Vacuum drainage
Vacuum drainage (technically correct: under pressure drainage ) describes a drainage process in which wastewater is sucked off the house connections (or individual drainage objects ) with the help of negative pressure .
history
The Dutchman Charles T. Liernur was granted a Prussian patent for "negative pressure drainage" as early as 1870 and was used in several cities (e.g. in the Paris suburb of Levallois-Perret in 1892), but was forgotten. It was considered unreliable because the pumping stations and the way the pipes were laid were not yet mature. Today, with around 1000 installations from various manufacturers, the process is considered reliable in Germany alone.
function
A vacuum tank is located in a central vacuum station, into which the dirty water from the connected buildings reaches via vacuum lines. A vacuum pump maintains a negative pressure in a range of z. B. -0.6 to -0.7 bar in relation to the atmosphere . A sewage pump conveys the dirty water from the vacuum tank to a sewage treatment plant. The negative pressure acts through the negative pressure lines connected to the tanks as far as the house connection shafts, where it is at least −0.15 bar below atmospheric pressure . When a certain amount of dirty water has accumulated in the house connection shaft, a sensor opens the suction valve via a control unit in order to suck out the dirty water. If the sensor, control unit and suction valve are pneumatic, no power supply is required. After or at the same time as the dirty water, 2 to 15 times the volume of air is sucked in; the air / water ratio can be set on the control unit. The vacuum lines are installed with systematically arranged high and low points. The dirty water collects at the low points and is pushed over the next high point by the air flowing in. It is a system comparable to the pneumatic tube. A negative pressure drainage system can lift wastewater by up to 4–5 m, in special cases even higher.
advantages
A gradient in the sewer pipe is not required. The dirty water can be transported over (small) jumps in height. Low-lying houses can also be connected. The system is therefore particularly suitable for flat terrain, high groundwater levels or difficult soil conditions (e.g. rocky soil).
The vacuum lines have a much smaller diameter than lines for free slope drainage. They are laid at a shallow depth, adapted to the terrain profile . Trenchless installation is also possible with restrictions. The construction costs are much lower.
No dirty water can escape from vacuum lines, even in the event of leaks. Leaks are easy to detect and can be precisely localized. Therefore the system is particularly suitable for water protection areas. Vacuum lines can therefore also be laid in a shared trench with drinking water lines.
The system is also particularly suitable for material flow separation. It is able to pump black and brown water. It enables the direct connection of negative pressure toilets and urinals .
Areas of application
A conventional free gradient system requires a deep installation and, if necessary, pumping stations and is therefore expensive. A pressure drainage system with a large number of pumps requires a local power supply and is very expensive for larger systems. The negative pressure system can be more economical in the case of flat terrain or high groundwater levels and when connecting more than 25-50 houses. In the cost comparison of the Federal / State Working Group on Water (Lawa), projects with 5 or more house connections are already considered economically feasible.
Vacuum drainage has been used decentrally for vacuum toilets in ships , airplanes and trains for decades because it works independently of internal and external pressure conditions. Vacuum toilets require less flushing water than conventional toilets .
- Vacuum drainage outside of buildings
- Laying the pipelines close to the surface
- Independent of slope and flexible in routing
- no deposits due to high transport speeds in the pipeline network
- stable even with fluctuating wastewater quantities (seasonal operation)
- Level laying in a trench, also together with drinking water and other material flows
- House connection shafts do not require an electrical power supply
- Exfiltrationssicher -einsetzbar in drinking water protection areas without double pipe wall
- easy division into building sections and expansion options
- Can be used in flood and flood areas
- no separation of solids and water on steep slopes
- Simple separation into material flows (e.g. gray and black water)
- Small diameter pipes
- Possibility to adapt to vacuum sanitary facilities and marinas
- Negative pressure drainage for settlements
- Inexpensive connection of settlements with low building density.
- shallow installation depth and narrow trenches; therefore also suitable for sensitive conditions (e.g. listed old towns)
- Minimizing traffic disruption
- Lines without side connections can also be laid using trenchless construction (e.g. using a controlled horizontal directional drilling process)
- Leak in the pipeline network
A leak is quickly recognized by the increased running time of the vacuum pumps and, in extreme cases, by the collapse of the negative pressure in the vacuum tank.
If inspection pipes are systematically installed in the vacuum system, leaks can be detected and localized quickly and precisely with a simple device (inflatable shut-off ball). If inspection pipes are installed at a distance of approx. 100 meters and gate valves at a maximum distance of 450 m (according to DWA116-1), sections of the pipeline network can be cut off.
The system remains intact and ready for use. A repair can be carried out with short response times during operation. With free-fall or pressure drainage systems, leaks in the pipeline network can only be identified and repaired with great effort. Permanently unnoticed exfiltration leads to pollution of the groundwater.
- Surveillance systems
Safe from extraneous water:
The valve releases can be counted mechanically by a counter or transmitted to the central vacuum station or control center via intelligent monitoring systems. In this way, the amount of wastewater discharged can be set in relation to one another, and illegal dischargers can be found in the event of rain or high groundwater levels.
House connection shafts - localize problems:
The valve position and the filling level of the storage space are transferred to the vacuum station or control center with precise positioning by intelligent monitoring systems. This simplifies the operation of vacuum systems considerably. Current vacuum systems are largely implemented with these monitoring options. Existing systems can be retrofitted.
Automatic troubleshooting:
In addition to the monitoring functions, control technology solutions are also incorporated in current vacuum systems. The valves are automatically triggered in order to bring air into the system in a targeted manner or to automatically eliminate faults on the valve. The most important thing is that the pneumatic actuation of the valves also works without electrical connection lines, thus maximizing functional reliability.
See also
Norms and Literature
- EN 1091
- DWA-A 116-1 (also known as ATV-DVWK-A 116, Part 1)
- WEF (Water Environment Federation) Alternative Sewer Systems (Second Edition - 2008)
- WSA 07 (Australian Code)
- AS 4310 - 2004 (Australian Vacuum Interface Valve Standard)
- Jörg Lange / Ralf Otterpohl : Wastewater. Handbook for sustainable water management. Donaueschingen 2000 (2nd edition) ISBN 3-9803502-1-5
Web links
- Vacuum sewerage
- Vacuum sewerage
- Vacuum sewerage
- Vacuum sewerage
- Vacuum drainage for buildings
- Vacuum sewerage in vacuum-guide
Individual evidence
- ↑ Stuttgart Reports on Urban Water Management - Volume 140 - University of Stuttgart ( Memento of the original from August 12, 2014 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF file; 293 kB)
- ↑ Ulrich Kunz: Pressure and vacuum drainage for properties , Association of Swiss Wastewater and Water Protection Experts , Verlag Verband Schweizer Wastewater and Water Protection Experts, 1996
- ↑ Jens Friedemann: Introduction to urban drainage , Werdau, June 2003, Institute for Water Management Halbach
- ↑ Georg Maybaum, Rainer Vahland, Wolfgang Oltmanns: Process Engineering in Geotechnical Engineering , Vieweg + Teubner Verlag, 2006, ISBN 3519003899 , p. 384ff ( preview in the Google book search)
