Human-powered Emptying and Transport

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 alternaor dehydration vaults. These technologies must be emptied with a shovel because the material is solid and cannot be removed with a vacuum or a pump (e.g. the fossa alterna, aroborloo, composting toilets or UDDTs).

When sludge is viscous or watery it should be emptied with a hand pump, a MAPET or a vacuum truck, and not with buckets because of the high risk of collapsing pits, toxic fumes, and exposure to unsanitised 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. 

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. Sludge hand pumps 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.

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 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 team of MAPET emptiers consists of three men. The emptying job starts with contacting the customer, negotiating over the price, picking up the MAPET equipment from its parking place and taking it to the customer's house.This preparation entails mixing the sludge with water (to make it more fluid) and (possibly) paraffin (to reduce the smell; MUELLER & RIJNSBURGER 1992).After the hose-pipes have been connected the sludge pumping can start. Depending on the sludge's viscosity and the pumping head, it can take five to twenty minutes to fill up one 200 litre tank with sludge. When a tank is full, the hose-pipes are disconnected and the tank is manoeuvred next to the dug hole, and topped over in discharge position. A pressure relieve valve is opened and the sludge flows to where it is supposed to be discharged. After putting the tank back in its original position, pumping can start anew and the vacuum tank is filled again. This routine is repeated until the required amount of sludge has been taken out. The equipment is then cleaned and returned to its parking place (MUELLER & RIJNSBURGER 1992). Care should be taken to find a solution where the sludge can be disposed of safely and sustainably.

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 labourer and provide an enabling environment by providing permits and licences, as well as helping to legalize the practice of emptying latrines manually.

Yet it has to be kept in mind that handling fresh excreta poses the operators and general public to unhealthy and unsightly conditions (DFID 1998). 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. After the work, all tools and also the workers hands must be cleaned with water and soap.

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.