The literature review of the sanitation conditions in coastal and waterfront communities indicated that the unsanitary means of disposing of human waste has negative impact to the health of the community and to the condition of the environment. In some of the communities reviewed, interventions have been done to improve sanitation conditions. Such interventions were either provision of sanitation facilities to the community by the local government or a simple system which the people themselves have adopted and used. This chapter provides a brief introduction to available low-cost sanitation systems and identifies which systems have been applied in coastal and waterfront communities and those built on low-lying areas.
3.1 Available Low-Cost Sanitation Technologies
Recent studies in sanitation identified several low-cost sanitation technologies. These excreta-disposal systems offer different degrees of user convenience, protection against the spread of diseases and water demand for their operation. They can be classified in several ways. A basic classification is based on whether the waste is disposed of within the site or is transported somewhere else. Under this classification, the technology is either on-site or off-site systems. On-site sanitation systems include those in which safe disposal of excreta takesplace on or near the plot or site of the toilet.(1) Systems included in this classification are; overhung latrines, trench latrines, pit latrines, Reed Odorless Earth Closet (ROEC), ventilated improved pit latrines (VIP), composting latrines, pour-flush latrines, and septic tanks. Off-site sanitation systems include those in which excreta are collected from the individual toilets and carried away from the plot to be disposed of.(2) Vault and cartage and bucket latrine are included in this category. Some of these systems involve the use of water and are therefore classified as wet systems. Others disallow the use of water, even for hygienic purposes, and are therefore classified as dry systems. Figure 3.1 shows the generic classification of sanitation systems.
Another way of classifying sanitation systems is through their application as either individual household sanitation technologies or community sanitation technologies.(3) Systems that are classified as household sanitation systems include the pit latrine, pour-flush toilets, composting toilets, aquaprivies and septic tanks, which are built in individual houses. Systems such as bucket latrines, vault toilets with vacuum-cart collection, communal toilets and sewerage systems are classified as community sanitation facilities.
Studies of appropriate technology for water supply and sanitation under the World Bank International Drinking Water Supply and Sanitation Decade (1980-1990) defined several comparative criteria to introduce the putative performance of these technologies. Among these criteria are the following: water supply service levels; soil condition requirements; cost; housing density; complementary investments; reuse potentials; environmental factors; self-help potential; and institutional constraints.(4) A descriptive comparison of sanitation technologies based on some of these criteria is shown in Table 3.1.
Recent studies on sanitation in developing countries identify some special requirements needed above the general criteria identified above. Nimpuno (1984) emphasizes operation, costs, construction, water requirements and urban adaptability as special considerations in the selection of sanitation technologies in developing countries.(5) For existing low-income settlements without adequate sanitation facilities it is of great importance that small-scale, even individual, household installations can be chosen, that in time the individual provisions can be linked up to form a network, and that the systems can be upgraded gradually.
In actual sanitation projects, one of the causes of their failure is the overemphasis on technological installations at the expense of behavioral considerations such as latrine usage and upkeep and general hygiene practice of the users.(6) In most of these projects, the stated priorities or goals often promote installation of facilities or numerical targets. Project planners pay little attention to the types of technologies acceptable to a given community, or to hygiene education needed to support the chosen option. Under these circumstances, it is more than simply a technical or economical analysis to the approach of providing adequate sanitation facilities. There is an element of deep-rooted cultural values which needs to be responded to in the process.(7)
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3.2 Sanitation Systems Used in Coastal and Waterfront Communities
Among the various options of low-cost sanitation systems mentioned above, a few have been used in some coastal and waterfront communities. These systems include both individual and community systems. Descriptions of how they were used and the factors affecting the success or failure of their usage are identified in the following discussion. It is important to note, however, that the analysis of the systems discussed are within the context of the community where they were used. Since this review is based on limited and scattered documentation, the degree of comprehensiveness of the discussion for each system vary.
