Oxygen transfer parameters and oxygen uptake rates revisited

Abstract

This paper provides a review of the essential equations and parameters that are used to design bioreactor aeration systems. Major objectives were to determine if the log-deficit method (LDM) and non-linear regression method (NLRM) yielded different results for the volumetric oxygen mass transfer coefficient (KL a)T and dissolved oxygen (DO) saturation concentration (Cs)T . Another objective was to compare and evaluate oxygen uptake rates (OURs) from the traditional BOD bottle technique with OURs determined from mass balances around completely-mixed activated sludge (CMAS) reactors. Full- and bench-scale, non-steady state reaeration tests were performed using sodium sulfite and cobalt chloride in addition to operating bench-scale CMAS reactors. Full-and bench-scale reaeration testing indicated there was no significant difference in the estimate of (KL a)T in tap water using the LDM or NLRM. Similarly, (Cs)T values were the same for the LDM and NLRM for 70 out of 119 reaeration tests. Actual oxygen uptake rates (AOURs) measured using the BOD bottle technique versus calculated oxygen uptake rates (COURS) were the same for 26 out of 51 data sets evaluated. The alpha-factor (α) increased as the solids retention time (SRT) was increased.