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<Sourcebook of Alternative Technologies for
Freshwater Augumentation PART C - CASE STUDIES 5.4 Composting Toilet Trial on Kiritimati, Kiribati Introduction In June 1995, a trial of composting toilets was initiated and funded on Kiritimati, Kiribati, by the Australian Government. The trial was conducted by a multi-disciplinary team from the Centre for Environmental Studies at the University of Tasmania, in co-operation with I-Kiribati counterparts, as one of several trials of composting toilets in the Pacific region. Other trials included a project conducted by Greenpeace in the Federated States of Micronesia (FSM), during 1992 and 1993, which involved the installation of two commercially-available designs and one locally-built composting toilet; and, the recent installation of 30 toilets, using 3 different commercial designs, on the Torres Strait islands (between Australia and Papua New Guinea). The Greenpeace trial in the FSM involved extensive community consultation at the implementation stage, while the Torres Strait trial had little community participation. However, neither of these projects resulted in the expanded use of composting toilets.
Figure 41. Line Islands, Republic of Kiribati, showing the location of Kirimati. Kiritimati (Christmas Island) or Abakiroroa (Faraway Island) is a coral atoll in the Line Islands, Republic of Kiribati. Kiribati is a small island nation of 33 coral islands dispersed along the Equator in the Central Pacific. There are three groups of islands and atolls, and Kiritimati is the southernmost atoll in a chain of islands known as the Northern Line Islands (Figure 41). Kiritimati is the largest coral atoll in the world, with a land area of 320 km2, and a total area of 640 km2, including a central lagoon, and many other lagoons, most of which are landlocked and hypersaline. Kiritimati has a highly variable rainfall pattern with an average of about 860 mm per year. The present population is approximately 3 000 people living in five villages: Banana, London, Poland, Main Camp, and Tabakea. Most of the I-Kiribati residents, except in Tabakea, are families of government employees. The land on the island is owned by the government of Kiribati. Water supply is provided from rooftop catchments or drawn from the groundwater (from freshwater lenses) by the use of wells, and there is some reticulation (see also Part C, Case Studies). The limited number of rainwater tanks is due to the erratic rainfall and long periods of drought. Groundwater is pumped from infiltration galleries constructed to skim freshwater from the top of the lenses. Deterioration in the quality of the groundwater has occurred through localised overpumping of the lenses. The groundwater is also affected by bacteriological and chemical pollution from human activities, particularly domestic pigs and dogs, latrines and septic tanks, greywater soakaways, fuel storage facilities, agricultural activities, and open rubbish and Babai (taro) pits . Technical Description The locally-built, dual-chamber batch composting toilets, shown in Figure 42, are characterised by two adjacent cubic chambers, approximately 1 m square on the sides, the top of which forms the floor of the toilet building; a pedestal or squat plate which opens into each chamber alternately; a floor grate to allow drainage of liquid into a drainage tray below; a drainage tray with a 50 mm outlet approximately 25 mm above the base of the tray that allows a standing liquid level as well as access in case of blockage; hinged doors to prevent the entry of flies; mesh-covered vent holes and a vent pipe that extends from the top of the chamber to approximately 1.5 m above the roof of the toilet building; and, a toilet building is erected on the top of the two chambers with the stairs and the door on the side opposite to the chamber doors.
Figure 42. Locally-built batch compost toilet. The average household size on Kiritimati is approximately 7 persons, although household sizes vary from 2 to more than 20. The variation of a particular household size over time appears to be greater than the variation between households. Despite this variability, estimates have been made of the required fallow volume of composting chambers see Table 9. On the basis of these assumptions, material deposited in the toilets should fill the composting bins in approximately six months, assuming an 800 l in volume for the composting chamber and making allowance for the volume of starting bulking agent and air space above the pile. TABLE 9. Estimated Generation of Material in Composting Toilets in Kiritimati.