a. Communal Toilets
The most common approach used to solve sanitation problems in coastal communities is the provision of communal toilets. This option has been considered as the only feasible and realistic sanitation improvement in high density low-income urban areas built on tidal mudflats.(8) Communal toilets or public toilets consist of a number of cubicles built on more stable grounds shared by community members. In Port Moresby, Papua New Guinea, six communal toilets were built initially on the mainland for the Koki settlement, which is a squatter community built entirely on the sea.(9) In the case of Jakarta, public toilets were also built under the Kampung Improvement Program for the kampung settlements located at swamp and marshy lands.(10) In Klong Khum in Bangkok, Thailand, public toilets were provided by the National Housing Authority of Bangkok.(11)
In the provision of communal toilets, problems caused by technical requirements and socio-cultural inacceptability of the facility were met. In Jakarta, the public toilets built were not used much and did not function properly because the collection tanks of the facility were flooded whenever it rained. Since users had to pay to use the facility, many children defecated over open drains instead.(12) In several cases, poor maintenance resulted in the facilities being abandoned. In the Koki settlement, the communal latrine did not function well, so people continued to use the sea for sanitation. Another problem is the poor proximity of the facility to the users. The residents of Klong Khum preferred to have latrines inside their houses, rather than use communal facilities which were distant from their homes.
b. Collection of Nightsoil
In communities where communal toilets were not acceptable, individual facilities were preferred. The problem with the provision of individual toilets is the limited options for safe disposal of human waste, especially for those houses that are built on areas with high groundwater level and those submerged in water. With these conditions, the most ideal means is to collect the human waste and transport it to another site for treatment or disposal.
In China, human excreta has for centuries, been looked upon as a valuable source of fertilizer. Hence, excreta in buckets are collected for reuse. Collection of nightsoil has been the traditional practice in the Zhou-zhuang fishing village. In this village, due to the absence of running water and a sewer system, the traditional matong, wooden portable chamber pots, continue to be used to collect human waste. An integral part of the early morning scenes of Zhou-zhuang are the matong set by the doorstep of each household for collection.(13)
This practice of collecting human waste demands the acceptability of wastehandling among the community members. In communities where the sight and handling of excreta is rejected, the waste has to be disposed of quickly. In some communities reviewed, especially those located on marshlands, other options for sanitary excreta disposal have been tried, but due to the high groundwater level, problems occurred with the use of such systems. Sanitation technologies used in these communities involve on-site treatment such as the septic tanks.
c. Septic Tanks
Septic tanks are comprised of a sealed tank having both an inlet and an outlet into which excreta are flushed from a conventional cistern flush toilet or a pour-flush toilet. The tank acts as a settlement unit in which solids settle out by gravity. The solids undergo a process of anaerobic decomposition which results in the production of water, gases, sludge and a layer of floating scum. In communities built on low-lying areas, septic tanks do not function properly since the subsoil structure is too impermeable for the leaching of the septic tank effluent. Being unable to permeate the soil, the effluent, still laden with pathogens, flows across the ground, thereby hastening the spread of diseases and not allaying it.(14)
In Jakarta, septic tanks do not operate properly because of flooding and the high ground water table, which means that much of the sewage from the septic tanks goes unfermented into canals and swamps. Low-permeability is a problem for the subsurface effluent disposal system. Eventually, the surrounding soil will cease to absorb the effluent thereby causing a failure in treating the effluent.(15)
Another problem with the use of this system is the requirement for an in-house connection of water supply for the system to operate. In communities where the water supply is not accessible, this system is not feasible. As in the case of the communities in the small islands of the South Pacific, pour-flush toilets linked with septic tanks were used. But due to the limited water supply, saltwater from the sea was used instead. The use of salt water to flush latrines retards decomposition and soakaway of sewage, hence making the system operate ineffectively.(16)
With high groundwater level seen as problem with the use of on-site systems, some sanitation technologies were designed for this condition. However, non-technical problems, such as implementation and usage problems were identified with the use of such systems, as in the case of the cesspools commonly used in Thailand.
