Vacuum sewers

Question 1

How big are the pipes?

Answer 1

75 - 90 mm

Question 2

How much is the vacuum?

Answer 2

A constant 0,4-0,5 bar

Question 3

How fast is the transport?

Answer 3

• 70km/h transport in pipes

Question 4

How is the system designed?

Answer 4

o Sewer goes up from the toilet, then down to the basement of building
o Transport pockets every 30 m - a bended pipe
o Valves by each toilet, inside each building, and by the property border on both sides
o Several lines of pipes instead of one big main pipe
o Valves before and inside pump station
o Pressure reader by the property and the pump station.
o Air removal by a carbon filter at pump station
o Heavy object trap before pump
 Manually emptied every 2 – 4 weeks
o Inspection wells at the end of the lines

Question 5

How is leakages found?

Answer 5

o Sectioning of sewer pipes at 3am for 10 minutes once per month
o Leakages spotted by decreasing underpressure

Question 6

How much more concentrated blackwater?

Answer 6

50 times the concentration

Question 7

What are some errors that have been noticed with vacuum sewers?

Answer 7

o Inside the property border due to lack of knowledge during installation
 Fixed with installation guides
o Flushing valves kept open in toilets
 Led to noise for the tenant
o Too small valves (25 – 50 mm)
 Blockages
o Pipes loosened due to faulty anchoring and vibrations due to the speed of transport

Question 8

What are some facts regarding maintenance?

Answer 8

o Under trial
o Nozzel or hot water
 No difference between them
o More wells needed

Question 9

What are some lessons learned of vacuum sewer systems?

Answer 9

o Demands interaction with stakeholders
o Lack of knowledge among stakeholders gives errors
o Long commitment from decision to implementation of area
o Formation of a strong municipal group early on helped a lot