Toilets can be constructed with stairs with hand rails, or concrete or timber ramps to facilitate access for the elderly or the disabled if required. It may also be possible to create a graded access to the toilet. Ideally, houses with raised floors, which are appropriate to Kiritimati conditions, could be designed with toilets attached to the house and staged access incorporated into the house design. The toilet buildings themselves should be able to accommodate the use of traditional wall cladding and roofing, such as coconut thatch for the roof and coconut sticks for the walls, as well as non-traditional cladding and roofing materials such as fibro and zincalume. It is recommended that the plumbing system providing for the drainage of liquid from the toilets be constructed of piping with a 50 mm minimum diameter; that a standing-liquid level of at least 25 mm be incorporated in the design; and, that access to clear blockages be ensured. Excess liquid is drained from the toilet into an evapotranspiration trench to ensure that such drainage does not reach the surface or contaminate the groundwater. The trench should be sized to minimise the probability of surcharging and planted with plant species that maximise evapotranspiration from the trench. The following indigenous species are suggested: Lepturus repens, a clumping grass; Fimbristylus cymosa, a sedge; and, Boerhavia repens, a ground cover. Numbelle, a hardy tree with edible leaves, can also be planted on the trench, and has been introduced on Kiritimati as part of the nutrition program. Raising the trench can prevent surface runoff from entering the trench and will maximise rainfall runoff from the top of the trench. A trench that is 2 m long, 600 mm wide, and 500 mm deep will have a less than 2% chance of surcharging, based on rainfall records for Kiritimati from 1917 to 1983, and assuming year-round discharge to the trench; a typical system would incorporate two such trenches, used alternately. In addition, each trench should be fitted with a durable plastic (e.g., HDPE) liner of at least 2 mm thickness. It should be buried in a trench on a bed of coral aggregate (which will deter crabs from burrowing underneath), and backfilled with coral aggregate around a slotted plastic pipe and topped with 200 mm sand, as shown in Figure 43. Food crop trees, such as papaya, banana or breadfruit, can then be planted adjacent to the trenches to further assist evapotranspiration. Plants or trees which provide organic matter for use as a bulking agent could also be planted on the trenches. Fencing is required to exclude domestic animals and children from the evapotranspiration trench area. However, suitable fencing remains an ongoing problem due the high cost of fencing materials (Table 10).
Figure 43. Sketch of the evapotranspiration trench. TABLE 10. Prices of Fencing Materials.
Extent of Use In 1982, the Government of Kiribati requested assistance from the Australian Government to improve and protect the Kiritimati water supply coincident with the opening of Kiritimati to immigration. A succession of studies and design missions to the island by a number of aid agencies over the subsequent 13 years have attempted to define the problems and propose solutions for water supply, development and other related issues. The Kiritimati composting toilet trial became part of the water supply project due to the reluctance of a donor government to reticulate contaminated water to the community, given the high incidence of enteric disease on Kiritimati (one source of transmission of these diseases is likely to be faecally-contaminated water), and it decided that effective sanitation be attended to at the same time that the water supply system was installed. The toilet sites were chosen in June 1994 by lottery as many people on the island had no toilet and wanted one, the lottery being considered the fairest means of site selection, and 12 toilets were installed in three villages on Kiritimati during November 1994. Because of pressure to start the project as soon as possible, the toilets were designed and prefabricated in Australia and shipped to Kiritimati. Eight of the toilets were of the Wheelibatch design shown in Figure 13 and four were Cage Batch designs; both designs are alternating batch toilets. The Wheelibatch toilets were installed in domestic locations on Kiritimati and the two large Cage Batch units were installed at the primary schools in two of the villages. One of the smaller Cage Batch units was installed at a community clinic that was being funded by the village residents, and the other was installed in a domestic location where the extended family members often numbered more than twenty. Due to concerns expressed by Ministry of Line and Phoenix Development staff that use of the prefabricated toilets would not be sustainable due to lack of locally-available spare parts and expertise once the aid programme was completed, three more toilets were constructed using an owner-built design at non-government houses where the owners were long-term residents, responsible for their own dwellings and leased land. It was thought that the response of these residents would more likely reflect that of the normal I-Kiribati villager. These participants were chosen by the Mayor of the village and the village committee of elders. Two of the toilets were given to families who had elderly disabled men as heads of the household, primarily as a sign of respect, and the third toilet was given by lottery to one of the many households that had requested a toilet when the project first began. The Mayor also offered to fund and build his own toilet to the Australian design (he had previously installed two septic-tank flush toilets in his home). Because of his understanding of the potential dangers to the water quality of the lenses from septic effluent, he intended to decommission the flush toilets when his composting toilet was built. In a similar manner, the men of each household who were to receive the toilets would be involved in the construction of their own toilets. Use of the prefabricated toilets during the 10 month project; women were more inclined to use the toilets as they offered some privacy, while teenaged boys reported that they were embarrassed to be seen entering the toilets, and the men preferred to use the bush or the beach. Toward the end of the trial, some families reported that everyone was using the toilet including the men. The gardening programme resulted in a significant increase in the participants= interest in the composting toilets. Use of locally-built toilets was much more consistent