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Masic, Alma
Publications (9 of 9) Show all publications
Masic, A. & Eberl, H. (2012). Persistence in a single species CSTR model with suspended flocs and wall attached biofilms (ed.). Bulletin of Mathematical Biology, 74(4), 1001-1026
Open this publication in new window or tab >>Persistence in a single species CSTR model with suspended flocs and wall attached biofilms
2012 (English)In: Bulletin of Mathematical Biology, ISSN 0092-8240, E-ISSN 1522-9602, Vol. 74, no 4, p. 1001-1026Article in journal (Refereed)
Abstract [en]

We consider a mathematical model for a bacterial population in a continuously stirred tank reactor (CSTR) with wall attachment. This is a modification of the Freter model, in which we model the sessile bacteria as a microbial biofilm. Our analysis indicates that the results of the algebraically simpler original Freter model largely carry over. In a computational simulation study, we find that the vast majority of bacteria in the reactor will eventually be sessile. However, we also find that suspended biomass is relatively more efficient in removing substrate from the reactor than biofilm bacteria.

Place, publisher, year, edition, pages
Encyclopedia of Global Archaeology/Springer Verlag, 2012
Keywords
wall attachment, CSTR, mathematical model, biofilm
National Category
Natural Sciences
Identifiers
urn:nbn:se:mau:diva-2735 (URN)10.1007/s11538-011-9707-8 (DOI)000301440700010 ()22131185 (PubMedID)2-s2.0-84857895450 (Scopus ID)13084 (Local ID)13084 (Archive number)13084 (OAI)
Available from: 2020-02-27 Created: 2020-02-27 Last updated: 2024-02-05Bibliographically approved
Masic, A., Bengtsson, J. & Christensson, M. (2010). Measuring and modeling the oxygen profile in a nitrifying Moving Bed Biofilm Reactor (ed.). Mathematical Biosciences, 227(1), 1-11
Open this publication in new window or tab >>Measuring and modeling the oxygen profile in a nitrifying Moving Bed Biofilm Reactor
2010 (English)In: Mathematical Biosciences, ISSN 0025-5564, E-ISSN 1879-3134, Vol. 227, no 1, p. 1-11Article in journal (Refereed)
Abstract [en]

In this paper we determine the oxygen profile in a biofilm on suspended carriers in two ways: firstly by microelectrode measurements and secondly by a simple mathematical model. The Moving Bed Biofilm Reactor is well-established for wastewater treatment where bacteria grow as a biofilm on the protective surfaces of suspended carriers. The flat shaped BiofilmChip P was developed to allow good conditions for transport of substrates into the biofilm. The oxygen profile was measured in situ the nitrifying biofilm with a microelectrode and it was simulated with a one-dimensional mathematical model. We extended the model by adding a CSTR equation, to connect the reactor to the biofilm through the boundary conditions. We showed the dependence of the thickness of the mass transfer boundary layer on the bulk flow rate. Finally, we estimated the erosion parameter λ to increase the concordance between the measured and simulated profiles. This lead to a simple empirical relationship between λ and the flow rate. The data gathered by in situ microelectrode measurements can, together with the mathematical model, be used in predictive modeling and give more insight in the design of new carriers, with the ambition of making process operation more energy efficient.

Place, publisher, year, edition, pages
Elsevier, 2010
Keywords
biofilm model, microelectrode, Moving Bed Biofilm Reactor, Oxygen profile
National Category
Other Biological Topics
Identifiers
urn:nbn:se:mau:diva-2428 (URN)10.1016/j.mbs.2010.05.004 (DOI)000281173500001 ()20580728 (PubMedID)2-s2.0-77955272642 (Scopus ID)10487 (Local ID)10487 (Archive number)10487 (OAI)
Available from: 2020-02-27 Created: 2020-02-27 Last updated: 2024-02-06Bibliographically approved
Masic, A., Bengtsson, J., Overgaard, N. C., Christensson, M. & Heyden, A. (2009). Determination of the oxygen profile in a nitrifying Moving Bed Biofilm Reactor by microelectrodes and a mathematical model (ed.). In: (Ed.), : . Paper presented at Processes in Biofilms, Davis, USA (2009).
Open this publication in new window or tab >>Determination of the oxygen profile in a nitrifying Moving Bed Biofilm Reactor by microelectrodes and a mathematical model
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2009 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

In this paper we determine the oxygen profile in a biofilm on suspended carriers in two ways: firstly by microelectrode measurements and secondly by a simple mathematical model. The Moving Bed Biofilm Reactor is well-established for wastewater treatment where bacteria grow as a biofilm on the protective surfaces of suspended carriers. The flat shaped BiofilmChipTM P was developed to allow good conditions for transport of substrates into the biofilm. Firstly, the oxygen profile was measured in situ the nitrifying biofilm with a microelectrode and secondly, the profile was simulated with a one-dimensional mathematical model. We refined a classical model by adding a dynamical tank equation, to connect the tank to the biofilm through the boundary conditions. This proved to be an important key in achieving relevant simulations. We also estimated the erosion parameter λ to increase the concordance between the measured and simulated profiles. Promising results have been obtained from our mathematical model. The accordance improved when simulating profiles without the boundary layer. Microelectrode measurements are a valuable tool in design of new suspended carriers.

