| CPC C02F 1/048 (2013.01) [B01D 3/14 (2013.01); B01D 5/00 (2013.01); C02F 1/40 (2013.01); C07C 253/34 (2013.01); C02F 2101/16 (2013.01); C02F 2101/38 (2013.01); C02F 2103/38 (2013.01); C02F 2209/02 (2013.01); C02F 2209/03 (2013.01)] | 8 Claims |

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1. A method for purifying of waste water comprising:
supplying a mixed stream including a wastewater and an acid component, added to the wastewater to lower the wastewater pH, to a first column, wherein the wastewater includes water, a nitrile-based monomer, and ammonia;
condensing an upper discharge stream of the first column to form a condensed stream, supplying the condensed stream to a decanter to separate the condensed stream into a water layer and an organic layer, and supplying components of the organic layer to a second column; and
separating a by-product from a lower discharge stream of the second column, and recovering the nitrile-based monomer from an upper discharge stream of the second column,
wherein a pH of the mixed stream ranges from 1.5 to 5.0, and
wherein the acid component includes one or more of acetic acid, nitric acid, sulfuric acid, phosphoric acid, formic acid, or cyanic acid.
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