초록 ▼

The invention relates to the treatment of waste water containing a harmful ion such as a heavy metal ion or fluorine ion by the coagulating sedimentation method using an inorganic coagulant such as an iron compound or an aluminum compound. After separating treated water from the sediment (sludge) in

The invention relates to the treatment of waste water containing a harmful ion such as a heavy metal ion or fluorine ion by the coagulating sedimentation method using an inorganic coagulant such as an iron compound or an aluminum compound. After separating treated water from the sediment (sludge) in which the harmful ion is incorporated in insoluble form, the pH of a mixture of the sediment and water is suitably adjusted to cause elution of the harmful ion from the sediment. Then the sediment is separated from the eluate and reused as an inorganic coagulant. By reusing the sediment in this manner, the waste water treatment is accomplished without producing a large quantity of sludge and the consumption of inorganic coagulant and auxiliary chemicals can be greatly reduced, while the concentration of the harmful ion in the treated water becomes sufficiently low.

대표청구항 ▼

[ What is claimed is:] [1.] A method of treating waste water containing a heavy metal ion selected from the group consisting of copper, arsenic, antimony, selenium, mercury, cadmium and lead, comprising the steps of:(a) adjusting the pH of the waste water and adding an inorganic coagulant to the was

[ What is claimed is:] [1.] A method of treating waste water containing a heavy metal ion selected from the group consisting of copper, arsenic, antimony, selenium, mercury, cadmium and lead, comprising the steps of:(a) adjusting the pH of the waste water and adding an inorganic coagulant to the waste water to form a hydroxide sediment which takes in the heavy metal ion in insoluble form;(b) adding a polymer coagulant to the water treated with the inorganic coagulant;(c) separating said hydroxide sediment from treated water;(d) adjusting the pH of a mixture of the separated sediment and water to cause elution of the heavy metal ion from the sediment, adding a polymer coagulant, and separating the sediment from the eluate containing the heavy metal ion; and(e) reusing the sediment separated from said eluate as said hydroxide sediment in step (a).