Development of a simplified model for the fixed biofilm reactor

2015 ◽  
Vol 72 (9) ◽  
pp. 1601-1610
Author(s):  
Sushovan Sarkar ◽  
Debabrata Mazumder
Keyword(s):  
Liquid Interface ◽  
Biofilm Reactor ◽  
Fast Method ◽  
Biofilm Thickness ◽  
Biofilm Model ◽  
Runge Kutta Method ◽  
Average Flux ◽  
Model Equations ◽  
The Relationship ◽  
Fixed Biofilm

A simplified fixed biofilm model was developed to formulate the relationship between the substrate concentrations at both the entry and exit, at the biofilm–liquid interface and at the biofilm attached surface along with average substrate flux in the biofilm, substrate flux at the biofilm–liquid interface and effective biofilm thickness. The model considered the substrate mass transport external to the biofilm and into the biofilm as per Fick's law and the steady state substrate as well as biomass balance for attached growth microorganisms. Monod's growth kinetics has been adopted in substrate utilization, incorporating relevant boundary conditions. The numerical solution of model equations was accomplished for calculating average flux and exit substrate concentration and thereafter the Runge–Kutta method was employed for determining effective biofilm thickness. Consequently, two computer programs were developed for the purpose of rapid solution. The model was satisfactorily applied to data available from the literature for checking its accuracy and was validated with the experimental results. The model was found to be an easy, accurate and fast method that can be used for process design of a fixed biofilm reactor.

Comparing global sensitivity analysis for a biofilm model for two-step nitrification using the qualitative screening method of Morris or the quantitative variance-based Fourier Amplitude Sensitivity Test (FAST)

2007 ◽  
Vol 56 (8) ◽  
pp. 85-93 ◽  
Author(s):  
D. Brockmann ◽  
E. Morgenroth
Keyword(s):  
Sensitivity Analysis ◽  
Global Sensitivity Analysis ◽  
Screening Method ◽  
Biofilm Reactor ◽  
Operating Conditions ◽  
Sensitivity Analyses ◽  
Fast Method ◽  
Biofilm Thickness ◽  
Global Sensitivity ◽  
Biofilm Model

Two different methods for global sensitivity analysis were compared exemplarily for a biofilm model for two-step nitrification. Especially for biofilm models, local sensitivity analysis is not very useful as parameters can vary over a large range. Parameters that were evaluated included kinetic and stoichiometric parameters, and also biofilm parameters, such as internal and external mass transfer, the biofilm thickness, and the biomass density. Global sensitivity analyses were performed for a range of operating conditions of a biofilm reactor. The results of the qualitative screening method of Morris were compared with the results of the quantitative variance-based method FAST regarding the input parameters indicated as unimportant. Both methods resulted in similar sets of parameters with a small influence on the model output, but the screening method of Morris required a much smaller number of model evaluations to compute the sensitivity measures than the FAST method.

Kinetics of biodegradation of phenolic wastewater in a biofilm reactor

2009 ◽  
Vol 59 (9) ◽  
pp. 1703-1711 ◽  
Author(s):  
Yen-Hui Lin ◽  
Tzu-Yang Hsien
Keyword(s):  
Model Simulation ◽  
Pilot Scale ◽  
Biofilm Reactor ◽  
Oil Refining ◽  
Orthogonal Collocation ◽  
Steady State Condition ◽  
Biofilm Thickness ◽  
Phenolic Wastewater ◽  
Biokinetic Parameters ◽  
Fixed Biofilm

This work presents a mathematical model to describe the biodegradation of phenolic wastewater in a fixed-biofilm process. The model incorporates diffusive mass transport and Haldane kinetics mechanisms. The model was solved using a combination of the orthogonal collocation method and Gear's method. A laboratory-scale column reactor was employed to verify the model. Batch kinetic tests were conducted independently to determine biokinetic parameters for the model simulation with the initial biofilm thickness assumed. The model simulated the phenol effluent concentration results well. Removal efficiency for phenol was approximately 94–96.5% for different hydraulic retention times at a steady-state condition. Model simulations results are in agreement with experimental results. The approaches of model and experiments presented in this paper could be used to design a pilot-scale or full-scale fixed-biofilm reactor system for the biodegradation of phenolic wastewater from petrochemical and oil refining plants.

