2.  Introduction
 Method of excreta disposal
1.Unsewered Areas:
-Service type latrines
-Non-service type latrines
2.Sewered disposal
-Water carriage system & sewage treatment
 Conclusion

3. INTRODUCTION
 According to WHO: “Sanitation generally refers to the
provision of facilities and services for the safe disposal
of human urine and faeces. Inadequate sanitation is a
mojor cause of disease world-wide and improving
sanitation is known to have a significant benefecial
impact on health both in households and across
communities.”

4. METHOD OF EXCRETA DISPOSAL
I. UNSEWERED AREAS:
1. Service Type Latrines (Conservancy system):
Night soil is collected from pail or bucket type of
latrines by human agency, & later disposed of by
burying or composting.
2. Non-service type (Sanitary latrines):
a. Borehole latrine
b. Dug well or pit latrine

5. c. Water-seal type of latrines
i.P.R.A.I
ii. R.C.A type
iii. Sulabh Shauchalaya
d. Septic tank
e. Aqua privy
3. Latrines suitable for camps & temporary use:
a.Shallow trench latrine
b.Deep trench latrine

6. SEWERED AREAS:
1.Water-carriage System:
a.Household sanitary fittings
b.House drain
c.Public sewer
d.sewer appurtenances
2.Sewage Treatments:
a.Primary Treatment
-Screening
-Removal of grit
-Plain sedimentation

7. b.Secondary Treatment
-Trickling filters
-Activated sludge process
c. Other Methods:
-Sea Outfall
-River Outfall
-Sewage Outfall
-Oxidation ponds

8. Excreta disposal in unsewered
areas:
1. Service Type (Conservancy System):


Colletion & removal of night soil by human agency is
called service type or conservancy system & the
latrines are called as service latrines
The night soil is carried by night ‘soil carts’ to the
place of final disposal where it is disposed by:
i. Composting
ii. Burial in shallow trenches

9. 2. Non-service type of latrines (Sanitary
Latrines):
 Excreta sould not contaminate the ground or surface
water
 Excreta should not pollute the soil
 Excreta should not be accesible to flies, rodents,
animals & other vehicles of transmission
 Excreta should create a nuisance due to odour or
unsightly appearance

10. TYPES OF SANITARY LATRINES:
1. BORE HOLE LATRINE:



It is the forerunner of the nonservice type of latrines.
First introduced by Rockefeller
foundation during 1930’s.
It consist of a circular 30 to 40
cm in diameter dug vertically
into the ground to a depth of 4-8
cm most commonly 6m.

11. 



Auger is required to dig a bore
hole.
In loose soils the hole is lined
with bamboo matting or earthen
ring.
A suitable foot rests is placed
over the hole
When the contents reach within
50 cm the squatting plate is
removed & the hole is closed.
Auger

12. MERITS:
 No need of services of a sweeper
 The pit is dark & unsuitable for fly breeding
 If the bore hole is located 15 m away from a source of
water supply there should be no danger of water
pollution.
DEMERITS:
 Bore hole fills up rapidly
 Auger is required which may not be readily available
 Difficult to dig a hole deeper than 3 m in loose soil

13. 2.DUG WELL OR PIT
LATRINE:
 First introduced in Singur, West Bengal in 1949-1950
 A circular pit about 75 cm in diameter & 3-3.5 m deep
is dug into the ground.
 In sandy soil the pit deepness is reduced to 1.5- 2 m.
 Pit is lined with pottery rings to prevent caving of the
soil.
 A concrete squatting plate is placed on top of the pit &
the latrine is enclosed with a superstructure.

14. ADVANTAGES:
 Easy to construct & no special equipment is required.
 The pit has longer life because of greater cubic capacity.
 A pit of 75 cm diameter & 3-3.5 m deep will last for about 5
yrs for a family.

15. 3.WATER SEAL LATRINE:
 Improvement in the designing for rural families is the
hand flushed “water seal” type latrine.
 Squatting plate is fitted with a water seal.
 2 important function:
1. Prevent access of flies by
a small depth of water in
a bent pipe called trap.
2. Prevents escape of odours &
foul gases & thereby eliminate
the nuisance from smell.

16. Sulabh shauchalaya:
 Invention of a patna-based firm.
 Low cost pour-flush, water seal type of latrine.
 It consist of specially designed pan & a water-seal trap.
 It is connected to a pit 3 feet square & as deep.
 Excreta undergoes bacterial decomposition & is
converted to manure.
 Requires very little water.

