Complete-mix aerated lagoon
Can you clarify your question?
A water treatment plant is a succession of ponds or lagoons, the first of which is aerated using floating turbines?
What exactly is your issue?
The aerated lagoon is often a solution that is used when natural ponds are no longer sufficient.
The advantage is that there is no engineering cost; you simply add floating turbines.
The disadvantage is the higher energy cost and the limited efficiency of the installation.
Does this help you?
The purpose of surface aeration is to provide more oxygen and therefore accelerate degradation of the pollutant load; this will allow you to save space. So, if you have opted for lagoon treatment, you clearly don't lack space; therefore, it is useless to increase costs by adding equipment you don't need—at least that is my view.