Hybrid chemical and biological process for decontaminating sludge from municipal sewage
US6855256B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 1, 2002 |
| Grant date | Feb 15, 2005 |
| Priority date | — |
| Expiry date | Aug 2, 2022 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC02F2303/04
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
The invention relates to a hybrid biological and chemical method for decontaminating sludge containing heavy metals and pathogenic microorganisms, consisting of the following steps: the sludge is mixed with an acidic leaching solution in order to acidify the sludge with a pH which is low enough to solubilize the majority of the heavy metals and to destroy most of the pathogenic microorganisms but which is also high enough to minimize the solubilization of fertilizing elements; oxidation-reduction of more than +400 mv is maintained, liquid-solid separation occurs in order to obtain a solid fraction comprising decontaminated acidic sludge and a liquid fraction comprising heavy metals which are dissolved in a leaching solution; the sludge is neutralized: and neturalized decontaminated sludge is recovered, whereby the fertilizing elements contained therein, i.e. carbon, nitrogen and phosphorus, remain substantially unchanged in relation to the initially contaminated sludge.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.