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Can I make the Pitvaq locally?

Yes, PID is willing to partner with other companies, outside of South Africa, who wish to make the Pitvaq. This will require payment of a licensing fee and the meeting of PID’s quality control standards. The vacuum pump will still be provided by PID.

How does the Pitvaq handle thick sludge?

The moisture content of pit latrine sludge encountered in the field varies widely, from as high as 95% to as low as 50%, where 50% represents a thick, stiff soil like sludge. In order for a suction hose to pick up sludge, the sludge must be able to flow. However one does not have to add much water to a dry, stiff sludge to get it to flow – typically the addition of 5% to 10% water to sludge (by volume) combined with thorough mixing makes even the thickest, stiffest sludge quite pumpable.

How does the Pitvaq handle trash?

If the pit contains a lot of trash, then it is advisable to fit the trash screen supplied to the end of the suction hose. The screen has a large number of 50 mm x 50 mm openings, and any small articles of trash which pass through the screen will not block the 75 mm suction hose. From time to time the trash screen will need to be rinsed with water and cleared, but that is quickly and easily done.

How does using the Pitvaq impact transport of sludge?

If the sludge must be transported for disposal elsewhere (i.e. not disposed of in a trench on site) then you need a tractor/truck and/or a trailer which can carry all the drums needed for emptying the pit. One cubic metre of sludge will fill 20 fifty litre capacity drums. A one-ton pickup truck with a trailer can move up to 40 full drums, or 2 m3 of sludge.

How long will the Pitvaq last?

The steel frame and chassis and the vacuum vessel are of robust design which will last many years. The most important part, the vacuum pump, is built to last for more than 10 000 hours of use (assuming it is kept lubricated and the vacuum tank float valve and moisture trap are kept in good working order). 10 000 hours represents more than 10 years of regular usage. The petrol engine may need to be replaced after two or three years, but small petrol engines (Honda type) can be found anywhere in the world and are not expensive.

How much does the Pitvaq cost?

The cost to manufacture the Pitvaq (including the vacuum tank and the hoses) in South Africa in 2020 is approximately 3 250 USD.
The cost of transport to other countries varies from as little as 600 USD to as much as 1 500 USD depending on distance and whether one uses road, sea or air freight, and on customs and clearance costs.

What consumables do I need to run the Pitvaq?

Petrol, oil, cleaning materials

What happens to the sludge once it’s pumped by the Pitvaq?

The sludge is sucked into the vacuum tank, which has a 50 litre capacity. From there the sludge is discharged into an empty drum. When the drum is full, it is sealed and then either taken to the waiting truck or trailer, or it is discharged into a disposal pit which has been dug for that purpose. If there is enough space, disposal of sludge into a soak pit is not unsanitary as soil is a very good medium for the containment of pathogens. After the pit is filled it is backfilled with soil so the sludge is well buried. What is not sanitary is surface disposal.
In some places there are treatment facilities provided for faecal sludge, and the sludge may be taken for disposal at these facilities.

What regular maintenance is required on the Pitvaq?

At the start of a day one should check that the engine has petrol and oil, and that the vacuum pump has oil. When a job is finished one needs to flush the suction hose and the vacuum tank with water, and the moisture trap should be drained. At the end of the day the vacuum tank and the hoses should be more thoroughly rinsed. After 20 to 30 hours of use, the engine oil and filters must be changed. At longer intervals the engine spark plug will need to be cleaned or replaced. More extensive engine overhauls should be done by a competent mechanic. The vanes in the vacuum pump will need to be replaced after 3 000 to 5 000 hours of use.

When was the Pitvaq invented?

The machine has evolved since the first prototype was tested in 2012, although the basic operating principle remains the same.