ESTIMATING OXYGEN TRANSFER KLa, SOTE AND AIR FLOW REQUIREMENTSIN FINE BUBBLE DIFFUSED AIR SYSTEMS

摘要

Oxygen demand in aerated activated sludge reactors varies with time, necessitating a varyingrnoxygen supply rate to maintain a desired dissolved oxygen (DO) concentration. This paperrndemonstrates how diffuser performance in fine bubble aeration systems can be modeled,rnaccounting for diffuser density, and changing SOTE with air flow per diffuser. The peaks andrnminimums in different zones of an activated sludge system usually will not be coincident, so it isrndifficult to accurately estimate total air requirements, as well as time-varying requirements. Thernapproach in this paper overcomes these problems through quantifying (1) the change in oxygenrnmass transfer coefficient (KLa) with changing air flow in each zone, and (2) accounting forrndifferent diffuser densities. If this modeling approach is incorporated in a process simulator thatrnquantifies time-and-space variations in oxygen demand, then accurate estimates of time-varyingrnair supply in different zones can be estimated, and hence more realistic estimates of total airrnsupply needs. Also, it allows a comprehensive analysis of the interaction between diffuserrndensity and oxygen transfer efficiency for the optimal design of aeration systems.