EP0500657A1 - A method of removing heavy metals form soil, sludge, compost and similar materials - Google Patents

A method of removing heavy metals form soil, sludge, compost and similar materials

Info

Publication number
EP0500657A1
EP0500657A1 EP19900916713 EP90916713A EP0500657A1 EP 0500657 A1 EP0500657 A1 EP 0500657A1 EP 19900916713 EP19900916713 EP 19900916713 EP 90916713 A EP90916713 A EP 90916713A EP 0500657 A1 EP0500657 A1 EP 0500657A1
Authority
EP
European Patent Office
Prior art keywords
heavy metals
ion exchanger
heavy metal
bonding agent
compost
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19900916713
Other languages
German (de)
French (fr)
Inventor
Sven Erik Jorgensen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
WRL APS
Original Assignee
WRL APS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by WRL APS filed Critical WRL APS
Publication of EP0500657A1 publication Critical patent/EP0500657A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
    • A62D3/00—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances
    • A62D3/30—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents
    • A62D3/33—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents by chemical fixing the harmful substance, e.g. by chelation or complexation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09C—RECLAMATION OF CONTAMINATED SOIL
    • B09C1/00—Reclamation of contaminated soil
    • B09C1/02—Extraction using liquids, e.g. washing, leaching, flotation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/68—Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water
    • C02F1/683—Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water by addition of complex-forming compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/004—Sludge detoxification
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
    • A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
    • A62D2101/40—Inorganic substances
    • A62D2101/43—Inorganic substances containing heavy metals, in the bonded or free state
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
    • A62D2203/00—Aspects of processes for making harmful chemical substances harmless, or less harmful, by effecting chemical change in the substances
    • A62D2203/02—Combined processes involving two or more distinct steps covered by groups A62D3/10 - A62D3/40

Definitions

  • the present invention relates to a method of removing heavy metals from soil, sludge, compost and similar materials.
  • a known method of removing heavy metals from soil, sludge or compost comprises extracting the heavy metals with acid.
  • the method suffers from the drawback that the heavy metal containing extract constitutes a problem of almost the same magnitude as the heavy metal containing material itself as the extract must either be disposed of by depositing, which is expensive and causes environ ⁇ mental problems or by processing at a special chemical reception plant which would in most cases also be too expensive.
  • a further drawback of the known method is that in extraction of sludge a very low pH value is often required as the heavy metals are present in a strongly bonded state in the dead cells in the sludge. Consequently, large amounts of acid and base are required to lower and readjust, respectively, the pH value.
  • the object of the present invention is to provide a method of removing heavy metals from soil, sludge, compost and similar mate ⁇ rials, whereby the heavy metals are concentrated to a larger extent than is the case in connection with the known methods.
  • This object is obtained according to the invention by a method which is characterized in that the heavy metal containing material is treated with an agent forming a complex with heavy metal ions so as to form a product consisting of a solid phase and a liquid phase containing a heavy metal complex, in that the liquid phase is separated off, in that the liquid phase separated off is treated with an ion exchanger so as to bond heavy metals onto the ion exchanger, and in that the heavy metals are optionally removed from the ion exchanger by eluation.
  • the heavy metal containing material is treated with a solid complex bonding agent in order to avoid an increase of the volume of the treated material. If the starting material is too dry the complex bonding agent is added as an aqueous solution.
  • the pH value of the mixture of the heavy metal containing material and the complex bonding agent should preferably be in the range of about 3 to 5.5 and if necessary an adjustment of the pH value is carried out by using e.g. nitrous acid or sulphuric acid. However, the starting material will often have a pH value of about 5.
  • the complex bonding agent may advan ⁇ tageously be added in solid form before the dewatering.
  • the treatment with the complex bonding agent may optionally be repeated one or more times in order to obtain a desired degree of removal of heavy metals.
  • EDTA or a mixture of EDTA and pyrophosphate is preferably used as complex bonding agent.
  • EDTA as a complex bonding agent it is preferably used in a concentration of from about 5 to about 50 mmol per litre of heavy metal containing material.
  • pyrophosphate it is preferably used in a concentration in the range of about 1 to about 50 mmol per litre of heavy metal containing material.
  • the solid matter is separated from the liquid, which separation may be carried out by e.g. sedimentation, centrifugation or filtration.
  • an ion exchanger based on bark is used, such as a sulphonated bark ion exchanger, as such ion exchangers are inexpensive.
  • a sulphonated bark ion exchanger is capable of specifically absorbing about 0.3 equivalent heavy metal per litre. By “specifically” is meant that the absorption can take place without the influence of other ions possibly present, such as sodium ions and calcium ions.
  • the overall capacity of the bark ion exchanger corresponds to about 1 equivalent per litre, but only about 30% of the ionic groups of the ion exchanger are specific to the absorption of heavy metals.
  • the duration of the treatment on the ion exchanger is preferably in the range of about 30 to about 120 minutes.
  • the collected heavy metals may optionally be eluted from the ion exchanger by e.g. acid so as to obtain the heavy metals.
  • the bark ion exchanger may be burnt using an exhaust gas filter whereby the heavy metals are further concentrated in the ashes.
  • the heavy metal containing material Prior to the treatment with the complex bonding agent the heavy metal containing material may be aired, whereby a considerably improved extraction of the heavy metals from the heavy metal con ⁇ taining material is obtained.
  • the further treatment of the extract on an inexpensive bark ion exchanger in addition to the above discussed substantial concentration provides the advantage that the problem of the expensive treatment or depositing of the environmen ⁇ tally harmful extract is avoided and that the liquid used for the extractions may be regenerated and recycled, whereby the expenses for chemicals for the extraction are reduced considerably.
  • 1 kg matured compost (wet basis) was aired for 30 minutes, and 20 mmol EDTA, 5 mmol pyrophosphate and 100 ml water were then added to reduce the content of dry matter to 60 % by weight.
  • the compost contained 105 ppm lead and 4 ppm cadmium (wet basis), which it was desired to reduce to 40 ppm lead and 1 ppm cadmium (dry matter basis). After 15 minutes a pH value of 5.0 was measured.
  • the 210 ml of extract were then treated on a sulphonated bark ion exchange column having a total volume of 100 ml.
  • the period of treatment was about 2 hours the calculated residence time in the column being about 1 hour.
  • the concentration of the extract of 52 ppm lead and 1.7 ppm cadmium was reduced to 1 ppm lead and 0.02 ppm cadmium by the treatment.
  • the harbour sludge contained 2100 ppm lead, 41 ppm cadmium, 760 ppm chromium and 1450 ppm copper on a dry matter basis, and after the extraction it contained 235 ppm lead, 17 ppm cadmium, 184 ppm chromium and 210 ppm copper.
  • the extract was treated on a 200 ml bark ion exchange column having a residence time of 45 minutes, whereby the heavy metal content of the extract was reduced to 12 ppm lead, 2 ppm cadmium, 12 ppm chromium and 2 ppm copper.
  • the bark ion exchanger was saturated by treatment with a total of 8 times 1.2 kg harbour sludge correspond ⁇ ing to a concentration of 48 times.
  • the extract which contained 208 ppm lead, was treated on a 100 ml bark ion exchange column having a residence time of 1 hour.
  • a liquid having the same heavy metal concentration as the extract it was determined that a total of 60 soil samples of 200 g each can be treated on the ion exchange column before it shows any sign of saturation. This corresponds to a concentration of 120 times.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Hydrology & Water Resources (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Soil Sciences (AREA)
  • Processing Of Solid Wastes (AREA)
  • Treatment Of Water By Ion Exchange (AREA)
  • Treatment Of Sludge (AREA)

