Determination of magnetic susceptibility of loaded micro-organisms in bio-magnetic separation

Microorganisms and microbial products can be highly efficient bioaccumulators of soluble and particulate forms of metals, especially from dilute external concentrations. The authors outline a video imaging technique in which biological particle velocity profiles were obtained as they interacted with a ferromagnetic wire in a single-wire cell. These profiles were further analyzed using a dedicated image processing workstation. The whole process is automated and is suitable for analyzing particles with different magnetic susceptibilities. The bioaccumulation systems investigated were of two categories. The first was an aerobic process in which the microorganisms of Bacillus subtilis and Candida utilis were used to precipitate metal phosphates onto their cell walls as they cleaved glycerol 3-phosphate, their energy source, from a solution containing uranyl ions. The second was an anaerobic process in which Desulfovibrio microbial biomass was used to reduce sulphate to sulphide