Method for purifying industrial sewage water
US5618439A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 24, 1994 |
| Grant date | Apr 8, 1997 |
| Priority date | — |
| Expiry date | Mar 24, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S210/912
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
A method for purifying aqueous solutions having varying concentrations of contaminants and/or various contaminants including ions of several metals and elements by conducting precipitation in a first precipitation stage by adding lime in a surplus quantity whereby a pH of about 12 is established and maintained in the solution and a major part of the contaminant content is precipitated so as to form a solution having a substantially constant composition and to form a precipitate that is isolated and removed together with residual lime. Precipitation is then conducted in a second precipitation stage by adding a reagent for precipitation at a pH in the range of 4-11 wherein residual contaminant in the formed solution from the first precipitation stage is precipitated the precipitate is isolated and returned to the first precipitation stage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.