Diurnal variation is characteristic of nearly all POTWs currently in operation. Equalizing the organic load to the process can significantly benefit the performance of the biological treatment process. The potential benefits of flow equalization have been recognized for over 20 years, although subsequent work has not been able to demonstrate reliable engineering designs to capitalize on these theoretical benefits. During the past decade, stricter environmental regulations have increased the interest and investment in nutrient removal processes. The successful development of Biological Nutrient Removal (BNR) treatment processes has accelerated this process. The data in this paper demonstrate that the ability to accurately measure and track biological reactions is crucial to the ability to equalize plant loadings. It is important to reiterate, in this regard, that the “bioreactor” which carries out the treatment reactions is a living cell and not a concrete tank. This manuscript presents new technology for the control of BNR treatment plants based upon direct measurements of cell metabolic activity, and presents results of preliminary experiments to control the waste load to biomass ratio independent of hydraulic flow fluctuations.

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