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Trace Elements in Biological Waste Treatment With Specific Reference to the Activated Sludge Process DENNIS K. WOOD, Graduate Student GEORGE TCHOBANOGLOUS, Associate Professor University of California, Davis Davis, California 95616 INTRODUCTION The role of nitrogen and phosphorus as essential nutrients for the proper operation of biological treatment processes is well documented. The role of trace elements as micronutrients, however, is not well defined. Due to the difficulty in measurement and the complex chemistry and biochemistry involved, the requirements for trace elements have not been determined. The purpose of this paper is to deliniate the significance of trace elements in biological waste treatment with specific reference to the activated sludge process. To do this, the material to be presented has been divided into sections dealing with 1) a review of the role of trace elements in biological systems, 2) a review of the sources of trace elements in wastewater and the mechanisms that may be responsible for their removal before utilization, 3) an analysis of the role of trace elements in the activated sludge process, and 4) the implications of the presence of absence of trace elements in the design and operation of biological treatment systems. TRACE ELEMENTS IN BIOLOGICAL SYSTEMS To understand the role of trace elements in biological waste treatment it will be useful to review 1) the importance of trace elements in microbial growth and metabolism, 2) their effects on population dynamics, and 3) trace element requirements in biological systems. Growth and Metabolism Trace elements are a requirement for the growth and metabolism of microorganisms. Essential and other trace elements are listed in Table I. Not all organisms require every essential element, though each element is required for the growth of at least one common organism. The other elements shown in Table I have been found in the ash of organisms, but their requirement for growth has not been established (1). Trace elements are required for two basic functions. First, they are required as metallic enzyme activators (2). An enzyme activator is a small molecule that stimulates growth, but unlike a coenzyme, is not an explicit part of the reaction. Second, they are required for the electron transfer in oxidation-reduction reactions. Iron is essential for aerobic bacterial growth, and it may be a universal requirement for all organisms (2, 3). It is responsible for the electron transport in cytochromes, a group of proteins whose prosthetic group prophyrin contains iron. A series of cytochromes is stepwise reduced and oxidized following the oxidation of flavoproteins. Iron is also required for the synthesis of certain enzymes including catalase, peroxidase, and aconitase which is required in the isomerization of citric acid to isocitric acid in the tricarboxylic acid cycle. Zinc and cobalt serve as metallic enzyme activators (2). These metals may be dissociable ions on the active sight of the enzyme. Zinc is required for the activities of carbonic anhydrase and carboxypeptidase A, an enzyme that exhibits both peptidase and estarase activity. Cobalt is required for the activity of carboxypeptidase and the synthesis of vitamin B-12. 648
Object Description
Purdue Identification Number | ETRIWC197462 |
Title | Trace elements in biological waste treatment with specific reference to the activated sludge process |
Author |
Wood, Dennis K. Tchobanoglous, George |
Date of Original | 1974 |
Conference Title | Proceedings of the 29th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,24462 |
Extent of Original | p. 648-661 |
Series | Engineering extension series no. 145 |
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 | 2009-06-05 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page648 |
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 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | Trace Elements in Biological Waste Treatment With Specific Reference to the Activated Sludge Process DENNIS K. WOOD, Graduate Student GEORGE TCHOBANOGLOUS, Associate Professor University of California, Davis Davis, California 95616 INTRODUCTION The role of nitrogen and phosphorus as essential nutrients for the proper operation of biological treatment processes is well documented. The role of trace elements as micronutrients, however, is not well defined. Due to the difficulty in measurement and the complex chemistry and biochemistry involved, the requirements for trace elements have not been determined. The purpose of this paper is to deliniate the significance of trace elements in biological waste treatment with specific reference to the activated sludge process. To do this, the material to be presented has been divided into sections dealing with 1) a review of the role of trace elements in biological systems, 2) a review of the sources of trace elements in wastewater and the mechanisms that may be responsible for their removal before utilization, 3) an analysis of the role of trace elements in the activated sludge process, and 4) the implications of the presence of absence of trace elements in the design and operation of biological treatment systems. TRACE ELEMENTS IN BIOLOGICAL SYSTEMS To understand the role of trace elements in biological waste treatment it will be useful to review 1) the importance of trace elements in microbial growth and metabolism, 2) their effects on population dynamics, and 3) trace element requirements in biological systems. Growth and Metabolism Trace elements are a requirement for the growth and metabolism of microorganisms. Essential and other trace elements are listed in Table I. Not all organisms require every essential element, though each element is required for the growth of at least one common organism. The other elements shown in Table I have been found in the ash of organisms, but their requirement for growth has not been established (1). Trace elements are required for two basic functions. First, they are required as metallic enzyme activators (2). An enzyme activator is a small molecule that stimulates growth, but unlike a coenzyme, is not an explicit part of the reaction. Second, they are required for the electron transfer in oxidation-reduction reactions. Iron is essential for aerobic bacterial growth, and it may be a universal requirement for all organisms (2, 3). It is responsible for the electron transport in cytochromes, a group of proteins whose prosthetic group prophyrin contains iron. A series of cytochromes is stepwise reduced and oxidized following the oxidation of flavoproteins. Iron is also required for the synthesis of certain enzymes including catalase, peroxidase, and aconitase which is required in the isomerization of citric acid to isocitric acid in the tricarboxylic acid cycle. Zinc and cobalt serve as metallic enzyme activators (2). These metals may be dissociable ions on the active sight of the enzyme. Zinc is required for the activities of carbonic anhydrase and carboxypeptidase A, an enzyme that exhibits both peptidase and estarase activity. Cobalt is required for the activity of carboxypeptidase and the synthesis of vitamin B-12. 648 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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