METHOD FOR TREATMENT OF SEWAGE WATER TO REMOVE HEAVY METAL IONS Russian patent published in 1995 - IPC

FIELD: sewage water treatment in electroplating. SUBSTANCE: sewage water is preliminarily filtered, concentrated in apparatus of back osmosis with withdrawal of permeate and concentrate. Concentrate is subjected to electrochemical treatment. Heavy metals are precipitated in form of hydroxides and returned for electrochemical treatment. Filtrate is evaporated and condensate is returned for mixing with sewage water. Concentration in back osmosis apparatus is carried out with recirculation of concentrate through 1/5-1/0 part of total surface of membranes in apparatus. Suspension of hydroxides of heavy metals is separated by ultrafiltration on semipermeable membranes with pores sizing . EFFECT: higher efficiency. 2 cl, 4 dwg, 2 tbl