Dissolve ozone in water with bubble diffusers

Ozone gas can be dissolved into liquid with simple bubble diffusers, similar to what is commonly used in the bottom of a fish aquarium for aeration. This is a simple and cost-effective method to dissolve ozone gas into liquid. As ozone is partially soluble into liquid the ozone gas will transfer into liquid immediately at the interface between the ozone gas bubble surface and the surrounding water.

Diffusers implement a gas permeable membrane that will disperse the gas stream into many smaller ozone gas bubbles in the water. As these ozone gas bubbles naturally rise to the surface of the water that ozone will transfer into the water due to contact between the liquid and gas bubble.

Advantages:

  • Low cost
  • Easy to setup
  • Low energy – does not require water pumps or elevated water pressures
  • Simple, reliable operation long-term

Disadvantages:

  • Generally the least efficient method of dissolving ozone into liquid
  • Diffusers can become plugged and may require periodic replacement
  • Difficult to use in pressurized water flows

Ozone gas is partially soluble into liquid. However, using proper methods and equipment high mass transfer efficiencies can be realized with any method of dissolving ozone into water. Review the tips below for success using an ozone gas bubble diffuser in your ozone application.

Fundamentals of ozone solubility:

  • Lower temperatures increase the solubility rate of ozone gas into liquid
  • Higher pressures increase the solubility rate of ozone gas into liquid
  • Higher ozone gas concentrations increase the solubility rate of ozone gas into liquid

Design considerations for your bubble diffuser and column:

Diffuser micron ratings – smaller is better!

Ozone gas bubble diffusers will be rated in micron size, or resulting bubble size the diffuser will create. The membrane that splits the gas stream into small bubbles will have pore sizes, smaller pores will result in smaller bubbles. This pore size or bubble size is normally referred to in a micron rating.

Micron = micrometer. Equal to 0.001 millimeter, or about 0.000039 inch

Smaller bubbles create more surface area of the gas the ozone is flowing in. Greater surface area will increase the ability of ozone gas to transfer into the liquid. See the example below:

Ozone gas bubble size compared

The image above shows the same gas volume (1 ft3) shown in one bubble, 8 identical bubbles, and 512 (8 tall x 8 wide x 8 deep) identical bubbles.

  • One 1 cubic foot sphere = 4.8 ft2 surface area
  • Eight 0.125 cubic foot spheres = 1 cubic foot = 1.2 ft2 each = 9.66 ft2 total surface area
  • Eighty 0.0125 cubic foot spheres = 1 cubic foot = 0.26 ft2 each = 20.8 ft2 total surface area
  • 512 0.001953 cubic foot spheres = 1 cubic foot = 0.07567 each = 38.7 ft2 total surface area

A bubble size ¼ the size (4.8 / 4 = 1.2) results in 8x more bubbles and double the overall surface area.

Relating this to your ozone gas flow. A 25 micron diffeser will create bubble sizes ¼ the size of a diffuser rated for 100 micron therefore creating more than 2x the surface area of gas contacting the water at the same flow-rate of gas flowing into water.

Smaller really is better!

Tank design – skinny is better!

Gas bubbles will naturally rise to the surface of water due to buoyancy. Therefore, the taller your tank, column or ozone tank is the longer your gas bubble will remain in the water increasing the opportunity for the gas to transfer into the liquid.

Taller tanks will also increase the water 

pressure at the bottom of the tank where the ozone gas diffuser will likely be placed. Greater water pressure will increase the natural solubility of ozone gas into liquid. For example:

11.33 feet of water = 5 PSI

5 PSI = 34% increase in ozone solubility vs 0 PSI

Increasing your water column by 11.33 feet will increase your solubility of ozone, or your mas potential ppm of ozone in water by 34%.

1 ppm becomes 1.34 ppm with no other changes.

A great example of separate columns is shown in the image and dimensions below. Both columns are 3 liters in volume, with a change in diameter from 2” to 4” the height is increased from 12” to 58”

If you have the opportunity when desiring your tank or reactor, choose the smallest diameter possible.

Skinny really is better!

Counter Current Flow

Ozone contacting basins can be designed with counter-current flow, where the water flows counter-current to the gas bubbles. While gas bubbles will naturally rise to the surface of the liquid due to buoyancy liquid can be forced into the path of the gas bubble to create additional turbulence. The diagram below shows a simple contactor basin design using baffles to create counter-current and con-current flows of ozone gas to liquid

Ozone gas countercurrent flow with bubble diffuser

This same technique can be applied to any column in flowing water using piping water flowing down a column that ozone gas is rising within. Consider this simple technique when designing your tank or piping system

Full page info on ozone diffusers HERE

Fundementals on ozone solubility into liquid HERE

Understand dissolved ozone vs ozone dosage

Purchase ozone diffusers here

Ozone Bubble Diffusers – stainless steel

We have recently obtained some new Stainless Steel Ozone Bubble Diffusers.  These are excellent options for your simple ozone system using a bubble diffuser.  These diffusers are constructed of sintered stainless steel and offer a 20 micron rating bubble size.  Max flow rates are 2.7 CFM and 5 CFM.

