NOVEL BIOCHEMICAL PATHWAYS IN THE
BIO-OXIDATION OF CORN WET-MILLING WASTES
R. L. Bruner, Senior Scientist
J. H. Smith, Researcher
Moffett Technical Center
CPC International, Inc.
Argo, Illinois
A. C. Schroeder, Assistant Researcher
Department of Thermal and Environmental Engineering
Southern Illinois University
Carbondale, Illinois
INTRODUCTION
In 1972 Bensing et al.  [1,2]  described the development of a biological waste treatment plant designed, from the earliest bench-model stage, for the treatment of mixed
process wastes from one specific corn wet-milling plant.    Because those design studies
were expected to break new ground in the problems of the wet-milling industry, they
were closely monitored, and given some financial support, by the United States EPA
[3,4].
The pilot-scale work was begun in 1966 and continued until 1974, during much of
that time under the active direction of various well-known consultant specialists.   Construction of the waste treatment plant (WTP), modeled on the completely mixed
activated sludge (CMAS) process, was completed and the WTP was in full operation by
late 1971.   But, dating from the initial commitment until 1977, the now-established
compliance of that WTP with effluent discharge criteria of the Illinois EPA has taken
more than ten years of corporate effort.
The waste-treatment literature on biooxidizing systems commonly treats the CMAS
system as a "single-track", linear process [5].    Beginning with adsorption of the "food"
molecule and dissolved oxygen (DO) by a bacterial cell, this process culminates only in
the formation of new cells, C02, and H20 [6,7,8].   By this view, the initial period of
contact is the most important feature of the process [ 1 ].   A concomitant assumption
is that, given adequate biomass and DO (neglecting trace nutrients and excluding a large
class of "non-biodegradables") [9], the process kinetics for oxidation of each component of the mixture can be summed, and that this summation will approximate the
kinetics for the mixture, and for wide fluctuations within that mixture [5].
As related to the Pekin WTP, these assumptions would imply that "shock-loading"
due to normal wastes should only increase the rate of DO-demand, and should only
result in a build-up of raw waste concentrations in presence of a thoroughly adapted
and responsive biomass.    An increase in effluent COD was thus accounted for as a
residual raw waste concentration, unmodified only because of oxygen limitations and
because of a lag in growth response by the bacteria.   In fact, however, Pekin "shock-
loading" had been known to decrease the rate of DO demand; to be accompanied by
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