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5 A RESPIROMETRIC METHOD FOR BIOKINETIC CHARACTERIZATION OF TOXIC WASTES Anthony F. Gaudy, Jr., Professor Anand Ekambaram, Graduate Research Assistant Department of Civil Engineering University of Delaware Newark, Delaware 19716 Alan F. Rozich, President Bioprocess Engineering, Inc. Wilmington, Delaware 198080936 INTRODUCTION Recent papers have described the use of kinetic models and parameters computed from the biokinetic constants included in them to predict performance of activated sludge processes treating either noninhibitory or toxic organic substrates.16 Our recent work has also suggested that the biokinetic parameters may play a role in industrial waste pretreatment programs, since relative numerical values of certain biokinetic parameters might be employed as one of the criteria for grading industrial wastes and establishing sewer charges.4'6 The major impediment to more general use of kinetic models in plant operations has been the need for periodic evaluation of the biokinetic constants and the realization that the procedures for obtaining numerical values of these constants is somewhat laborious. Numerical values of the kinetic constants depend largely upon the nature of the waste and the biological composition of the activated sludge which is degrading the carbon sources in the waste. Since these numerical values can be expected to change from time to time, their determination is best accomplished on a routine basis. In a recent paper,4 we pointed out some of the experimental difficulties in determining the values of the constants by the generally accepted batch growth procedures, and we have shown that the accumulated oxygen uptake curve could be used to compute the growth curves from which values of n at various concentrations of substrate, S0, could be determined. The approach, under conditions wherein measurement of growth was by the usual method, i.e., optical density, was difficult and the "02 surrogate" technique, as it was called, saved much labor and time in amassing the required data. The method was shown to reproduce growth curves for heterogeneous microbial populations metabolizing noninhibitory carbon sources. Equations for calculating the concentration of either biomass or soluble substrate remaining in the system from the 02 uptake data are given below: X, = Xc + AO,,/R (1) COD, = COD0  A02 ,/RY, (2) It should be obvious that the equations are applicable only during the substrate removal period. Also, it should be noted that the analyst is interested mainly in the early, or exponential growth, portion of the curve. The R term in the equation can be calculated from the cell yield, Y,, and the oxygen equivalent (COD) of the biomass, Ox in accord with the following equation. R = 1/Y, Ox (3) The R values also can be obtained directly from the growth data using the following equation. R = A 02 ,/(X,  X0) (4) It can be seen that R represents the amount of respiratory oxygen used in producing a unit mass of cells. In a previous paper,4 we mentioned that we were extending the work to a known inhibitory substrate and to whole industrial wastes. 43rd Purdue Industrial Waste Conference Proceedings, I 1989 Lewis Publishers, Inc., Chelsea, Michigan 48118. Printed in U.S.A. 35
Object Description
Purdue Identification Number  ETRIWC198805 
Title  Respirometric method for biokinetic characterization of toxic wastes 
Author 
Gaudy, Anthony F. Ekambaram, A. (Anand) Rozich, Alan F. 
Date of Original  1988 
Conference Title  Proceedings of the 43rd Industrial Waste Conference 
Conference Front Matter (copy and paste)  http://earchives.lib.purdue.edu/u?/engext,39828 
Extent of Original  p. 3544 
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 
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Date Digitized  20090812 
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Capture Details  ScandAll 21 
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Description
Title  page 35 
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 fi5650C 
Capture Details  ScandAll 21 
Transcript  5 A RESPIROMETRIC METHOD FOR BIOKINETIC CHARACTERIZATION OF TOXIC WASTES Anthony F. Gaudy, Jr., Professor Anand Ekambaram, Graduate Research Assistant Department of Civil Engineering University of Delaware Newark, Delaware 19716 Alan F. Rozich, President Bioprocess Engineering, Inc. Wilmington, Delaware 198080936 INTRODUCTION Recent papers have described the use of kinetic models and parameters computed from the biokinetic constants included in them to predict performance of activated sludge processes treating either noninhibitory or toxic organic substrates.16 Our recent work has also suggested that the biokinetic parameters may play a role in industrial waste pretreatment programs, since relative numerical values of certain biokinetic parameters might be employed as one of the criteria for grading industrial wastes and establishing sewer charges.4'6 The major impediment to more general use of kinetic models in plant operations has been the need for periodic evaluation of the biokinetic constants and the realization that the procedures for obtaining numerical values of these constants is somewhat laborious. Numerical values of the kinetic constants depend largely upon the nature of the waste and the biological composition of the activated sludge which is degrading the carbon sources in the waste. Since these numerical values can be expected to change from time to time, their determination is best accomplished on a routine basis. In a recent paper,4 we pointed out some of the experimental difficulties in determining the values of the constants by the generally accepted batch growth procedures, and we have shown that the accumulated oxygen uptake curve could be used to compute the growth curves from which values of n at various concentrations of substrate, S0, could be determined. The approach, under conditions wherein measurement of growth was by the usual method, i.e., optical density, was difficult and the "02 surrogate" technique, as it was called, saved much labor and time in amassing the required data. The method was shown to reproduce growth curves for heterogeneous microbial populations metabolizing noninhibitory carbon sources. Equations for calculating the concentration of either biomass or soluble substrate remaining in the system from the 02 uptake data are given below: X, = Xc + AO,,/R (1) COD, = COD0  A02 ,/RY, (2) It should be obvious that the equations are applicable only during the substrate removal period. Also, it should be noted that the analyst is interested mainly in the early, or exponential growth, portion of the curve. The R term in the equation can be calculated from the cell yield, Y,, and the oxygen equivalent (COD) of the biomass, Ox in accord with the following equation. R = 1/Y, Ox (3) The R values also can be obtained directly from the growth data using the following equation. R = A 02 ,/(X,  X0) (4) It can be seen that R represents the amount of respiratory oxygen used in producing a unit mass of cells. In a previous paper,4 we mentioned that we were extending the work to a known inhibitory substrate and to whole industrial wastes. 43rd Purdue Industrial Waste Conference Proceedings, I 1989 Lewis Publishers, Inc., Chelsea, Michigan 48118. Printed in U.S.A. 35 
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