MODELING OXIDATION DITCHES USING THE IA WPRC ACTIVATED SLUDGE MODEL WITH HYDRODYNAMIC EFFECTS

1994 ◽  
Vol 30 (2) ◽  
pp. 185-192 ◽  
Author(s):  
Anastasios I. Stamou
Keyword(s):  
Steady State ◽  
Activated Sludge ◽  
Flow Velocity ◽  
Dispersion Coefficient ◽  
Aerobic Oxidation ◽  
Model Parameters ◽  
Activated Sludge Model ◽  
Average Flow Velocity ◽  
Oxygen Requirements ◽  
Hydrodynamic Effects

A mathematical model is presented to predict the concentrations of the active heterotrophic biomass, the readily biodegradable substrate (soluble COD) and the dissolved oxygen (DO) in a completely aerobic oxidation ditch. The model involves the one-dimensional convection-dispersion equations for biomass, COD and DO. Hydrodynamic effects are represented in the model by the values of the average flow velocity and the dispersion coefficient. Biological processes are described in the model according to the IA WPRC activated sludge model, using typical values for the model parameters at 10°C. The equations are solved with the finite volume method. The application of the model leads to the following conclusions: (i) Steady state biomass concentrations are almost constant throughout the ditch. (ii) Steady state COD concentrations in the ditch are very low, and COD removal efficiency is practically independent of the values of the flow velocity and the dispersion coefficient. The distribution of the COD concentration in the ditch is less uniform, when small values of the dispersion coefficient are used. (iii) The distribution of the DO concentration in the ditch is very sensitive to the values of the flow velocity, the dispersion coefficient and to the capacity of the rotors. DO concentrations increase when the dispersion coefficient decreases or the flow velocity increases. (v) Daily sludge production, oxygen requirements and sludge age are calculated equal to 0.44 g (g COD removed)‒1, 0.56 g (g incoming COD)‒1 and 6.3 days, respectively.

Model Calibration for the High-Purity Oxygen Activated Sludge Process – Algorithm Development and Evaluation

1993 ◽  
Vol 28 (11-12) ◽  
pp. 163-171 ◽  
Author(s):  
Weibo (Weber) Yuan ◽  
David Okrent ◽  
Michael K. Stenstrom
Keyword(s):  
Activated Sludge ◽  
High Purity ◽  
Model Calibration ◽  
Process Model ◽  
Model Parameters ◽  
Complex Method ◽  
Activated Sludge Process ◽  
Activated Sludge Model ◽  
Kinetic Coefficients ◽  
Calibration Algorithm

A model calibration algorithm is developed for the high-purity oxygen activated sludge process (HPO-ASP). The algorithm is evaluated under different conditions to determine the effect of the following factors on the performance of the algorithm: data quality, number of observations, and number of parameters to be estimated. The process model used in this investigation is the first HPO-ASP model based upon the IAWQ (formerly IAWPRC) Activated Sludge Model No. 1. The objective function is formulated as a relative least-squares function and the non-linear, constrained minimization problem is solved by the Complex method. The stoichiometric and kinetic coefficients of the IAWQ activated sludge model are the parameters focused on in this investigation. Observations used are generated numerically but are made close to the observations from a full-scale high-purity oxygen treatment plant. The calibration algorithm is capable of correctly estimating model parameters even if the observations are severely noise-corrupted. The accuracy of estimation deteriorates gradually with the increase of observation errors. The accuracy of calibration improves when the number of observations (n) increases, but the improvement becomes insignificant when n>96. It is also found that there exists an optimal number of parameters that can be rigorously estimated from a given set of information/data. A sensitivity analysis is conducted to determine what parameters to estimate and to evaluate the potential benefits resulted from collecting additional measurements.

scholarly journals A practical protocol for calibration of nutrient removal wastewater treatment models

2011 ◽  
Vol 13 (4) ◽  
pp. 575-595 ◽  
Author(s):  
Giorgio Mannina ◽  
Alida Cosenza ◽  
Peter A. Vanrolleghem ◽  
Gaspare Viviani
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Nutrient Removal ◽  
Model Calibration ◽  
Wastewater Treatment Plants ◽  
Optimal Parameter ◽  
Model Parameters ◽  
Activated Sludge Model ◽  
Treatment Models ◽  
Glue Method