Keywords
biofilm model, Moving Bed Biofilm Reactor, nitrifying biofilms, oxygen profile
National Category
Computational Mathematics
Identifiers
urn:nbn:se:mau:diva-12389 (URN)10379 (Local ID)10379 (Archive number)10379 (OAI)
Conference
Processes in Biofilms, Davis, USA (2009)
Available from: 2020-02-29 Created: 2020-02-29 Last updated: 2022-06-27Bibliographically approved
Masic, A., Bjerkén, C., Overgaard, N. & Heyden, A. (2008). A Combined Model for Biofilm Development and Biocorrosion (ed.). In: (Ed.), : . Paper presented at Life Sciences (SIAM), Munich, Germany (2008). SIAM
Open this publication in new window or tab >>A Combined Model for Biofilm Development and Biocorrosion
2008 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

We propose a combined model investigating the interplay between a growing biofilm on a metallic surface and environmental suported stress corrosion. The biofilm model incorporates both substrate diffusion, bacteria metabolism and biofilm development, making it possible to estimate the pH at the metallic surface. The biocorrosion model is based on strain driven dissolution. The final model iterates between biofilm development that changes the pH at the surface and biocorrosion that changes the geometry of the substratum.

Place, publisher, year, edition, pages
SIAM, 2008
Keywords
biofilm modeling, biocorrosion
National Category
Materials Engineering
Identifiers
urn:nbn:se:mau:diva-12778 (URN)7311 (Local ID)7311 (Archive number)7311 (OAI)
Conference
Life Sciences (SIAM), Munich, Germany (2008)
Available from: 2020-02-29 Created: 2020-02-29 Last updated: 2022-06-27Bibliographically approved
Overgaard, N. & Masic, A. (2008). Computation of Steady-state Solutions to a Mixed Culture Biofilm Model (ed.). In: (Ed.), : . Paper presented at European Conference on Mathematical and Theoretical Biology, Edinburgh, Scotland (2008).
Open this publication in new window or tab >>Computation of Steady-state Solutions to a Mixed Culture Biofilm Model
2008 (English)Conference paper, Oral presentation only (Other (popular science, discussion, etc.))
Keywords
biofilm modeling, steady-state computation
National Category
Computational Mathematics
Identifiers
urn:nbn:se:mau:diva-12553 (URN)7308 (Local ID)7308 (Archive number)7308 (OAI)
Conference
European Conference on Mathematical and Theoretical Biology, Edinburgh, Scotland (2008)
Available from: 2020-02-29 Created: 2020-02-29 Last updated: 2022-06-27Bibliographically approved
Masic, A., Overgaard, N. & Heyden, A. (2008). Efficient Calculation and Analysis of Steady State Solutions for a Mathematical Model of Nitrifying Bacteria in a Moving Bed Biofilm Reactor (ed.). In: (Ed.), : . Paper presented at Biofilms, Munich, Germany (2008). Biriwa Education Services
Open this publication in new window or tab >>Efficient Calculation and Analysis of Steady State Solutions for a Mathematical Model of Nitrifying Bacteria in a Moving Bed Biofilm Reactor
2008 (English)Conference paper, Published paper (Other academic)
Abstract [en]

We consider a mathematical model for the nitrification of municipal waste water in a moving bed biofilm reactor. The model consists of two interacting parts. The first part is an essentially one-dimensional mixed-culture biofilm model, based on the classical differential equation paradigm introduced by Wanner and Gujer (Biotech. Bioeng. 28, 1986). This part models nutrient transport, growth and internal composition of the bacterial film located on the inside of the individual AnoxKaldnes-carrier chips in the reactor. The second part of the model describes the nutrient concentrations in the reactor tank. Here we use the standard differential equations for a completely mixed (continuously stirred) reactor. The interaction between the two parts of the system is comprised in the boundary conditions, i.e. the nutrient concentrations at the biofilm-water interface.

