Process for treating arsenic-containing waste water
US5840194A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 9, 1996 |
| Grant date | Nov 24, 1998 |
| Priority date | — |
| Expiry date | Dec 9, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S210/911
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
The present invention provides a process for treating arsenic-containing waste water, comprising adding an oxidizing agent, if necessary, to arsenic-containing waste water to oxidize trivalent arsenic in the waste water into pentavalent arsenic; adding a calcium compound to adjust the pH to 12 or higher; separating it into solid and liquid (first solid/liquid separation); calcining the resulting sludge, while adding a ferric salt to the treated solution to adjust the pH to 6-9 after the solid/liquid separation; and separating it into solid and liquid (second solid/liquid separation). According to the present invention, it is possible to remove arsenic from waste water efficiently to yield treated water satisfying various tolerance limits under various regulations, while the arsenic-containing sludge separated from the waste water can become harmless in subsequent continuous steps.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.