17. 4. SEPTIC TANK
 Key component of the septic system.
 A small-scale sewage treatment system common in
areas with no connection to main sewage pipes
provided by local governments on private
corporations.
 It is a satisfacory means of disposing excreta & liquid
wastes but do not have access to a public sewerage
system.

18. DESIGN FEATURES:
 There are various designs: single chambered & double
chambered septic tanks.
 Single chambered: for small installations.
 Two compartments are expensive.
The main design features:
 Capacity: The minimum capacity should be 500
gallon.
 Length: length is usually twice the breadth.
 Depth: 1.5-2 m.

19.  Liquid depth: 1.2 m
 Air space: Minimum of 30 cm between the level of
liquid & undersurface of the cover.
 Bottom:
 Inlet & outlet:
 Cover:
 Retention period:

20. Working of Septic Tank:
 The solids settle down to form sludge.
 Lighter solids form scum.
 The first stage of purification called anaerobic
digestion.
 A portion of solid is transferred into liquids & gases
in the form of bubbles.
 Effluent contains numerous bacterial, cysts, organic
matters in solution or fine suspension.
 The effluent is allowed to percolate into sub-soil by
means of perforated or open-jointed pipes laid in
trenches.

21.  Millions of aerobic bacteria in the upper layers of soil
attack the organic matter present in the effluent.
 Thus the organic matter is oxidised into stable end
products.

22. Operation & Maintenance:
 Use of soap water & disinfectants should be avoided as
they are injurious to bacterial flora.
 Desludging: Contents of the tank should be bailed out
atleast once a year.
 New built tank is first filled with water & then seeded
with ripe sludge from another septic tank.

23. 5. AQUA PRIVY:
 It functions like a septic tank.
 It consist of a water-tight chamber.
 A short drop pipe dips from latrine floor into the
water.
 The shape of the tank may be circular or rectangular.
 A capacity for 1 cubic m is recommended for 6 yrs or
more.

24.  Night soil undergoes purification
by anaerobic digestion.
 A vent should be provided for
escape of gases.
 It should be treated the same
manner as the septic tank.
 The digested sludge should be
removed at intervals.

25. LATRINES SUITABLE FOR TEMPORARY
USE:
1. SHALLOW TRENCH LATRINE:

Simple trench

30 cm wide & 90-150 cm deep.

Length depends on number of users: 3-3.5 m for 100
people.

Seperate trenches for men & women should be provided.

26. 
Earth from trench should be piled up at the side.

Its an arrangement for a short period (1 week).

It must be covered when the trench is filled 30 cm
below the ground level.

27. 2. DEEP TRENCH LATRINE:
 Intended for longer duration( a few week- a few
months)
 Its 1.8-2.5 m deep and 75-90 cm wide.
 A superstructure is built for privacy & protection.

28. II. SEWERED AREAS
WATER CARRIAGE SYSTEM:
 Its collecting & transporting of human excreta & waste
water by a network of sewers to the place of ultimate
disposal.
 There are 2 types of carriage system:
i.The combined sewer system: (sewage & surface water)
ii.The seperate sewer system: (sewage)

29. A Water Carriage System consists of the
following elements:
1. HOUSEHOLD SANITARY FITTINGS:
The usual household sanitary fittings:
i.Water closet,
ii.Urinal, &
iii.Wash basin.

30. i.
WATER CLOSETS:

2 types: Indian Squatting type & Western Commode
type.

The water closets are provided with a ‘flushing rim’.

The closet is connected to a cistern by a pipe 2.53.75cm in diameter.

The flushing cistern normally holds 15 l of water

31.  For efficient performance of water closet:
-Water seal area should not be more than
7.5 cm.
-There should not be any sharp corners in
the trap.
-The volume of water should not exceed
1.75 l to maintain a minimum of 50 mm
deep water seal.
-The interior of the bowl should be
vertical atleast 50-75 mm just above the
surface of water seal.

32. 2.HOUSE DRAIN:
 10 cm in diameter & is laid in the courtyard about 15
cm below the ground level.
 The house drain empties the sewage into the main
sewer.
3.PUBLIC SEWER:
 Not less than 22.5 cm in diameter, bigger ones may be
2-3 m in diameter.
 Laid 3 m below ground level with ‘self cleansing’
velocity of 2-3 feet per second.

33. 4. SEWER APPURTANCES:
 These are manholes & traps.
 Manholes are placed:
i. whenever there is a change in direction of sewer.s
ii. at the meeting point of 2 or more sewers.
iii. at distance of 100 m in long straight runs.

34.  Traps are placed in 3 situation:
i.under the basin of water
closet
ii.where the house drain joins
the public drain
iii.where surface wastes water
enters the drain.