from the outset. This may have been due to the more integrated design and because they had been built by village residents. At the schools, the usage was consistently low for a number of reasons. The toilet was rather conspicuous and the children were sometimes teased for using it. The teachers insisted on locking the toilet so the children had to ask the head teacher for the key. As many of the children had chronic diarrhoea, this would have been a demanding requirement. Most of the teachers did not use the compost toilet but continued to use flush toilets in the teachers= houses nearby, which would not have provided very encouraging example to the children. The teachers became more interested in the composting toilet through the gardening program, and it is anticipated that, when a greater number of people have composting toilets at home, the children will feel less conspicuous using the toilets at school. Operation and Maintenance To maintain the composting process, it is preferable that a small handful of a bulking agent, such as dried leaves or coconut fibres, 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 develop an unpleasant odour. The smell usually disappears after a quantity of leaves is deposited in the toilet. As many housewives on Kiritimati sweep up leaves around the house each day (and burn them), it is not too difficult for them to collect enough leaves to have a ready supply by the toilet. 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 fallow bin. 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 these can be dropped into the toilet as additional bulking agent. In Kiribati, women are responsible for sanitation in the home, and were able to complete all the above chores without any apparent difficulty. Most women reported that it was easier than looking after a water based-toilet. 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 poultry will dig up the compost and scatter it around. For the elderly or disabled who could not climb the stairs to the toilet, a relative collects their excrement in a basket lined with leaves and deposits the contents in the toilet. It is common practice to provide a pan to those confined to the house, so emptying the material into the composting toilet is not too much of an adjustment. Disabled persons who were more agile were able to climb the stairs with assistance. If the toilet happens become blocked, the unit can be cleared with a stick inserted through the access point in the outlet pipe. The drainage connections are standard polypipe hose fittings and unlikely to need replacing as they remain connected, except for the odd occasion when the drain needs to be unblocked. Building repairs to the frame or concrete bins could be made with locally-available materials. If the false floor in the bins is made of treated pine, the timber may slowly rot and require to be replaced every six or seven years. This is a simple carpentry task. The pedestal used in the trial was made of fibreglass and the vent pipe was PVC, although other materials could be used or substituted during subsequent repairs. Little else requires maintenance in this alternating batch composting toilet design. Level of Involvement The introduction of composting toilets requires considerable input from local personnel skilled in health education and community consultation probably, probably over a 2 to 3 year period. A curriculum development officer to work in the schools with teachers and students on water quality and sanitation issues would also be useful. 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 water-borne 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 composting toilet. 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 cooperation of the women in the community, and sensitive issues are more effectively discussed between persons of the same gender. Likewise, initiating a gardening programme should be undertaken by a person having both experience with the hygienic use of human excreta in small-plot gardening in physically antagonistic circumstances, and awareness of local cultural considerations. An informational programme was undertaken as part of this project to inform the community about composting toilets. As each culture has different attitudes about sanitation, and each community has different requirements and limitations, ongoing consultation with the residents was a critical aspect of implementation. The development of the informational programme was developed with the assistance of I-Kiribati staff. The informational programme developed included a documentary/educational video (made in cooperation with two committed women on a shoe-string budget), posters, and T-shirts. A song about the toilets, and mimed dance, were composed with the input of the school teachers and the Chief of Police, and most of the children could sing it after a couple of lessons. There were regular discussions with all the trial participants on a one-to-one, and on a group, basis. One of the most effective strategies for sustained community involvement was the gardening programme that was undertaken at each trial site by the householders or persons responsible for the toilets. This involved planting fruit trees and the establishment of a modest vegetable and flower garden if the householder expressed interest. This joint effort served to create relationships that helped to bridge the language and culture gap, create more enthusiasm for the composting toilet, and reinforced the sanitation project , the English meaning of which translates as "Working together for healthy families, clean environment, fertile gardens and pure water". The sanitation-garden programme was linked to a community-wide gardening competition which was being conducted as part of a nutrition programme by the Health Department. Costs The approximate unit cost of the locally-built composting toilets on Kiritimati, including the toilet building, was between $1 500 and $2 000, including all materials, I-Kiribati labour, and the liquid drainage trench construction. A breakdown of these costs is shown in Table 11. Effectiveness of the Technology The composting toilet system will be sustainable if the end-product can be disposed of by the users within the house site. For this reason, the compost must be free of odours and disease-causing organisms, and have a not unpleasant appearance. Six of the toilets included in this project were ready to be emptied of compost during September 1995. 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. TABLE 11. Approximate Unit Costs of Composting Toilets, Buildings and Liquid Drainage Trenches.