Carbon tetrachloride biodegradation in a fixed-biofilm reactor and its kinetic study

1998 ◽  
Vol 38 (8-9) ◽  
pp. 155-162 ◽  
Author(s):  
G. Jin ◽  
A. J. Englande
Keyword(s):  
Carbon Tetrachloride ◽  
Continuous Flow ◽  
Model Comparison ◽  
Biofilm Reactor ◽  
Pseudomonas Cepacia ◽  
Initial Concentration ◽  
Biphasic Model ◽  
Providencia Stuartii ◽  
Kinetics Of ◽  
Fixed Biofilm

Kinetics of Carbon Tetrachloride biodegradation are evaluated in a continuous-flow fixed-biofilm reactor with controlled initial redox potential. The column was seeded with a mixed culture of indigenous microorganisms Pseudomonas cepacia and Providencia stuartii. The fixed biofilm reactor exhibited 98%–99.9% biodegradation of CT introduced into the reactor at an initial concentration of about 200 μg/l for retention times of 1 to 4 days respectively. Four models were employed to evaluate the kinetics of CT biodegradation. These included: Eckenfelder (1989), Arvin (1991), Bouwer and McCarty (1985) and a biphasic model. Comparison of calculated results with observed results between these models agreed very closely to each other (0.968 < R2 < 0.999). Predicted performance was best described by the model of Bouwer and McCarty (1985). However, the biphasic and Eckenfelder models provided excellent correlations and were much simpler to apply. The biphasic model yielded very good correlations of the data for all detention times evaluated; whereas, the Eckenfelder model effected comparable results only at the longer retention times studied.

scholarly journals Comparison of the Concentration of Risk Elements in Alluvial Soils Determined by pXRF In Situ, in the Laboratory, and by ICP-OES

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 938
Author(s):  
Ladislav Menšík ◽  
Lukáš Hlisnikovský ◽  
Pavel Nerušil ◽  
Eva Kunzová
Keyword(s):  
Precision Agriculture ◽  
Alluvial Soil ◽  
Coefficient Of Determination ◽  
Fast Method ◽  
Agricultural Practice ◽  
Regression Equations ◽  
Icp Oes ◽  
Risk Elements ◽  
The Relationship

The aim of the study was to compare the concentrations of risk elements (As, Cu, Mn, Ni, Pb, Zn) in alluvial soil, which were measured by a portable X-ray fluorescence analyser (pXRF) in situ (FIELD) and in the laboratory (LABORATORY). Subsequently, regression equations were developed for individual elements through the method of construction of the regression model, which compare the results of pXRF with classical laboratory analysis (ICP-OES). The accuracy of the measurement, expressed by the coefficient of determination (R2), was as follows in the case of FIELD–ICP-OES: Pb (0.96), Zn (0.92), As (0.72), Mn (0.63), Cu (0.31) and Ni (0.01). In the case of LABORATORY–ICP-OES, the coefficients had values: Pb (0.99), Zn (0.98), Cu and Mn (0.89), As (0.88), Ni (0.81). A higher dependence of the relationship was recorded between LABORATORY–ICP-OES than between FIELD–ICP-OES. An excellent relationship was recorded for the elements Pb and Zn, both for FIELD and LABORATORY (R2 higher than 0.90). The elements Cu, Mn and As have a worse tightness in the relationship; however, the results of the model have shown its applicability for common use, e.g., in agricultural practice or in monitoring the quality of the environment. Based on our results, we can say that pXRF instruments can provide highly accurate results for the concentration of risk elements in the soil in real time for some elements and meet the principle of precision agriculture: an efficient, accurate and fast method of analysis.

