Section 1. CHEMICAL WASTES
BIOLOGICAL TREATABILITY OF SPECIFIC ORGANIC COMPOUNDS
FOUND IN CHEMICAL INDUSTRY WASTEWATERS
Enos L. Stover, Associate Professor
Don F. Kincannon, Professor
Bioenvironmental and Water Resources Engineering
School of Civd Engineering
Oklahoma State University
Stillwater, Oklahoma 74078
INTRODUCTION
Effluent limitations for organic compounds have typically been developed in terms
of surrogate indicators such as BODs, COD and TOC. Present trends indicate the effluent
limitations of the future wdl also include limitations on certain specific organic compounds
found in wastewaters. An initial list of 114 organic compounds of concern called the "priority pollutant" list has been developed for investigations. The majority of the preliminary
investigations to date have consisted of analytical methods development and screening of
wastewaters for assessment of the presence and magnitude of contamination of these various
chemical compounds [ 1,2 ].
This new concept dealing with limitations on the specific pollutants is causing concern.
The present data base on the specific compounds is practically nonexistent when it comes
to predicting the treatability and fate of these compounds during wastewater treatment
operations. The physical, chemical and biochemical characteristics of these compounds
become important during biological treatment due to the combined possibilities of stripping, adsorption and/or biological oxidation. To accomplish adequate prediction of the
removability and more specifically the treatabdity of individual compounds, the existing
data base for removal of specific compounds must be increased.
All kinetic design models have originated from a substrate mass balance assuming substrate removal based on biological consumption. Stripping and biological adsorption are
not included in this balance, and the amount of substrate stripped is not predicted. Thus, a
more logical substrate mass balance should consider substrate removal by biological consumption, stripping and adsorption. Models describing joint biological removal and stripping have been presented by Gaudy et al. (3), and Freeman et al. [4]. These models are a
step in the right direction; however, much research and knowledge of the chemical, physical
and biodegradable characteristics of individual compounds in complex mixtures, such as
industrial wastewaters, are required for development of accurate predictive models. The
stripping of biodegradable volatile organic compounds during activated sludge treatment
is significantly affected by biological oxidation [51. As previously indicated [5], the removal of volatde, strippable organic compounds is enhanced by biological degradation,
whde volatile compounds that are only removed by stripping are limited by their physical
characteristics and reactions. Therefore, attempts to predict the behavior of specific compounds based entirely on the physical and chemical properties or molecular structure without knowledge of the impacts of biochemical reactions can lead to erroneous predictions.
The research project reported in this chapter was designed to gain knowledge of the
treatabdity and fate of specific organic compounds found in complex industrial wastewaters. The impacts of considering substrate stripping and adsorption for prediction of
the fate of organic compounds and for determination of the biokinetic constants required