Standard oxygen transfer rate: The oxygen transfer rate under standard conditions (SOTR) of the O2Max® aerator depends on the aerator, the speed, the submergence of the aerator and the geometry of the aeration tank. In the table below the range of the SOTR can be found in relation to the motor power and tank dimensions.
For other applications such as oxidation ditches or lagoons, please contact us.
The load on a sewage treatment plant is varying almost continuously. Therefore the oxygen transfer capacity required is not constant as well. To optimize energy consumption the oxygen input of the aerator should be adjusted accordingly. There are two possibilities to adjust the power input and oxygen transfer of the aerator: by changing submergence or by changing speed.
The submergence range of a surface aerator is limited to a certain maximum and minimum value. Exceeding these values will cause reduction of efficiency. The variation of submergence can be created by changing the height of the aeration unit or by changing the water level. The last possibility is the cheapest but also the most time consuming.
At present the most popular way of regulating the power input of a surface aerator is by changing the speed. The speed of a surface aerator is limited to a certain maximum and minimum value. Exceeding these values will cause reduction of efficiency. The maximum and minimum speed for the O2Max® aerator is related to the diameter of the aerator and the peripherical speed. The peripherical speed is limited to about 6.5 m/s.
There are two methods of changing speed: application of a two speed motor or application of frequency control. With aid of a two speed motor the power input can be changed in steps from 100% at high speed to about 50% at low speed to zero when switched off. Applying a frequency control enables every power input in between 0% and 100%.
Changing the number of aerators in operation
When several aerators are applied in just one tank power adjustment can also be done by switching aerators on and off. The steps in the total power input depends on the number of aerators. The power input of the aerators should be adjusted to the real demand. All possibilities have been indicated previously. Spaans Babcock has all the knowledge to help you with advice about process and product design that will make your work easier.