Activated sludge models can be very useful for designing and managing wastewater treatment plants (WWTPs). However, as with every model, they need to be calibrated for correct and reliable application. Activated sludge model calibration is still a crucial point that needs appropriate guidance. Indeed, although calibration protocols have been developed, the model calibration still represents the main bottleneck to modelling. This paper presents a procedure for the calibration of an activated sludge model based on a comprehensive sensitivity analysis and a novel step-wise Monte Carlo-based calibration of the subset of influential parameters. In the proposed procedure the complex calibration issue is tackled both by making a prior screening of the most influential model parameters and by simplifying the problem of finding the optimal parameter set by splitting the estimation task into steps. The key point of the proposed step-wise procedure is that calibration is undertaken for sub-groups of variables instead of solving a complex multi-objective function. Moreover, even with this step-wise approach parameter identifiability issues may occur, but this is dealt with by using the general likelihood uncertainty estimation (GLUE) method, that so far has rarely been used in the field of wastewater modelling. An example from a real case study illustrates the effectiveness of the proposed methodology. Particularly, a model was built for the simulation of the nutrient removal in a Bardenpho scheme plant. The model was successfully and efficiently calibrated to a large WWTP in Sicily.

Benefits of Including Unaerated Zones in Nitrifying Activated Sludge Plants

1987 ◽  
Vol 19 (1-2) ◽  
pp. 195-207 ◽  
Author(s):  
P. L. Dold ◽  
G v. R. Marais
Keyword(s):  
Activated Sludge ◽  
Ph Control ◽  
Task Group ◽  
Simulation Studies ◽  
Activated Sludge Model ◽  
Nitrate Load ◽  
Oxygen Requirements ◽  
Aeration Capacity ◽  
Activated Sludge Systems

In nitrifying activated sludge systems several practical advantages accrue from inclusion of unaerated (anoxlc) zones. Accepting the general activated sludge model proposed by the IAWPRC Task Group, as modified by Dold and Marals (1985), simulation studies on nitrifying and nltrlfylng-denltrlfylng systems demonstrate the advantages of the latter with respect to (1) reduction in dally oxygen requirements, (2) reduction in effluent nitrate load, (3) elimination of pH control, (4) alleviation of the stringency in D.O. control, and (5) reduction in the required peak aeration capacity.

Calibration of an Activated Sludge Model Based on Human Expertise and on a Mathematical Optimization Technique – a Comparison

1992 ◽  
Vol 25 (6) ◽  
pp. 141-148 ◽  
Author(s):  
Oskar Wanner ◽  
Jürg Kappeier ◽  
Willi Gujer
Keyword(s):  
Activated Sludge ◽  
Optimization Technique ◽  
Mathematical Optimization ◽  
The Other ◽  
Sequential Procedure ◽  
Alternative Methods ◽  
Model Parameters ◽  
Activated Sludge Model ◽  
Parameter Values ◽  
Mathematical Optimization Technique

Two alternative methods, which both can be used to estimate some of the kinetic parameters of the IAWPRC Activated Sludge Model Nr. 1, are compared. By one method, which is based on professional experience and expertise, the unknown parameter values are determined one after the other by a sequential procedure. By the other method, the parameter values are determined simultaneously by use of a mathematical optimization technique. Both methods allow a good fit of a set of 25 experimental oxygen respiration rate time-series and yield accurate estimates of the model parameters. The sequential procedure can readily be employed for the evaluation of single experiments. The optimization technique is more suitable for the evaluation of larger data sets and allows for additional analysis of the data.

scholarly journals Steady-State Methodology for Activated Sludge Model 1 (ASM1) State Variable Calculation in MBR

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3220
Author(s):  
Ameni Lahdhiri ◽  
Geoffroy Lesage ◽  
Ahmed Hannachi ◽  
Marc Heran
Keyword(s):  
Steady State ◽  
Activated Sludge ◽  
Treatment Plant ◽  
Operating Parameters ◽  
State Variables ◽  
Activated Sludge Model ◽  
Carbon And Nitrogen ◽  
Conventional Activated Sludge ◽  
Analytical Expressions ◽  
Relevant Factors

