Method for treating water by ballasted flocculation and decantation
US7311841B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 19, 2002 |
| Grant date | Dec 25, 2007 |
| Priority date | — |
| Expiry date | Jul 28, 2023 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC02F2305/12
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
The invention concerns a water treatment method which consists in introducing coagulated water in a flocculation zone, to enable flocculation of microflocs in the presence and around a ballast; introducing the mixture in a decantation zone; separating the treated water in overflow and a mixture of sludge and the ballast in underflow; conveying at least part of said mixture to a sludge/ballast separating system and recycling into or upstream of the flocculation zone the ballast and part of the sludge introduced in said separation system. The invention is characterized in that it comprises steps which consists in conveying the mixture to the sludge/ballast separating system; in subjecting said mixture to a ballast concentration, extracting the ballast from the sludge extracted from the separation system; and more than 20% of the volume entering the sludge/ballast separating system is recycled into or upstream of the flocculation zone, after passing through at least part of the sludge/ballast separation system; and the ballast has an effective diameter greater than 60 micrometers, and the sludge extracted from the treatment system has a concentration higher than 5 g/L.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.