A Batch Respirometric Experiment (BRE) Model was created and the model calibration involved the assessment of the relevant bio-kinetic parameters. The inhibition kinetics were used in the activated sludge process model of the COST simulation benchmark model (Copp, 2002), which was used to assess the impact of both dyes on the performance of the COST simulation benchmark wastewater treatment works.
ROMAN SYMBOLS
OED Optimal experimental design SoIXo Initial substrate/biomass ratio ZES Substrate/biomass ratio.
CONTENTS
MATHEMATICAL MODELLING THEORY 3-1
LIST OF TABLES
INTRODUCTION
- Textile Effluent and Municipal Bylaws
- Project Outline
- Thesis Outline
The accuracy with which the result system describes the negative impact of textile dyes on activated sludge processes in sewage treatment plants is investigated. In this chapter, the influence of textile dyes on the efficiency of treatment plants is assessed, and COST simulation criteria were used for this assessment.
LITERATURE REVIEW
The Score System
The Exposure Score gives an indication of the potential presence of the substance in the environment. Knowledge of the flow rate and reactor volume is required to calculate the residence time QnIV .The.
Optimal Experimental Design (OED)
- Optimal experimental design concept
- ASMl components
- Activated sludge model No. 3 (ASM3)
- Structural identifiability
- Practical identifiability
The first step in the model building procedure is to clearly define the purpose of the model before building the model. Once you have completed the first two tasks, an initial iteration of the model building procedure can begin.
Parameter Estimation of Dynamic Models
The structural identifiability of the dynamic model is determined from the given model structure and assuming that model variable data perfectly matches the model. It can be concluded that from the structural identifiability study that combinations of the model parameters and not the individual parameters are identifiable. Practical identifiability is related to the quality of the data; it is whether the available data is rich enough in information to identify and obtain accurate values for the model parameters (Dochain and Vanrolleghem, 2001).
In this section, concepts and theory of the parameter estimation process used in this study are discussed. The selection of the parameters to be estimated is an important step in the parameter estimation procedure.
MATHEMATICAL MODELLING THEORY
Practical identifiability
The parameter deviation of the estimated parameters indicates the level of confidence that can be placed in the estimated parameters. The sensitivity equations can be determined in many different methods; the most popular are the analytical derivation and a numerical approximation of the sensitivity. The sensitivity measure measures the average sensitivity of the model output to changes in the parameter ()j (in the mean square sense).
This objective function is shown in Equation 3-17; it is the cost function of the WEST trajectory optimizer used in the parameter estimates of this study. Initially, the selection of the parameter to be estimated and the experimental data must be specified.
Batch Respirometric Experiments Setup
- The bioreactor and respirometer
The UCT DO/OUR meter (Randall et al., 1991) was used to monitor dissolved oxygen concentration and determine oxygen uptake rate (OUR), an overview of the components of this instrument is shown in Figure 4-1. The OUR meter component schematic is shown in Figure 4-1 and consists of an analog module, microprocessor system, and keyboard/display unit. The operation of all input/output devices on the OUR meter is controlled by the microprocessor unit under program control.
The linear regression analysis of the collected DO time data pairs is assisted by three statistical functions written in the microprocessor software for the variables time (X) and DO concentration (Y). ClearSigma's statistical function clears all variables at the start of each curve fitting procedure, the UpdateSigma function calculates running totals of X, Y, XY, X 2 , y2 and N (the number of data points collected) and the CalcStat function calculates the following statistical parameters based on the current values of the running totals, mean and standard deviation of X and Y values, m slope of the line (ie OUR), c the Y-intercept of the line, and r the correlation coefficient in linear least squares regression (Randall et al., 1991).
Analytical Tests
The OED Procedure Applied to the Batch Respirometric Experiment Design
In addition, unreliable estimates of maximum specific growth parameters and half-saturation constants of heterotrophic and autotrophic biomass were obtained, since insufficient data points were measured from the starting point to the maximum value of oxygen uptake (OURmax). and at the OURmax value (refer to Figure 4-4 in Figure 4-6). A major objective of this experimental design is to obtain sufficient data points measured in the area from the start point to the maximum oxygen uptake value (OURmax) and to the OURmax value. The previous experiment design produced insufficient data points from the start point to OURmax and the OURmax value.
The respirometric profiles of the sodium acetate and ammonium chloride substrate peaks from this experiment design are shown in Figure 4-10 and Figure 4-11, respectively. This experimental design achieved all of the above objectives; Sufficient measured data points in the region from the onset of the peak to the maximum oxygen uptake value (OU~x) and at the OURmax value were obtained, reliable parameter estimates of maximum specific growth rates (fJmH and fJmA) and half-saturation constants (Ksand KNH) and the duration of the experiments were considerably shorter.
