Coarse Bubble Diffusers 103

Coarse bubble diffusers are suitable for almost any type of water and wastewater application. The primary application of coarse bubble diffuser systems today are as indicated below: 

Aerobic Digestion Applications
  • Coarse bubble diffusers have been the traditional diffusers used in these applications. The standard design rate for this application is 30 scfm per 1000 ft of tank volume.
  • Flexible membrane difffuers are being applied to a significant degree as the operating efficiency and back-flow prevention benefits of flexible membrane diffusers are being realized. Furthermore,, with the application of grid type designs, improved mixing is obtained. When properly applied, flexible membrane diffusers provide the end user with an ability to reduce the air rate to the digester by as much as 50% while maintaining mixing and dissolved oxygen concentrations.
Mechanically Thickened Sludge Applications
  • High solids applications require aggressive aeration energy for mixing and oxygenation. Coarse bubble diffusers with back-flow prevention capabilities perform well in these applications. Diffuser units that do not have back-flow prevention capabilities should not be used in these e applications, as the units will mechanically plug. Flexible membrane diffusers may also be applied and offer increased oxygen transfer efficiency benefits over coarse bubble diffusers.

Auto-Thermophilic Aerobic Digestion (ATAD)
  • These applications are high solids, high temperature applications. Coarse bubble diffusers with back-flow prevention capabilities perform well in these application and materials of construction should be evaluated to handle the elevated operating temperatures associated with this application. 

 Small or Package Plant Systems
  • Energy concerns are less significant for these applications and the desire for make these applications ideal for coarse bubble diffusers. 


  • Flexible membrane diffusers are being used to a greater degree in these applications as the technology used d in current state-of-the-art diffusers provides more repeatability and operating efficiency. 
Air Stripping
Air stripping has been used for groundwater and other applications where volatile compounds are present. The high volume capacity of coarse bubble uni its is ideally suited for this application. 

Coarse bubble diffusers come in many varieties and can be simple to apply. It should be noted that all coarse bubble diffuser systems operate at approximately the same energy consumption or operating efficiency. There is little differentiation in the operating efficiency of coarse bubble diffusers when properly applied. I Inn general, coarse bubble diffuser units require approximately 2 times the energy of high efficiency and fine pore aeration systems. 

Please refer to the EDI FlexAir®, EDI PermaCap5™, and the 9-inch FlexAir Disc coarse bubble diffusers for applications where coarse bubble may be preferred. 

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