Mixed Aeration: Using Pure Oxygen to Supplement Oxygen Requirements in High Rate Processes

摘要

Pure oxygen supplementation of air-based systems has been used successfully as a low cost, easyrnto implement solution to short and long term oxygen requirements. When implementing suchrndevices, one typically assumes the volumetric mass transfer coefficient, kLa, for pure oxygen isrnthe same as for air. This may be justified, since oxygen diffusivity is slightly higher than airrn(11%) but the interfacial area for pure oxygen transfer is lower (-18% at 30% oxygen utilization).rnLarge scale clean water tests were conducted with air and pure oxygen for fine bubble membranerndiffusers at 7-49% basin coverage, flows between 0.5 and 6.1 Nm3/h/mdiff and depths of 3 and 6rnmeters to compare the kLa values. In all cases the kLa for oxygen was higher, attributed to thernincrease in diffusivity and reduced coalescence of smaller bubbles.