Use of Sequencing Batch Reactors for
Waste Treatment — CPC International,
Corpus Christi, Texas
ROBERT L. IRVINE, Engineer
Quirk, Lawler, and Matusky, Engineers
New York, New York
WILLIAM B. DAVIS, Associate Professor
Civil Engineering Department
Texas A & M University
Corpus Christi, Texas
INTRODUCTION
This paper represents a six month study of waste characterization and design
criteria for effluent discharges from two widely different processes involved in the
corn refining wet milling industry. Variations in manufacturing process operations
create a variable waste volume and strength which critically influenced the design
phase.
The wastes associated with this design are those produced during the
manufacture of modified or dry starches and in the wet milling process. The dry
starch manufacturing process is a batch-wise operation which produces a wide variety
of distinct products and wastes which have characteristics significantly different than
those normally associated with waste treatment design. The starches are basically
classified as hydroxyethylated, acid modified, phosphorylated, cationic and mill
starches. The two basic wastes from the wet milling operation are from the feed and
dextrose processes. These wastes are usually combined as a single waste stream which
is fairly uniform in waste characteristics.
Laboratory studies for design data had been obtained for the wet milling
process at the CPC International plant at Pekin, Illinois. As a result major emphasis
was given to the dry starch problem at Corpus Christi. Nevertheless studies were
carried out on the wet milling waste to verify the similarity of the wet milling wastes
from both the Pekin and Corpus Christi plants.
LABORATORY STUDIES
The total laboratory effort involved the following:
1. Acclimation procedures
2. Hydraulic selection of organism in continuous flow reactors
3. Batch   studies   to   determine   reaction   rates,   cell   yield   and   oxygen
requirements
450