Samples of compost from the bins were inspected for the presence of Ascaris lumbricoides (round worm), Trichuris trichiura (whip worm), Ancylostoma duodenale, Nector americanus (hook worm), and intestinal protozoan cysts. Bacterial tests of the compost were also undertaken. Samples of pig faeces from an enclosed pen, liquid from a drainage trench, and a fresh stool from a child from one of the trial households were included in the tests as baseline data on enteric pathogens. Trichuris trichiura (whip worm) eggs were detected in all the compost samples inspected (Table 12), which accords with information received from health workers who reported that whip worm was the single most common worm infection on the island. However, composting for at least six months appeared to be sufficient to destroy the Trichuris eggs, as the eggs in compost showed signs of degradation. In addition to the Trichuris eggs, the fresh faeces contained a large number of Giardia lamblia cysts, which was also confirmed as prevalent by the health workers. However, there was no evidence of Giardia cysts in the compost. Subsequent laboratory tests indicated a total absence of faecal coliform, faecal streptococci, shigella, and salmonella bacteria in the compost samples. A number of pH tests were also performed in the laboratory on the compost using a Gallenham single-probe pH stick (Table 13) and indicate a range that could be expected with mature, stable compost. TABLE 12. Results of Pathogen Testing of Compost Samples: September 1995.
a Test not performed, assumed to be numerous. Advantages The advantages of installing a locally-designed composting toilet include increased local participation in, and ownership of, the project; increased familiarity with the concept and principles of composting toilets through owner-building; increased likelihood of sustainable maintenance due to the use of locally-available materials; immediacy of construction; groundwater quality protection; reduced water usage compared to water-borne systems; and, production of compost for gardening. TABLE 13. Results of pH Tests on Compost Samples.
Disadvantages Disadvantages of this technology include access problems for the elderly and disabled; creation of potential health hazards if the compost is removed too early; proliferation of insects if the toilet lid is not kept down; and, cost (the units could be too expensive for island people to afford). Cultural Acceptability Introduction of new sanitation technology in any culture is a complex and sensitive process as it affects peoples' lives in the most intimate manner. In Australia, on the occasions when composting toilets have failed, there was a lack of an information component in their implementation, or inadequate pre-sales consultation and after-sales support. In Kiribati, taboos related to sorcery were a concern as were certain taboos relating to menstruating women using the toilets, although these issues did not seem to be a problem within the family. At the outset, there was a definite aversion to the prospect of using the end-product as compost or any thing else that might result in contact with the waste. However, when the piles in the toilets did produce compost, there was relief and a marked increase in interest in the toilets. Neighbours who had previously been disinterested or even hostile to the project requested a composting toilet because they wanted to be able to use the compost as a soil improvement in their gardens. As previously noted, people were also concerned about using a toilet which was elevated above and climbing the stairs to use the toilet. To conform to a variety of local customs, the toilets were designed with a low pedestal which allowed sitting in a semi-squatting position, and strong enough to support squatting on the seat if desired. In contrast to the composting toilet project, the installation of septic-tank toilet systems on Kiritimati has occurred over many years, and, now, is often considered an indication of status to have a flush toilet in the house. As with the composting toilets, the I-Kiribati initially found these toilets unacceptable, but, over a period of 40 years and with the persistent efforts of community heath educators, the flush toilets have been increasingly accepted. However, recent evidence would suggest that water-borne sanitation systems are contributing to the high incidence of enteric disease on the island. Because septic systems do little to reduce pathogens, BOD, or nutrients in the effluent (Berg et al., 1976), and discharge directly to the groundwater, parasitic reinfection and disease transmission occurs, in part, through contaminated drinking water (Table 14). Dye tracer studies showed that effluent from a decommissioned septic tank, which was continuing to receive grey water, appeared in a drinking supply well, 2.5 m from the tank within five weeks. Given the extended survival rate of certain pathogens in water, especially viruses and worm eggs, this result suggests that effluent from septic tanks could also contaminate wells at some distance from the toilet. These findings, however, no doubt, contributed to the initial scepticism surrounding the proposed introduction of the composting toilets, and created some initial difficulties in community acceptance of these systems as a means to reduce the incidence of water-borne diseases. TABLE 14. Results of Pathogen Indicator Tests of Water Samples.
