Brown and Caldwell Home Page
Technical Papers RECENT PAPERS    ALL PAPERS

Brown and Caldwell engineers and scientists are technical and thought leaders in the environmental sector. Meet the people who have been advancing innovation for more than 70 years.
Author      Title/Abstract      


“The Effect of Degree of Recycle on the Nitrifier Growth Rate”
Author: Jose Jimenez, Henryk Melcer, Denny Parker and John Bratby
Date: 1/111
Water Environment Research, Vol. 83, No. 1, January 2011, pp. 26-35.

The nitrifier maximum specific growth rate, mA,max, is a critical parameter for the design and performance of nitrifying activated sludge systems. Although many investigations studied mA,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 mA,max. Based on the results obtained during this investigation, a 15% decrease in mA,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. Water Environ. Res., 83, 26 (2011).

This library contains published materials for which copyrights may be owned by entities other than Brown and Caldwell, but which are stored for limited uses by BC employees. Technical papers authored by BC employees generally may be printed and shared electronically with clients and prospective clients outside BC. Technical papers cannot be sold, and technical papers shared outside BC must have proper attribution of the original sponsoring organization or conference where the paper was presented. This attribution is embedded in each technical paper file when it is loaded into this library. Published articles from magazines or trade journals which are stored in this library are FOR INTERNAL USE ONLY and SHOULD NOT be distributed to clients or others outside BC, without express permission of the copyright owner. For questions regarding copyrights associated with any document in this library, or questions regarding copyrights in general, contact the Legal Department.