«Low Cost Systems for the Management of Sludge from Toilets and Shower Units Current Techniques and Improved Options in Ambositra and Mahanoro ...»
Low Cost Systems for the
Management of Sludge
from Toilets and Shower
Current Techniques and Improved Options in
Ambositra and Mahanoro (Madagascar)
The WASHplus project supports healthy households and communities by creating and delivering
interventions that lead to improvements in water supply, sanitation, and hygiene (WASH) and
indoor air quality (IAQ). This five-year project (2010-1015) funded through USAID’s Bureau for
Global Health (AID-OAA-A-10-00040), uses at-scale programming approaches to reduce diarrheal diseases and acute respiratory infections, the two top killers of children under five years of age globally. WASHplus can integrate WASH and IAQ activities into existing education, HIV/AIDS, maternal and child health, nutrition programs and education programs build strong in-country partnerships to increase impact. In addition, WASHplus is charged with promoting innovation in the WASH and IAQ sectors.
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Merri Weinger Office of Health, Infectious Diseases and Nutrition Bureau for Global Health U.S. Agency for International Development Washington, DC 20523 Table of Contents
2. Management of Toilet and Shower Units in Ambositra and Mahanoro
2.1. Toilet and Shower Units by C-Change/HIP
2.1.1 The Case of Ambositra
2.1.2 The Case of Mahanoro
2.2. Maintenance of the Pits
2.2.1 General Considerations
2.2.2 The Case of Ambositra
2.2.3 The Case of Mahanoro
3. Management of Fecal Sludge in Ambositra and Mahanoro
3.1 Existing Services in Ambositra
3.2 Services Existing in Mahanoro
3.3 Local Techniques for Emptying Pits
4. Appropriate Systems Proposed for Managing Sludge from Public Toilets
4.1 Alternative Technologies
4.2 Technical Options Proposed
4.2.1 Basis for the Design
4.2.2 Removal of Sludge
4.2.3 Transportation of Sludge
4.2.4 Disposal/Treatment Sites
4.2.5 Disposal/Treatment Techniques
4.2.6 Technical Process Proposed
4.2.7 Financial Aspects
4.3. Structure of a Sludge Management Service
4.4. Sludge Management Service for Private Latrines
1. Introduction In countries in the southern hemisphere, sanitation coverage is ensured at 70 percent through individual facilities, which are the most accessible technical option in both rural areas and urban settings (Department of Water and Sanitation in Developing Countries, at the Swiss Federal Institute of Aquatic Research and Technology).
Under this sanitation system, excreta are stored in pits where fecal matter undergoes partial decomposition and forms sludge that must be regularly emptied out.
As illustrated in the graph above, pits can be emptied two ways: through the use of cesspit emptiers (conventional method) and manual emptying, which is done informally in many cases and is unhealthy in general. In addition, dedicated areas rarely exist for discharging sludge, let alone sludge treatment plants.
This is the case in Madagascar where all the emptied sludge is discharged in human settlement areas and rivers.
In the context where proper excreta disposal is not available, efforts to build and use latrines only delay the impact of open defecation instead of eliminating it. This applies to public toilet and shower units found in neighborhoods where households cannot build their own facilities or to congested areas such as marketplaces and bus stations. These facilities generate significant amounts of sludge, which presents a very complex management issue.
At the behest of the U.S. Agency for International Development (USAID) funded WASHplus project, PRACTICA assessed the current situation and suggested appropriate options for the management of sludge from three toilet and shower units. These units were rehabilitated in July 2010 by the USAID Hygiene Improvement Project (HIP) in two regional sites, Ambositra and Mahanoro.
Low Cost Sludge Removal | washplus.org | 1 Management of Toilet and Shower Units in Ambositra and Mahanoro
2.1. Toilet and Shower Units by C-Change/HIP 2.1.1 The Case of Ambositra Ambositra is an urban commune with more than 32,800 inhabitants and is located in the region of Amoron’i Mania in the central highlands of Madagascar.
The commune is connected to the network of the national water company JIRAMA and the water is extracted from Lake Tsiandrazandoha, nine kilometers from the town, in Anasana in the rural commune of Ankazoambo. In regard to sanitation, the latrine-use rate was estimated at 92 percent at the regional level in 2009 (Base de Données Eau et Assainissement – BDEA).
In July 2010 C-Change/HIP rehabilitated two toilet and shower units in the neighborhood of Alakamisy, near the bus station, and in the neighborhood of Sabotsy, near the marketplace. While the commune owns the facilities, the municipality contracted the management to private managers.
With a monthly turnover of MGA (Malagasy Ariary) 520,000 and a monthly profit of MGA 280,000 (about US $120), the operation of toilet and shower units in Sabotsy is a profitable activity.
2.1.2 The Case of Mahanoro Mahanoro is a commune located on the eastern coast of Madagascar in the Atsinanana region with 39,879 inhabitants. It was recently upgraded to an urban commune.
