1006 PLANNING WATER SUPPLY AND SANITATION PROJECTS IN DEVELOPING NATIONS
3) Should be simple and inexpensive to construct
and operate
4) Should not cause ground water or surface water
contamination
5) Should not cause soil contamination.The appropriate technology for human waste disposal in
developing nations fall into two major applications (1) rural,
and urban areas without sewers, and (2) urban areas having
municipal sewers. Appropriate technology for each of the
above applications are discussed below:
Rural and Urban Areas without Municipal Sewers
The environmentally acceptable methods of human waste
disposal in rural areas include various types of sewerless
composting toilets. Common examples of such toilets are
bored-hole latrine, pit privy, vault privy, septic privy, chemi-
cal toilet, soil or composting toilet, methane forming toilet,
and box-and-can privy. 26,27 These devices are simple and
inexpensive to build and operate. Each of these devices is
briefly discussed below.
Bored-hole Latrine: Bored-hole latrines consist of a hole
in the ground 25 to 60 cm in diameter, and 2 to 3 meters deep.
The hole may be braced to prevent it from caving. A concrete
slab with a hole cut in it may be placed over it, and the entire
assembly is made into an outhouse. When the hole is filled,
the structure is moved to another hole. Fly and odor problems
are controlled by keeping the hole covered, and dropping dry
soil in the hole on a regular basis. Deep bored-hole latrines
present danger of ground-water pollution.^26
Pit or Vault Privy: Pit or vault privies can serve the needs
of homes, schools or groups of homes. A concrete pit or vault
is constructed in the ground and a toilet seat is located on
the top. The seat cover must be kept closed to prevent flies
from entering. Odor is a problem. A vent pipe raised over the
roof has been helpful in odor control. In 3 to 4 months when
the pit or vault becomes full, there is the unpleasant job of
cleaning it. Some vaults have two compartments. When one
compartment is full it is kept closed for 2 to 3 months while
the other side is used. During this time, the excreta is decom-
posed, and cleaning becomes less objectionable. Pit or vault
privies with separate back covers have also been used. These
back covers help in the cleaning operation.^26
Septic Privy: Septic privies utilize a liquefying tank
similar to a septic tank. The waste is digested and overflow
may be discharged into a percolation field. The toilet has a
shallow trap. After use the toilet must be flushed by pouring
2 to 3 liters of water.^26
Chemical Toilet: Chemical toilets consist of a tank in
which waste accumulates. The toilet seat is provided directly
over the tank. Caustic soda (sodium hydroxide (NaOH))
is most commonly used to kill the bacteria and to liquefy
the wastes. The caustic soda dosage is 1 to 2 kg of sodium
hydroxide per month for a family of four. The tank is emptied
periodically. If caustic soda is used the tank contents can be
carefully applied over farming land. Many types of chemical
toilets are available from various manufacturers. 26,28,29
Soil or Composting Toilet: This is dry toilet capable of
being used indoors. The toilet consists of a wooden framewith toilet seat, and a bucket lined with a plastic bag. The
toilet is started with a layer of dry soil 10 to 15 cm deep.
Users must sprinkle several scoops of soil after each use.
Once or twice a week, the bag is removed, tied and stored.
After a decomposition of several weeks the contents are
spread over farm land.^30
A more involved is the Clivus Multrum composting
toilet. This toilet was developed and has been successfully
used for some time in Sweden and is now manufactured
in the United States.^31 The toilet is capable of composting
toilet waste, kitchen wastes, and even leaves and grass. It
has three sloping chambers and is started with a layer of peat
moss four to five inches thick. Design and operational details
may be obtained in Ref. 31. Another toilet similar to Clivus
Multrum toilet is the Toa-Throne compost toilet also devel-
oped in Sweden.
Another dry composting toilet that has been proven
highly successful in Vietnam, offers a suitable system for
all developing nations.^32 The toilet consists of two-holer
outhouse in which only one hole is used at any one time.
There is no raised seat, instead each hole is placed in a squat-
ting plate at floor level. The urine flows out and soaks into
the ground outside the outhouse. The fecal wastes go into
the other hole. The user must drop dry soil or ash after use.
When the toilet is two-thirds full, the rest is filled with soil,
and the vault is tightly sealed. The other side is started. After
a composting period of approximately 45 days the contents
are taken out and used over the farm as rich compost. 33,34
Methane Farming Toilet: In India small biogas plants are
extensively built in rural areas. These biogas plants anaero-
bically digest animal manure and other organic wastes, and
the methane is used to light, heat, and power the farms.
Singh gave the basic design and construction details of
such toilet.^34 Other designs of anaerobic digesters utilizing
human, animal and other organic wastes are used in Kenya
and Brazil. 35 – 37 Morris developed a package unit for meth-
ane generation from human wastes.^37 Khandelwal provided
design and operational details on dome-shaped biogas plants
used in India.^38 Eusebio and Rabino provided design of large
biogas plants used in Philippines, India and Africa.^39
Box-and-can Privy: The toilet system consists of a
wooden box, the lid and toilet seat. The can or pail is remov-
able through the top or side of the box. The cans are removed
manually under regular scavenger service, emptied, cleaned,
and replaced. This system is most commonly used in cities
that do not have a sewerage system.
This type of system is associated with odors and serious
fly problems if the lids are not tightly closed after use. For
satisfactory operation there should be a regular scavenger
service, preferably under a governmental supervision with
ordinances covering types and size of box and can, method
of emptying and cleaning of the cans, and ultimate disposal
of the human waste. A speedy and convenient way is to use
identical toilet boxes and cans for the entire community. The
scavengers remover the can and place it in his vehicle without
emptying, and replacing a clean can. The vehicle when full is
taken to a central disposal facility for emptying, and replac-
ing with clean cans. The disposal facility should be located inC016_008_r03.indd 1006C016_008_r03.indd 1006 11/18/2005 11:01:58 AM11/18/2005 11:01:58 AM