Modelling of the Transient Behaviour of a Membrane-Attached Biofilm Reactor under Successive Pulses of a Synthetic Wastewater Substrate

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Margarita Mercedes González-Brambila ◽  
Felipe Lopez-Isunza
Keyword(s):  
Biofilm Reactor ◽  
Synthetic Wastewater ◽  
Residual Water ◽  
Monod Kinetics ◽  
Heterogeneous Model ◽  
Transient Behaviour ◽  
Relative Contribution ◽  
Dual Substrate Limitation ◽  
Diffusion Convection ◽  
Dual Substrate

This work deals with the theoretical and experimental study of the transient behaviour of a membrane-attached biofilm reactor (MARB) when it is exposed to a series of pulse injections of concentrated solutions of sodium acetate, used as a synthetic wastewater. The MARB is connected to a reservoir tank with full recirculation containing the synthetic wastewater, and oxygen permeates through the wall membrane to the biofilm attached to it. For the two experiments reported in this work air is also sparged into the residual water in the tank providing an extra source of oxygen that diffuses simultaneously from the membrane and from the liquid into the biofilm. A pseudo-heterogeneous model using Monod kinetics with dual substrate limitation was employed to predict the observed evolution of substrate and dissolved oxygen concentrations in the MABR. The model accounts for the counter-diffusion of substrate and oxygen as well as for the reaction within the biofilm. It also predicts biomass growth and the production of extra cellular polymers, which in turn causes the biofilm to grow. Transport and kinetic parameters previously estimated, are used in the model to predict the growth rates in the biofilm and allow the analysis of the relative contribution of the rates of mass transport by diffusion, convection and growth reaction.

scholarly journals Impact of Dual Substrate Limitation on Biodenitrification Modeling in Porous Media

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 890
Author(s):  
Mostafa Abaali ◽  
Jérôme Harmand ◽  
Zoubida Mghazli
Keyword(s):  
A Priori ◽  
Growth Function ◽  
Single Type ◽  
A Priori Error Estimate ◽  
Single Substrate ◽  
Spatially Distributed ◽  
Dual Substrate Limitation ◽  
Diffusion Convection ◽  
Reaction Equations ◽  
Dual Substrate

In this work, we consider a model of the biodenitrification process taking place in a spatially-distributed bioreactor, and we take into account the limitation of the kinetics by both the carbon source and the oxidized nitrogen. This model concerns a single type of bacteria growing on nitrate, which splits into adherent bacteria or free bacteria in the liquid, taking all interactions into account. The system obtained consists of four diffusion-convection-reaction equations for which we show the existence and uniqueness of a global solution. The system is approximated by a standard finite element method that satisfies an optimal a priori error estimate. We compare the results obtained for three forms of the growth function: single substrate limiting, “multiplicative” form, and “minimum” form. We highlight the limitation of the ‘ single substrate limiting model”, where the dependency of the bacterial growth on the nitrate is neglected, and find that the “minimum” model gives numerical results closer to the experimental results.

scholarly journals Proof of concept of wastewater treatment via passive aeration SND using a novel zeolite amended biofilm reactor

2018 ◽  
Vol 78 (10) ◽  
pp. 2204-2213 ◽  
Author(s):  
Liang Cheng ◽  
Raphael Marie-Guillaume Flavigny ◽  
Md Iqbal Hossain ◽  
Wipa Charles ◽  
Ralf Cord-Ruwisch
Keyword(s):  
Oxygen Supply ◽  
Energy Requirement ◽  
Operation Mode ◽  
High Energy ◽  
Biofilm Reactor ◽  
Low Energy ◽  
Treated Wastewater ◽  
Synthetic Wastewater ◽  
Bulk Solution ◽  
Nutrient Removal Efficiency

Abstract The current paper describes a novel passive aeration simultaneous nitrification and denitrification (PASND) zeolite amended biofilm reactor that removes organic carbon and nitrogen from wastewater with low-energy consumption. Next to the ammonium oxidizing bacteria (AOB), this reactor contained naturally enriched glycogen accumulating organisms (GAOs) and zeolite powder to initially adsorb BOD (acetate) and ammonium (NH4+-N) from synthetic wastewater under anaerobic conditions. Draining of the treated wastewater exposed the biofilm directly to air enabling low-energy oxygen supply by passive aeration. This allowed the adsorbed ammonium to be oxidized by the AOB and the produced nitrite and nitrate to be reduced simultaneously by the GAOs using the adsorbed BOD (stored as PHAs) as carbon source. Overall, with an operation mode of 1 h anaerobic and 4 h aerobic phase, the nutrient removal efficiency after single treatment was about 94.3% for BOD and 72.2% for nitrogen (NH4+-N). As high-energy aeration of the bulk solution for oxygen supply is completely avoided, the energy requirement of the proposed PASND biofilm reactor can be theoretically cut down to more than 50% compared to the traditional activated sludge process.

