Characteristics of a novel low density cell-immobilized magnetic supports in liquid magnetically stabilized beds

• Low density non-porous magnetic particles were prepared using sand core.
• The prepared particles showed good adsorption behavior toward Escherichia coli.
• The particles showed relatively low liquid fluidizing velocity in MSBs.
• Liquid fluidized magnetically stabilized bioreactor was operated using magnetic immobilized cells.
• The conversion was 30% higher than that using traditional dense particles.

The adsorptive and hydrodynamic characteristics of low density non-porous magnetic supports used for biocatalyst immobilization have been investigated. The magnetic particles consist of a sand core have been covered with a magnetite layer followed by a layer of nano size activated carbon or fly ash with the aid of epoxy resin. The resulted particles showed good adsorbing behavior toward resting cells of Escherichia coli from batch culture of different cell concentrations. The maximum adsorption capacity for both particles were calculated using Langmuir isotherm model as 18 (1.22 million cells) and 14 (0.95 million cells) mg/g, respectively. The hydrodynamic study in a liquid magnetically stabilized beds confirms that these particles have lower fluidizing velocity and attain a higher expanded stabilized bed than particles of magnetic dense core. These results confirm the applicability of these particles to immobilize microorganisms for different applications. It was found that the conversion using these particles was 30% higher than that using traditional dense magnetic particles due to the longer residence times in the bed.