Activated Sludge Treatment of Coal-Gasification Effluent in a Petrochemical Plant – II. Metal Accumulation by Heterotrophic Bacteria

The metal-tolerant bacterial population of an activated sludge process treating coal gasification effluent in a zero-effluent water reclamation system was studied. Atomic absorption analyses of liquid and solids fractions of sludge showed that Fe, Cr, Zn, Ag, Hg, Cu, Cd, Pb, Ni, and Co were present in decreasing concentrations respectively, and that in all cases solids fractions contained highest metal concentrations. Seventeen metal-tolerant bacteria were isolated from the sludge and were shown to remove metals from broths in which they grew. In further broths also containing 100 mg ℓ⁻¹ of metal ions, Pseudomonascepacia, Flavobacterium sp., Ps. sp., and Enterobacteraerogenes effected biosorption of iron; Ps. maltophila and Ps. paucimobilis (Strain 2) biosorbed copper; Ps. cepacia (strain 1) and Aeromonashydrophila biosorbed zinc; Ps. pseudomallei and Ps. cepacia (strain 1) biosorbed chromium, and Ps. cepacia (strain 2) and Zoogloea sp. effected biosorption of nickel.