Vacuum sewer

Valves open and reseal automatically when the system is used, so differential pressure can be maintained without expending much energy pumping.

A single central vacuum station can collect the wastewater of several thousand individual homes, depending on terrain and the local situation.

Dutch engineer Charles Liernur first applied negative pressure drainage to sewers in the second half of the 19th century.

[2][non-primary source needed] Technical implementations of vacuum sewerage systems began in 1959 in Sweden.

[citation needed] Historically, vacuum sewers have been a niche product, used only in trains, airplanes, and flat areas with sandy soils and high ground water tables.

In order to ensure reliable transport, the vacuum sewer line is laid in a saw-tooth (length-) profile.

The air-to-liquid ratio is usually maintained by collecting liquid/air simultaneously or controller units that adjust their opening times according to the pressure in the system.

Flat terrain, unfavorable soil (rocky or swampy ground), or a high groundwater table (which requires dewatering trenches) can make gravity sewerage systems much more expensive.

Vacuum systems are used in many environmentally sensitive areas such as the Couran Cove Eco Resort close to the Barrier Reef in Australia.

Valves, collection pits, intake vents, and control systems need to be designed to keep functioning despite cold, snow and ice.

Many Nordic Countries utilize vacuum sewers, it is helpful to have some type of marker or monitoring to locate valves when they are buried under the snow for extended periods.

with conventional gravity sewer systems, sedimentation problems can easily occur as automatic flushing by daily waste water does not take place.

The Formula 1 race tracks in Shanghai and Abu Dhabi are using a vacuum sewer system for that reason.

Vacuum sewer systems may be selected for their fast (avoiding conflicts with traffic and tourism), cost-effective and flexible installation.

Sewage systems usually thermophilically compost biosolids which have been separated and dewatered from a standard gravity sewer.