Bubble Diffusion

14th Apr 2020

Ozone is a gas, therefore proper gas/liquid contact mechanisms are critical to efficient system design. Bubble diffusers are a popular, inexpensive method to inject ozone into water. The ozone gas transfer area occurs immediately at the interface between the ozone bubble surface and the surrounding water.

Bubble Diffusion:

Diffusers permit ozone gas to pass through a porous membrane thus creating many small ozone bubbles in the water, similar to a fish tank air stone. As the ozone bubble rises, the gas at the bubbles edge will transfer into the water. Using a diffuser requires enough pressure to overcome the height of the water and any restrictions in the diffusers due to hole size.

Advantages:

  • Low Cost
  • Easy to set-up
  • Low energy - does not require a water pump

Disadvantages:

  • Inefficient - ranges from 10-25% (dependent on water height)
  • High water columns/vessels are typically required
  • Difficult to use in pressurized water flows
  • Diffuser pores can become plugged requring cleaning
  • The diameter of a gas bubble has a dramatic impact on surface area as shown below!
  • Be picky when it comes to selecting a bubble diffuser. It can mean the difference between success and failure.
  • The transfer of ozone gas into water is directly related to its surface area (total bubble surface area).
  • It is critical to prevent the water from back-flowing through the bubble diffuser and going into the ozone generator. The best method of prevention is to use multiple check valves (for redundancy) and a water trap

4.8 ft² diameter = 14.8 inch / 1 Bubble

185 ft² diameter = 10 mm / 54,000 Bubbles

1,800 ft² diameter = 1 mm / 54,000 Bubbles

Conclusion: Additional smaller bubbles give you more mass transfer!

Click here to learn more about ozone transfer via bubble diffusion.