aWHO drinking water guidelines suggest that E. coli or thermo-tolerant coliform organisms must not be present in 100 ml samples of water intended for drinking. An appraisal of the composting toilet programme, conducted in September 1995, indicated that, of the 316 households participating, 258 households liked the composting toilet. On this basis, it was decided to extend the programme to include some 200 to 300 composting toilets, with the intention of eventually providing composting toilets throughout the island. The project was conducted almost entirely by the two Health Department staff members. Future Development of the Technology Thorough research and development of composting toilets for various applications in both the developed and developing world is a relatively recent phenomena. This study has shown the technology to be a simple, sustainable sewage treatment option, well-suited to the needs of the Kiritimati community. However, further research is required, over a reasonable time frame, to set reliable guidelines for the handling of toilet compost, as appropriate guidelines have not yet been established by regulatory and health authorities for the handling of toilet compost. It is necessary also to identify other factors that may affect pathogen kills, such as the pH and moisture content of the compost, and develop the necessary modifications of this technology. It is important that microbiological and parasitological data be collected and analysed to fully assess the utility of this technology in the longer term. Information Sources Contacts Dr. Leonie Crennan, University of Tasmania, Hobart, Australia. Bibliography Anda, M., K. Mathew, and G. Ho 1991. Appropriate Technology Hygiene Facility for Small Communities. Water Science and Technology, 24(5):163-173. Berg, G. et al. 1976. Viruses in Water. American Public Health Association, Washington. Berry, G. 1995. Composting Toilet Trial: Kiritimati Water and Sanitation Project: Progress Report No. 3, Part 2. Australian Agency for International Development, Canberra. Canter, L.W. and R.C. Knox 1985. Septic Tank Effects on Groundwater Quality. Lewis Publishers, Boca Raton, Florida. Chapman, P. 1993. Compost Toilets: An Option for Human Waste Disposal at Remote Sites, Masters Dissertation, Lincoln University, Canterbury, New Zealand. Chaplin, S.W. 1993. Alternative Supplies: Rainwater Collection Systems, Graywater Systems, and Composting Toilets. In: Proceedings of CONSERV93, American Water Works Association, Las Vegas. Crennan, L. 1994. Composting Toilet Trial: Kiritimati Water and Sanitation Project: Progress Report No. 1. Australian Agency for International Development, Canberra. Crennan, L. 1995. Wet and Dry Conservancy: The Politics and Practicalities of On-site Sanitation, Thesis for Doctor of Philosophy, Centre for Environmental Studies, University of Tasmania, Hobart, Australia. Crennan, L. and S. White 1994. Composting Toilet Trial: Kiritimati Water and Sanitation Project: Progress Report No. 2. Australian Agency for International Development, Canberra. Crennan, L. and S. White 1995a. Composting Toilet Trial: Kiritimati Water and Sanitation Project: Progress Report No. 3, Part 1. Australian Agency for International Development, Canberra. Crennan, L. and S. White 1995b. Composting Toilet Trial: Kiritimati Water and Sanitation Project: Progress Report No. 4. Australian Agency for International Development, Canberra. Fahy, P. 1992. From Waste to Resource: Utilising Human Animal and Plant Wastes in Horticulture Through Efficient Composting. Biological and Chemical Research Institute Report, NSW Agriculture, Rydalmere. Gangaiya, P. 1994. Land-Based Pollution Sources in Kiribati: A Case Study. University of South Pacific, Suva. Gotaas, H. 1956. Composting, Sanitary Disposal and Reclamation of Organic Wastes. World Health Organisation, Geneva. Handreck, K. 1993. Composting: Making Soil Improver from Rubbish, Division of Soils. Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia. Lewis, W.J., S.S.D. Foster, and B.S. Drasar 1980. The Risk of Groundwater Pollution by On-site Sanitation in Developing Countries: A Literature Review. International Reference Centre for Waste Disposal, Duebendorf. Lombardo and Associates 1981. State of the Art Assessment of Compost Toilets and Greywater Treatment Systems. The Winthrop Rockefeller Foundation, Little Rock, Arkansas. Marjoram, T. 1983. Pipes and pits under the palms: Water Supply and Sanitation in the South Pacific. Waterlines, 2(1):14-17. Markell, E.K. and V. Marietta 1981. Medical Parasitology. W. B. Saunders Company, London. McGarry, M.G. and J. Stainforth 1978. Compost, Fertilizer, and Biogas Production from Human and Farm Wastes in the Peoples Republic of China. International Development Research Centre, Ottawa. Rogers, E. 1995. Diffusion of Innovations, Fourth Edition. The Free Press, New York. Safton, S. 1993. Human Intestinal Parasites in Composting Toilet Systems. Dissertation for Degree of Master of Applied Science, Medical Laboratory Science, Charles Sturt University, Wagga Wagga, Australia. Winter, S.J. 1988. Construction Manual for a Water-sealed Toilet. United Nations Development Programme, New York.
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