Oxygen‐transfer efficiency of fine‐pore diffused aeration systems: energy intensity as a unifying evaluation parameter

Assessing the clean‐water oxygen‐transfer characteristics of aeration devices is a critical step in the design and operation of aeration systems for activated‐sludge processes. A fundamental model has been developed for assessing the clean‐water oxygen‐transfer characteristics of fine‐bubble (fine‐pore) aeration devices. This model is based on a proposed fundamental parameter, energy intensity ( E I ; kW/m 3 ), which is the energy required to deliver air to the aerated volume per unit of aerated volume. The standard oxygen transfer rate (SOTR, g/m 3 · s) is shown to be related to E I through a second‐degree equation: SOTR = −11.5 E I 2 + 2.27 E I (r 2 = 0.951). The model applies over a wide range of diffuser types, diffuser densities, tank dimensions, and specific air flows. The results suggest that opportunities for increasing oxygen‐transfer efficiencies of fine‐bubble aeration systems remain, particularly by reducing mean bubble sizes and reducing E I requirements.