A PILOT STUDY FOR THE REMOVAL OF PRIORITY POLLUTANTS
BY THE PACT PROCESS
J. W. Cormack, Associate
D. Y. Hsu, Process Engineer
Greeley and Hansen Engineers
Chicago, Illinois 60606
and
G. Simms, Wastewater Superintendent
Department of Public Works
Kalamazoo, Michigan 49007
INTRODUCTION
Federal regulation 40 CRF 403 requires publicly owned treatment works (POTWs) receiving
wastewater flow in excess of 5 MGD to implement an industrial pretreatment program no later than
July 1, 1983. One of the essential parts of such a program is to determine the maximum allowable concentration of various pollutants in industrial discharged to the POTW.
The POTW in the City of Kalamazoo, Michigan, is currently being renovated and expanded to
convert the existing activated sludge process to a powdered carbon activated sludge (PACT) plant
with an annual design flow of 53.3 MGD. As the new plant will not be on line until 1985, pilot studies
were conducted to provide information as to the expected performance of the full scale plant. A pilot
study concerned with the removal of conventional pollutants (BOD and suspended solids) and
nitrification had been conducted previously for the development of the design parameters for the full
scale PACT plant [1]. The study to be discussed herein is related to the priority pollutants identified in
the Industrial Pretreatment Regulations [2]. It was conducted to determine the plant tolerance limit
and the removal efficiency for the priority pollutants found in the plant influent. The tolerance limit is
needed to determine the concentration at which those pollutants would interfere with the performance
of the PACT plant. The removal efficiency is needed to determine the maximum influent concentrations at which the plant effluent will comply with the applicable water quality standards. The plant
performance, for the purpose of this study, is described in terms of the removal of BOD, COD, SS,
and phosphorous, nitrification, and the settling characteristics of the mixed liquor.
THE PILOT PLANT
Figure 1 shows the process diagram for the pilot unit. The main part of this system is a Biospheric
Model 61 pilot plant. It has a nominal capacity of 10 gph and is equipped with one 20-inch diameter
primary clarifier, one 20-inch diameter final clarifier, and six 8-inch diameter plexiglass aeration
cylinders. For the purpose of this study, the primary clarifier was used as a mixing tank for preparing
the plant influent.
The main advantage of this type of pilot plant is its flexibility. The six aeration cylinders can be
arranged in various ways to simulate the flow regime and step mode for the full scale plant. In this
study, the aeration cylinders were connected in series to simulate the plug flow regime designed for the
full scale plant. After the full scale plant is operational, consideration may be given to operating the
plant with a different flow regime or step mode. In this case the pilot plant can be used to predict the
403