The complexity of Activated Sludge Model No. 1 (ASM1) is one of the main obstacles slowing its widespread use, particularly among wastewater treatment plant (WWTP) professionals. In this paper, a simplification procedure based on steady-state mass balances is proposed for the conventional activated sludge process (ASP) configuration, consisting of an aerated bioreactor and a perfect settler (without particular compounds in the outlet). The results do, in fact, show perfect suitability to a membrane bioreactor process (MBR). Both organic carbon and nitrogen removal were investigated. The proposed approach was applied to ASM1, and simple analytical expressions of the state variables were obtained. These analytical expressions were then validated by comparison to simulations given by the original ASM1 (implemented in GPS-X software). A strong match (less than 4% of error overall) was obtained between both results in the steady-state; consequently, these analytical expressions may be useful as tools for quickly estimating the main state variables, feeding the filtration models, or identifying the interaction between operating parameters. Moreover, this enables a sensitivity analysis, covering relevant factors such as kinetics or operating parameters. For instance, the sludge retention time (SRT) effect is lower on XBH and XS at high SRT (˃20 days), while it is more pronounced on XP and XI as their variations with SRT are linear.

Application of the Marais - Ekama Activated Sludge Model to Large Plants

1982 ◽  
Vol 14 (6-7) ◽  
pp. 581-598 ◽  
Author(s):  
H A Nicholls
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Activated Sludge ◽  
Large Scale ◽  
Unsteady State ◽  
Activated Sludge Model ◽  
Nitrate Concentrations ◽  
Utilisation Rate ◽  
Oxygen Utilisation ◽  
State Responses

The Marais-Ekama model was used to successfully predict the performance of two 50 000 m3/d five-stage nutrient removing activated sludge plants. The experimental data used to test the model was obtained by monitoring the feed, effluent and contents of each reactor in the process, every two hours for 4 days. In addition, a respirometer was developed to measure the oxygen utilisation rate automatically every 30 minutes. All data collected was found to be valid, as acceptable COD and nitrogen balances across the plants were possible. The data was then compared with the steady state and unsteady state responses of the model. It was found that the model could successfully predict the COD, TKN, Ammonia and nitrate concentrations in the effluent and illustrate some shortcomings in the process layouts. This indicated that the model could be used by designers and operators of large-scale plants to predict performance and highlight problem areas.

Verification of Radiocarbon Transport Predicted by Numerical Modeling in the Porous Formation of NE Hungary Considering Paleo-Hydrogeology

Radiocarbon ◽  
2019 ◽  
Vol 62 (1) ◽  
pp. 219-233 ◽  
Author(s):  
Ferenc Székely ◽  
József Deák ◽  
Péter Szűcs ◽  
László Kompár ◽  
Balázs Zákányi ◽  
...  
Keyword(s):  
Steady State ◽  
Groundwater Flow ◽  
Flow Velocity ◽  
Land Surface ◽  
Flow Model ◽  
Radioactive Tracer ◽  
Reduction Factor ◽  
Average Flow Velocity ◽  
Velocity Reduction ◽  
Solute Transport Modeling

ABSTRACTVerification of a groundwater flow model by radiocarbon (14C) data are presented taking into consideration the paleo-hydrogeological changes. Northeastern area of the Great Hungarian Plain was a deep-lying flat area, and its central part (Nyírség) has been uplifted in the last 15,000 years. These geological events have drastically changed the hydrogeological conditions of Nyírség. The groundwater flow system is composed of the Quaternary-Pliocene-Upper Pannonian clastic sediments. Groundwater flow modeling has been performed to define the main lateral and vertical flow directions and velocities controlling the propagation of the environmental radioactive tracer 14C. Solute-transport modeling was used to calculate the 14C activity. The recent steady-state groundwater flow velocity was reduced to a reasonable value characterizing the average flow velocity over the 15 ka simulation period using “trial and error” method. The best fit between the simulated and measured 14C data was achieved by assuming 0.4 flow velocity reduction factor. Results indicate that the present steady-state flow model with this flow velocity reduction factor is capable of reproducing the observed 14C data taking into account the effect of the significant uplift of the part of the land surface in the last 15 ka in NE Hungary.

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