METHOD FOR RECOVERING LOW- AND MEDIUM-DEMINERALIZED LOW-ACTIVE LIQUID WASTES Russian patent published in 2004 - IPC

FIELD: recovery of liquid radioactive wastes using membrane-sorption method. SUBSTANCE: method includes pre-cleaning of liquid radioactive wastes by means of mechanical and ultraviolet filters 3 and 4, respectively, and accumulation of pre-cleaned wastes in intermediate tank 10; cleaning and desalting of pre-cleaned wastes with aid of back-osmosis filters 6; separation of flows at output back-osmosis filters into effluents and concentrate involving return of concentrate to intermediate tank through settling reactor 11 that functions to soften concentrate due to settling liquid salts therein; secondary cleaning of effluents by passing them through ion exchangers 13 and accumulation of purified water in tank at the same time checking concentrate and effluents for salt content at outputs of back-osmosis filters, and checking effluents for salt content at ion exchangers. Effluents are then passed depending on their salt content at output of back-osmosis filters to ion exchangers in case salt content is lower than permissible value or to second intermediate tank, if their salt content is higher than that; as soon as waste concentrate contained in first intermediate tank attains permissible value of salt content, as checked at inlet of back-osmosis filters, this concentrate is conveyed from first intermediate tank and from settling reactor for case-hardening. Inlet of back-osmosis filters and output of settling reactor are changed over to second intermediate tank 12, and effluent path outlet is changed over to inlet of ion exchangers. As soon as salt content of effluents at outlet of back-osmosis filters attains permissible value (over 0.2 g/l), ion exchangers are turned off, and effluents are conveyed to first intermediate tank. Concentration process for liquid radioactive wastes accumulated in second intermediate tank is continued until value of 50 g/l is attained, whereupon concentrate is passed from second intermediate tank and from settling reactor for case-hardening. After that source liquid radioactive wastes are added and the process is resumed. EFFECT: optimized operating conditions for back-osmosis filters and ion exchangers; enhanced environmental friendliness. 4 cl, 1 dwg