Biofilm modeling with AQUASIM

2004 ◽  
Vol 49 (11-12) ◽  
pp. 137-144 ◽  
Author(s):  
O. Wanner ◽  
E. Morgenroth
Keyword(s):  
Plug Flow ◽  
Biofilm Reactor ◽  
Bulk Fluid ◽  
One Dimensional ◽  
Biofilm Thickness ◽  
Spatial Gradients ◽  
Biofilm Reactors ◽  
Microbial Species ◽  
Substrate Removal ◽  
Biofilm Modeling

AQUASIM is a computer program for the identification and simulation of aquatic systems. The program includes a one-dimensional multisubstrate and multispecies biofilm model and represents a suitable tool for biofilm simulation. The program can be used to calculate substrate removal in biofilm reactors for any user specified microbial system. One-dimensional spatial profiles of substrates and microbial species in the biofilm can be predicted. The program also calculates the development of the biofilm thickness and of the substrates and microbial species in the biofilm and in the bulk fluid over time. Detachment and attachment of microbial cells at the biofilm surface and in the biofilm interior can be considered, and simulations of sloughing events can be performed. Furthermore, AQUASIM allows pseudo two-dimensional modeling of plug flow biofilm reactors by a series of biofilm reactor compartments. The most significant limitation of the model is that it only considers spatial gradients of substrates and microbial species in the biofilm in the direction perpendicular to the substratum.

Significance of Spatial Distribution of Microbial Species in Mixed Culture Biofilms

1991 ◽  
Vol 23 (7-9) ◽  
pp. 1365-1374 ◽  
Author(s):  
M. Fruhen ◽  
E. Christan ◽  
W. Gujer ◽  
O. Wanner
Keyword(s):  
Spatial Distribution ◽  
Mixed Culture ◽  
Biofilm Reactor ◽  
Constant Thickness ◽  
Nitrification Rate ◽  
Significant Shift ◽  
Bulk Fluid ◽  
Microbial Species ◽  
Substrate Removal ◽  
Biofilm Model

Experimental data from a biofilm reactor, in which two groups of organisms (Nitrifiers and Heterotrophs) compete for dissolved oxygen, were analyzed by a Mixed Culture Biofilm Model. The objective was to investigate to what extent and how fast relative abundance and spatial distribution of microbial species in a mixed culture biofilm changed upon variations of the bulk fluid substrate composition, and what the consequences of these changes were for substrate removal. Experimental results showed that within nine days the nitrification rate in a biofilm of constant thickness could change by a factor of five. Model predictions indicated that these changes must be due to a significant shift of the biofilm population. The distribution of the autotrophic and heterotrophic species over the depth of the biofilm turned out to be an important aspect of mixed culture biofilm behavior. Since it is difficult to observe the microbial population and its spatial distribution experimentally, the Mixed Culture Biofilm Model has proved to be a valuable tool for the interpretation of the observed phenomena.

Engineering aspects of a mixed methanotrophic culture in a membrane-aerated biofilm reactor

2004 ◽  
Vol 49 (11-12) ◽  
pp. 255-262 ◽  
Author(s):  
E. Casey ◽  
S. Rishell ◽  
B. Glennon ◽  
G. Hamer
Keyword(s):  
Oxygen Uptake ◽  
Biofilm Reactor ◽  
Specific Rate ◽  
Suspended Cell ◽  
Biofilm Thickness ◽  
Biofilm Reactors ◽  
Uptake Rates ◽  
Methane Uptake ◽  
Cell Processes ◽  
Oxidation Efficiency

Methanotrophic biodegradation using the membrane-aerated biofilm reactor (MABR) is a technology offering several advantages over both conventional biofilm reactors and suspended-cell processes. In this study the oxidation efficiency of a methanotrophic biofilm in a 1.5 litre MABR was investigated. Measurements of oxygen and methane uptake rates together with biofilm thickness were taken for developing biofilms. It was found that the specific rate of metabolic activity of the biofilm was unusually high as determined by the methane and oxygen uptake rates. Microbial activity stratification was evident and the location of stratified layers of oxygen consuming components of the consortium could be manipulated via the intra-membrane oxygen pressure.

