Air Diffusers

What are Dryden Aqua Air Diffusers?

The Dryden Aqua Air Diffuser is a semi-flexible, high-efficiency fine bubble air diffuser available in 9 different lengths,depending on the air, oxygen or carbon dioxide through-put required . It provides oxygen transfer rates of up to 5kg/kw, 10m3/h of air and 1 kg of O2/h. Its semi-flexible construction with its own internal ballast will stay on the bottom of the lagoon or pit without the need to be anchored to the floor. The Dryden Aqua Air Diffuser is quick and easy to install and can be maintained while air blowers are operating and water reservoir is full. 

The Dryden Aqua Air Diffuser combines excellent performance with cost effectiveness for aeration, oxidation and biological treatment.

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Dryden Aqua Air Diffuser Advantages

Solid diffusers have problems with carbonate and iron deposition which blocks the diffusers. Solid diffusers are therefore very difficult to clean and maintain. Flexible membrane diffusers stay largely free of fouling, however they need a heavy frame or are anchored to the base of the aeration tank, this makes the diffusers much more expensive and difficult to handle, it also makes them difficult to use in lagoons, or in retrofitting systems.

The Dryden Aqua diffuser is a hybrid unit, because it is semi flexible, carbonates and metal oxides simply crack off the unit. Also because our diffuser has its own internal ballast it does not need to be anchored to the base of the tank. If any cleaning or maintenance is required, the diffuser is simple pulled out of the tank using the ½” air delivery hose. The tank can be full of water and the air blowers running when the diffuser is removed. Normal operating life is from 5 to 10 years.

Oxygen transfer data

Product code

Length of diffusers

Diffuser weight 

Air Flow m3/hr
(+/- 20 %)

Oxygen Transfer kg of O2/day per diffuser at different depths at 20 °C and 50% O2 saturation





2m depth

3m depth

4m depth


0.33 m

0.5 kg


2 kg O2

2.5 kg O2

3 kg O2


0.66 m

1.0 kg


4 kg O2

5 kg O2

6 kg O2


1.00 m

1.5 kg


6 kg O2

7.5 kg O2

9 kg O2


1.33 m

2.0 kg


8 kg O2

10 kg O2

12 kg O2


1.66 m

2.5 kg


12 kg O2

12 kg O2

15 kg O2


2.0 m

3.0 kg


14 kg O2

15 kg O2

18 kg O2


2.33 m

3.5 kg


16 kg O2

17 kg O2

21 kg O2


2.66 m

4.0 kg


18 kg O2

20 kg O2

24 kg O2


3.0 m

4.5 kg


20 kg O2

22 kg O2

27 kg O2


Oxygen Transfer Performance

Oxygen solubility is a function of temperature; the above table is at 20 °C. At an oxygen tension less than 1 mg/l, at a depth of 5 m, water temperature of 10 °C, in an activated sludge system we recorded an oxygen transfer coefficient of 7 kg of oxygen per kW of energy expended. In most situations the transfer will be between 2 kg and 5 kg of per kW of energy.

Surface aerators waste a huge amount of kinetic energy throwing the water into the air, transfer coefficient is 1 kg to 2 kg of oxygen per kW. Membrane diffusers are more efficient at 2 kg to 3 kg of oxygen per kW. The Dryden Aqua diffuser at over 5 kg is therefore the most efficient fine bubble diffuser available and is ideal for retrofit applications as a simple drop in product, for lakes, tanks, lagoons and aeration channels for clean water and waste water treatment.


The diffusers require an air blower or compressor to drive the system. The air pressure required depends upon the depth of the water, in most situations the blower should be sized to give up to 1 bar air pressure with water depths up to 5 m. Positive displacement 100 % oil free blowers are best, such as a diaphragm or linear compressors, rotary vanes, or rotary lobe compressors. If the water is over 5m depth, claw compressors should be used, and for the highest pressure screw compressors are appropriate.

The compressor should be located adjacent to the air diffusers. However you could locate the compressor many 1000`s of meters from the diffusers if the pipe work is sized accordingly. The pipe work should be in metal, if plastic pipe is used, then the first 6 meters of pipe work should be metal in order to bring the air temperature down to at least 90 °C in the plastic pipe. In lakes and lagoons, make an air ring main and come off the ring main with ½” flexible hose, fit a diffuser on the end of the hose, and then simply drop the diffuser into the tank. Installation is therefore simple and very quick.

AFM Filter oeffentl

Waste water treatment in Bangladesh with Air Diffusers