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28 TOXICITY EVALUATION OF PERSISTENT ORGANIC CONTAMINANTS James R. Hartman, Graduate Student Clifford R. Lange, Graduate Student Mark R. Matsumoto, Assistant Professor A. Scott Weber, Assistant Professor Department of Civil Engineering State University of New York at Buffalo Buffalo, New York 14260 INTRODUCTION Since the end of World War II, the development rate of new xenobiotic chemicals has increased rapidly. The United States Environmental Protection Agency's (EPA) chemical inventory list contains more than 62,000 industrial substances excluding foods, drugs, cosmetics, and pesticides.1 A large number of xenobiotic chemicals are resistant to biological degradation, or are degraded at very low rates. This resistance to biodegradation is termed persistence. Persistence of xenobiotics can be attributed to: 1) the inhibitory nature of the chemical substance to the microorganisms; and/or 2) the microorganisms' lack of necessary enzymatic pathways necessary for the breakdown of specific compound(s). Many of the existing procedures for assessing the biodegradability (persistence) of xenobiotics rely upon assessing the performance of bench-scale biological reactors which have specific wastes or chemicals as a part of their influent. However, such investigations are useful only in determining the effect of specific wastes or compounds on treatment performance. Thus, while pilot testing has an important function, the factors which cause persistence cannot be established. Establishing the cause of persistence is an important step in determining how to deal with a compound which resists biodegradation. For example, when the enzymatic pathways required for degradation are lacking, the course of action may be to induce the enzymes via acclimation. Alternately, the addition of bacteria which possess the desired pathways, a process termed bioaugmentation, may also be used as a means of overcoming enzymatic deficiencies. However, if persistence is due to inhibition or toxicity, dilution or selective removal of these compounds to levels which are less inhibitory may be required before biological treatment. In cases of extreme inhibition, biological treatment may be impossible, and removal must be accomplished by physical and/or chemical means. Clearly, what is needed to design effective systems for the biological treatment of xenobiotics is a methodology which can be used to determine the degree and cause of persistence. However, differentiation between persistence due to inhibition and enzyme deficiency is difficult and use of a single experimental test can lead to erroneous conclusions. The primary objective of the study described in this paper was to examine various, easily performed tests that could be used for assessing persistence of xenobiotic chemicals and determine the relative merits of each test. The ultimate goal of this research is to develop an approach for assessing the degree and cause of persistence associated with xenobiotic biodegradation and thereby determine operating conditions which are favorable for biological treatment of specific wastes and compounds. EXPERIMENTAL METHODS A series of experimental studies were performed using selected synthetic chemicals known to be inhibitory and persistent. Testing was separated into three categories: 1) methods testing persistence; 2) methods testing acute toxicity; and 3) methods measuring metabolic activity as an indication of the combined effect of acute toxicity and/or enzyme deficiency persistence. 265
Object Description
Purdue Identification Number | ETRIWC198728 |
Title | Toxicity evaluation of persistent organic contaminants |
Author |
Hartman, James R. Lange, Clifford R. Matsumoto, Mark R. Weber, A. Scott |
Date of Original | 1987 |
Conference Title | Proceedings of the 42nd Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,38818 |
Extent of Original | p. 265-274 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-08-03 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 265 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | 28 TOXICITY EVALUATION OF PERSISTENT ORGANIC CONTAMINANTS James R. Hartman, Graduate Student Clifford R. Lange, Graduate Student Mark R. Matsumoto, Assistant Professor A. Scott Weber, Assistant Professor Department of Civil Engineering State University of New York at Buffalo Buffalo, New York 14260 INTRODUCTION Since the end of World War II, the development rate of new xenobiotic chemicals has increased rapidly. The United States Environmental Protection Agency's (EPA) chemical inventory list contains more than 62,000 industrial substances excluding foods, drugs, cosmetics, and pesticides.1 A large number of xenobiotic chemicals are resistant to biological degradation, or are degraded at very low rates. This resistance to biodegradation is termed persistence. Persistence of xenobiotics can be attributed to: 1) the inhibitory nature of the chemical substance to the microorganisms; and/or 2) the microorganisms' lack of necessary enzymatic pathways necessary for the breakdown of specific compound(s). Many of the existing procedures for assessing the biodegradability (persistence) of xenobiotics rely upon assessing the performance of bench-scale biological reactors which have specific wastes or chemicals as a part of their influent. However, such investigations are useful only in determining the effect of specific wastes or compounds on treatment performance. Thus, while pilot testing has an important function, the factors which cause persistence cannot be established. Establishing the cause of persistence is an important step in determining how to deal with a compound which resists biodegradation. For example, when the enzymatic pathways required for degradation are lacking, the course of action may be to induce the enzymes via acclimation. Alternately, the addition of bacteria which possess the desired pathways, a process termed bioaugmentation, may also be used as a means of overcoming enzymatic deficiencies. However, if persistence is due to inhibition or toxicity, dilution or selective removal of these compounds to levels which are less inhibitory may be required before biological treatment. In cases of extreme inhibition, biological treatment may be impossible, and removal must be accomplished by physical and/or chemical means. Clearly, what is needed to design effective systems for the biological treatment of xenobiotics is a methodology which can be used to determine the degree and cause of persistence. However, differentiation between persistence due to inhibition and enzyme deficiency is difficult and use of a single experimental test can lead to erroneous conclusions. The primary objective of the study described in this paper was to examine various, easily performed tests that could be used for assessing persistence of xenobiotic chemicals and determine the relative merits of each test. The ultimate goal of this research is to develop an approach for assessing the degree and cause of persistence associated with xenobiotic biodegradation and thereby determine operating conditions which are favorable for biological treatment of specific wastes and compounds. EXPERIMENTAL METHODS A series of experimental studies were performed using selected synthetic chemicals known to be inhibitory and persistent. Testing was separated into three categories: 1) methods testing persistence; 2) methods testing acute toxicity; and 3) methods measuring metabolic activity as an indication of the combined effect of acute toxicity and/or enzyme deficiency persistence. 265 |
Resolution | 300 ppi |
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