In klong or canal settlements in Bangkok, Thailand, the most common type of sanitation technology used is the cesspool. The cesspool consists of concrete rings which are about 0.75 meter in diameter with small holes through the rings. The rings are stacked below the latrine floor and fixed above it is a ceramic toilet bowl with or without a water trap. The floor of the latrine is generally raised above the floor level to avoid overflow during the rains.(17) The cesspool is widely accepted by the residents because of its ease of construction and low cost. The construction materials are available in prefabricated form and construction at the site takes only a few hours, and no special skills are required. Most of the households construct their own latrines.(18)
The cesspool was designed for areas with a high ground water level. It was launched as a low-cost solution for urban areas in Thailand in the early seventies.(19) The original design of the cesspool, consists of two interconnected tanks; the first tank for settling solids, the second tank, the soakage, where purified effluent flows. The first tank has a ventpipe, since most of the biogas is produced here, and an inlet for the waste is a squatting plate with a water seal. Both tanks are made of concrete rings; the first one has a tight bottom, the second one has no floor. This design requires a regular removal of sludge, but the system still percolates a considerable quantity of unstabilized organic matter and pathogens into the ground water.(20) This system operates well in sites with a high ground water level. The high ground water level keeps the second tank filled with fluids, allowing secondary treatment of effluent before it soaks away. If there is a low ground water level, the overflowing fluids from the first tank will soakaway into the ground before any secondary treatment takes place, resulting in considerable pollution.(21)
Despite the wide application and acceptance of the technology by the residents of the klong settlements, sanitation and environmental problems occur in the actual installations of the cesspool. This is because the system was not constructed properly based on the original design of the cesspool. In the study of sanitation conditions of two klong settlements in Bangkok, namely, Klong Khum and Klong Toey, conducted by Monsoor (1990) and Deloria (1991), respectively, the common observation is the installation of only one tank instead of two. Since there is no secondary treatment of effluents, fresh fecal matter percolate and fluids leach directly into the surrounding water. The leaching effect constitutes long term health hazards and causes severe pollution.(22) In the Klong Toey settlements, Monsoor observed that fecal solids from poorly constructed cesspools seeped into the water and were exposed.(23) Figure 3.2 illustrates the cesspool as used in the klong settlements.
Other problems associated with simplified cesspools are improper construction of the tanks and absence of the vent pipe. Surveys in the two klong settlements showed that the tanks were not embedded into the ground, and cylinders were stacked up until they reached the floor level of the house. Deloria observed that in Klong Khum, ventpipes were not installed in the cesspool. The vent pipe supposedly helps prevent the methane gas from accumulating in the vault which might otherwise cause harm or unprecedented explosion. Furthermore, dislodging of the built cesspool is a problem since most of the latrines do not have an off-set vault and no manhole is provided. Latrine owners would abandon it once it is full or would break the vault and replace it with a new one.(24)
e. Composting Toilets
In swampy and flood-prone areas of Vietnam, the Vietnamese composting toilets are used and are considered to function well in such ground conditions. As shown in Figure 3.3, this system is a family unit consisting of two above-ground tanks for dry and anaerobic composting.(25) The two watertight tanks serve by turns as receptacles for defecation and composting. Unlike other composting toilets, the composting process takes place without aeration or turning over of the material. Ashes are added to the fresh excreta to achieve suitable carbon-nitrogen ratio, to eliminate odor and prevent the presence of flies. The system also involves the separation of urine treatment to reduce acidity and humidity, and to lower the nitrogen content of the waste pile. The urine is placed in another container with either water or soil and ashes, which after a few days, can be used a garden fertilizer.
The main advantages of this system are the non-disposal of waste into the ground and the possibility of building the vault above the ground, despite the adverse ground conditions. However, the success of this system relies on a high degree of user care and attention, as in the case of Vietnam, where careful use and maintenance of the composting toilet is not difficult.
The problem with the low-cost options described earlier is that they are demanding from the user's point of view. In most cases, the users have to be involved in the maintenance and operation of the systems. In the earlier attempt to provide sanitation facilities for coastal and waterfront communities, the sewerage system was considered technically appropriate. Also, since it provides the "flush and forget comfort" to the user,(26) this approach supposedly simplifies the solution. However, the actual application of the sewerage system is found to be not at all feasible as in the case of the Koki settlements, Port Morsby.
f. Sewerage System
The sewerage system is considered technically feasible in coastal and waterfront communities, but due to high capital requirements, and a large amount of water supply to operate the system, such option will remain inappropriate. In the Koki settlements in Port Moresby, Papua New Guinea, a sewerage system was initially provided as part of the master plan of the community. As shown in Figure 3.4, the official upgrading process involved the expansion of the community towards the sea by building long walkways. This approach was implemented because it was traditional for the people to live above the water and they were able to moor their boats near their houses.(27) Thus, the sewerage system was integrated with the proposed upgrading scheme.
