A new tracer gas method to measure oxygen transfer and enhancement factor on RBC

The aim of this study was to test a new application of tracer gas in rotating biological contactors (RBC). Our method using propane as tracer gas, is able to quantify the purely physical gas liquid exchange. The procedure was utilized on RBC in order to measure: (a) the physical transfer coefficient with clean discs (Kla) in tap water and in waste water (Kla' = alpha Kla), and (b) the biological oxygen transfer in the presence of biomass in tap water and waste water (E Kla'). In the latter case an enhancement factor "E" had to be defined in order to allow for the very large increase in the transfer coefficient due to biological activity. The results are compared to those obtained by other authors. They confirm the excellent efficiency of rotating biological contactors (RBC) as aeration systems and the usefulness of propane as tracer gas to quantify the gas transfer in such systems. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.