Specific energy dissipation rate for fluidized-bed bioreactors

Huang, Jow-Lay; Wu, Chun‐Sheng

doi:10.1002/(sici)1097-0290(19960620)50:6<643::aid-bit5>3.0.co;2-k

Cited by 25 publications

(12 citation statements)

References 10 publications

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“…E for the unfluidization state When superficial liquid velocity u l is less than the minimum superficial fluidization velocity u mf , the bed is under unfluidization state, where the sludge holdup keeps constant and the bed expansion ratio is zero. Based on statics equilibrium principles (Huang and Wu, 1996), u mf can be expressed under the liquidsolid bi-phasic condition as follows: …”

Section: Bed Expansion Ratiomentioning

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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Section: Bed Expansion Ratiomentioning

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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“…(Angelidaki et al, 1999). The detachment rate is modeled as a firstorder function of the specific energy dissipation rate ω in the gas-solid-liquid fluidized bed zone Huang and Wu, 1996), as a secondorder function of the biofilm thickness δ and a firstorder function of the mass concentration of each species i (see the term 2 S E i k X ωδ , Table 1). E k is assumed to be the same for all biological species and must be estimated from experimental data (Mussati et al, 2005a).…”

Section: Mass Balance Equations For Biological and Chemical Speciesmentioning

confidence: 99%

“…Fluidization characteristics such as fluidized bed height and phase holdups (volume fractions) are critical because of their influence on the residence time, specific biofilm superficial area in the biologically active zone, reactor size, mass transfer and biofilm detachment rate (Bonnet et al, 1997). Authors (Abdul-Aziz and Asolekar, 2000;Bonnet et al, 1997 ;Diez Blanco et al, 1995;Huang and Wu, 1996;Huang et al, 2000) have studied some aspects of the AFBR hydrodynamics hypothesizing a two-phase solidliquid system because of the minimal amount of gas present, or as a three-phase gas-solid-liquid system (Yu and Rittmann, 1997) using the generalized wake and bubble model (GWBM) developed by Bathia and Epstein (1974) for describing the hydrodynamics. Many of these works consider hydrodynamic steady state reactors and hypothetical steady state values of biofilm thickness.…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical investigation of anaerobic fluidized bed biofilm reactors

Fuentes¹,

Mussati²,

Aguirre³

et al. 2009

Braz. J. Chem. Eng.

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-This work presents an experimental and theoretical investigation of anaerobic fluidized bed reactors (AFBRs). The bioreactors are modeled as dynamic three-phase systems. Biochemical transformations are assumed to occur only in the fluidized bed zone. The biofilm process model is coupled to the system hydrodynamic model through the biofilm detachment rate; which is assumed to be a first-order function of the energy dissipation parameter and a second order function of biofilm thickness. Non-active biomass is considered to be particulate material subject to hydrolysis. The model includes the anaerobic conversion for complex substrate degradation and kinetic parameters selected from the literature. The experimental set-up consisted of two mesophilic (36±1ºC) labscale AFBRs (R1 and R2) loaded with sand as inert support for biofilm development. The reactor start-up policy was based on gradual increments in the organic loading rate (OLR), over a four month period.Step-type disturbances were applied on the inlet (glucose and acetic acid) substrate concentration (chemical oxygen demand (COD) from 0.85 to 2.66 g L -1) and on the feed flow rate (from 3.2 up to 6.0 L d -1 ) considering the maximum efficiency as the reactor loading rate switching. The predicted and measured responses of the total and soluble COD, volatile fatty acid (VFA) concentrations, biogas production rate and pH were investigated. Regarding hydrodynamic and fluidization aspects, variations of the bed expansion due to disturbances in the inlet flow rate and the biofilm growth were measured. As rate coefficients for the biofilm detachment model, empirical values of

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“…Good hydrodynamic behavior is provided and mass transfer between sludge and liquid is strengthened in the bed fluidization state . However, if the velocity of the fluid is increased still further, the granules are ultimately blown out of the bed and the bed enters the transportation state, which is never desired for AFB, and the extra energy is dissipated according the interrelation between the specific energy dissipation rate and flow rate . Therefore, study of the bed optimum fluidization velocity ( u opt ) is necessary for treatment efficiency and stability of AFB operation.…”

Section: Introductionmentioning

confidence: 99%

Optimum fluidization velocity of granular sludge bed for anaerobic fluidized‐bed bioreactors

Chen

Dai

Xiao

et al. 2013

J of Chemical Tech & Biotech

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BACKGROUND The models presented for bed optimum fluidization velocity (uopt), which was worthwhile for treatment efficiency and operation stability of anaerobic fluidized-bed bioreactors (AFB), were developed for AFB, and the anaerobic granular sludge diameter (dp) and shape were analyzed by a dynamic image analyzer. RESULTS The results showed that the granular size from 0.05 to 0.30 cm sludge dominated the total biomass (accounted for 92.34%) in an expanded granular sludge bed reactor, the mean sphericity 0.835 and mean granular diameter 0.1606 cm were achieved. The uopt range was 0.000949–0.2851 cm s‐1 when dp was 0.05–0.30 cm, and the fluidization number was 8.43–38.77. The maximum value of 0.2851 cm s‐1 was the basic parameter for pump power matching. From parametric sensitivity analyses, uopt was significantly influenced by liquid holdup, granular diameter, granular density and liquid viscosity. CONCLUSION According to the models of uopt, a better operating scheme for AFB can be provided; from parametric sensitivity analysis, further optimizing designs of such bioreactors can be achieved. © 2013 Society of Chemical Industry

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Specific energy dissipation rate for fluidized-bed bioreactors

Cited by 25 publications

References 10 publications

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

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

Experimental and theoretical investigation of anaerobic fluidized bed biofilm reactors

Optimum fluidization velocity of granular sludge bed for anaerobic fluidized‐bed bioreactors

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