60    ACTIVATED SLUDGE TREATMENT OF SELECTED
AQUEOUS ORGANIC HAZARDOUS WASTE
COMPOUNDS
Margaret K. Koczwara, Research Assistant
James E. Park, Research Associate
Richard J. Lesiecki, Research Associate
Department of Civil and Environmental Engineering
University of Cincinnati
Cincinnati, Ohio 45221
Douglas W. Grosse, Environmental Engineer
U.S. Environmental Protection Agency
Hazardous Waste Engineering Research Laboratory
Cincinnati, Ohio 45268
INTRODUCTION
As a result of the Hazardous and Solid Waste Amendments of 1984 and the concurrent land
disposal restrictions rule, EPA is in the process of demonstrating achievable treatment techniques to
be used as alternatives to the land disposal of hazardous wastes. Data are being collected for this
purpose from three types of sources, in the following order of priority: 1) waste generators that also
treat the waste; 2) commercial facilities (other than generators); and 3) EPA in-house research treatment facilities. The work being done at the USEPA Test & Evaluation (T&E) Facility falls in the third
category.
The USEPA, in conjunction with the University of Cincinnati College of Engineering, conducts a
variety of pilot and bench scale waste treatment research projects at the T&E Facility. The purpose of
several of the current projects is to develop the capability of evaluating the applicability of proposed
treatment methods to both inorganic and organic hazardous wastes. The inorganic hazardous wastes
to be tested are primarily metals and cyanide-bearing wastes while the organic wastes include spent
halogenated and non-halogenated solvents as well as wastes from still bottoms or process wastewaters.
For aqueous spent solvent wastes containing contaminants in concentrations up to 10,000 mg/L,
the activated sludge process has been proposed as a potential applicable treatment technology. However, these solvent contaminants may be present in the wastes at concentrations toxic to the activated
sludge biomass or they may be easily stripped into the atmosphere, creating an environmental hazard.
Likewise, many of the contaminants may readily be associated with the resultant waste sludges due to
sorption, precluding land disposal of the sludge. It is also possible that they may be recalcitrant and
require a different treatment approach. For these reasons, the removal mechanisms for the contaminants must be assessed. Evaluation of the fate of the contaminants at several concentrations spanning
the range of solubility of the compounds is also desirable.
Prior to testing industrially generated hazardous wastes, two prototype bench-scale activated sludge
systems have been set up and are being used to evaluate the fates of two selected aqueous organic
hazardous waste constituents, methyl ethyl ketone (MEK) and 1,1,1-trichloroethane (TCA). Both
compounds will be tested at three different concentrations spaced to span the solubility range for each
compound. The data for two test concentrations of each compound are the subject of this paper.
ACTIVATED SLUDGE PLANT DESIGN AND OPERATION
The main components in each system consisted of a completely-mixed, continuous flow reactor
(15.2 cm I.D. cylinder) and two clarifiers (primary and secondary) as shown in Figure I. System
components were composed of either glass (reactors, clarifiers), Teflon (tubing, connectors) or stainless steel (valves, covers) to prevent reactive interactions with the compounds being tested and to
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