«Low Cost Systems for the Management of Sludge from Toilets and Shower Units Current Techniques and Improved Options in Ambositra and Mahanoro ...»
Dredging of drainage canals and sewers by the municipality’s mobile teams (Ambositra) The work is done using basic tools such as ladders, pails, shovels, and wheelbarrows.
In Mahanoro, the general practice is to bury sludge near the latrines. The sandy soil in the region makes it easy to dig a trench to bury sludge. If it rains, one has to wait two days before digging. The operation is done by day and does not take more than one hour for a 100 L bucket latrine.
The operation does not require any material when it consists of emptying a bucket latrine. For a pit, the client provides a pail.
The main problems mentioned by the men who empty pits are summarized in the following table.
Fecal sludge removal services are available in Mahanoro and in Ambositra. Unfortunately, they present serious health hazards for those who perform the operation as well as for the population.
By moving the sludge just a few meters away from where it was collected, the traditional operation of pit
emptying does not provide a real solution at a citywide level. The main areas for improving the service include:
Making the pit emptying operations more hygienic Disposing the sludge out of the town The challenge will be to keep costs at an affordable level once transportation costs are factored into what is usually paid for traditional pit emptying.
In regard to the toilet and shower units, the poor logistics available to the traditional pit emptying teams and their low capacity call for other operators to step in that have the capacity to coordinate operations, manage vehicles, and commit to quality of services.
4. Appropriate Systems Proposed for Managing Sludge from Public Toilets The objective is to design a system that is effective, hygienic, affordable, environmentally friendly, and sustainable for emptying pits and processing the sludge from the public toilets built/rehabilitated by C-Change/HIP in the communes of Ambositra and Mahanoro.
The present study explores the issue of management of sludge emptied from the toilet and shower units built/rehabilitated by C-Change/HIP. The results may be used for the management of sludge from other public toilets as well as private facilities, though additional data will be required (statistical, analysis of sludge, etc.) and additional reflection will have to occur to take into account differing logistical needs and impacts.
Also at an experimental stage, the solar sludge oven could offer a rustic solution in Ambositra given the fairly low amount of sludge produced by the two toilet and shower units and sunny conditions in the region (an annual average of 5,000 Wh/m², SODA 2005).
Finally, though it may appear basic, burying the sludge in trenches for planting can be a limited solution but suited to the context of the study communes where much space is available, cultural revulsion to feces is strong, and technical capacity is low.
Co-composting has to be discarded as an option because of the strong cultural revulsion against the use of human excreta in farming in Madagascar. In addition, introducing this practice in Ambositra may be harmful to the reputation of the compost produced by the International Youth Chamber.
On the other hand, the hygienic aspect of dried sludge produced in solar ovens may work in favor of the adoption of sludge for different purposes.
4.2 Technical Options Proposed 4.2.1 Basis for the Design
4.2.2. Removal of Sludge Though more tools are used in Ambositra, the practices to remove and transfer sludge are about the same in the two communes.
In terms of weight, 6 m3 of sludge weighs 8 metric tons. Thus, the energy required and the health hazards incurred while emptying the pits of the toilet and shower units are huge. Adequate manual labor (one individual per m3 of sludge), with the right equipment and training on the basic rules of hygiene, should be provided.
The logistics of the sludge removal technique proposed is summarized in the following table:
4.2.3 Transportation of Sludge The two communes have designated areas for disposing the sludge at an average of 2.5 km from the toilet and shower units built/rehabilitated by C-Change/HIP. The use of vehicles must be considered when emptying these facilities whose capacity is more than 6 m3.
Smaller scale pit emptying (1 to 2 m3) could use systems drawn by men or animals. In Mahanoro, where the terrain is flat, rickshaws could be used for transporting the bucket latrines.
Very limited choices of vehicles exist in Mahanoro, and it is difficult to convince transporters to load fecal sludge onto their vehicles. Given the size of the toilet and shower unit built/rehabilitated by C-Change/HIP (12 m3), a 3 m3 trailer hauled by a tractor would be necessary; we have found an owner of a tractor who is willing to do this.
(1) Number of vehicles required to empty a pit of 6 m3. (2) Jerry cans of 60 L used for handling the sludge. Their number will depend on the vehicle used. (3) Transportation rental for sludge to the disposal site (2.5km) by night. (4) Cost of procuring the jerry cans + trailer.
Except for the 3 m3 trailer, the proposed vehicles will transport sludge in plastic jerry cans of 60 L for easier handling and for better hygiene. In practice, the number of jerry cans will range from 8 to 60 depending on the vehicles used.
Even though several trips will be required when using a Peugeot 404 pick-up, this would allow a reduction in the number of jerry cans. The 3 m3 trailer will make unloading easier and will require only eight jerry cans.
