Section Seven
INDUSTRIAL WASTE CASE HISTORIES
C. PETROCHEMICAL, DYE, AND POLYMERS
78    SIMULATION FOR OPTIMIZATION OF A BIOLOGICAL
WASTEWATER TREATMENT PROCESS
AT A PETROCHEMICAL PLANT
Richard M. Jones, Senior Process Engineer
Wastewater Technology Centre
Ontario, Canada
Peter L. Dold, Associate Professor
Alison J. Baker, Graduate Assistant
Troy A. Briggs, Graduate Student
Department of Civil Engineering, McMaster University
Ontario, Canada
INTRODUCTION
An Ontario petrochemical plant was concerned with the operation of the activated sludge system
treating its wastewaters and wanted to evaluate different operating strategies to optimize system
performance. A schematic illustration of this treatment facility is shown in Figure 1. The plant
consists ot four aeration basins (ATI, AT2, AT3, and AT4) and three clarifiers (SC) and receives a
number of different influent streams which feed into the system at different points. Streams 1 and 2
are combined in an aerated equalization tank (ET) before feeding into AT2. Streams 3, 4, and 5 are
fed directly into ATI.
The flowrates and loadings associated with each of the influent streams are also presented in Figure
1. Streams 1 and 2 account for a large portion of the total influent flow, but the concentrations of
each stream are relatively low. On the other hand, Streams 3, 4, and 5, are highly concentrated
streams with relatively low flows. The present operating configuration was developed to maximize the
hydraulic residence time of the highly concentrated, low flow streams which tend to contain hard-to-
degrade compounds.
Another important operating issue is that the influent wastewaters contain low levels of nitrogen. In
addition, under the present operating configuration, the nitrogen loading is not evenly distributed
through the plant. Figure 1 shows that although approximately 50% of the COD load is associated
\Q
4
0.01
3
\coo
LOAD
31
8
12
%NH3
LOAD
41     1
49    2-*-
ET -i
6     3-
0     4-
4   s-+\
AT1
AT2 -*-
AT3
Figure 1.    Schematic
illustration of the
petrochemical plant
activated sludge process.
49th Purdue Industrial Waste Conference Proceedings, 1994 Lewis Publishers, Chelsea, Michigan 48118. Printed in
U.S.A.
737