Activated sludge treatment of coal-gasification effluent in a petrochemical plant. II. Metal accumulation by heterotrophic bacteria

Samples of metal-acclimated biomass from an activated sludge plant treating coal gasification effluents were analysed by atomic absorption spectrometry. The metals iron, chromium, zinc, silver, mercury, copper, cadmium, lead, nickel and cobalt were present in decreasing magnitude, the larger fraction in the solids phase. Seventeen metal-tolerant species of bacteria were isolated and cultivated on nutrient media supplemented with 100 mg metal salts per litre, to determine their relative affinities for different metals. Several species could accumulate iron, two Pseudomonas species biosorbed copper, two other species biosorbed chromium, and others accumulated zinc and nickel.