Extraction of heavy metals using microorganisms and high gradient magnetic separation

It is pointed out that a large number of microorganisms have affinity to ingest or precipitate ion species onto their surfaces. In the case of magnetic ionic species, magnetic separation methods could be applied to remove the ion-loaded organisms from the surroundings. A wide range of metal ions were studied in the experiments described. The results show that the microorganisms developed an appreciable magnetic moment which lends to their removal by magnetic separation. The biomagnetic separation process was shown to be effective in reducing the concentration of a large number of ions either in multi-ion solutions or in a single metal ion solution. Reduction in most instances was from 10-100 p.p.m. to 10-100 p.p.b., a 90% removal. The single wire technique proved useful in the magnetic characterization of the microorganisms. The results indicate that this procedure is effective in estimating the magnetic susceptibilities of individual particles. The process described will have applications in the mineral processing industry, in the treatment of effluents from the nuclear industry, and in the recovery of precious metals