Ozone diffusers
Ozone Bubble Diffusers

We offer these diffusers in 2 sizes.  Each has a 6″ long diffuser attached to a pipe nipple with a 1/4″ Male NPT threaded connection.  The difference in sizes we offer are only diameter differences.  This allows more surface area of the diffuser itself, and therefore a higher maximum flow capacity.

Quantity discounts are offered for each diffuser, see our website for details on discounts.

Ozone Diffuser Features:

  • Sintered stainless steel construction is strong and reliable for many years of service
  • Threaded connection offers a solid seal to your piping or tubing
  • Hex nipple allows a wrench to be used to tighten or later remove the diffuser from your fitting or piping, this eliminates the potential of breaking the diffuser when twisting the sintered steel
  • Welded construction
  • 20 micron rating allows for very small ozone bubbles
  • 6″ length is sufficient to offer great surface area, but without the extra length to minimize damage

Ozone bubble diffuser
Ozone Diffuser – 1/2″ diameer shown

ozone bubble diffuser welded and capped end
Welded end of diffuser shown

Stainless ozone diffuser with hex nipple
Hex nipple and threaded connection of ozone diffuser shown. A solid seal is made with the stainless threaded connection and hex nipple.

 

Tips for using a bubble diffuser:

  • Before attempting to dissolve ozone into water ensure you understand the principles of ozone solubility well.  Click HERE for more information
  • Water tank must be vented to safely remove excess ozone/oxygen from the tank
  • Diffuser should be placed at the bottom of the tank
  • Taller tanks and taller water heights will increase mass transfer of ozone into water as the water pressure is higher at the bottom of the tank, and the gas bubble must travel farther in the water.
  • Ozone generated from oxygen will dissolve into water more efficiently than ozone generated from air
  • Ozone generated at high concentrations will dissolve into water most efficiently, target the highest concentration ozone possible when using a bubble diffuser.
  • Colder water temperatures will achieve highest dissolved ozone levels.
  • Use counter-current water flows across the bubble diffuser

ozone bubble diffuser
Drawing of example of ozone bubble diffuser in use

Above drawing gives a great example of how an ozone bubble diffuser can be used in a very simple system.  A great advantage to this system vs those that use a venturi injector is that there is no water pump required in this system, this is a very passive, and energy efficient system.  Many of the failure prone pieces of equipment of a traditional ozone injection system are not used in this system.  Consider this in your next ozone system.

ozone bench-test system
Ozone bench-test system using bubble diffuser

A great opportunity to use an ozone diffuser is a simple bench-test system.  Set-up a column to dissolve ozone into constructed of glass or PVC.  We use PVC pipe and place a diffuser in the bottom of the pipe via a tee.  This allows the column to be 5-feet tall or more.  This allows a great opportunity to maximize ozone transfer into water.

The drawing above shows a complete system, if you are interested in setting a system like this up, let us know.  We sell and rent all this equipment, or can provide this testing for you in our facility.

 

Stainless Steel Ozone Sparge Diffuser

Oxidation Technologies, now offers stainless steel ozone sparging diffusers for bubbling ozone into water.  These are both constructed of sintered stainless steel for long term reliability and fine pore micro-bubble creation in water.

SS1 Diffuser:

The SS1 diffuser uses a barbed connection for easy connection to the tubing.  Flow rates up to 10 LPM are acceptable with the SS1 diffuser.  A compact size and easy connection make this a great diffuser for a wide variety of applications, from ozonated olive oil, to large water treatment applications.

SS1 in action bubbling ozone into water real-time
SS1 Bubbling ozone in water

 

Stainless Steel ozone sparge diffuser
SS1 Ozone Diffuser

See video of the SS1 Diffuser in action in video below. Notice that as gas flow through the diffuser increases the bubble diameter remains fairly consistent. This is an important distinction and characteristic. In many stone diffusers the bubbles will grow in length and overall size as flow increases, thereby decreasing efficiency with higher flows.

For a larger diffuser option we offer the SS6 Ozone Diffuser. This is commonly used in water treatment, or In-situ groundwater remediation applications. The SS6 offers a 1/4″ Male NPT connection for a solid threaded connection to tubing or pipe. The SS6 offers flow rates up 2.7 CFM through one diffuser, while providing tiny bubbles at even the lowest flow rate of water.

Stainless Steel ozone sparging diffuser
SS6 Stainless Steel Diffuser

 
Video below shows the SS6 diffuser in action. Video shows flow rate of oxygen increasing from 2 to 25 LPM. Notice how fine pore bubbles stay small throughout flow-range.

To learn more about dissolving ozone into water see our ozone solubility information at link below:
Ozone Solubility