METHOD FOR THERMOCHEMICAL DESALTING OF NATURAL AND WASTE WATERS Russian patent published in 1999 - IPC

FIELD: water treatment. SUBSTANCE: invention relates to integrated methods for exhaustive purification of sulfate-bicarbonate-type natural and waste waters that can be used, for example, in heat and power engineering. Method includes mixing initial water with waste water, lime treatment, coagulation and clarification of mixture, sodium cycle, concentration in evaporators, recarbonization of concentrate with relief gas-vapor vaporizer mixture, mixing recarbonized concentrate with part of concentrated waste water, acid, or alkali, separating resultant precipitate, diluting clarified solution and utilizing it for regeneration of sodium-cationite filters, isolation of concentrated part of regeneration waste water, precipitating calcium sulfate therein and treating part of this waste water with lime. According to invention, recarbonized concentrate is mixed with part of concentrated waste water, acid, or alkali at ratio ensuring contents of calcium and magnesium in mixture by 2 to 8 mg-equ/l exceeding contents of carbonate and hydrate ions, respectively. As alkali, part of lime-treated concentrated waste water is utilized, and precipitate resulting from above-mentioned mixing with solution contained in it is further mixed with concentrated part of regeneration waste water. Waste water treated in the process has hardness higher than 20-30 mg-equ/l and a part of it, after treatment with lime and separation of precipitate, is utilized for preparing lime milk, whereas a part of sodium-cycled water with summary chloride level by 2 to 8% lower than that in initial water enters closed heat system. EFFECT: enhanced water desalting efficiency. 7 cl, 1 dwg