METHOD OF SEWAGE PURIFICATION FROM MERCURY COMPOUNDS Russian patent published in 1996 - IPC

FIELD: sewage purification from mercury compounds in production of caustic soda and chlorine by electrolysis of sodium chloride with mercury cathode. SUBSTANCE: mercury compounds are settled from sewage using reactant, that has sulfide of metal and salt of iron. Mercury bearing sediment is separated and subjected to thermal treatment with evaporation of mercury. So treated sediment has sulfides of iron and calcium. The product is used as reactant to settle mercury from following portions of sewage. Mercury concentration in sewage is decreased from 21 to 0.025 mg/l and may be further decreased to 0.0005 mg/l using following treatment of sewage with anionite. Mercury is utilized as metal. EFFECT: improved quality of sewage purification from mercury compounds. 1 cl