Performance of Automatic Wastewater Compositors
DANIEL J. HARRIS, Sanitary Engineer
WILLIAM J. KEFFER, Head
Field Investigations Section
Surveillance and Analysis Division
U.S. Environmental Protection Agency, Region VII
Kansas City, Missouri 66115
INTRODUCTION
The Environmental Protection Agency, Region VII Field Investigations Section is
responsible for planning the surveys and conducting the sample collection activities of the
Surveillance and Analysis Division, which provides the water quality data needs of the
agency for the four-state region of Iowa, Kansas, Missouri, and Nebraska. During the past
two years the Field Investigations Section has experienced a dramatic expansion in demand
for wastewater chemistry data on point source discharges. In order to provide data for
enforcement efforts, compliance monitoring, water quality standards evaluation, and waste
treatment facility operational assistance and performance evaluation, the section has been
forced to curtail manual methods of sample collection and to rely upon commercially
available automatic wastewater sampling equipment.
To date the section has purchased fifty commercial compositors of fifteen makes and
models from seven manufacturers. Approximately 90,000 hr of field operational experience
with the units on municipal and industrial raw and treated wastewater under summer and
winter conditions has been accumulated. As the Field Investigations Section gained
experience with this equipment and generated considerable water quality information,
discrepancies in data were noted which appeared to result from variations in sampler
performance.
This paper reports the results of four studies which were conducted for the purpose of
comparing the water chemistry data of samples collected concurrently with various makes
and models of commercially available sampling equipment.
COMPARISON STUDIES
RICHARDS-GEBAUR AFB STUDY
The AFB is served by a 5,680-cu m/day (1.5-mgd) standard rate trickling filter plant
with effluent chlorination. The sampling stations set up at this facility included the raw
waste and the final effluent.
A QCEC Model CVE sampler* was installed to collect time-composite samples (15-
min cycle time) at the influent and, concurrently, an ISCO Model 1391-X** was used to
collect discrete samples at 2-hr intervals for manual flow proportioning and compositing.
Flow measurements were obtained with a Manning Dipper Stage Recorder*** and a staff
gage installed in the throat of the 22.9-cm (9-in) Parshall flume located at the plant influent.
*        Quality Control Equipment Company, P.O. Box 2706, Des Moines, Iowa 50315
**      Instrumentation Specialties Company, P.O. Box 5347, Lincoln, Nebr. 68505
***    Manning Environmental Corp., 112 Dakota Avenue, Santa Cruz, Calif. 95060
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