Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>
The compost and hygiene
To keep the composting
toilet system simple and sustainable it is important that the end product can
be disposed of by the users within the house site. Therefore the compost should
be free of disease causing organisms. Testing the compost reveals how effective
the composting process has been within a particular time frame, and indicates
guidelines for usage.
Six of the
toilets were ready to be emptied of compost during the September 1995 visit.
The compost in each case had the appearance of decomposing bulking agent
(whichever leaves or fibre had primarily been added to the toilet during use)
and had a pleasant humus odour.
To maintain the composting
process, it is preferable that a small handful of bulking agent such as dry
leaves or coconut fibre be deposited in the toilet after defecation to allow a
suitable mix of material containing nitrogen and carbon.
If people forget to add the bulking agent,
the pile will eventually smell unpleasant.
Usually if a quantity of leaves is then deposited in the toilet, the
As many housewives in
Kiritimati sweep up leaves around the house each day and burn them, it was not
too difficult for them to collect enough leaves to have a ready supply by the
When the bin that is being
used is full, it is simply a matter of unscrewing the pedestal and changing it
over to the side of the empty bin. The
toilet can also be designed to have a pedestal or squat plate over each bin so
there is no need to make a change.
However changing the pedestal and closing the first bin ensures that no
one will mistakenly use the bin that is now undergoing a fallow period.
When the fallow period is
complete the compost can be shovelled out of the bin and mulched around fenced
fruit trees. If the trees are not
fenced, pigs and chooks will dig up the compost and scatter it around.
The pedestal rarely requires
cleaning as it is low and splayed to avoid material collecting on the
inside. If the seat becomes dirty it
can be wiped with wet leaves or rags and then these can be dropped into the
As Kiribati women are
responsible for sanitation in the home, all the above chores were conducted by
the female head of the family, without any apparent difficulty.
Most women reported that it was easier than
looking after a water based toilet.
It would be unusual for the
drain to become blocked as solid matter is filtered through the false floor at
the base of the bin. However, if
necessary, the pipe to the trench is approximately half a meter long and could
be cleared with a stick through the access point.
Material for repairs to the
building frame or the concrete bins would be available on the island.
There is little else that requires
maintenance in this alternating batch composting toilet design.
The introduction of
composting toilets requires considerable input from local personnel skilled in
a health education and community consultation probably over 2-3 years.
Curriculum Development Officer to work
with teachers and students in the schools on water quality and sanitation
issues would be most useful at the beginning of the project.
For government housing a Sanitation Officer
responsible for basic maintenance of toilet structure and on-going advice as to
usage of the toilet and the compost would need to be on call in the same way as
a plumber would be readily available for attention to waterborne systems.
This person should receive remuneration that
reflects his or her essential role in the community to counteract any negative
association attached to people who take care of toilets.
For long term residents in non government housing
most maintenance issues could be handled by the householder once they have been
exposed to the initial education program, and are in the habit of using the
If composting toilets are
initially to be introduced by expatriates it is important to include both
female and male team members.
Implementation will depend primarily upon the co-operation of the women
in the community, and sensitive issues are more effectively discussed between
persons of the same gender. Initiating
the gardening program should be undertaken by a person with cultural awareness
and good people skills in addition to having experience with the hygienic use
of human excreta in cultivation, and small plot gardening in physically
Water Based Sanitation Systems
A centralised sewerage
system was installed in Tarawa the capital of Kiribati and some maintenance and
pollution problems have been experienced as a result.
Pits, aqua privies and septic tank toilet systems have also been
installed with the assistance of aid donors and used on Kiritimati for many
years. It is often considered to be an
indication of status to have a flush toilet in the house.
Health education programs have been
conducted throughout Kiribati over the last 40 years to deter people from using
the traditional location of the bush and the beach for defecation, and to use a
water based toilet or pit latrine instead.
In some places people have been fined a dollar if they were caught using
the beach and their excrement was not immediately removed by the tide.
I-Kiribati initially found the water based
toilets unacceptable for a variety of reasons but over time and with the
persistent efforts of community heath educators the flush toilets have been
accepted and increasingly desired by the I-Kiribati.
It is therefore a very difficult adjustment to be now told (once
again by outsiders) that water borne sanitation systems may be contributing to
the high incidence of enteric disease on the island and that a practice that
was advocated as a health measure may be a cause of ill health.
It is understandable that the composting
toilet trial has been viewed with considerable wariness and scepticism, and
technology transfer must be conducted with caution, patience and some degree of
In the case of
the aqua privy and the septic tank system the effluent from the toilet is
discharged directly to the ground water.
The septic tank if well maintained provides primary sedimentation but in
any circumstances does little to reduce pathogens, BOD or nutrients in the effluent.
Berg et al. (1976:: 175) suggests that primary sedimentation will not remove
viruses at all, and if such effluent is chlorinated will only remove 50% of
viruses. If the septic tank is not
emptied when necessary then solids will also overflow into the leachfield.
The truck used for emptying septic tanks has
been out of action for some time on Kiritimati so the residents either allow
the tank to overflow or empty the tanks by hand and dispose of the sludge nearby,
or in the lagoon. The appropriately
sized horizontal trench that can ordinarily provide some treatment of the
effluent from septic tank is not used in Kiribati because of the highly porous
soil and the inclination to flooding in the rainy season.
The leachfield is instead a vertical funnel
that facilitates direct drainage to the ground water.
As water borne enteric diseases such as Giardiasis are very
common on Kiritimati, it is likely that reinfection is maintained partly
through contaminated water. However,
this has not been empirically proven.
Transmission of disease would also be caused through not washing hands
after defecation and from flies that come in contact with exposed faecal
Thorough research and
development of mesophilic composting toilets for application in a variety of
resource constrained circumstances in the developed and developing world is a
relatively recent phenomena. This study
is certainly not presented as the final word on the subject.
It is hoped that the technical and
educational developments that have occurred to date will be expanded upon by
those most suited to do so, that is, the individuals and communities that use
the toilet, and adapt it to their own needs.
Although the composting toilet is strongly recommended as a simple
sustainable sewage treatment option it is not the intention of the author to be
a technological missionary on this issue.
While advocating due
consideration of composting toilets it is not implied that centralised sewerage
systems or on-site water borne methods such as septic tanks or pourflush
latrines do not have a valid role. It
is rather to suggest that in any country, the most appropriate technology
should be applied in each location, and that the selection from a range of
equally accessible technical options should be based on a thorough appraisal of
the cultural, socio-economic and ecological context to be serviced.
An Australian funded project constructing composting toilets on Kiritimati
is currently being implemented. Thus
the suitability of composting toilets on Kiritimati will not be know for
another year or two.