A review, with 26 refs., of methods for removal of Hg from wastewater. The integrated industrial plant used in Poland for biolog. treatment of wastewater from brine electrolysis was presented. Seven mercury reductase-contg. bacterial species were used in the active-bed bioreactor. A decrease in Hg concn. from 2.5-6.0 mg/L down to 150-400 mu g/L was achieved.