Document Type


Date of Award

Fall 12-31-1980

Degree Name

Doctor of Engineering Science in Civil Engineering


Civil and Environmental Engineering

First Advisor

James R. Pfafflin

Second Advisor

Gordon Lewandowski

Third Advisor

Paul C. Chan

Fourth Advisor

Robert Dresnack

Fifth Advisor

Eugene B. Golub


A new mathematical model, derived from first principles of mass balance, is proposed for describing the mass transfer response of an activated sludge aeration tank in terms of a fluidized bed. The operational data to verify the proposed model were taken from an existing conventional wastewater treatment plant and a bench scale pilot plant.

The mass transfer rate, (KdAs), was presented by an empirical dimensionless group function as follows:

((KdAs)Dp/Dv) = fAc (uDp/ν)a ((ν/Dν)(MLSS))b


Sh = f(Ac/As ) (Rep)a (Sc(MLSS))b

where the definition of each parameter is given in the Glossary.

It was found that the coefficient of the dimensionless group function, f, and exponential indices of the dimensionless group function, a and b, were very approximately to unit. The activated sludge process, in terms of a fluidized bed model, can be described by this dimensionless group function. This is the first effort to apply this approach to the understanding of the activated sludge process.

The other investigation of this study was to predict the characteristics of an existing plant, based on the associated properties of a bench scale pilot plant. It was found that two distinct first order responses could be utilized to predict the operating BOD removal in the aeration tank of the activated sludge process. BOD removal in the initial portion of the aeration tank was found to be independent of the Mixed Liquor Suspended Solids concentration, but strongly dependent on the Mixed Liquor Suspended Solids concentration in the later stages.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.