METHOD OF REMOVING CHROMATES FROM WASTE WATER Russian patent published in 1998 - IPC

FIELD: waste water treatment. SUBSTANCE: invention relates to cleaning waste water from Cr(VI) compounds and may be used in mechanical engineering, metal working, etc. for treating water prior to be reused or discarded into sewage system. Invention aims at removing Cr(VI) compounds from waste water without formation of concentrated unusable solutions. Objective of invention consists in regeneration of anionite and is achieved as follows: waste water is passed through filters with high-basicity anion-exchange resin that is further regenerated by reactive agent. Regeneration is accomplished by solutions of salts of strong acids or alkali metals or their mixture, and produced chromates are purified from chromates and reused for correcting composition and acidification. During these operations, concentration of alkali metal chlorides, sulfates, nitrates, or their mixtures is maintained within the range from 4 to 10 wt % and pH value as high as 3. When correcting water, solution obtained is fried of Cr(VI) compounds by reagents or by other ways and, once clarified and correction of salt concentration and pH value completed, are reused for regeneration operation. To prevent considerable dilution of eluate before regeneration and before washing after regeneration, filter is completely emptied by replacement with compressed air. Wash water polluted by salts and Cr(VI) compounds, is combined with other waste waters to be treated in the first treatment step. EFFECT: enhanced waste water treatment efficiency.