Oxygen Transfer Rates of Various types Aeration Devices

Select correct oxygen transfer rate equipments for the aeration tank’s air requirement, so you can be saved air compressor energy effectively

Equipments/Devices 
Typical ratings,Ib O2 /hp-hr
Submerged aerators 4.0
  Porous diffusers 1.5
Surface aerators
  Plate 2.0-2.5
  Turbine 3.0-3.5
  Propeller 2.5-3.5
  Combination aerators 2-3 2-3

Except in cases of degasification, aeration requirement is a function of degree of oxygen deficiency in the water and the oxygen-consuming reactions taking place.

Oxidation of iron and manganese requires much less oxygen on a pound-per-1000 gallons basis than biochemical oxidation of organic material (BOD).

In addition, BOD concentrations in both industrial and municipal waste water are generally much higher than the concentration of iron and manganese found in natural waters. Aeration capacity requirements for BOD removal, therefore, far exceed those of any other oxygen-consuming reaction.

The oxidation of both iron and manganese takes place most readily at a pH over 8. Theoretically, 1.0 mg/L O2 oxidizes approximately 7 mg/L of either Fe2+ or Mn2+. Oxidation of these metals requires increasing oxygen concentration to near saturation.

Oxygen requirements for biochemical oxidation processes (BOD removal) are well established for municipal applications. In cases where no industrial wastes are included with the sewage, aeration capacity is strictly a function of loadings and the type of treatment process to be applied. Some plants provide more or less aeration capacity depending on the extent to which the sludge is being aerated
and the amount of de-nitrification required.

so, thing afore mentioned criteria before going to select exact oxygen transfer equipments for your needs.

 

Author: T.P.Sivanandan


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