As natural oxygenation is enhanced, ponds can be deeper and are suited for colder climates. Mechanical aerators provide oxygen and keep aerobic organisms suspended and mixed with water.

The dissolved and suspended organics from original wastewater and products of anaerobic catabolism on bottom of lagoon are oxidized by intermediate depths of lagoon.

In this case as BOD level is not that high, hence retention time considered is 6 hrs. Volume of tank= Flow x Retention time. Volume= 800 X 6= 4800m³.

Aerated lagoon is a method to reduce BOD in raw water. This also reduces TSS in raw water. The TSS is reduced to around 50-200 ppm.

The inlet valve opens and tank is being filled in, while mixing is provided by mechanical means (no air). This stage is also called anoxic stage.

In this case as BOD level is not that high, hence retention time considered is 6 hrs. Volume of tank= Flow x Retention time. Volume= 8 X 6= 480m³.

In case of aerated lagoon carried out facultatively least power is consumed. This is also known as partial mixing as both anaerobic and aerobic digestion takes place. Around 1-2.5 kW/1000m3 of electricity is consumed.

The cylinder has a length of 7 mm and a diameter of 10 mm (not including fins). Lately larger carrier of similar shape was introduced, intended for use in plants with coarse inlet sieves.

The BOD removal for moving bed bioreactor is 3.5-4.5 Kg BOD/m³day. The Moving bed bioreactor removes nitrogen also. These are provided with diffusers in order to provide aeration.

The depth for bioxmedia is considered generally as 1.2 m. The total liquid depth for a tank is depth of biox media + liquid depth above biox media + liquid depth below biox media. The bio media increases efficiency to degrade BOD.