BOD Progression in Soluble Substrates -
VII Temperature Effects
G. J. KEHRBERGER, Public Health Service Trainee
J. D. NORMAN, American Oil Company Fellow
E. D. SCHROEDER, Public Health Service Trainee
A. W. BUSCH, Associate Professor of Environmental Engineering
Department of Chemical Engineering
Rice University,
Houston, Texas
INTRODUCTION
Temperature affects the rate of substrate utilization in a biological system in
two major ways. One is the effect of temperature changes on the rate of reaction of the organisms and the substrate. The other is the effect of temperature
changes on the diffusion of substrate to the organisms. Previously the effect of
temperature on the rate of substrate utilization was considered a function only of
the enzymatic reactions within the bacterial cells. The purpose of this paper is
to discuss the validity of this assumption, and to present a model of a biological
system based on the principles of transport phenomena which offers an explanation
of the effect of temperature on the rate of substrate utilization.
Concepts presented in this paper are based on studies of the microbial degradation of glucose, a soluble substrate. However, these concepts are applicable
to any growing microbial system.
THEORETICAL DEVELOPMENT
The effect of temperature on the rate of substrate utilization is usually assumed to be primarily a thermochemical phenomenon. This assumption is made
on the basis that the oxidation of organic material by microorganisms involves a
series of enzymatic reactions that follow the laws of thermodynamics and rate
theory (1). An empirical temperature relationship commonly found in the biological literature was suggested by Arrhenius in 1889 for the effect of temperature
on simple chemical reactions.
k = A e
•E/RT
(1)
k = Reaction velocity
A = constant
E = Activation energy
R = Gas constant
T = Absolute temperature
Arrhenius extended the equation to complex biological systems through the
use of an overall activation energy for an organism.
Another approach to evaluation of the effect of temperature on the rate of
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