Abstract
The nitrifier maximum specific growth rate, mu(A),max, is a critical parameter for the design and performance of nitrifying activated sludge systems. Although many investigations studied mu(A),max, only a few have dealt with the effect of the reactor configuration on this important kinetic parameter. Bench- and full-scale trials were devised to study the effect of the internal mixed-liquor recycle (IMLR) on the nitrifier growth rate constant. The nitrifier growth rate constant for an existing activated sludge plant was determined at different operational conditions using the high food-to-microorganism ratio (F/M) test and by process model calibration. Overall, the results obtained during this study indicate that high IMLR values have a negative effect on mu(A),max. Based on the results obtained during this investigation, a 15% decrease in mu(A),max was observed at an IMLR of 4Q or higher. It is surmised that, at high IMLRs, the reactor behavior shifts from a plug-flow configuration to a "quasi" complete-mix configuration, influencing either the species selection in activated sludge population or at least the adaptation of specific species. These results have a tremendous effect on the design of activated sludge processes that incorporate IMLR for denitrification, such as the Bardenpho, Modified Ludzack-Ettinger (MLE), University of Cape Town (UCT), and Phoredox or anaerobic-anoxic-aerobic (A2/O) processes.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