A Numerical Model for Studying the Effect of Plasma Layer on the Process of Blood Oxygenation in the Pulmonary Capillaries

1990 ◽  
Vol 112 (4) ◽  
pp. 457-463 ◽  
Author(s):  
Maithili Sharan ◽  
M. P. Singh ◽  
A. Aminataei
Keyword(s):  
Molecular Diffusion ◽  
Plasma Layer ◽  
Nonlinear Partial Differential Equations ◽  
Homogeneous Model ◽  
Blood Oxygenation ◽  
Facilitated Diffusion ◽  
Heterogeneous Model ◽  
The Core ◽  
Pulmonary Capillaries ◽  
Diffusion Convection

A two layer model for the blood oxygenation in pulmonary capillaries is proposed. The model consists of a core of erythrocytes surrounded by a symmetrically placed plasma layer. The governing equations in the core describe the free molecular diffusion, convection, and facilitated diffusion due to the presence of haemoglobin. The corresponding equations in the plasma layer are based on the free molecular diffusion and the convective effect of the blood. According to the axial train model for the blood flow proposed by Whitmore (1967), the core will move with a uniform velocity whereas flow in the plasma layer will be fully developed. The resulting system of nonlinear partial differential equations is solved numerically. A fixed point iterative technique is used to deal with the nonlinearities. The distance traversed by the blood before getting fully oxygenated is computed. It is shown that the concentration of O2 increases continuously along the length of the capillary for a given ratio of core radius to capillary radius. It is found that the rate of oxygenation increases as the core to capillary ratio decreases. The equilibration length increases with a heterogeneous model in comparison to that in a homogeneous model. The effect of capillary diameters and core radii on the rate of oxygenation has also been examined.

scholarly journals Treatment of Synthetic Wastewater in a Pre-Denitrification Biofilm Reactor Packed with Polyurethane Media

2012 ◽  
Vol 16 ◽  
pp. 1642-1649 ◽  
Author(s):  
Jiang Chundong ◽  
Xu Zhi ◽  
Fei Qingzhi ◽  
Guo Haiyan
Keyword(s):  
Biofilm Reactor ◽  
Synthetic Wastewater

Optimization modelling of anaerobic biofilm reactors

1994 ◽  
Vol 30 (12) ◽  
pp. 347-355 ◽  
Author(s):  
Makram T. Suidan ◽  
Joseph R. V. Flora ◽  
Pratim Biswas ◽  
Gregory D. Sayles
Keyword(s):  
Ionic Species ◽  
Gas Production ◽  
Biofilm Reactor ◽  
Operating Conditions ◽  
Reactor Performance ◽  
Monod Kinetics ◽  
Ph Changes ◽  
Biofilm Model ◽  
Steady State Model ◽  
Completely Stirred Tank Reactor

A rigorous steady state model of acetate-utilizing methanogenic biofilms is developed accounting for the mass transfer of neutral and ionic species, pH changes within the biofilm, pH-dependent Monod kinetics, chemical equilibrium, electroneutrality, gas production within the biofilm, and the presence of a concentration boundary layer (CBL). In contrast to traditional biofilm models where the pH is assumed to be constant within the biofilm, an increase in pH in acetate-utilizing methanogenic biofilms is predicted. Furthermore, significant differences can exist between the flux predictions using the traditional models and when pH changes within the biofilm are taken into account. The optimum pH for acetate-utilizing biofilms is less than the optimum defined for suspended-growth systems. The biofilm model is coupled to a model of a completely-stirred tank reactor (CSTR), and strategies for the optimization of biofilm reactor performance are examined. For a fixed set of operating conditions, an optimum influent pH can be defined that corresponds to the maximum removal efficiency and flux of acetate into the biofilm.

Carbon membrane-aerated biofilm reactor for synthetic wastewater treatment

2007 ◽  
Vol 30 (4) ◽  
pp. 217-224 ◽  
Author(s):  
Huijun Liu ◽  
Fenglin Yang ◽  
Tonghua Wang ◽  
Qiang Liu ◽  
Shaowei Hu
Keyword(s):  
Wastewater Treatment ◽  
Biofilm Reactor ◽  
Synthetic Wastewater ◽  
Carbon Membrane

Simplified and Monod kinetics in one-dimensional biofilm reactor modelling: a comparison

2001 ◽  
Vol 43 (1) ◽  
pp. 295-302 ◽  
Author(s):  
L. Bonomo ◽  
G. Pastorelli ◽  
E. Quinto
Keyword(s):  
Liquid Film ◽  
Removal Rate ◽  
Experimental Tests ◽  
Biofilm Reactor ◽  
Kinetic Approach ◽  
Monod Kinetics ◽  
One Dimensional ◽  
Monod Kinetic ◽  
The One ◽  
Reactor Models

A theoretical study supported by some experimental tests has been carried out with the aim of comparing one-dimensional (1-D) biofilm reactor models that use simplified (zero- and first-order) and Monod kinetics. Two different situations have been compared: one rate-limiting substrate with or without liquid film diffusion. The results obtained show that the use of a simplified kinetic approach compared to the Monod kinetic approach determines (1) an unjustified overestimate of the removal rate, especially for thin biofilms, and (2) an excessive overestimate of the liquid film layer thickness necessary to justify high kinetic orders. Even if recent research projects show that biofilm structure is more complicated than the one assumed in the modelling approach used in this study, nevertheless 1-D models still now continue to be the only ones that can reasonably support process engineers in biofilm reactor design, due to their intrinsic simplicity and the need for small sets of input data and parameters that can be obtained theoretically or often empirically.

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