A comparative study of the magnetic separation characteristics of magnetotactic and sulphate reducing bacteria

Many microorganisms have an affinity to accumulate metal ions onto their surfaces which results in metal loading of the biomass. Microbial biomineralization of iron results in a biomass which is often highly magnetic and can be separated from water systems by the application of a magnetic field. This article reports on the magnetic separation of biomass containing microbial iron oxide (Fe3O4, present within magnetotactic bacteria) and iron sulphide (Fe1-XS, precipitated extracellularly by sulphate reducing bacteria) in a single wire cell. Since such bacteria can be separated magnetically, their affinity to heavy metal or organic material accumulation render them useful for the removal of pollutants from waste water. The relative merits of each bacterium to magnetic separation techniques in terms of applied magnetic field and processing conditions are discussed. (C) 1998 American Institute of Physics. [S0021-8979(98)38611-9].