Wastewater is discharged into the collection chamber. Once the wastewater rises to a certain level in the chamber the vacuum valve opens. This is triggered by a switch mechanism on the ball float.
The differential pressures between the pipe network (vacuum) and collection chamber (atmospheric pressure) draws the wastewater into the pipe network and transports it to the vacuum station, where it is collected in the vacuum tank storage.
Due to the high speed of transport this means that the wastewater is in the network for only a short period of time, therefore septicity is not an issue.
Once the level in the vacuum storage tank reaches a predetermined level discharge pumps empty the tank and send the effluent to the nearest treatment facility.
The Pipe Network
The pipe network consists of PVC or HDPE pipes. A central
vacuum station keeps this pipe network under negative
pressure. Due to their small diameter, the pipes can be laid
at depths of 80 to 120 centimetres under the ground
surface thus alleviating the need for the deep excavations
of traditional gravity drainage. The addition of air makes
the wastewater lighter, which leads to higher transport
speeds. The pipe network is laid in a ‘saw tooth profile’.
Within this profile, a mixture of wastewater and air from the
collection chamber is transported to the vacuum station.
Within the pipeline network, the wastewater at rest flows into deeper lying ‘pockets’. Once a collection chamber in the pipeline network is activated, the mixture of wastewater and air is transported towards the vacuum station.
Once the collection chamber is emptied, the entire system will come to rest. One transportation cycle has then been completed.
Vacuum Station Functions
The wastewater from the collection chamber is transported through the pipe network and enters in the vacuum tank. The vacuum in the tank is generated by vacuum pumps. The extracted air from the vacuum tank can be purified with a Bio-filter. The level in the tank is measured with an ultrasonic transducer. The discharge pump(s) will be activated at high level and the wastewater will be transported to the nearest treatment facility. The discharge pump(s) will stop automatically at low level.