From biofilm ecology to reactors: a focused review

2017 ◽  
Vol 75 (8) ◽  
pp. 1753-1760 ◽  
Author(s):  
Joshua P. Boltz ◽  
Barth F. Smets ◽  
Bruce E. Rittmann ◽  
Mark C. M. van Loosdrecht ◽  
Eberhard Morgenroth ◽  
...  
Keyword(s):  
Negative Impact ◽  
Salt Water ◽  
Granular Sludge ◽  
Biofilm Reactor ◽  
Ammonium Oxidation ◽  
Microbial Conversion ◽  
Water Stream ◽  
Biofilm Reactors ◽  
Reactor Technology ◽  
Biofilm Modeling

Biofilms are complex biostructures that appear on all surfaces that are regularly in contact with water. They are structurally complex, dynamic systems with attributes of primordial multicellular organisms and multifaceted ecosystems. The presence of biofilms may have a negative impact on the performance of various systems, but they can also be used beneficially for the treatment of water (defined herein as potable water, municipal and industrial wastewater, fresh/brackish/salt water bodies, groundwater) as well as in water stream-based biological resource recovery systems. This review addresses the following three topics: (1) biofilm ecology, (2) biofilm reactor technology and design, and (3) biofilm modeling. In so doing, it addresses the processes occurring in the biofilm, and how these affect and are affected by the broader biofilm system. The symphonic application of a suite of biological methods has led to significant advances in the understanding of biofilm ecology. New metabolic pathways, such as anaerobic ammonium oxidation (anammox) or complete ammonium oxidation (comammox) were first observed in biofilm reactors. The functions, properties, and constituents of the biofilm extracellular polymeric substance matrix are somewhat known, but their exact composition and role in the microbial conversion kinetics and biochemical transformations are still to be resolved. Biofilm grown microorganisms may contribute to increased metabolism of micro-pollutants. Several types of biofilm reactors have been used for water treatment, with current focus on moving bed biofilm reactors, integrated fixed-film activated sludge, membrane-supported biofilm reactors, and granular sludge processes. The control and/or beneficial use of biofilms in membrane processes is advancing. Biofilm models have become essential tools for fundamental biofilm research and biofilm reactor engineering and design. At the same time, the divergence between biofilm modeling and biofilm reactor modeling approaches is recognized.

Mathematical modelling of biofilms and biofilm reactors for engineering design

2010 ◽  
Vol 62 (8) ◽  
pp. 1821-1836 ◽  
Author(s):  
J. P. Boltz ◽  
E. Morgenroth ◽  
D. Sen
Keyword(s):  
Engineering Design ◽  
State Of The Art ◽  
Treatment Plant ◽  
Black Box ◽  
Biofilm Reactor ◽  
Engineering Practice ◽  
Software Developers ◽  
One Dimensional ◽  
Biofilm Reactors ◽  
Consensus Report

Mathematical models are critical to modern environmental biotechnology—both in research and in the engineering practice. Wastewater treatment plant (WWTP) simulators are used by consulting engineers and WWTP operators when planning, designing, optimizing, and evaluating the unit processes that comprise municipal and industrial WWTPs. Many WWTP simulators have been expanded to include a submerged completely-mixed biofilm reactor module that is based on the mathematical description of a one-dimensional biofilm. Leading consultants, equipment manufacturers, and WWTP modelling software developers have made meaningful contributions to advancing the use of biofilm models in engineering practice, but the bulk of the engineering community either does not use the now readily available biofilm reactor modules or utilizes them as ‘black-box’ design tools. The latter approach results in the mathematical biofilm models being no more useful than the empirical design criteria and formulations that have been historically applied to biofilm reactor design. The present work provides a consensus report on the state-of-the art, areas of uncertainty, and future needs for advancing the use of biofilm models in engineering design.

