Method of decontaminating solid materials contaminated with heavy metals

• US 5,849,567 A
• Filed: 04/28/1997
• Issued: 12/15/1998
• Est. Priority Date: 03/31/1995
• Status: Expired due to Fees

• Current Assignee: Gsf-Forschungszentrum Fur Umwelt Und Gesundheit GmbH
• Original Assignee: Gsf-Forschungszentrum Fur Umwelt Und Gesundheit GmbH
• Inventors: Fischer, Klaus, Riemschneider, Peter, Bieniek, Dieter, Bipp, Hans-Peter, Kettrup, Antonius
• Primary Examiner(s): Redding, David A.
• Application Number:
  US08/847,852
• Time in Patent Office: 596 Days
• Field of Search: 435/262.5, 210/661, 210/666, 210/681, 210/683, 210/684, 210/685, 210/688, 210/912, 588/1, 588/252
• US Class Current: 435/262.5
• CPC Class Codes: B09C 1/02 Extraction using liquids, e.g. washing, leaching , flotation
• CPC Class Codes: B09C 1/10 microbiologically, biologically or by using enzymes
• CPC Class Codes: Y10S 210/912 Heavy metal

Abstract

In a method for reducing the content of heavy metals of solid materials, particularly of soils, a 0.1-10% aqueous solution of chemically modified biomasses of waste and residue materials is applied to the solid material whereby the heavy metals are released and extracted from the solid material. The biomass solution residues remaining in the solid material after the heavy metal extraction procedure is rapidly biodegradable so that no objectionable traces remain in the solid materials or soils.

Claims

1. A method for reducing the content of heavy metals in solid materials comprising the steps of subjecting a biomass consisting of at least one of molasses, succrose, peeling sludge, starch, whey powder and carbohydrate-containing residues to an oxydation digestion process to provide chemically modified biomasses, preparing a 0.1-10% aqueous solution of said chemically modified biomasses, and extracting heavy metals containing compounds from said solid materials using said aqueous solution of said chemically modified biomasses.

2. A method according to claim 1, wherein said heavy metals containing compounds which are extracted from said material include Cu, Zn, Ni, Cd, Pb, and Cr.

3. A method according to claim 1, wherein said aqueous solution used for the extraction of the heavy metals includes only organic substances derived from waste materials and residues with the addition of up to 15% by weight based on the total organic carbon content (TOC) of natural compounds.

4. A method according to claim 1, wherein all chemically identifiable major compounds of said aqueous solution used for the extraction of said heavy metals are naturally occurring compounds.

5. A method according to claim 4, wherein said chemically identifiable compounds are rapidly biodegradable when applied to soils.

6. A method according to claim 4, wherein said chemically identifiable compounds comprise essentially chelate formers adapted to cause the release of said heavy metals.

7. A method according to claim 6, wherein said chelate formers comprise compounds with at least two metal coordinating molecule groups.

8. A method according to claim 7, wherein said metal coordinating molecule groups include one of carboxyl COOH)-- and hydroxyl (OH--)-- groups.

9. A method according to claim 1, wherein said digestion process comprises chemical oxidation of said biomasses.

10. A method according to claim 1, wherein said digestion process comprises electrochemical conversion.

11. A method according to claim 1, wherein said digestion process comprises conversion by hydrogenperoxide.

12. A method according to claim 1, wherein said digestion process comprises enzymatic conversion.