scholarly journals Biofilm carrier migration model describes reactor performance

2017 ◽  
Vol 75 (12) ◽  
pp. 2818-2828 ◽  
Author(s):  
Joshua P. Boltz ◽  
Bruce R. Johnson ◽  
Imre Takács ◽  
Glen T. Daigger ◽  
Eberhard Morgenroth ◽  
...  
Keyword(s):  
Plug Flow ◽  
Biofilm Reactor ◽  
Bulk Liquid ◽  
Reactor Performance ◽  
Reactor Model ◽  
Operational Conditions ◽  
Limit Model ◽  
Biofilm Model ◽  
Reactor Models ◽  
The Impact

The accuracy of a biofilm reactor model depends on the extent to which physical system conditions (particularly bulk-liquid hydrodynamics and their influence on biofilm dynamics) deviate from the ideal conditions upon which the model is based. It follows that an improved capacity to model a biofilm reactor does not necessarily rely on an improved biofilm model, but does rely on an improved mathematical description of the biofilm reactor and its components. Existing biofilm reactor models typically include a one-dimensional biofilm model, a process (biokinetic and stoichiometric) model, and a continuous flow stirred tank reactor (CFSTR) mass balance that [when organizing CFSTRs in series] creates a pseudo two-dimensional (2-D) model of bulk-liquid hydrodynamics approaching plug flow. In such a biofilm reactor model, the user-defined biofilm area is specified for each CFSTR; thereby, Xcarrier does not exit the boundaries of the CFSTR to which they are assigned or exchange boundaries with other CFSTRs in the series. The error introduced by this pseudo 2-D biofilm reactor modeling approach may adversely affect model results and limit model-user capacity to accurately calibrate a model. This paper presents a new sub-model that describes the migration of Xcarrier and associated biofilms, and evaluates the impact that Xcarrier migration and axial dispersion has on simulated system performance. Relevance of the new biofilm reactor model to engineering situations is discussed by applying it to known biofilm reactor types and operational conditions.

SERIES SOLUTION OF TYPHOID FEVER MODEL USING DIFFERENTIAL TRANSFORM METHOD

2018 ◽  
Vol 3 (1) ◽  
pp. 67
Author(s):  
O J Peter ◽  
Oluwaseun B Akinduko ◽  
C Y Ishola ◽  
O A Afolabi ◽  
A B Ganiyu
Keyword(s):  
Typhoid Fever ◽  
Disease Transmission ◽  
Series Solution ◽  
Transformation Method ◽  
Type Model ◽  
Transform Method ◽  
Runge Kutta Method ◽  
Differential Transform ◽  
Model Equations ◽  
Non Linear System

This paper presents an analysis of PSIuIeTR type model, which are used to study the transmission dynamics of typhoid fever diseases in a population. Basic idea of typhoid fever disease transmission using compartmental modeling is discussed. Differential Transformation Method (DTM) is discussed in detail, which is used to compute the series solution of the non-linear system of differential equation governing the model equations. The validity of the (DTM) in solving the proposed model is established by classical fourth-order Runge-Kutta method which is implemented in Maple 18. Graphical results confirm that (DTM) is in good agreement with RK-4 and this produced correctly same behaviour of the model, thus validating the efficiency and accuracy of (DTM) in finding the series solution of an epidemic model.

Perchlorate removal using two component biodegradable carriers in particle-fixed biofilm reactor

2014 ◽  
Vol 49 (3) ◽  
pp. 234-244
Author(s):  
Fang He ◽  
Fusheng Li ◽  
Haihong Zhou ◽  
Lingling Niu ◽  
Liguo Wang
Keyword(s):  
Carbon Source ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Polymer Particle ◽  
Biofilm Reactor ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Biofilm Reactors ◽  
Gradient Gel Electrophoresis ◽  
Perchlorate Removal ◽  
Fixed Biofilm

