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Influence of upflow velocity on performance and biofilm characteristics of Anaerobic Fluidized Bed Reactor (AFBR) in treating high-strength wastewater.

Jaafari J, Mesdaghinia A, Nabizadeh R, Hoseini M, Kamani H, Mahvi AH - J Environ Health Sci Eng (2014)

Bottom Line: The results demonstrated that the AFBR system is capable of handling an exceptionally high organic loading rate.The average biomass concentration per unit volume of the AFBR (as gVSSatt L(-1) expended bed) decreased with the increase of upflow velocity in the range of 0.5-1 m min(-1) at all applied organic loading rates.The bed porosity increased from the bottom to the top of the reactor.

View Article: PubMed Central - PubMed

Affiliation: School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.

ABSTRACT
One of the key parameters in Fluidized Bed reactors is the control of biofilm thickness and configuration. The effect of upflow velocity on performance and biofilm characteristics of an Anaerobic Fluidized Bed Reactor was studied in treating Currant wastewater at various loading rates. The reactor used this study was made of a plexiglass column being 60 mm diameter, 140 cm height, and a volume of 3.95 L. The results demonstrated that the AFBR system is capable of handling an exceptionally high organic loading rate. At organic loading rates of 9.4 to 24.2 (kg COD m(-3)) at steady state, reactor performances with upflow velocities of 0.5, 0.75 and 1 (m min(-1)) were 89.3- 63.4, 96.9 - 79.6 and 95 - 73.4 percent, respectively. The average biomass concentration per unit volume of the AFBR (as gVSSatt L(-1) expended bed) decreased with the increase of upflow velocity in the range of 0.5-1 m min(-1) at all applied organic loading rates. The total biomass in the reactor increased with increases in the organic loading rate. The peak biomass concentration per unit volume (as gVSSatt L(-1) expended bed) was observed at the bottom part of the reactor, then it droped off slowly towards the top. The biofilm thickness increased from the bottom to the top of the reactor representing a stratification of the media in the AFBR. The bed porosity increased from the bottom to the top of the reactor.

No MeSH data available.


Effect of liquid upflow velocity on pressure drop.
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Fig2: Effect of liquid upflow velocity on pressure drop.

Mentions: The reactor was made of a plexiglass column being 60 mm diameter, 140 cm height, and a volume of 3.95 L. The enlarged top section of column was used as a gas–solid separator. The enlarged section had diameter of 100 mm with a volume of 1.48 L (Figure 1). The bottom of the reactor was flat with symmetrically placed four pores through which flow was equally distributed into the reactor. The column has six sampling ports located at 5, 30, 55, 80, 105 and 130 cm above the reactor bottom. The recycled flow was drawn from the top section using a Circulator Pump and then fed upward into the reactor. Reactor temperature was controlled by Aquarium Heater at 35 ± 2°C. The reactor was loaded with 1.48 kg media made of PVC with a mean diameter of 2 mm as a biofilm carrier to a settled depth of 0.6 m. The particles had a specific gravity of 1.45, a porosity of 0.4, and a specific surface area of 1800 m2 m−3. The bed expansion in fluidized bed reactor was 30% during the start-up period. The expansion of the bed should be determined based on consideration of the minimum fluidization velocity. Some studies have been determined the factors affecting minimum fluidization velocity and maximum pressure drop [23–25]. Also, Peng and Fan [26] developed theoretical models for estimating of minimum fluidization velocity and maximum pressure drop, based on the dynamic balance of forces exerted on the particle. Some of the well known correlations available for predicting the minimum fluidization velocity (Umf) and maximum pressure drop (Pmax) for tapered beds are those by Peng and Fan. The influence of superficial velocity on pressure drop in reactor is illustrated and shown in Figure 2. By increasing upflow velocity to 0.75 (m min−1), pressure drop increased, then, with increasing superficial velocity to more than 0.75 (m min−1), pressure drop remained constant. So, to ensure that the fluidization condition is exist, the superficial velocity should not be less than the minimum fluidization velocity which is 0.75 m min−1 in our reactor. Also, upflow velocity in start-up period was adjusted 0.75 (m min−1). After the start-up period, the real Currant wastewater was fed to the reactor and upflow velocities in different organic loading rate were adjusted to 0.5, 0.75 and 1 m min−1.Figure 1


Influence of upflow velocity on performance and biofilm characteristics of Anaerobic Fluidized Bed Reactor (AFBR) in treating high-strength wastewater.

