Applications of fine and ultra-fine bubble technology

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Applications of fine and ultra-fine bubble technology

Nikuni KTM pumps create consistent fine bubble discharges. Fine bubble diameters of air or a gas in a liquid are to be found between 1 and 50 microns, whereas ultra-fine bubbles are found at diameters less than 1 micron

Fine and ultra-fine bubbles

(Please see our technology pages for more downloads and information)

Bubble nomenclature can be confusing with the terms 'microbubble' and 'nanobubble' being used interchangeably, even in print.

In order to contribute to the recognition of a common standard, Aeration&Mixing© have adopted the terms used by Japan's Fine Bubble Industries Association (FBIA) who have greatly advanced international understanding in many areas of bubble research; see this video link...

At Aeration&Mixing in accordance with FBIA we class fine bubbles as those with diameters from 1µm to 50µm, and ultra-fine bubbles as those with diameters of less than 1µm.

Nikuni KTM pumps are precision made devices which can create consistent fine bubble discharges in a carrier fluid at an average fine bubble diameter of 25µm. Smaller fine bubbles can be produced by these pumps with additional equipment provided by A&M©.

Fine bubbles at a diameter of only 25µm have many uses particularly because, they not only provide an excellent bubble-to-particle ratio for DAF and IAF/IGF applications, but they are small enough to enable good mass-transfer of gasses to liquids.

Fine bubbles are best applied in tanks and vessels rather than in open lagoons or lakes, as their action is essentially gentle rather than the creating strong mixing needed for the treatment of active sludges.

A fine bubble in tap water has a life of approximately 2 minutes, after which it disappears. When a fine bubble disappears, one of two states will have occurred;

  • a) a proportion will have collapsed and the gas dissolved into the carrier liquid or at the surface of the carrier fluid; 
  • b) the remainder will have fractured into a large number of ultra-fine bubbles, sometimes called nano-bubbles, often as many as 200 million per ml with diameters ranging from 50 to 250nm

Ultra-fine bubbles have been measured with diameters as small as circa 50nm, completely invisible to the human eye and only visible in clusters under the backscattering of green laser light. In simple terms, particles present will reflect whereas fine and ultra-fine bubbles refract light. Whereas fine bubbles have a life rarely extending beyond two minutes, ultra-fine bubbles can exist for many months and in some special cases, for years.

Current international research is seeking ways of collapsing ultra-fine bubbles at a time of user's choosing, an area of research in which A&M is active.

The principal current uses of fine bubbles include:

  • Injecting gasses into liquids
  • Changing the state of fluids
  • Separating particles of waste by flotation e.g. DAF/IGF etc.
  • Cleaning and sterilization
  • Medical treatments and procedures

Future uses of ultra-fine bubbles include:

  • Advanced drug delivery
  • Further new medical treatments
  • Significant new cleaning techniques
  • Major advances in sterilization techniques and CIP technologies
  • Food and drink sector product developments

Fine bubble technologies are a fascinating area of science constantly evolving yielding new discoveries.

One of the most useful articles on fine and ultra-fine bubbles has been written by Professor Martin Chaplin and can be found via the following link...