A New Dimensionless Criterion for the Oxygen Transfer Efficiency in Both Surface and Subsurface Aeration Systems

Abstract

The effect of power consumption on oxygen transfer efficiency has been evaluated in both surface and subsurface aeration systems. For this purpose a new dimensionless number To, named “efficiency criterion”, has been proposed.Using this number, the efficiency of different aeration systems could be compared.The comparison has been achieved by taking into consideration the data furnished by full-scale experimental models.The results have proved that of two aerators with identical diameters and the same rotational velocity reaching the maximum To, the one with a higher power consumption had a higher efficiency.The results regarding the subsurface aeration systems show that the efficiency of aeration equipment can be continuously increased if the bubbles' diameters are decreased.