Analysis of hydrodynamic effects on biofilm thickness in fluidized-bed tapered bioreactors

Particuology ◽  
2021 ◽  
Author(s):  
Daniela Maria Koerich ◽  
Leonardo Machado da Rosa
Keyword(s):  
Fluidized Bed ◽  
Biofilm Thickness ◽  
Hydrodynamic Effects

Contribution of hydrodynamic characteristics on the performance of an aerobic biofilm conical fluidized bed

2011 ◽  
Vol 63 (6) ◽  
pp. 1160-1167 ◽  
Author(s):  
D. Zhou ◽  
X. T. Bi ◽  
S. Dong
Keyword(s):  
Fluidized Bed ◽  
Microbial Population ◽  
Expansion Ratio ◽  
Hydrodynamic Characteristics ◽  
Internal Circulation ◽  
Axial Distribution ◽  
Biofilm Thickness ◽  
Cell Matrix ◽  
Bed Expansion ◽  
Conical Fluidized Bed

The performance of a conical fluidized bed (TFB) bioreactor, including the biofilm thickness, microbial space density, microbial cell matrix and its efficiency for COD degradation at a bed expansion ratio of 14 to 90%, was studied and compared with a cylindrical fluidized bed (CFB) bioreactor. The hydrodynamic characteristics of the TFB, especially the internal-circulation of bioparticles associated with its unique tapered geometry of the bed, created a much more uniform axial distribution of the bioparticles, leading to the formation of thinner and more compacted biofilms in the TFB compared to that in the CFB. The thinner biofilm in the TFB tended to be stable and possessed more than 6 times of microbial population density compared to the CFB. As a result, thinner biofilms in the TFB contributed to a higher COD removal efficiency, which remained at over 95% at operated expansion ratios, about 15 to 25% higher than that in the CFB.

Predicting bed dynamics in three-phase, fluidized-bed biofilm reactors

1994 ◽  
Vol 29 (10-11) ◽  
pp. 231-241 ◽  
Author(s):  
H. T. Chang ◽  
B. E. Rittmann
Keyword(s):  
Fluidized Bed ◽  
Flow Rate ◽  
Liquid Flow ◽  
Gas Flow ◽  
Liquid Flow Rate ◽  
Gas Flow Rate ◽  
Biofilm Growth ◽  
Biofilm Thickness ◽  
Three Phase ◽  
Proper Design

This paper presents a unified model that inter-relates gas flow rate, liquid flow rate, and hold-ups of each of the liquid, gas, and solid phases in three-phase, fluidized-bed biofilm (TPFBB) process. It describes how carrier properties, biofilm properties, and gas and liquid flow velocities control the system dynamics, which ultimately will affect the density, thickness, and distribution of the biofilm. The paper describes the development of the mathematical model to correlate the effects of gas flow rate, liquid flow rate, solid concentration, and biofilm thickness and density. This knowledge is critically needed in light of the use of TPFBB processes in treating industrial wastewater, which often has high substrate concentration. For example, the proper design of the TPFBB process requires mathematical description of the cause-effect relationship between biofilm growth and fluidization.

Process Analysis of Fluidized Bed Biofilm Reactor for Denitrification

1987 ◽  
Vol 19 (1-2) ◽  
pp. 151-162 ◽  
Author(s):  
H. Harada ◽  
H. Ando ◽  
K. Momonoi
Keyword(s):  
Mathematical Model ◽  
Fluidized Bed ◽  
Process Analysis ◽  
Biofilm Reactor ◽  
Dynamic State ◽  
Bulk Liquid ◽  
Biofilm Thickness ◽  
Substrate Conversion ◽  
Denitrification Reactor ◽  
Denitrification Process

A mathematical model is proposed herein to describe the dynamic behavior of the denitrification process in a fluidized bed biofilm reactor. The model basically consists of the following four submodels: bioparticles fluidization, bulk liquid flow pattern, substrate conversion within biofilm and biofilm thickness development. As for intrinsic denitrification reaction, a consecutive two-step reaction kinetics with nitrite as an intermediate product is adopted. All parameters needed for simulation were experimentally determined. Verification of the model was obtained in a dynamic state using a laboratory-scale fluidized bed denitrification reactor under well defined conditions.

