Waterguide - Membrane degasser

What is membrane degassing?

Membrane degassing is used to reduce the amount of dissolved CO2 in the permeate of a reverse osmosis unit, or potentially between the first and second stage of a reverse osmosis unit. In this way, the membrane degasser reduces the conductivity of the permeate as well as the load on the downstream electrodeionisation (EDI). The ultrapure water series UP-S7 contains a reverse osmosis stage and an EDI stage with joint Siemens S7 control and is already set up for installation of a membrane degasser between the reverse osmosis and EDI stages.

Operating principle

Stripping air is used to remove dissolved CO2 from the permeate. The permeate is conveyed through a membrane module with PP hollow fibres, which only allows gas to pass through, but not water.

The permeate and stripping air are conveyed countercurrent for optimum degassing results.


  • Considerable improvements to the quality of the permeate and diluate
  • No use of chemicals
  • Robust and reliable physical process
  • Compact enough to be integrated into the UP series

What is the physical law behind membrane degassing?

Henry’s law, which is named after the British physician and chemist, William Henry, describes how a gas behaves when it dissolves in a fluid.

What components does a membrane degassing unit have?

The membrane degasser installed in the unit contains an air filter, pressure regulator and air flow meter. On site, it is supplied with compressed air. With larger degassers, a side channel compressor (SV) is included.

Please get in touch for information about special applications, such as oxygen degassing, degassers with FDA-approved modules, or for permeate with a dissolved CO2 value > 30 mg/l.



You can find more information on membrane degassing in our product center:

Membrane degasser in a customised UP 12000 ultrapure water unit

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