Section Five
RESPIROMETRY
55    USE OF RESPIROMETRY TO EVALUATE THE
BIODEGRADABILITY OF EMULSIFIED SPECIALTY
CHEMICAL PRODUCTS
Richard J. Colvin, Project Engineer
Alan F. Rozich, Presidenl
Bioprocess Engineering, Inc.
Wilmington, Delaware 19808
Bruce J. Hough, Principal Environmental Engineer
Hercules Incorporated
Wilmington, Delaware 19894
Anthony F. Gaudy, Jr., Professor Emeritus
Department of Civil Engineering
University of Delaware
Newark, Delaware 19716
INTRODUCTION
In recent years, the demand for higher quality effluents in the pollution control field have led to the
need to quantify the removal capability of biological treatment processes. One tool that has recently
seen resurgence in the environmental field is the use of respirometry for the design and operation of
biological wastewater treatment plants. Respirometry or oxygen uptake measurements are key
because they can be utilized to quantify the ability of a particular biomass system to degrade target
wastes. Several papers have been recently published describing the use of respirometric techniques to
determine the values of the biokinetic constants for biological systems treating toxic and nontoxic
organic compounds.''2'3'4 Work has also been done utilizing these techniques on actual municipal5,6'7
and industrial8 waste systems. Other results showed that respirometric techniques can be used to
predict plant effluent quality for a municipal activated sludge process.5 For the current work, Hercules Incorporated desired to evaluate the biodegradability of five of its paper chemical products in
anticipation of the startup of their HKC Korea Waste Plant which has to treat these production
facility wastewaters. The goals of this work were twofold. The first objective was to estimate the
effluent quality that will be produced by the activated sludge process as measured by the Korean COD
method. The second goal of this work was to identify any troublesome or recalcitrant components
which may contribute to the effluent COD by passing through the biotreatment process.
MATERIALS AND METHODS
The general testing approach involved the operation of a bench-scale activated sludge unit in
conjunction with separate batch testing. A waste stream containing equal COD portions of the target
components was developed and fed to a bench-scale activated sludge reactor which was operated at a
long mean cell residence time (MCRT) in order to simulate extended aeration conditions. After a
three-week acclimation period, biomass was harvested from the bench-scale reactor and used in
separate batch respirometry tests to identify the biodegradability of the individual component wastes.
Bench-scale reactor effluent samples were also collected toward the end of the work to determine
COD and BOD removal capability.
A 1.5 liter glass reactor was used as the bench scale activated sludge reactor. This reactor was
charged with 1 liter of tap water and 500 ml of biomass seed that was obtained from a Hercules
Incorporated plant treating similar wastes. Mixing and dissolved oxygen were provided using an
45th Purdue Industrial Waste Conference Proceedings, © 1991 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Primed in U.S.A.
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