Uncertainty in bulk-liquid hydrodynamics and biofilm dynamics creates uncertainties in biofilm reactor design

2010 ◽  
Vol 61 (2) ◽  
pp. 307-316 ◽  
Author(s):  
J. P. Boltz ◽  
G. T. Daigger
Keyword(s):  
Mass Transfer ◽  
Surface Area ◽  
Reactor Design ◽  
Structure And Function ◽  
Biofilm Reactor ◽  
Bulk Liquid ◽  
Biofilm Thickness ◽  
Biofilm Reactors ◽  
Suspended Growth ◽  
And Function

While biofilm reactors may be classified as one of seven different types, the design of each is unified by fundamental biofilm principles. It follows that state-of-the art design of each biofilm reactor type is subject to the same uncertainties (although the degree of uncertainty may vary). This paper describes unifying biofilm principles and uncertainties of importance in biofilm reactor design. This approach to biofilm reactor design represents a shift from the historical approach which was based on empirical criteria and design formulations. The use of such design criteria was largely due to inherent uncertainty over reactor-scale hydrodynamics and biofilm dynamics, which correlate with biofilm thickness, structure and function. An understanding of two fundamental concepts is required to rationally design biofilm reactors: bioreactor hydrodynamics and biofilm dynamics (with particular emphasis on mass transfer resistances). Bulk-liquid hydrodynamics influences biofilm thickness control, surface area, and development. Biofilm dynamics influences biofilm thickness, structure and function. While the complex hydrodynamics of some biofilm reactors such as trickling filters and biological filters have prevented the widespread use of fundamental biofilm principles and mechanistic models in practice, reactors utilizing integrated fixed-film activated sludge or moving bed technology provide a bulk-liquid hydrodynamic environment allowing for their application. From a substrate transformation perspective, mass transfer in biofilm reactors defines the primary difference between suspended growth and biofilm systems: suspended growth systems are kinetically (i.e., biomass) limited and biofilm reactors are primarily diffusion (i.e., biofilm growth surface area) limited.

Modelling biofilm anaerobic reactor with effluent from hydrolytic/acidogenic reactor as substrate

2019 ◽  
Vol 79 (8) ◽  
pp. 1534-1540 ◽  
Author(s):  
Marisol Vergara Mendoza ◽  
Rodrigo Torres Sáez
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Biofilm Reactor ◽  
Methane Formation ◽  
Biofilm Thickness ◽  
Substrate Removal ◽  
Maximum Value ◽  
Degrading Bacteria ◽  
Acidogenic Reactor ◽  
Concentration Curves

Abstract This work presents modelling of an anaerobic biofilm reactor using ceramic bricks as support. The results were compared with the experimental data. It was observed that the substrate concentration curves showed the same tendency. The methane formation curves showed significant differences. The substrate removal efficiency was 83%. In the steady state, the experimental data were higher than the model, from the result the substrate degrading bacteria grew enough to reach biofilm and that the effect of the shear stress was more significant as the biofilm increased in thickness. To the methane production, the model in steady state reached a maximum value of 0.56 m3 CH4/m3 *d and the experimental data reached 0.42 (m3 CH4/m3 * d). The biofilm thickness calculated by the model was 14 μm.

Biofilm Structure – An Important and Neglected Parameter in Waste Water Treatment

1989 ◽  
Vol 21 (8-9) ◽  
pp. 805-814 ◽  
Author(s):  
F. R. Christensen ◽  
G. Holm Kristensen ◽  
J. la Cour Jansen
Keyword(s):  
Wastewater Treatment ◽  
Structural Changes ◽  
Waste Water Treatment ◽  
Experimental Investigations ◽  
Biofilm Reactors ◽  
Substrate Removal ◽  
Treatment Processes ◽  
Laboratory Reactor ◽  
Biofilm Structure ◽  
Kinetics Of

Experimental investigations on the kinetics of wastewater treatment processes in biofilms were performed in a laboratory reactor. Parallel with the kinetic experiments, the influence of the biofilm kinetics on the biofilm structure was studied at macroscopic and microscopic levels. The close interrelationship between biofilm kinetics and structural changes caused by the kinetics is illustrated by several examples. From the study, it is evident that the traditional modelling of wastewater treatment processes in biofilm reactors based on substrate removal kinetics alone will fail in many cases, due to the inevitable changes in the biofilm structure not taken into consideration. Therefore design rules for substrate removal in biofilms used for wastewater treatment must include correlations between the removal kinetics and the structure and development of the biological film.

