Every compressed air system will always produce condensate. The correct handling of the condensate is an important task. Due to its composition, it often poses a danger to the environment and its production. Condensate is often highly enriched in dirt, oil and pollutants. It is produced at almost all parts of the treatment chain: compressor, cyclone separator, refrigeration dryer, filter or the compressed air receiver.

The amount of condensate produced depends on the amount of compressed air produced and the condition of the processed air. The season also plays an important role. With a compressor (compressed air volume: 12 m³/min), approx. 70 liters of condensate are produced per day in winter, and up to 150 liters in summer.

The components of the condensate are:

  • Oil-water mixture
  • Dirt such as corrosion particles from the pipes or contamination of the air that was already present before
  • pollutants from components of the ambient air drawn in

Just 1 liter of oily condensate can contaminate up to 1 million liters of groundwater. Therefore, oily condensate is considered “waste requiring special monitoring” (European Waste Code 130802) and must be disposed of in accordance with special regulations. It can only be disposed of by authorized waste disposal companies or must be treated on site.

Drain and treat condensate

Condensate drains drain liquids from the system without letting too much compressed air escape. The discharge is done by an electronic level-controlled condensate drain.

Condensate treatment: There are two ways to separate water and oil. On the one hand, separation by gravity (filtration) or by splitting plants (for emulsions).

TypeStatic oil-water separatorsAdsorption splittingMembranfiltration
Features– gravity separation of free oil and dirt

– Adsorption of residual oil on activated carbon

– low maintenance effort

– no external energy


– reliable splitting of emulsions

– simple procedure

– drastic reduction of the amount of waste to <0.5

– residual oil content in waste water <1 mg/l


– Residual oil content of treated waste water <1 mg/l
To consider– separation of stable emulsions not possible

– regular replacement of the activated carbon filters

– disposal of the residual materials and the used activated carbon


– process for compressed air condensates with emulsified oil contents <1

– disposal of separated flakes


– limited concentration

– exclude ingredients hazardous to membranes