Zero discharge treatment method for steel pickling waste water

The invention discloses a zero discharge treatment method for steel pickling waste water. The zero discharge treatment method for the steel pickling waste water comprises the following steps: carrying out filtration treatment on the steel pickling waste water by virtue of a grille; introducing the steel pickling waste water subjected to the filtration treatment into a high-efficiency oxidation pond; recycling the steel pickling waste water subjected to high-efficiency oxidation into a pickling tank in a steel pickling process, and heating the steel pickling waste water in the pickling tank; adding acid into the heated pickling tank, and then carrying out pickling treatment on steel; carrying out filtration treatment on waste water at the outlet of the pickling tank by virtue of a grille; introducing the steel pickling waste water subjected to filtration treatment by virtue of the grille into a crystallizing pond, and carrying out crystallization at normal temperature; and carrying out the steps on mother liquor of the crystallizing pond. The zero discharge treatment method for the steel pickling waste water has the advantages that investment for process equipment cost and operating cost is greatly reduced, medicaments such as calcium hydroxide are not adopted, even more important, usage amount of sulphuric acid is reduced, waste water discharge problem is not produced, and the crystallization carried out at normal temperature is adopted for obtaining ferrous sulphate heptahydrate crystal byproduct.