constructed when a sewer crosses a stream crosses a stream or deep cut or road or railway line

sufficient pumping capacity

__________ has to be provided to meet the peak flow, at least 50% as stands by. two or more pumps are always desirable at sewage pumping stations.

100mm

the minimum opening at both suction and delivery ends of pumps shall not less than ______ of diameter

centrifugal, pneumatic ejector

types of pumps

centrifugal pumps

classified based on their specific speed (N/s)

specific speed

speed in impeller in rpm at which

axial, mixed, radial

types of centrifugal

axial flow pump

head us developed by the **propelling** of the impeller vanes on the liquid.

mixed flow pump

pumps develops head partly by centrifugal action and partly by the lift of the impeller vane on the liquid.

radial flow pump

head development is by the action of centrifugal force.

pneumatic ejector pump

mostly used for lifting large quantities of sewage for low lifts, though their effieciency is

40%

compressed air pressure required should be at least ____ higher than that required to rise all the

15 years

wet well, dry well, suction and delivery pipe, masonary structure

types of pumping station

wet well

all drained sewage is collected

dry well

where the pumps are houses

suction and delivery pipes

with control valves

masonary structure

to store all the above

rectangular, circular in shape, circular in shape

based on shape, wet and dry

rectangular

with dry and wet well adjacent to each other

circular in shape

the central dry well and peripheral wet wll