Results of Batch Respirometric Experiments
The concentration of sodium acetate and ammonium chloride were 30 mg COD/L and 8 mg NIL, respectively. The concentration of dye spikes doubled after each addition of spikes (Kong et al., 1996). Chapter 2, previous studies have observed that autotrophic biomass is more sensitive to toxic substances than heterotrophic biomass; this is again inferred from comparisons between acetate and ammonia substrate profiles.
A conclusion as to whether the high-point ink has a greater inhibitory effect than the low-point ink cannot be made by comparing the respective respiometric profiles. This conclusion can only be made after obtaining the inhibitory kinetic parameters (refer to Chapter 5) and using them in the COST simulation benchmark (refer to Chapter 6) and analyzing the results from the COST simulation benchmark.
CHAPTERS
BRE MODEL SIMULATION RESULTS AND DISCUSSION
Background on the COST and the COST Simulation Benchmark
- Steady-state simulations
- Dynamic simulations
This section provides an overview of the simulation benchmark model (Copp, 2002); plant layout, process models and influencing components are described. The design of the simulation measuring plant consists of 5 activated sludge units in series with a secondary settler. In the reference COST simulation protocol, protocol control strategies are evaluated using three inflow composition perturbations.
As already mentioned in section 6.2.2.1, activated sludge model no. 1 (ASM 1) biological kinetic process model of the COST comparative simulation model, and the default stoichiometric and kinetic parameter values are presented in Table 6-3 and Table 6-4, respectively. The modifications to the biological kinetic model of the comparative simulation discussed in Section 6.3 were performed in the WEST model editor.
Performance Index of Simulation Benchmark
- Effluent quality index
The number of violations represents the number of times the wastewater treatment plant is in violation of the effluent limitations (ie, the number of times the plant effluent rises above the effluent limitation). Moreover, it can be concluded that the high-point dye (Drimarene Violet K2-RL) has a greater negative impact on the performance of the wastewater treatment works model than the low-point dye (Levafix Blue CA gran ), since in figure 6-3 it is observed that with the increase in the concentration of both dyes, the EQI of the high point dye has a greater increase than the low point dye. The conclusion mentioned above; that both dyes have an inhibitory effect on wastewater treatment works processes and that the high point dye (Drimarene Violet K2-RL) has a greater negative impact on the performance of the wastewater treatment works model black than the low-point ink (LevaflX Blue CA gran), are repeated once again when we look at Figure 6-6 and Figure 6-7.
Since in Figure 6-6 and Figure 6-7 the number of ammonia discharge violations and the percentage time that the facility is in violation of the ammonia discharge limitations increases as the concentration of both dyes increases, and in Figure 6-6 and Figure 6-7 have the high-scoring dye has a greater number of ammonia discharge violations and the percentage of time the facility is in violation of the ammonia discharge limitations is greater than the low-scoring dye. To summarize, it is concluded from simulation performed on the simulation benchmark model; that both dyes used in this study have an inhibitory effect on wastewater treatment processes and that the high-scoring dye has a greater negative impact than the low-scoring dye on wastewater treatment plant performance.
DISCUSSION
Titration is a method for obtaining information about biological nitrogen removal processes of activated sludge by monitoring pH. This study investigated the effect of test substances on aerobic activated sludge processes. The combination of batch respirometric experiment (BRE) activated sludge model and respirometric experiment successfully obtained kinetic data representing the inhibition caused by textile dyes.
VANROLLEGHEM P and SPANJERS H (1998) A hybrid respirometric method for more reliable estimation of activated sludge model parameter. WElJERS S and VANROLLEGHEM P (1997) A procedure for the selection of best identifiable parameters in the calibration of activated sludge model no.
APPENDIX A
I REAGENT PREPARATION Hydrochloric Acid Titrant
APPENDIXB
Press the "A" key to enter the meter into mode A, the instrument will display the dissolved oxygen concentration (mg/L) and temperature (COC). To zero the DO, place the DO probe in sodium sulfite solution (27 g/L) and leave it in the solution until the dissolved oxygen concentration (DO) reading is stable for approximately 1 minute.
APPENDIXC
APPENDIXD
I OPERATIONAL MANUAL
The offset DO value and sample rate are adjusted in the main menu of the DOMPC program. The test was used to evaluate the COD of the wastewater used as substrate in the respirometric experiments. A blank consisting of 10 ml of distilled water, in place of the substrate, was refluxed in the same manner.
The test was used to estimate the total solids content of the activated sludge that was used in the respiometric experiments. The remainder of the 3 samples from the TSS test are ignited at 550 cC for 2 hours.
APPENDIXE
- PARAMETER ESTIMATION SIMULATION DATA
