NITRIFICATION AND ACTIVATED SLUDGE FOAMING ...

unique and must develop its own set of conditions and control measures for addressing relative process
issues. The work effort described and the resulting information presented in this paper is part of a
program to promote continuous improvement at the WRF - a key initiative throughout CMU.
The WRF treatment system includes flow equalization, primary clarifiers, Modified Ludzack-Ettinger
(MLE) activated sludge system, tertiary sand filters, and anaerobic digesters. Historically, the WRF has
had issues with foaming conditions which caused issues in the aeration basins and in downstream unit
processes - conveyance foaming, secondary clarifier excessive scum, excessive blinding of final filters,
and impacts to water reuse program. Figures 1 and 2 present typical nocardial foam and scum
conditions.
Figure 1 – Nocardial foam on aeration basin surface
Figure 2 – Nocardial scum on secondary clarifier surface
Compliance with ammonia nitrogen limits is challenged at times by periodic ammonia pass-through of the
aeration basins particularly during winter operating conditions.
This paper discusses the relationships of nitrification and foaming, presents the results of process data
evaluations, presents control approaches used to control foaming and to enhance nitrification reliability
and overall plant operations, and provides insight to others that may be experiencing similar process
challenges.