Abstract: The present invention is related to a purification method metal(s) containing water wherein: the process is fully continuous, the water flows through a sand filter, inoculated with viable micro-organisms, a part of the micro-organism biomass, loaded with metals, is evacuated, and the micro-organism biomass loss is equal to the micro-organism biomass growth.

Abstract: Precipitating of metals and degrading of xenobiotic organic compounds is carried out with a reactor containing microorganisms immobilized on a membrane made of an inorganic oxide such as ZrO.sub.2, Sb.sub.2 O.sub.3, or Al.sub.2 O.sub.3 and an organic polymer such as polysulfone. The membrane has a skin side and an open side, and pores of the skin side are smaller than pores of the open side. The microorganisms are immobilized as a biofilm on the skin side of the membrane. A nutrient chamber supplies a nutrient solution to the open side of the membrane and the nutrient solution passes through the membrane from the open side to contact the microorganisms on the skin side. An effluent chamber supplies an effluent solution containing a metal in the form of a salt, a xenobiotic compound such as a chlorinated organic compound or both to the biofilm of microorganisms on the skin side, and the microorganisms precipitate the metal and/or degrade the xenobiotic compound.