It will be necessary to store and wash the containers. The idea of transporting sludge in disposable plastic bags, such as those used for packaging fertilizer, was considered at some point, but this option was discarded due to the excessive cost (MGA 2,500 or $1.25 per 60 L bag).
Several types of vehicles can be used. The choice will depend on logistical considerations (storage space for the jerry cans, management of the trips, etc.), the availability of transporters in the field as well as the rates they will propose.
Subcontracting sludge transportation aims to minimize initial investments as well as avoid the issue of maintaining vehicles, which is the main cause of concern in managing pit emptying services.
However, it should be noted that there is a hamlet 200 m from the site.
In Mahanoro, the mayor suggested using an uncultivated plot of more than 3 ha located 3 km from downtown. The site seems to be suitable because of its easy access and lack of nearby human dwellings. However, aerial photos of the zone suggest land could be available at a closer distance, which would facilitate transportation.
The selection of a disposal/treatment site depends on the amount of sludge. In our case, the potential sites suggested by the mayors seem to be suitable. Ultimately, the decision will fall to the municipal council, which will also have to take into account the need for sludge disposal in terms of the town’s scale.
Use: Treatment of sludge from a pit emptying service extended to all facilities This technique can be applied to public toilets only when the sludge from these facilities can be mixed with sludge from private homes (Strauss).
Description: An unplanted drying bed is simple and permeable, and it allows the liquid portion of the sludge to be loaded onto it. The sludge then drains and evaporates. About 50 percent to 80 percent of the sludge’s volume percolates as liquid. However, the sludge is not stabilized.
The bottom of the drying bed is fitted with holes that allow leachate to drain. Above the drains, layers of sand and gravel bear the sludge and allow the liquid to run into the drain.
The sludge must be spread in layers of less than 20 cm to dry effectively.
With the pit emptying operation lasting about five hours and costing about MGA 430,000 (US $220) to remove and treat the sludge from a 6 m3 pit, the alternative systems for emptying the pits could result in the development of a profitable operation.
However, it should be noted that pits of 6 m3 can be emptied for less than MGA 100,000. Without regulations, it will be very difficult to promote a new service that is four times more expensive than informal services.
In the event that the service provider owns the vehicle that would transport the sludge, the transportation cost may be significantly cut and the profit would increase accordingly (a profit margin up to 50 percent),
as described in the following table:
In the intervention communes, where 6 m3 of sludge has to be emptied every eight months, as in the case of Ambositra, and 12 m3 of sludge every 15 months in Mahanoro, the unit managers will have to designate MGA 40,000 to 50,000 per month depending on the scenario.
In practice, it may be advisable to entrust the development of the burial sites to the communes and in return provide them with the pit emptying kits needed to launch a pilot service (exclusive of the vehicle).
4.3. Structure of a Sludge Management Service Article 41 of the Water Code stipulates: “Urban and rural communes are the owners and contracting authorities for the collective sewage system located in their respective territory. They exert this duty through the Municipal Council.” As such, the municipalities must develop a municipal sanitation plan that specifies how sludge should be managed. The service for managing sludge from toilet and shower units should be included in this plan.
In the two communes, the mayors indicated that they would prefer delegating the management of sludge from the public toilets to service providers rather than to one of their technical departments.
However, with one or two pit emptying operations per year per commune, the maintenance of CChange/HIP toilet units is not an activity that is large enough to attract private operators. In addition, the improved pit emptying techniques must be regularly practiced to be mastered.
The commune in Ambositra has eight public toilets. Assuming that these are managed and used as C-Change/HIP’s two toilet and shower units and adding in the needs of hotels, healthcare institutions, and private homes for pit emptying services, a profitable activity may be initiated.
In Mahanoro, no other public toilet units or similar structures that have large pits need to be regularly emptied. However, there is a sizeable demand for bucket latrine disposal services among households, which would pay regularly for emptying.
Which Service Provider(s)?
Improved pit emptying practices require service providers to transport the sludge out of town and treat it properly as part of the disposal process.
During the assessment, the toilet and shower unit managers interviewed expressed interest in expanding their business to include this service. A competent pit emptying team in Ambositra also expressed interest.
In practice, an information session should be held in each commune to identify potential providers. Through this consultation, the terms and conditions of the collaboration could be defined (distribution of the initial investment, need for technical support, etc.) and a call for expression of interest could be sent out.
What will be the Commune’s Role?
First of all, the commune should encourage the population to adopt improved pit emptying practices. Its role will vary according to negotiations with the selected service provider(s). It may develop the burial site and will have to monitor and assess the activities and results of the service provider(s).
What would be the Service’s Structure?
The service’s structure will depend mainly on the proposals submitted to the commune and the ensuing
negotiations. Overall, it may look similar to the following illustration:
Low Cost Sludge Removal | washplus.org | 26