Section Two
INDUSTRIAL WASTES
A. GENERAL
15    A MATHEMATICAL MODELING APPROACH TO SIZING
DIVERSION BASINS FOR INDUSTRIAL FACILITIES
Alison M. Martin, Senior Engineer
Tommy Martin, Associate Engineer
James M. Montgomery, Consulting Engineers, Inc.
Metairie, Louisiana 70002
INTRODUCTION
Industrial organic chemical manufacturing facilities, particularly those that use batch production
processes, produce wastewater of very high variability in both organic loading and flow. Typically, an
industrial wastewater treatment plant uses an upstream equalization basin to help dampen flow rates
and organic loads. This is particularly important in the case of biological treatment (such as activated
sludge or fixed-film bioreactors), because these systems can be very sensitive to organic shock
loadings.
Generally, an on-line equalization basin is designed primarily for flow equalization. Organic load
dampening is a result of this flow equalization. Many facilities have determined, however, that a
separate basin is also necessary to divert high organic load flows for subsequent controlled return to
the equalization basin. This diversion and retention of high organic load flows results in a reduction
or "shaving" of peak organic loads. Additionally, many plants manufacture chemicals that are toxic to
biosystems even at relatively low loadings; a separate, off-line storage basin (or diversion basin) may
be required so that potentially toxic streams can be slowly bled back into the treatment system.
In the design of a new biological wastewater treatment system, a trade off exists between the sizes of
the aeration, equalization, and diversion basins. The size and operating costs of the aeration basin are
minimized if organic peaking can be held relatively low. However, the corresponding sizes of the
diversion and equalization basins will be larger. A careful economic analysis of different alternatives
in tank sizing is important in any new design in order to optimize capacity and reduce cost.
Traditionally, sizing of biological unit processes and equalization basins for flow dampening is a
fairly straightforward procedure. However, the sizing of an off-line diversion basin is a technique that
is still rather "black box". A computer model has been developed that rapidly calculates the diversion
basin size required for a set of flow and organic concentration data with user input system constraints.
This model takes the guesswork out of the sizing procedure and can be used to check diversion basin
sizes determined by other methods.
BACKGROUND
Typical design of equalization basins for municipal facilities is based on flow equalization. Determination of equalization basin size, using historical diurnal flow rates, is a straightforward procedure. The use of schematic mass diagrams is the classical sanitary engineering method for sizing these
basins.1 Wastewater generated at industrial facilities, however, cannot be easily characterized due to
high variability in flows and organic loadings. Therefore, sizing of equalization basins for these
facilities may be based on flow, organic loading, or both parameters. When both parameters are used,
the resulting more conservative design (larger basin) is selected.
For industrial facility equalization basin sizing based on organic loading, more recent methods have
been developed. A new biological treatment facility at the Tennessee Eastman Company plant in
Kingsport, Tennessee, utilized a peaking factor method for the sizing of diversion and equalization
46th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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