The invention discloses a method for treating
pickling wastewater in iron and steel industry. The method comprises the following steps: a) introducing
pickling wastewater into a regulating tank, a
chromium reduction tank and a heavy
metal catcher; b) separating heavy
metal precipitate produced in reaction from clear liquor through an ultramicro separating
machine, carrying out primary
fluoride removal on the clear liquor in a
fluoride removal filter; c) feeding the
mixed solution subjected to primary
fluoride removal into a primary precipitating tank for separating non-
ferrous precipitate from water, then carrying out secondary fluoride removal on the clear liquor in a fluoride reaction tank; and d) feeding the
mixed solution subjected to secondary fluoride removal into a secondary precipitating tank for separating non-
ferrous precipitate from water, and emitting the separated clear liquor into a clear water tank for storage. The method has high
metal particle separation efficiency, the ultramicro separation
machine has
concentration effect, so no concentration tank is required for separating the precipitate from the clear liquor to save space and the labor force, the indexes of iron,
chromium,
nickel, fluoride and the like in the clear liquor emitted from the secondary precipitating tank can all meet the national-level standard requirement.