Periodic and Non Periodic (Complex) Behavior of a Model of Bioreactor With Cell Recycling

Ibrahim, G.; Ramadan, Mohamed A.; El-Marouf, S.A.A.; Al-Mahdi, Abdo M.

doi:10.3844/jmssp.2007.1.11

Cited by 7 publications

(3 citation statements)

References 20 publications

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“…Bioreactors are in fact known to exhibit a number of nonlinear phenomena. These include bistability between nontrivial steady states and washout, the occurrence of multiple steady states (the famous hysteresis phenomenon) as well as the occurrence of oscillations . The mechanisms of most of these phenomena are not well understood, but they are known to be strongly dependent on the inherent mechanisms of the biodegradation (growth kinetics and yield coefficients) as well as on operating parameters of the process (feed flow rate, feed concentration, recycle ratio…etc.…”

Section: Introductionmentioning

confidence: 99%

“…There are a number of structured and more complex models available in the literature to describe wastewater biodegradation. Gamal et al ., for instance, studied the stability characteristics of a model of activated sludge process that was structured upon substrate and intermediate component growth depending processes. The model kinetics were, on the other hand, based on substrate and intermediate product inhibition effects.…”

Section: Introductionmentioning

confidence: 99%

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A fundamental analysis of dynamics of waste biodegradation in aerobic processes

Ajbar

AlZeghayer

2013

Asia-Pacific J Chem Eng

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This paper studies the static and dynamic behavior of a biological wastewater treatment process consisting of an aerobic bioreactor and a settler. The process is described by a three-variable model that takes explicitly into account the mass balance of oxygen. The analysis is carried out for the general case where the biomass specific growth rate is assumed to depend arbitrarily on substrate, biomass, and oxygen. The biomass yield coefficient is also assumed to depend arbitrarily on the substrate. General conditions describing the behavior of the model are derived. The general analysis is applied to an experimentally validated model where the specific growth rate depends on substrate and oxygen following a multiplicative Monod form. Practical diagrams are constructed that delineate the effect of various operating parameters on the performance of the biodegradation. The model is also studied for the case of a variable yield coefficient. The analysis shows the existence of a periodic behavior for some range of model parameters. The results of the paper allowed a useful understanding of the dynamics of the aerobic biodegradation including the effect of operating parameters, the specific growth rate, and the biomass yield coefficient on the existence of instabilities in the process. Figure 1. Schematic diagram of the bioreactor-settler process.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A fundamental analysis of dynamics of waste biodegradation in aerobic processes

Ajbar

AlZeghayer

2013

Asia-Pacific J Chem Eng

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“…All the studies carried out on the ASP as of now have primarily considered an unstructured model for the aerator. Recently, Ibrahim et al, 9 have proposed a structured model which is based upon growth processes depending upon substrate and intermediate components. In the present study, we propose a structured cybernetic model for the activated sludge process.…”

Section: Introductionmentioning

confidence: 99%

Conceptual Analysis of the Effect of Kinetics on the Stability and Multiplicity of a Coupled Bioreactor−Separator System Using a Cybernetic Modeling Approach

Kumar

Zeyer

Kienle

et al. 2009

Ind. Eng. Chem. Res.

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In this work, the nonlinear behavior of a bioreactor coupled to a separator is analyzed. The main focus is on the effect of kinetics on the stability and multiplicity of the coupled system using a cybernetic modeling approach. One example of such a system is the activated sludge process. In this work we consider the growth of a culture of Pseudomonas putida in a medium containing phenol and glucose. We propose a cybernetic model which accounts for the regulatory features in the microorganism in a qualitative way in the aerator. These regulatory features control the rate of uptake of the substrates by the cells in the aerator. We use kinetics with self-substrate inhibition and cross-substrate inhibition effects. We observe a strong dependence of the window of multiplicity on kinetics. We depict that introduction of the more detailed kinetics into the model considerably widens the multiplicity region and helps the experimentalist to design the experiments. We use flocculation kinetics in the bioreactor which is the key for the settling of the suspended solids. The more realistic limiting flux condition is also introduced in the settler. We depict that under such conditions the resulting model of the coupled system exhibits nongrowth associated maintenance phenomena which occur at low dilution rates. The model equations governing the system behavior are ordinary differential equations and algebraic equations. In this work we vary the dilution rate and study the behavior of the system. We observe a shift in the uptake rates of the substrates as we vary the dilution rate. A two parameter continuation is also carried out to investigate the effect of other operating parameters on the nonlinear behavior.

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