HEAVY METAL-CONTAINING WASTEWATER TREATMENT METHOD AND ITS SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a heavy metal removal system capable of reducing a generation rate of sludge containing ferrite from a treating raw water.

SOLUTION: The pH of the treating raw water W is controlled from 3 to 6 in a first flocculation tank 11. The heavy metals inhibiting the production of ferrite in the raw water W is insolubilized. Part of ferrous ions in the raw water W is oxidized into ferric ions. The pH of the raw water W is controlled from 7 to 11 in a second flocculation tank 21. Sludge M containing ferrite is produced in the raw water W. The sludge M from the raw water W is subjected to solid-liquid separation in a first settling tank 31. Part of the sludge M is returned to the second flocculation tank 21. As a result, the sludge M containing ferrite can efficiently be produced from the raw water W, and the generation rate of the sludge M can be reduced.

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