Scale-up and biomass hold-up characteristics of biological fluidized bed reactors

1994 ◽  
Vol 29 (10-11) ◽  
pp. 353-360 ◽  
Author(s):  
I. Ozturk ◽  
M. Turan ◽  
A. H. Idris
Keyword(s):  
Fluidized Bed ◽  
Scale Up ◽  
Experimental Studies ◽  
Scaling Up ◽  
Pilot Scale ◽  
Fluidized Bed Reactors ◽  
Biofilm Thickness ◽  
Study Results ◽  
Scaling Down ◽  
Comprehensive Study

This paper presents a comprehensive study results on scale-up and biomass hold-up characteristics of biological fluidized bed reactors (BFBR). The overall objective of this study was to establish and test some basic design criteria for the scaling-up or scaling-down of anaerobic fluidized bed reactors. A 12.5 1 laboratory-scale fluidized bed was designed and constructed based on a geometrically similar 70 1 pilot scale fluidized bed and the process performances were compared. Biomass hold up characteristics of the BFBRs were also investigated during the experimental studies. A general expression was developed for predicting the biological fludized bed porosities. Using this expression, both the local and overall fluidized bed porosities could be predicted depending on biofilm thickness, expansion coefficient, media diameter and density. The validity of this expression was tested with the data from this study.

scholarly journals Analysis of the Hydrodynamic Effects of Gas Permeation in a Pilot-Scale Fluidized Bed Membrane Reactor

2018 ◽  
Vol 9 (1) ◽  
pp. 67
Author(s):  
Chenxi Bai ◽  
Yao Xiao ◽  
Ruifeng Peng ◽  
John Grace ◽  
Yumin Chen
Keyword(s):  
Fluidized Bed ◽  
Bubble Size ◽  
Membrane Reactor ◽  
Scale Up ◽  
Pilot Scale ◽  
Gas Permeation ◽  
Gas Extraction ◽  
Gas Velocity ◽  
Attenuation Rate ◽  
Hydrodynamic Effects

This study experimentally investigates the effects of gas extraction/addition, via multiple vertical membrane panels, on the hydrodynamics in different regions of a pilot-scale gas fluidized bed membrane reactor (FBMR), based on differential pressure signals measured at different vertical bed sections at high temperature. In a bed section where membrane panels were installed and activated, the extraction of gas caused the average bubble size to increase, but decreased the number of small- and medium-sized bubbles. This effect of gas extraction penetrated into bed sections above the active membrane panel, but attenuated with increasing distance away from the extraction location. The attenuation rate was much faster in FBMR with lower bed voidage, mainly due to the large decrease of the drag force exerted by gas extraction on fluidizing gas in a denser bed. With the same inlet gas velocity, gas addition favored the growth of bubbles, especially in the upper bed sections compared with operation without gas permeation. The increase of the effective fluidizing velocity was the major reason for the increase of the bubble size during gas addition. These findings preliminarily suggest that membrane units should not be installed in or below fast-reacting zones in a scale-up FBMR, and operation with a lower bed voidage is preferable to avoid the formation of large bubbles enhanced by gas extraction.

Fluidized bed reactor operation for groundwater denitrification

1994 ◽  
Vol 29 (10-11) ◽  
pp. 509-515 ◽  
Author(s):  
M. Green ◽  
M. Shnitzer ◽  
S. Tarre ◽  
B. Bogdan ◽  
G. Shelef ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Loading Rate ◽  
Fluidized Bed Reactor ◽  
Reactor Operation ◽  
Biofilm Thickness ◽  
Loading Rates ◽  
Nitrite Removal ◽  
Sand Particles ◽  
Nitrate And Nitrite ◽  
Very High

Groundwater denitrification was carried out in a laboratory scale fluidized bed reactor using sand particles as the biomass carrier. This paper is concentrated on the fluidized bed reactor operation at very high nitrate loading rates (between 30 to 100 kg.NO3/m3 reactor/day) with corresponding short retention times (5 to 1.5 minutes). The effects of nitrate loading rate on nitrate and nitrite removal, as well as on reactor biomass profiles and biofilm characteristics, are presented in this article. The results of the present study indicate that this type of reactor can operate efficiently at retention times shorter than 3 minutes and at nitrate loading rates higher than 70 kg.NO3/m3/day. However, this system requires careful control of the biofilm thickness to achieve a reliable reactor operation.