Phosphorus Release Kinetics in Biofilm Reactors

1992 ◽  
Vol 26 (3-4) ◽  
pp. 567-576 ◽  
Author(s):  
F. A. Ruiz-Treviño ◽  
S. González-Martínez ◽  
C. Doria-Serrano ◽  
M. Hernández-Esparza
Keyword(s):  
Phosphorus Removal ◽  
Release Kinetics ◽  
Phosphorus Release ◽  
Organic Substrate ◽  
Biofilm Reactor ◽  
Substrate Uptake ◽  
Biofilm Reactors ◽  
Initial Substrate ◽  
Linear Behaviour ◽  
Substrate Concentrations

This paper presents the kinetic analysis, using Generalized Power-Law equations to describe the results of an experimental investigation conducted on a batch submerged biofilm reactor for phosphorus removal under an anaerobic/aerobic cycle. The observed rates and amounts of phosphorus release and organic substrate uptake in the anaerobic phase leads to a kinetic model in which these two variables are dependent on each other with a non-linear behaviour and reach equilibrium values in both cases, at different times and are function of rate constants ratio. The model has a good fit with experimental data except for C uptake at anaerobic contact times longer than four hours, where other kinetics are implied. Kinetic parameters were obtained with different initial substrate concentrations, anaerobic contact cycles, and type of substrates.

scholarly journals The Dynamic Response of Nitrogen Transformation to the Dissolved Oxygen Variations in the Simulated Biofilm Reactor

2021 ◽  
Vol 18 (7) ◽  
pp. 3633
Author(s):  
Qianqian Lu ◽  
Nannan Zhang ◽  
Chen Chen ◽  
Miao Zhang ◽  
Dehua Zhao ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Copy Number ◽  
Stable State ◽  
Quantitative Relationship ◽  
Nitrogen Transformation ◽  
Biofilm Reactor ◽  
Short Term ◽  
Nirs Gene ◽  
Biofilm Reactors ◽  
Recovery Times

Lab-scale simulated biofilm reactors, including aerated reactors disturbed by short-term aeration interruption (AE-D) and non-aerated reactors disturbed by short-term aeration (AN-D), were established to study the stable-state (SS) formation and recovery after disturbance for nitrogen transformation in terms of dissolved oxygen (DO), removal efficiency (RE) of NH4+-N and NO3−-N and activity of key nitrogen-cycle functional genes amoA and nirS (RNA level abundance, per ball). SS formation and recovery of DO were completed in 0.56–7.75 h after transition between aeration (Ae) and aeration stop (As). In terms of pollutant REs, new temporary SS formation required 30.7–52.3 h after Ae and As interruptions, and seven-day Ae/As interruptions required 5.0% to 115.5% longer recovery times compared to one-day interruptions in AE-D and AN-D systems. According to amoA activity, 60.8 h were required in AE-D systems to establish new temporary SS after As interruptions, and RNA amoA copies (copy number/microliter) decreased 88.5%, while 287.2 h were required in AN-D systems, and RNA amoA copies (copy number/microliter) increased 36.4 times. For nirS activity, 75.2–85.8 h were required to establish new SSs after Ae and As interruptions. The results suggested that new temporary SS formation and recovery in terms of DO, pollutant REs and amoA and nirS gene activities could be modelled by logistic functions. It is concluded that temporary SS formation and recovery after Ae and As interruptions occurred at asynchronous rates in terms of DO, pollutant REs and amoA and nirS gene activities. Because of DO fluctuations, the quantitative relationship between gene activity and pollutant RE remains a challenge.

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