METHOD FOR PURIFYING NIGRE Russian patent published in 1997 - IPC

FIELD: organic chemistry; environmental control; purification of effluents resulting from butter-and-fat industry. SUBSTANCE: inventive novelty of proposed method resides in using two-step electric flotation process to purify nigre. Treatment duration in first flotation step is 10-25 min, and in second - 3-10 min. Prior to flotation, pH value of nigre-containing liquor is adjusted at 3-6. Prior to proceeding to second flotation step, lime milk is added until pH of liquor becomes 6.5-10.0. EFFECT: effective approach to purification of nigre-contaminated effluents.