A Continuous Flow Kinetic Model to Predict
The Effects of Temperature on the Toxicity
of Oil Refinery Waste to Algae
JAMES H. REYNOLDS, Research Fellow
E. JOE MIDDLEBROOKS, Professor and Head
DONALD B. PORCELLA, Associate Professor
Civil and Environmental Engineering
Utah State University
Logan, Utah 84321
INTRODUCTION
The combination of thermal and toxic waste discharges is a problem currently
affecting many regions of our nation and one which will threaten many others in the future.
Toxic wastes have been discharged by municipalities and industrial complexes for many
decades; however, excessive thermal discharges are of a more recent era (1,2,3,4). Now
thermal and toxic discharges often occur side by side. In addition, amny industrial toxic
wastes are discharged at elevated temperatures.
Industrial effluents, municipal discharges, electrical power generating facilities and
even agricultural runoff tend to increase the temperature of natural water systems.
Electrical power generating facilities have been singled out as the major source of future
thermal pollution (1,2,5). An expected increase of six times by the year 2000 (6) in electrical
power generation will undoubtedly increase the present level of thermal pollution. Heated
effluents from these generating facilities will place an additional strain on water systems
which are already receiving toxic wastes.
Also, many industries, such as pulp and paper mills, tanneries, and oil refineries,
discharge toxic wastes (7,8,9) at extremely high temperatures. The temperature of an oil
refinery waste may range anywhere from 22 C (71 F) to 41 C (106 F) (8). These high
temperatures could have a significant effect on the toxicity of a given waste. It is therefore
necessary, to develop relationships which will evaluate and predict the effects of increased
temperatures on the toxicity of various wastes.
This paper presents a continuous flow kinetic model to predict the effects of
temperature on the toxicity of oil refinery waste to algae. The model is based on enzyme
inhibition kinetics and was verified using semi-continuous and continuous flow
experiments. Phenol was employed as the controlling inhibitor or toxicant and the algae,
Selenastrum capricornutum, was the test organism.
Algae were selected as the test organisms because: 1) they are the basis for the food
chain and thus the principal food source for larger aquatic organisms; and 2) they are
involved in lagoon treatment of wastes. Thus toxicants which affect algae would affect the
total food chain and might interfere with certain aspects of waste treatment. This particular
species, Selenastrum capricornutum was employed becuase it has been specified for use in
algal assay work by the Environmental Protection Agency (10).
LITERATURE REVIEW
Oil Refinery Waste
Oil refinery wastes are heterogeneous toxicants and their composition is extremely
variable. Therefore, it is impossible to completely and accurately describe or characterize a
typical effluent. The characteristics of specific waste discharges for a particular refinery
have often appeared in the literature (5, 7, 8, 11, 12, 13, 14, 15, 16, 17). The most common
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