Place, publisher, year, edition, pages
Biriwa Education Services, 2008
Keywords
biofilm modeling, steady state
National Category
Computational Mathematics
Identifiers
urn:nbn:se:mau:diva-12517 (URN)7301 (Local ID)7301 (Archive number)7301 (OAI)
Conference
Biofilms, Munich, Germany (2008)
Available from: 2020-02-29 Created: 2020-02-29 Last updated: 2022-06-27Bibliographically approved
Masic, A., Bengtsson, J., Overgaard, N., Christensson, M. & Heyden, A. (2008). Investigation of Oxygen Profile in a Nitrifying Moving Bed Biofilm Process: Theory and Validation of a Mathematical Model (ed.). In: (Ed.), : . Paper presented at World Water Congress (IWA), Vienna (2008). Biriwa Education Services
Open this publication in new window or tab >>Investigation of Oxygen Profile in a Nitrifying Moving Bed Biofilm Process: Theory and Validation of a Mathematical Model
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2008 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

Mathematical modelling has intertwined with other research areas and become an important tool in the analysis of different phenomena, such as biofilms. Several mathematical models can be used to reproduce and predict the behaviour of biofilms. Depending on the conditions, such as substrate concentrations or temperature, one can have many different models representing the variety of processes.

Place, publisher, year, edition, pages
Biriwa Education Services, 2008
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:mau:diva-12758 (URN)7310 (Local ID)7310 (Archive number)7310 (OAI)
Conference
World Water Congress (IWA), Vienna (2008)
Available from: 2020-02-29 Created: 2020-02-29 Last updated: 2022-06-27Bibliographically approved
Masic, A., Bjerkén, C., Overgaard, N. & Heyden, A. (2008). Investigation of the Interaction between Biocorrosion and Biofilm Development based on the pH Profile (ed.). In: (Ed.), : . Paper presented at Biofilms, Munich, Germany (2008). Biriwa Education Services
Open this publication in new window or tab >>Investigation of the Interaction between Biocorrosion and Biofilm Development based on the pH Profile
2008 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

We propose a combined model for investigating the interplay between a growing biofilm on a metallic surface and stress corrosion. The biofilm model incorporates both substrate dissolution, bacteria metabolism and biofilm development, making it possible to estimate the pH at the metallic surface. The biofilm model is base on the well-known Wanner-Gujer model, cf. [1] for biofilm development and applied to a metabolism involving pH, cf. [7,8,9]. Including pH in the metabolism makes it possible to estimate the pH at the substratum as a function of the biofilm thickness, which then can be provided as input to the biocorrosion model.

Place, publisher, year, edition, pages
Biriwa Education Services, 2008
Keywords
biofilm modeling, biocorrosion
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:mau:diva-12339 (URN)7392 (Local ID)7392 (Archive number)7392 (OAI)
Conference
Biofilms, Munich, Germany (2008)
Available from: 2020-02-29 Created: 2020-02-29 Last updated: 2022-06-27Bibliographically approved
Masic, A., Overgaard, N. & Heyden, A. (2008). Parameter Estimation in Biofilm Models (ed.). In: (Ed.), Proceedings. Oral Pres. 8th. Int. IWA Conf. on Biofilm Technologies: . Paper presented at Biofilm Technologies, Singapore (2008) (pp. 257-258). International Water Association
Open this publication in new window or tab >>Parameter Estimation in Biofilm Models
2008 (English)In: Proceedings. Oral Pres. 8th. Int. IWA Conf. on Biofilm Technologies, International Water Association , 2008, p. 257-258Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

Mathematical modeling of biofilm development has been an active research topic during the latest years. The main purpose of these models is to understand and predict biofilm growth and development. One of the first mathematical model was the so called Wanner-Gujer model, where a one-dimensional model capable of describing multiple species development was proposed. Later on, more advanced models, incorporating more dimensions, eps-production, cell-to-cell-signalling and other properties have been developed. The major obstacle when trying to predict biofilm development using these mathematical models is that a huge number of parameters are needed, such as parameters in the bacterial metabolism, growth and detachment rates. Some of these parameters are possible to measure in experimental conditions, but others are more difficult, such as the detachment rate. In this paper, we will propose a methodology for estimating parameters in mathematical models of biofilm development from comparison of model prediction and experimental data. The proposed method is based on parameter identification methods used in automatic control theory. We will especially focus on the determination of the detachment rate in the Wanner-Gujer model.

Place, publisher, year, edition, pages
International Water Association, 2008
Keywords
biofilm modeling, parameter estimation
National Category
Computational Mathematics
Identifiers
urn:nbn:se:mau:diva-12440 (URN)7300 (Local ID)7300 (Archive number)7300 (OAI)
Conference
Biofilm Technologies, Singapore (2008)
Available from: 2020-02-29 Created: 2020-02-29 Last updated: 2022-06-27Bibliographically approved
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