Vacuum Degassing

The process of improving sludge thickness and stabilization by using vacuum  

Vacuum Degassing technology is a new and unique, but fully proven technology with over a decade of full-scale BNR operating experience in Europe. This technology is now being introduced to North America to provide effective year round Biological Nutrient Removal with unparalleled low cost, minimal land use, and high treatment efficiency for existing and new activated sludge Waste Water Treatment Plants. The core of the proprietary, worldwide patented Vacuum Degassing technology is a unique process enhancement of BNR treatment by vacuum degassing of mixed liquor. The MLSS is degassed in a low energy input Vacuum Degassing tower immediately after biological treatment and before secondary clarification. MLSS vacuum degassing results in major improvements of sludge settling, thickening and stabilization in clarifiers. RAS concentrations of up to 2% and MLSS concentrations of 6,000 to 8,000 mg/l or more are routinely achieved.

vacuum degasing

Major Feature of Technology

Technical Efficiency

  • True Anoxic and Anaerobic conditions to optimize BNR processes
  • No floating scum nuisance on secondary clarifiers, so collection, management and disposal of scum are reduced or eliminated
  • Operator-friendly, stable WWTP performance and minimum process supervision required
  • Allows for substantially reduced WAS production and use of WAS Gravity Thickening options

Technical Efficiency

  • Reduced Biotreatment cells size up to approximately 50% smaller than conventional activated sludge BNR WWTPs of same depth
  • Energy savings up to 50% for mixing of reduced volume Bio Cells
  • Reduced secondary clarifiers surface area by up to 30%
  • Thicker WAS up to 2% reduces dewatering costs, energy consumption, and chemicals use


  • Eliminates sludge bulking even for high filamentous organism conditions, and helps prevent potential nocardia infestations
  • Consistent high RAS concentrations up to 2%
  • Maintains year-round MLSS concentrations of 6,000 to 8,000 mg/l or higher
  • No settled sludge pop up in secondary clarifiers
  • Protects from storm flow hydraulic overloading and poor performance
  • High Resistance to organic shocks and impacts from maximum hour hydraulic overloading