USE OF A RAPID BIOASSAY FOR ASSESSMENT OF INDUSTRIAL
WASTEWATER TREATMENT EFFECTIVENESS
Nicholas A. Casseri, Environmental Technologist,
Wei-chi Ying, Associate Scientist
Stanley A. Sojka, Manager
Environmental Technology
Occidental Chemical Corporation, Research Center
Grand Island, New York 14072
INTRODUCTION
The effective treatment of industrial and municipal wastewaters is of paramount importance in
safeguarding our aquatic environment. Effluent quality is traditionally expressed in pH, dissolved
oxygen, biochemical oxygen demand, chemical oxygen demand, total organic carbon, total dissolved
solids, total suspended solids, some specific compound concentrations, and other related parameters.
Even the most comprehensive physicochemical characterization of an effluent does not directly indicate any possible adverse effects on the ecosystem of the receiving stream. The collective effects of all
the physical, chemical, and biological properties of an effluent are exhibited in the observed toxicity.
Bioassay can thus play a vital role in assessing the effectiveness of a waste treatment process in reducing the incipient toxicity of a manufacturing effluent, municipal wastewater, or landfill leachate.
The use of rapid bioassay procedures for determining the aquatic toxicity of effluents and pure
compounds has been a recent development. Dutka and Kwan [1] compared four microbial toxicity
testing systems which offered fast results relative to the conventional bioassays using fish (fathead
minnows) or invertebrates (Daphnia magna). They found the Beckman Microtox system, which utilizes a bioluminescent marine bacterium as the test organism, to be both fastest and most sensitive.
Table I presents Microtox EC50 and reported fish LC50 for a variety of known toxicants [2]. Relative
toxicity data have also been compiled for many industrial and municipal, raw and treated, effluents as
shown in Figure 1 [3]. The fish results represent several test methods, species, times, temperatures,
and other factors. For both single toxicants and complex effluents, the Microtox and fish bioassay
data are found to be in good general agreement recognizing that the fish bioassays were not standardized.
The U.S. EPA and the Province of Alberta, Canada, have conducted extensive comparative
studies between the Microtox, fish, and Daphnia bioassays [4,5,6]. While regulatory agencies have yet
to approve the Microtox procedure for use in the effluent permitting, they acknowledge the fact it is a
useful tool in effluent monitoring since inexpensive yet reliable toxicity data can be obtained quickly.
Based on these studies and our own laboratory findings [7], the Microtox bioassay was selected as the
system of choice for research into the rapid assessment of industrial wastewater treatment effectiveness.
MATERIALS AND METHODS
Cultures
The fathead minnows used during this study were obtained from EG&G Bionomics (lot 0-82A14).
The 2,200 individuals in this lot were all hatched between 4/01/82 and 4/30/82. The fish were evenly
divided among three twenty-gallon glass aquariums equipped with Dynaflo Power Filters, and aeration through glass sparging tubes was provided by a Whisper 800 aquarium air pump. The fish were
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