In upgrading the community, walkways were built over the sea with houses located at both sides. Water supply pipes ran along these walkways and the point of tapping was located at the front of each house. The sewage plastic pipes were suspended underneath the walkway. Sewage was then collected into a central tank and from there pumped into the municipal sewerage system. In 1977, the upgrading was completed except that the sewerage system has not been made to work. People still defecated in the open sea. Children played with the plastic pipes under the walkways and damaged them. It was difficult to ensure both privacy and cleanliness in the toilet blocks provided. In fact, the pump for the sewerage system was never used. It is exceedingly doubtful whether the sewerage scheme will ever be made to work successfully.(28)
In summary, the sanitation system applied in the communities reviewed in this chapter, include communal toilets, on-site technologies such as septic tanks and cesspools, and off-site technologies such as the bucket latrine and sewerage systems. Problems associated with the use of communal toilets include poor proximity and access to the user, poor maintenance of the toilets and poor functioning of the treatment systems used, which resulted in non-usage of the facility. Septic tanks used in flood-prone areas or areas with high ground water levels do not function well due to poor soil conditions. In the case of the cesspool, though designed for areas with high groundwater level, pollution problems still occur due to poor implementation and usage of the system. Malfunctioning of these on-site systems result in health and environmental problems in the community rather than improving it. Other options used are off-site treatment technologies such as the bucket latrine and the sewerage system. The bucket latrine is an acceptable means to collect waste in the watertowns in China. However, social and cultural acceptance of waste handling is the main limiting factor for other cultures. Sewerage was attempted, as in the case of the Koki settlement. But due to the high cost accompanied by the high water service level required, such technology remains not feasible in coastal communities.
From this discussion, it can be concluded that the location and environmental conditions of the coastal and waterfront communities limit sanitation options to those which involve the off-site treatment of waste. Poor soil conditions characterized by high ground water level and poor permeability makes on-site options technically inappropriate. This makes provision of individual sanitation systems difficult especially in communities built above inundated land or those built above the surface water. Options requiring collection of human waste, such as the bucket latrine, may be technically feasible, even in communities built above the water. However, this system is only feasible in cultures where the handling of excreta is acceptable. Economically and technically, the provision of communal toilets built on more stable land appears to be the most feasible option. However, it is important to consider the social and cultural limitations of this option as well as the maintenance and operation requirements.
The discussion of the usage of sanitation systems presented in this chapter provides only bits and pieces of information since the data gathered for each system are limited and are of varying degrees of scope. To be able to analyze comprehensively the problems associated with the provision of sanitation systems in coastal and waterfront communities, a prototypical coastal community is studied. The succeeding chapters present the case study.[ TopOfPage(); ]
3. John M. Kalbermatten, De Anne Julius and Charles Gunnerson, Appropriate Technology for Water Supply and Sanitation: A Summary of Technical and Economic Options, (Washington D.C.: World Bank, 1980), p. 3.
5. For the system to be acceptable in low-income communities in developing countries the following considerations must be met: (1) the daily operation should require minimal educational and technical instructions which can be taught to all ages. A simple, safe toilet routine should suffice for the daily operation of the system; (2)the construction costs should not exceed 10% of the total house investment; (3) the maintenance requirements be low that the construction require mainly local materials and be executed by semi-skilled labor; (4) the use of water to dilute and transport the excreta should be avoided since water is scarce and water treatment entails high cost; and (5) since a great majority of the urban dwellers in developing countries do not have access to satisfactory excreta disposal systems, it is important to require that disposal systems are identified for existing housing areas. Application should also be possible in existing high density areas. Krisno, Nimpuno, "Viable Low Cost Sanitation Options", in Water and Sanitation: Economic and Sociological Perspectives, ed. Peter G. Bourne, Florida: Academic Press Inc. 1984, p.266-267.