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KKI 215

Sulzer Nopon disc diffuser system KKI 215

Membrane disc diffusers for reliable and energy-efficient fine-bubble aeration of tanks in wastewater treatment plants. Suitable for normal continuous aeration systems as well as where intermittent aeration is required, e.g. biological nutrient removal and SBR processes.


  • Self-cleaning EPDM membrane with slits;
  • Membrane is fixed by a threaded screw-on ring;
  • Elastic non-return valve;
  • Sulzer Nopon wedge piece fixing to the pipe means that no glue, solvent   or welding is needed in assembly;
  • Thread based fixing available as an option;
  • Wedge piece fixing makes it easy to increase, decrease or relocate   diffusers when process requirements change;
  • Applicable to various pipe materials and dimensions;
  • Option for deep basins;
  • Possibility for future increase of aeration capacity by installing 300 mm PRF retrofit discs on existing KKI bodies;
  • Inlet air temperature is up to 80°C.

Working principle

The membrane bulges and slits open during aeration by the pressure of compressed air. The support plate distributes the air evenly over the entire surface of the membrane. Air is spread into small bubbles, when released through the membrane. When the air flow is turned off, the pressure of the water above presses the membrane disc tightly to the support plate closing the small slits on the membrane. The non-return valve closes and makes sure that no water enters the pipeline.

Components and materials

  Description Material
1 Main body uPVC
2 Wedge piece uPVC
3 Support plate Glassfiber reinforced polypropylene
4 Screw-on ring uPVC
5 Support part uPVC
6 Membrane disc EPDM
7 Non-return valve EPDM
8 O-Ring NBR

Model range (wedge attachment)

  KKI 215 D90 KKI 215D D90 KKI 215 D88,9 KKI 215 4”
Pipe 90mm PVC 90mm PVC 88,9mm SS NS4” PVC
Main body HSA 215 HSA 215 HSA 215 HSA 4
Wedge piece HSK 215 HSK 215 HSK 215 HSK 4
Support plate HTL 215 HTL 215 HTL 215 HTL 215
Screw-on ring HKR 215 HKR 215 HKR 215 HKR 215
Support part - HTO 215 - -
Membrane disc HIK 215 HIK 215 HIK 215 HIK 215
Non-return valve HVK 215 HVK 215 HVK 215 HVK 215
O-Ring HOR 19 HOR 19 HOR 18 HOR 19

Model range (thread attachment)

  KKI 215 R½ KKI 215 R½K KKI 215 BSF½
Fitting R½ cylindrical thread (ISO 228/1) R½ taper thread (ISO 7/1) BSF½ thread (½”-16 BSF)
Main body HSA 215 R½ HSA 215 R½K HSA 215 BSF½
Support plate HTL 215 HTL 215