Effects of biofilm growth, gas and liquid velocities on the expansion of an anaerobic fluidized bed reactor (AFBR)

Díez, V.; Encina, Pedro A. García; Fdz‐Polanco, F.

doi:10.1016/0043-1354(95)00001-2

Cited by 57 publications

(28 citation statements)

References 5 publications

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“…Consequently, H GLS and H LS increased as u l and u g increased. Similar results were also observed by Diez-Blanco et al, 36 who used a carrier with a low specific gravity. In contrast, a bed contraction effect was noted by Stewart and Davidson, 37 who used a carrier with a high specific gravity.…”

Section: Effect Of Internal Biogas Production On Expansion Behavior Osupporting

confidence: 88%

Expansion characteristics of an anaerobic fluidized bed reactor with internal biogas production

Wu¹,

Huang

Gou

2005

J of Chemical Tech & Biotech

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More realistic dynamic bed-expansion experiments using a three-phase anaerobic fluidized bed reactor (AFBR) with and without internal biogas production were conducted for the establishment of correlation equations for the mean volume ratio of wakes to bubbles (k). A predictive model was also developed for the expansion characteristics of the three-phase AFBR with internal biogas production. The predicted bed-expansion heights (H GLS ) deviated by only ±10% from the experimental measurements for the three-phase AFBR. According to the modeling results, if a three-phase AFBR is loaded into a carrier with low specific gravity (dry density of carrier, ρ md = 1.37 g cm −3 ; wet density of carrier, ρ mw = 1.57 g cm −3 ) and operated at a high superficial liquid velocity (u l = 4.0 cm s −1 ), the ratio of H GLS to H LS at a high superficial gas velocity (u g = 1.5 cm s −1 ) can reach as high as 271%. A higher fluidized-bed height has a greater effect on the bed-expansion behavior because of the decrease in liquid pressure (surrounding gas bubbles) along the fluidized-bed height. From parametric sensitivity analyses, H GLS is most sensitive to the parameter reactor width (X), especially within a small X/X 0 range of ±10%; sensitive to ρ mw , diameter of the carrier, ρ md and total mass of carrier and least sensitive to u l , biofilm thickness and u g .

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Section: Effect Of Internal Biogas Production On Expansion Behavior Osupporting

confidence: 88%

Expansion characteristics of an anaerobic fluidized bed reactor with internal biogas production

Wu¹,

Huang

Gou

2005

J of Chemical Tech & Biotech

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“…Immobilized cell methods can be divided mainly into two groups: the binding method (Blanco et al, 1995;Mulcahy and Shieh, 1987) and the entrapping method (Hashimoto and Furukawa, 1987;Chen and Lin, 1994;Kudlich et al, 1996). In our previous study, a mixed culture having a high capacity for rapid decolorization of azo dye was immobilized by a phosphorylated polyvinyl alcohol (PVA) gel (Chen et al, 2003b).…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic characteristics of immobilized cell beads in a liquid–solid fluidized‐bed bioreactor

Wu¹,

Chen²,

Chen³

et al. 2003

Biotech & Bioengineering

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This study examined the hydrodynamic characteristics of a liquid-solid fluidized-bed bioreactor using elastic particles (PVA gel beads) of various diameters as carriers. The drag coefficient-Reynolds number, velocity-voidage, and expansion index-Reynolds number relationships observed during fluidization of PVA gel beads in a fluidized bed in our experiments were compared with the published results. Predictions made from previous correlations were examined with our new experimental findings, revealing the inadequacy of most of these correlations. Thus, new correlations describing the above-mentioned relationships are suggested. The drag coefficient of immobilized cell beads is larger than that of free cell ones at the same Reynolds number because the surface of the immobilized cell beads is rougher. For multiparticle systems, the correction factor, f(epsilon), is a function of the falling gel bead properties (Reynolds number) as well as the fluidized gel bead properties (Archimedes number), and depend strongly on the bed voidage (epsilon). A new simple relation was developed to predict easily the epsilon value from 0.5-0.9 at 4,986 < A(r) < 40,745 or 34 < Re(t) < 186. For all the immobilized cell beads used in this study, the prediction error of the bed voidage was less than 5% at epsilon > 0.5. The prediction equations in this study can be further applied to analyzing the hydrodynamic characteristics of a fluidized-bed reactor using similar entrapped elastic particles as carriers.

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“…SAB can operate effectively and stably under bed fluidization state, which can maintain a fixed bed expansion ratio and provide good hydrodynamic behavior (Diez Blanco et al, 1995;Sowmeyan and Swaminathan, 2008b). Therefore, the sensitivity analyses of main parameters (X) such as u l and u g for bed expansion behavior under fluidization state were performed on the basis of the following parameter values: u l =2.00 mm/s, u g =2.00 mm/s, d p =Φ1.14 mm, D=Φ100 mm, ρ p =1.052 g/cm 3 , and ε g , k, v i , n, and u t obtained by using Eqs.…”

Section: Parametric Sensitivity Analyses Of Bed Expansion Behavior Unmentioning

confidence: 99%

Bed expansion behavior and sensitivity analysis for super-high-rate anaerobic bioreactor

Chen

Zheng

Cai

et al. 2010

J. Zhejiang Univ. Sci. B

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Abstract:Bed expansion behavior and sensitivity analysis for super-high-rate anaerobic bioreactor (SAB) were performed based on bed expansion ratio (E), maximum bed sludge content (V pmax ), and maximum bed contact time between sludge and liquid (τ max ). Bed expansion behavior models were established under bed unfluidization, fluidization, and transportation states. Under unfluidization state, E was 0, V pmax was 4 867 ml, and τ max was 844-3 800 s. Under fluidization state, E, V pmax , and τ max were 5.28%-255.69%, 1 368-4 559 ml, and 104-732 s, respectively. Under transportation state, washout of granular sludge occurred and destabilized the SAB. During stable running of SAB under fluidization state, E correlated positively with superficial gas and liquid velocities (u g and u l ), while V pmax and τ max correlated negatively. For E and V pmax , the sensitivities of u g and u l were close to each other, while for τ max , the sensitivity of u l was greater than that of u g . The prediction from these models was a close match to the experimental data.

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Effects of biofilm growth, gas and liquid velocities on the expansion of an anaerobic fluidized bed reactor (AFBR)

Cited by 57 publications

References 5 publications

Expansion characteristics of an anaerobic fluidized bed reactor with internal biogas production

Expansion characteristics of an anaerobic fluidized bed reactor with internal biogas production

Hydrodynamic characteristics of immobilized cell beads in a liquid–solid fluidized‐bed bioreactor

Bed expansion behavior and sensitivity analysis for super-high-rate anaerobic bioreactor

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