Jaafari J, Mesdaghinia A, Nabizadeh R, Hoseini M, Kamani H, Mahvi AH - J Environ Health Sci Eng (2014)

Effect of liquid upflow velocity on pressure drop.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4256795&req=5

Fig2: Effect of liquid upflow velocity on pressure drop.
Mentions: The reactor was made of a plexiglass column being 60 mm diameter, 140 cm height, and a volume of 3.95 L. The enlarged top section of column was used as a gas–solid separator. The enlarged section had diameter of 100 mm with a volume of 1.48 L (Figure 1). The bottom of the reactor was flat with symmetrically placed four pores through which flow was equally distributed into the reactor. The column has six sampling ports located at 5, 30, 55, 80, 105 and 130 cm above the reactor bottom. The recycled flow was drawn from the top section using a Circulator Pump and then fed upward into the reactor. Reactor temperature was controlled by Aquarium Heater at 35 ± 2°C. The reactor was loaded with 1.48 kg media made of PVC with a mean diameter of 2 mm as a biofilm carrier to a settled depth of 0.6 m. The particles had a specific gravity of 1.45, a porosity of 0.4, and a specific surface area of 1800 m2 m−3. The bed expansion in fluidized bed reactor was 30% during the start-up period. The expansion of the bed should be determined based on consideration of the minimum fluidization velocity. Some studies have been determined the factors affecting minimum fluidization velocity and maximum pressure drop [23–25]. Also, Peng and Fan [26] developed theoretical models for estimating of minimum fluidization velocity and maximum pressure drop, based on the dynamic balance of forces exerted on the particle. Some of the well known correlations available for predicting the minimum fluidization velocity (Umf) and maximum pressure drop (Pmax) for tapered beds are those by Peng and Fan. The influence of superficial velocity on pressure drop in reactor is illustrated and shown in Figure 2. By increasing upflow velocity to 0.75 (m min−1), pressure drop increased, then, with increasing superficial velocity to more than 0.75 (m min−1), pressure drop remained constant. So, to ensure that the fluidization condition is exist, the superficial velocity should not be less than the minimum fluidization velocity which is 0.75 m min−1 in our reactor. Also, upflow velocity in start-up period was adjusted 0.75 (m min−1). After the start-up period, the real Currant wastewater was fed to the reactor and upflow velocities in different organic loading rate were adjusted to 0.5, 0.75 and 1 m min−1.Figure 1

Bottom Line: The results demonstrated that the AFBR system is capable of handling an exceptionally high organic loading rate.The average biomass concentration per unit volume of the AFBR (as gVSSatt L(-1) expended bed) decreased with the increase of upflow velocity in the range of 0.5-1 m min(-1) at all applied organic loading rates.The bed porosity increased from the bottom to the top of the reactor.

View Article: PubMed Central - PubMed

Affiliation: School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.

ABSTRACT
One of the key parameters in Fluidized Bed reactors is the control of biofilm thickness and configuration. The effect of upflow velocity on performance and biofilm characteristics of an Anaerobic Fluidized Bed Reactor was studied in treating Currant wastewater at various loading rates. The reactor used this study was made of a plexiglass column being 60 mm diameter, 140 cm height, and a volume of 3.95 L. The results demonstrated that the AFBR system is capable of handling an exceptionally high organic loading rate. At organic loading rates of 9.4 to 24.2 (kg COD m(-3)) at steady state, reactor performances with upflow velocities of 0.5, 0.75 and 1 (m min(-1)) were 89.3- 63.4, 96.9 - 79.6 and 95 - 73.4 percent, respectively. The average biomass concentration per unit volume of the AFBR (as gVSSatt L(-1) expended bed) decreased with the increase of upflow velocity in the range of 0.5-1 m min(-1) at all applied organic loading rates. The total biomass in the reactor increased with increases in the organic loading rate. The peak biomass concentration per unit volume (as gVSSatt L(-1) expended bed) was observed at the bottom part of the reactor, then it droped off slowly towards the top. The biofilm thickness increased from the bottom to the top of the reactor representing a stratification of the media in the AFBR. The bed porosity increased from the bottom to the top of the reactor.

No MeSH data available.