How can such a simple system work so well?
The system consists of toilets and greywater interfaces connected to a vacuum generator via the piping.
Generating vacuum in the piping
The basic principle behind a vacuum toilet system is to use differences in air pressure to transport sewage from toilets and urinals (sometimes also greywater). In our modern vacuum systems, the Vacuumarator™ pump generates vacuum directly in the piping system. The entire piping system is kept at a constant vacuum level, normally between 35% and 50% (in a Constant Vacuum System - CVS™).
Transporting sewage from toilets
When a toilet is flushed, a valve in the toilet opens. Approximately 60 litres of air along with about 1 litre of water is sucked into the piping system because of the vacuum present in the piping. The water and sewage create a "slug", which is transported through the piping system because of the different air pressure levels in front of and behind the slug.
During the transport through the vacuum piping, the slug is affected by gravity and flattens out after a time. Slugs have to be re-formed in the piping. This is done by installing low points in the piping, known as transport pockets. As blackwater builds up in the transport pockets, new slugs are formed. At the next flush of a toilet, the slug moves on and re-forms again and again in transport pockets further down the piping system.
Simple yet advanced pump
Vacuum is generated by one or more Vacuumarator™ pumps. Black water is macerated and pumped to a sewage treatment plant or a collecting tank.
Sewage transport in a vacuum piping system
1) When you flush the toilet, a valve in the toilet mechanism opens. Air and about 1 liter (1/4 gal.) is sucked into the piping.
2) The liquid waste forms a "slug" which moves at great speed through the pipes, as it is pushed inwards by the outside air. This happens because the air pressure is lower inside the piping than in the room outside (vacuum), and has several benefits - one of which is to allow piping to be laid upwards. The "slug" levels out after a while.
3) In long piping systems and where pipes are to be laid upwards, we collect water in low points in the piping to form new "slugs" as the liquid moves through the piping. These low points are called transport pockets.
4) Inside the pump, toilet waste is ground into tiny particles and discharged to a public sewer, collecting tank or treatment plant.