Water Quality Model Incorporates Unconventional Bod Reduction

Emerald M. Roider
Trieu V. Le
Donald Dean Adrian
Thomas G. Sanders

DOI: 10.2190/G764-H6TX-7178-Q118


Biochemical Oxygen Demand (BOD) reduction through the joint action of BOD decay expressed as an unconventional second order reaction and sedimentation is incorporated into a dissolved oxygen (DO) sag model for a river. A term named the Phelps-Thomas index, which is a function of the reaeration and sedimentation rate constants, is introduced and presented as a composite measure of river and wastewater rejuvenation characteristics. Calculations using ranges of reaeration and sedimentation rates show the Phelps-Thomas index has values between -2 and 10 or larger, with large values associated with rapid recovery of DO. The time at which the minimum DO occurs is calculated numerically. Examples apply the DO sag model to logging debris in a stream.

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