Complete nitrogen removal from waste and drinking water in a fluidized-bed bioreactor/Eliminación de nitrógeno de aguas residuales y agua para el consumo en un biorreactor de lecho fluidizado

1996 ◽  
Vol 2 (3) ◽  
pp. 165-171 ◽  
Author(s):  
Zs. Csikor ◽  
L. Czakó ◽  
P. Miháltz ◽  
J. Holló
Keyword(s):  
Drinking Water ◽  
Fluidized Bed ◽  
Nitrogen Removal ◽  
High Performance ◽  
Removal Rate ◽  
Drinking Water Treatment ◽  
Reactor Performance ◽  
Biofilm Thickness ◽  
Order Of Magnitude ◽  
Activated Sludge Processes

The use of fluidized-bed bioreactors in waste and drinking water treatment has several advantages, the most significant of which is the specific removal rate, which is an order of magnitude higher than that of equivalent activated sludge processes. In this paper, the usual concept of nitrification-denitrification in separated units is replaced by a new concept in which the two processes are performed together in a single high-performance fluidized-bed. Based on the former nitrifying reactor, new equipment was designed. This reactor contained a fluidized bed with separated aerobic and anoxic sections for nitrification and denitri fication respectively. This was accomplished by the use of different-diameter sand as carrier material and appropriate reactor shape, recirculation, feed and aeration conditions. The reactor (20 L fluidized-bed volume) was operated for 3 months. It was fed with synthetic waste water (50 L/h) containing 25-40 mg NH4 +-N/L. Propionic acid and ethanol in a 1:4 ratio were used as the carbon source (2.3 g C/L) for deni trification, fed in at different points of the reactor. Ammonium removal reached 50%, while denitrification was 75%. The total nitrogen removal rate was 0.8-1.2 kg N/m 3.d. A new simple hydrostatic pressure method was used to monitor biofilm thickness in the fluidized bed. During the experiments the oxidation-reduc tion potential (ORP) was tested as a tool to monitor reactor performance; its use for the control of the process was found to be limited.

Population dynamics of methanogenic biofilm consortium during a start-up period of anaerobic fluidized bed reactor

1994 ◽  
Vol 29 (10-11) ◽  
pp. 361-368 ◽  
Author(s):  
N. Araki ◽  
H. Harada
Keyword(s):  
Fluidized Bed ◽  
Biofilm Formation ◽  
Fluidized Bed Reactor ◽  
Fluidized Bed Reactors ◽  
Microbial Activities ◽  
Acetate Production ◽  
Biofilm Thickness ◽  
Start Up ◽  
Seed Sludge ◽  
Initial Biofilm

The changes in physical properties and microbial activities were investigated during initial biofilm formation in lab-scale anaerobic fluidized bed reactors. Four different upflow velocities, i.e., 4, 7, 14 and 25 m·hr−1 were applied to four respective reactors of an equal size. The upflow velocities caused a prominent difference in the pattern of initial biofilm formation. The biofilm thickness attained eventually approximately 100 μm after 100 days of operation, independent of upflow velocity. On the contrary the biofilm density varied from 4.4 to 24.1 mg-VSS·cm−3 with an increase in the upflow velocity imposed. The activity of acetoclastic methane production increased remarkably 15 to 30 fold of seed sludge, regardless of upflow velocity. Microbial activities with respect to acetate production, H2-utilizing methanogenesis and acetate-utilizing methanogenesis increased finally up to 3-4 times as large as those of suspended grown sludge in a chemostat.

Biofilm Performance of a Fluidized Bed Biofilm Reactor for Drinking Water Denitrification

1992 ◽  
Vol 26 (3-4) ◽  
pp. 555-566 ◽  
Author(s):  
V. Z. Lazarova ◽  
B. Capdeville ◽  
L. Nikolov
Keyword(s):  
Drinking Water ◽  
Fluidized Bed ◽  
Nitrate Reduction ◽  
Protein Concentration ◽  
Biofilm Reactor ◽  
Physiological Characteristics ◽  
Fluidized Bed Bioreactor ◽  
Biofilm Thickness ◽  
Residual Nitrite ◽  
Bed Expansion

The properties of two biofilms generated with different predominant organisms were studied in a laboratory-scale fluidized bed bioreactor. Bed expansion, biofilm thickness, biofilm density, protein and polysaccharide concentrations were measured and compared. A high polysaccharide concentration was observed in the less dense and more fragile biofilm of Ps. aeruginosa. The more active biofilm of Ps. stutzeri was characterized by higher protein concentration and density. The results demonstrated that the biofilm performance mostly depended on the physiological characteristics of the preponderant organism. Complete nitrate reduction was reached in both biofilms at very low biofilm thickness. Elevated residual nitrite was observed only in the biofilm of Ps. aeruginosa.

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