In this research, biocompounds designed out of two polymers having different degradability was investigated for use as the sole carbon source and biofilm carrier to remove perchlorate in particle-fixed biofilm reactors. Both laboratory batch and column experiments were conducted with perchlorate contaminated groundwater. Batch experiments demonstrated clearly that ClO4– was removed from the aqueous phase readily and the degradation rate constants (k) changed in the range of 0.23–0.37 mg/L h as ClO4– concentration increased from 2 to 8 mg/L. Simultaneous perchlorate and nitrate degradation occurred in the polymer bioreactor. Effluent concentrations of perchlorate varied positively with temperature and fitted the Arrhenius equation expression as k=k20•100.0316(t–20) over the range of 13–30 °C. No perchlorate was detected in the effluent of polymer columns after 20 days’ startup. Complete perchlorate removal was observed at a hydraulic loading rate doubled to 1.8 mL/min. Images prove the concept of the pore and filament structure within the biocompounds, which provide both a heterotrophic biofilm and carbon source. Denaturing gradient gel electrophoresis analysis and partial sequencing of 16S rRNA genes indicated that formerly reported perchlorate-reducing bacteria were present in the polymer particle-fixed biofilm reactors.

scholarly journals Land subsidence and hydrodynamic compaction of sedimentary basins

1998 ◽  
Vol 2 (2/3) ◽  
pp. 159-171 ◽  
Author(s):  
H. Kooi ◽  
J. J. de Vries
Keyword(s):  
Response Time ◽  
Land Subsidence ◽  
Sedimentary Basins ◽  
Sediment Loading ◽  
Dimensional Model ◽  
One Dimensional ◽  
Model Equations ◽  
Sediment Layers ◽  
The Relationship

Abstract. A one-dimensional model is used to investigate the relationship between land subsidence and compaction of basin sediments in response to sediment loading. Analysis of the model equations and numerical experiments demonstrate quasi-linear systems behaviour and show that rates of land subsidence due to compaction: (i) can attain a significant fraction (>40%) of the long-term sedimentation rate; (ii) are hydrodynamically delayed with respect to sediment loading. The delay is controlled by a compaction response time τc that can reach values of 10-5-107 yr for thick shale sequences. Both the behaviour of single sediment layers and multiple-layer systems are analysed. Subsequently the model is applied to the coastal area of the Netherlands to illustrate that lateral variability in compaction-derived land subsidence in sedimentary basins largely reflects the spatial variability in both sediment loading and compaction response time. Typical rates of compaction-derived subsidence predicted by the model are of the order of 0.1 mm/yr but may reach values in excess of 1 mm/yr under favourable conditions.

Two-dimensional cellular automaton model for mixed-culture biofilm

2004 ◽  
Vol 49 (11-12) ◽  
pp. 193-198 ◽  
Author(s):  
G.E. Pizarro ◽  
C. Garcia ◽  
R. Moreno ◽  
M. E. Sepulveda
Keyword(s):  
Steady State ◽  
Structural Heterogeneity ◽  
Constant Thickness ◽  
Two Dimensional ◽  
Active Biomass ◽  
Biofilm Thickness ◽  
Biofilm Model ◽  
Systems Models ◽  
Microbial Mass

Structural and microbial heterogeneity occurs in almost any type of biofilm system. General approaches for the design of biofilm systems consider biofilms as homogeneous and of constant thickness. In order to improve the design of biofilms systems, models need to incorporate structural heterogeneity and the effect of inert microbial mass. We have improved a 2D biofilm model based on cellular automata (CA) and used it to simulate multidimensional biofilms with active and inert biomass including a self-organizing development. Results indicate that the presence of inert biomass within biofilm structures does not change considerably the substrate flux into the biofilm because the active biomass is located at the surface of the biofilm. Long-term simulations revealed that although the biofilm system is highly heterogeneous and the microstructure is continuously changing, the biofilm reaches a dynamic steady-state with prediction of biofilm thickness and substrate flux stabilizing on a delimited range.

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.

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