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The effect of bubble size on the efficiency and economics of harvesting microalgae by foam flotation.

Coward T, Lee JG, Caldwell GS - J. Appl. Phycol. (2014)

Bottom Line: The smaller bubbles generated by the ceramic sparger under constant or oscillating airflow had significantly faster rise velocities when compared to the larger bubbles produced by the limewood spargers.The faster velocities of the smaller bubbles were due to momentum transfer to the liquid phase.Analyses of the harvest economics revealed that the ceramic flat plate sparger with an oscillating airflow delivered the best overall cost-benefit relationship.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical Engineering and Advanced Materials, Merz Court, Newcastle University, Newcastle upon Tyne, NE1 7RU England UK.

ABSTRACT

The effect of bubble size and rise velocity on the efficiency of a foam flotation microalgae harvesting unit was determined. Three sparger and input airflow combinations were used: (1) limewood sparger with constant airflow, (2) ceramic flat plate sparger with constant airflow and (3) ceramic flat plate sparger with an oscillating airflow. The ceramic sparger with oscillating flow generated the smallest bubbles within the liquid pool and the largest bubbles within the foam phase. This delivered the highest levels of biomass recovery due to enhanced bubble-algae collision and attachment efficiencies. The smaller bubbles generated by the ceramic sparger under constant or oscillating airflow had significantly faster rise velocities when compared to the larger bubbles produced by the limewood spargers. The faster velocities of the smaller bubbles were due to momentum transfer to the liquid phase. Analyses of the harvest economics revealed that the ceramic flat plate sparger with an oscillating airflow delivered the best overall cost-benefit relationship.

No MeSH data available.


Related in: MedlinePlus

The harvest concentration factor (defined in Eq. 1) gained using each of three different sparger/airflow setups. LCF = limewood sparger with constant flow, CCF = ceramic flat plate sparger with constant flow, and COF = ceramic flat plate sparger with oscillating flow
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Fig6: The harvest concentration factor (defined in Eq. 1) gained using each of three different sparger/airflow setups. LCF = limewood sparger with constant flow, CCF = ceramic flat plate sparger with constant flow, and COF = ceramic flat plate sparger with oscillating flow

Mentions: Sparger type and setup had a major influence on the harvest concentration factor and biomass recovery. Figure 6 shows that the COF setup achieved high concentration factors of 427 ± 35, which approximates to performance improvements of 78 and 267 % relative to the CCF and LCF setups, respectively. Figure 7 shows the volume of culture that needs to be processed relative to the biomass recovered; this is an important consideration that significantly impacts the economics of further processing. The COF setup achieved the most favourable biomass to culture volume ratio within the batch system leaving only 13.5 mL of residual culture volume from the recovery of 376 mg of microalgae biomass (equivalent to a biomass concentration of 27.8 g L−1) compared with 30.7 mL with the recovery of 234 mg of biomass for the LCF setup (equivalent to a biomass concentration of 7.6 g L−1).Fig. 6


The effect of bubble size on the efficiency and economics of harvesting microalgae by foam flotation.

Coward T, Lee JG, Caldwell GS - J. Appl. Phycol. (2014)

The harvest concentration factor (defined in Eq. 1) gained using each of three different sparger/airflow setups. LCF = limewood sparger with constant flow, CCF = ceramic flat plate sparger with constant flow, and COF = ceramic flat plate sparger with oscillating flow
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig6: The harvest concentration factor (defined in Eq. 1) gained using each of three different sparger/airflow setups. LCF = limewood sparger with constant flow, CCF = ceramic flat plate sparger with constant flow, and COF = ceramic flat plate sparger with oscillating flow
Mentions: Sparger type and setup had a major influence on the harvest concentration factor and biomass recovery. Figure 6 shows that the COF setup achieved high concentration factors of 427 ± 35, which approximates to performance improvements of 78 and 267 % relative to the CCF and LCF setups, respectively. Figure 7 shows the volume of culture that needs to be processed relative to the biomass recovered; this is an important consideration that significantly impacts the economics of further processing. The COF setup achieved the most favourable biomass to culture volume ratio within the batch system leaving only 13.5 mL of residual culture volume from the recovery of 376 mg of microalgae biomass (equivalent to a biomass concentration of 27.8 g L−1) compared with 30.7 mL with the recovery of 234 mg of biomass for the LCF setup (equivalent to a biomass concentration of 7.6 g L−1).Fig. 6

Bottom Line: The smaller bubbles generated by the ceramic sparger under constant or oscillating airflow had significantly faster rise velocities when compared to the larger bubbles produced by the limewood spargers.The faster velocities of the smaller bubbles were due to momentum transfer to the liquid phase.Analyses of the harvest economics revealed that the ceramic flat plate sparger with an oscillating airflow delivered the best overall cost-benefit relationship.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical Engineering and Advanced Materials, Merz Court, Newcastle University, Newcastle upon Tyne, NE1 7RU England UK.

ABSTRACT

The effect of bubble size and rise velocity on the efficiency of a foam flotation microalgae harvesting unit was determined. Three sparger and input airflow combinations were used: (1) limewood sparger with constant airflow, (2) ceramic flat plate sparger with constant airflow and (3) ceramic flat plate sparger with an oscillating airflow. The ceramic sparger with oscillating flow generated the smallest bubbles within the liquid pool and the largest bubbles within the foam phase. This delivered the highest levels of biomass recovery due to enhanced bubble-algae collision and attachment efficiencies. The smaller bubbles generated by the ceramic sparger under constant or oscillating airflow had significantly faster rise velocities when compared to the larger bubbles produced by the limewood spargers. The faster velocities of the smaller bubbles were due to momentum transfer to the liquid phase. Analyses of the harvest economics revealed that the ceramic flat plate sparger with an oscillating airflow delivered the best overall cost-benefit relationship.

No MeSH data available.


Related in: MedlinePlus