Human-Powered Emptying and Transport
Human-powered emptying and transport refers to the different ways by which people can manually empty and/or transport sludge and solid products generated in onsite sanitation facilities.
Human-powered emptying of pits, vaults and tanks can be done in one of two ways:
- using buckets and shovels, or
- using a portable, manually operated pump specially designed for sludge (e.g., the Gulper, the Rammer, the MDHP or the MAPET).
Some sanitation technologies can only be emptied manually, for example, the Fossa Alterna (S.5) or Dehydration Vaults (S.7). These technologies must be emptied with a shovel because the material is solid and cannot be removed with a vacuum or a pump. When sludge is viscous or watery it should be emptied with a hand pump or a vacuum truck, and not with buckets because of the high risk of collapsing pits, toxic fumes, and exposure to unsanitized sludge. Manual sludge pumps are relatively new inventions and have shown promise as being low-cost, effective solutions for sludge emptying where, because of access, safety or economics, other emptying techniques are not possible.
Sludge hand pumps, such as the Gulper, work on the same concept as water hand pumps: the bottom of the pipe is lowered into the pit/tank while the operator remains at the surface. As the operator pushes and pulls the handle, the sludge is pumped up and is then discharged through the discharge spout. The sludge can be collected in barrels, bags or carts, and removed from the site with little danger to the operator. Hand pumps can be locally made with steel rods and valves in a PVC casing.
Manual sludge pumps like the Pooh Pump or the Gulper are relatively new inventions and have shown promise as being low-cost, effective solutions for sludge emptying where, because of access, safety or economics, other sludge emptying techniques are not possible. The pump works on the same concept as a water pump: the handle is pumped, the liquid (sludge) rises up through the bottom of the pump and is forced out of a tap (sludge spout). Hand-pumps can be made locally with steels rods and valves in a PVC casing. The bottom of the pipe is lowered down into the pit/tank while the operator remains at the surface to operate the pump, thus removing the need for someone to enter the pit. As the operator pushes and pulls the handle, the sludge is pumped up through the main shaft and is then discharged through the V-shaped discharge spout. The sludge that is discharged can be collected in barrels, bags or carts, and removed from the site with little mess or danger to the operator.
A MAPET (MAnual Pit Emptying Technology) consists of a manually operated pump connected to a vacuum tank mounted on a pushcart. A hose is connected to the tank and is used to suck sludge from the pit. When the wheel of the hand pump is turned, air is sucked out of the vacuum tank and sludge is sucked up into the tank. Depending on the consistency of the sludge, the MAPET can pump up to a height of 3 m. A motorized version of the MAPET is the Vacutug, developed by UN-Habitat.
One example of such a pump is The Gulper. This is a simple hand pump used to empty wet pit latrines and drain interceptor tanks. It consists of PVC pipes for the body, and stainless steel valves and puller rod. The Gulper is lowered into the pit with a footrest at ground-level. The operator raises and lowers a puller rod, which pushes the sludge from the pit up through a pipe into a bucket or bag. Using the gulper, operators no longer need to climb into the pits and come in contact with the septic sludge. It is also much less time consuming as it removes around 3 litres of sludge per stroke. It is a cheaper method of improving sanitation, than trying to replace the pits by proper latrines. For more information about the Gulper.
Tricycles and push carts can be used to transport containers and oil drums containing urine or excreta. Push carts and tricycles (pedal or motorised) can access small streets. Tricycles can speed up the collection operation and increase the radius of the collection in urban areas, transporting the containers to transfer stations or to community treatment facilities. From transfer stations, urine and excreta can be loaded onto trucks or tractors, which can haul a larger volume over a long distance. Tricycles can collect door to door, although urine can also be collected in larger containers serving a number of houses.
| - Potential for local job creation and income generation
- Simple hand pumps can be built and repaired with locally available materials
| - Spills can happen which could pose potential health risks and generate offensive smells |
- Time consuming: emptying pits out can take several hours/days depending on their size
Hand pumps can be used for liquid and, to a certain degree, viscous sludge. Domestic refuse in the pit makes emptying much more difficult. The pumping of sludge, which contains coarse solid wastes or grease, can lead to clogging of the device, and chemical additives can corrode pipes, pumps and tanks. The hand pump is a significant improvement over the bucket method and could prove to be a sustainable business opportunity in some regions.
Manually operated sludge pumps are appropriate for areas that are not served or not accessible by vacuum trucks, or where vacuum truck emptying is too costly. They are well suited to dense, urban and informal settlements, although the type and size of transport vehicle determines the feasible distance to the discharge point. Large vehicles may not be able to manoeuvre within narrow streets and alleys, while smaller vehicles may not be able to travel long distances. These technologies are more feasible when there is a Transfer Station (C.7) nearby.
Depending on cultural factors and political support, workers dealing with manual emptying may be viewed as providing an important service to the community. Government-run programmes should strive to legitimize the work of the labourers and create an enabling environment by providing permits and licences, as well as helping to legalize the practice of emptying latrines manually. The most important aspect of manual emptying is ensuring that workers are adequately protected with gloves, boots, overalls and facemasks. Regular medical exams and vaccinations should be required for everyone working with sludge.
Operation & Maintenance
It is a common practice to add chemicals or oil during the pit emptying process to avoid odours. This is not recommended, however, because it causes difficulties in the subsequent treatment units, as well as additional health threats to the workers. If manual access to the contents of a pit requires demolishing the slab, it may be more cost-effective to use a manual sludge pump to empty the latrine. However, hand pumps cannot empty the entire pit and, therefore, emptying may be required more frequently (once a year).
Manually operated sludge pumps require daily maintenance (cleaning, repairing and disinfection). Workers who manually empty latrines should clean and maintain their protective clothing and tools to prevent contact with the sludge.
- Eales, K. (2005). Bringing Pit Emptying out of the Darkness: A Comparison of Approaches in Durban, South Africa, and Kibera, Kenya. Building Partnerships for Development in Water and Sanitation, London, UK.
- Available at: bpdws.org (A comparison of two manual emptying projects)
- Ideas at Work (2007). The ‘Gulper’ – a Manual Latrine/Drain Pit Pump. Ideas at Work, Phnom Penh, KH.
- Available at: ideas-at-work.org (Case study about a test of the Gulper by informal service providers)
- Muller, M. and Rijnsburger, J. (1994). MAPET. Manual Pit-latrine Emptying Technology Project. Development and Pilot Implementation of a Neighbourhood Based Pit Emptying Service with Locally Manufactured Handpump Equipment in Dar es Salaam, Tanzania. 1988–1992. WASTE Consultants, Gouda, NL.
- Available at: washdoc.info
- Oxfam (2008). Manual Desludging Hand Pump (MDHP) Resources. Oxfam GB, Oxford, UK.
- Available at: desludging.org (Manual for the MDHP)
- Pickford, J. and Shaw, R. (1997). Technical Brief No. 54: Emptying Pit Latrines. WEDC, Loughborough University, Leicestershire, UK.
- Available at: lboro.ac.uk/well
The material on this page was adapted from:
Elizabeth Tilley, Lukas Ulrich, Christoph Lüthi, Philippe Reymond and Christian Zurbrügg (2014). Compendium of Sanitation Systems and Technologies, published by Sandec, the Department of Water and Sanitation in Developing Countries of Eawag, the Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.
The 2nd edition publication is available in English. French and Spanish are yet to come.