Water in the town is provided by the national water company JIRAMA, which uses a borehole, but most of the population uses a “tany” pump to draw from the shallow groundwater. The sanitation access rate at the regional level was 65 percent in 2009 (BDEA). In addition, the population uses latrine buckets made from low-volume metal barrels that are emptied onsite.
The town has a toilet and shower unit next to the marketplace, and the facility is managed by a woman from Manakara. According to the mayor, no one in the village wanted to take the job for fear of damage to his/her social image. The toilet and shower unit is well kept and receives many users, as reflected in the following table.
The operation of the toilet and shower unit in Mahanoro also results in profits. As shown above:
The monthly gross profit from the operation of the toilet and shower unit is about MGA 400,000 with a daily average of 160 to 200 users.
The management delegation contract does not clearly specify whether the task of emptying the pits falls to the commune or the manager. However, the profits resulting from the unit’s operation should cover the cost of this task.
2.2. Maintenance of the Pits 2.2.1 General Considerations The three toilet and shower units use a septic system under which excreta are flushed then processed in a suite of chambers for anaerobic digestion, settlement, and filtration through a bacterial bed (pozzolana).
Model of a septic tank installed in the toilet and shower units
Emptying the pits actually consists of removing the excess sludge and potential solid waste. It is not aimed at disinfecting the pit. If the pit operates well, it is possible to empty only the scum on top and the sludge at the bottom and leave the liquid. In addition, the pit must not be fully emptied, as a layer must be left to allow for the digestion process.
F: number of years between two emptying operations Vf: Total capacity of the pit (in liters) Ve: Daily volume of water entering the pit (in liters) N: Number of resident users Fe: Environmental factor (1.5 in our case) A: Average sludge accumulation rate (80l/user/year)
During an inspection conducted as part of PRACTICA’s assessment, it was noted that the pits of the two toilet and shower units in Ambositra were in urgent need of being emptied. The sludge and scum started obstructing the pits’ drains up to the level of the bacterial filters as seen in the pictures below.
Ambositra: Mobile manholes should be installed to make it easier to check the pits. The sludge has thickened and does not settle. The drains are obstructed. The pits lack maintenance.
Thus, eight months into service, the septic tanks of the toilet and shower units already had to be emptied.
This seems to confirm the soundness of the formula above, whose application shows that the pits have to be emptied every seven months for Sabotsy and every nine months for Alakamisy due to their intensive use (see calculations in Annex 1).
2.2.3 The Case of Mahanoro The toilet and shower unit in Mahanoro is fitted with a large pit (12.8 m3) with a design complicated by numerous repairs and rehabilitations.
A checkup did not find any major problem. The pit seems to operate normally but given the toilets’ level of use, the pit should be emptied every year (see calculations in Annex 1).
The assessment identified three informal pit emptying teams. One of them includes four municipal employees who in their regular jobs are in charge of maintenance and garbage collection. Occasionally, they offer their services, as private operators, to public institutions, offices, or private people. The two other teams are comprised of two and three members, respectively.
It is likely that other teams operate in Ambositra and that some households empty their pits on their own.
According to the teams, members engage in other activities such as harvesting, plumbing, carpentry, etc.
It is important to note that while the daily income from these activities ranges from MGA 1,500 to 3,000 ($
0.75 to 1.50), a team member can earn up to MGA 40,000 ($20) in three days by emptying a large pit (more than 6 m3).
3.2 Services Existing in Mahanoro The municipality provides no sanitation services in Mahanoro but reported its plans to do so pursuant to its upgrade into an urban commune. However, to date no cesspit emptier operates in this area.
The disposal of fecal sludge constitutes a difficult problem for most households that use bucket latrines made of halved barrels (about 100 L) that must be emptied every four months. As the local population has a strong cultural revulsion against excreta, they resort to the services of third parties to empty their barrels.
There seems to be only two people who are willing to empty pits and barrels in Mahanoro.
One of the workers explained that emptying pits creates such a social stigma against him that he is prohibited from being buried in the family tomb. As in Ambositra, the men who empty pits drink heavy amounts of alcohol and participate in other income-generating activities such as harvesting, dock unloading, charcoal making, etc.
In Mahanoro, pit emptying services are offered by informal handymen who are more or less marginalized.
In the past, one formal operator planned to launch a cesspit emptying service in Ambositra.
In both communes, the rates for emptying pits are high compared to the earnings of more traditional daily jobs. In Mahanoro, for instance, one day worked as a harvester pays MGA 2,500 ($1.25) while emptying a bucket latrine of 100 L, which is done in one hour, pays MGA 5,000 ($2.50).
3.3 Local Techniques for Emptying Pits In Ambositra, the pits to be emptied are usually simple pits or septic tanks, and the technique used depends on the outlets available. In some cases, the sludge is discharged into a drainage canal. More often, it is buried in trenches or holes dug nearby.
When it is not possible to dig a trench or a hole, the sludge is discharged into drainage canals. As transportation from one place to another is involved in this case, the operation may take much more time and may have to be spread over several nights (up to three).