Abstract

Le procédé décrit, qui sert à extraire les métaux lourds d'un sol, d'une boue, d'un compost, et de matériaux similaires, consiste à traiter le matériau contenant les métaux lourds avec un agent qui forme un complexe avec les ions de métaux lourds, en vue d'obtenir un produit composé d'une phase solide et d'une phase liquide contenant un complexe de métaux lourds, à séparer la phase liquide ainsi obtenue et à traiter le liquide ainsi séparé avec un échangeur d'ions en vue d'obtenir la liaison des métaux lourds sur l'échangeur d'ions.The process described, which is used to extract heavy metals from soil, mud, compost, and the like, involves treating the material containing heavy metals with an agent that complexes with ions of heavy metals, in order to obtain a product composed of a solid phase and a liquid phase containing a complex of heavy metals, in separating the liquid phase thus obtained and in treating the liquid thus separated with an ion exchanger in order to obtain the bonding of heavy metals on the ion exchanger.

Description

A method of removing heavy metals from soil, sludge, compost and similar materials
The present invention relates to a method of removing heavy metals from soil, sludge, compost and similar materials.
In recent years the deposition and use of sludge and compost have become an increasing problem due to the content of heavy metals. Thus, it is impossible to use sludge from e.g. municipal purifica¬ tion plants and having a high content of heavy metals for compost¬ ing. Furthermore, in many cases it is not possible to deposit heavy metal containing sludge directly at the most natural site, viz. agricultural land. Consequently, it becomes necessary to deposit the sludge at disposal sites or burn it, which alternatives both cause other environmental problems and entail considerable costs.
Furthermore, many building sites and land areas, such as old chemi¬ cal depots, are contaminated with heavy metals.
A known method of removing heavy metals from soil, sludge or compost comprises extracting the heavy metals with acid. However, the method suffers from the drawback that the heavy metal containing extract constitutes a problem of almost the same magnitude as the heavy metal containing material itself as the extract must either be disposed of by depositing, which is expensive and causes environ¬ mental problems or by processing at a special chemical reception plant which would in most cases also be too expensive. A further drawback of the known method is that in extraction of sludge a very low pH value is often required as the heavy metals are present in a strongly bonded state in the dead cells in the sludge. Consequently, large amounts of acid and base are required to lower and readjust, respectively, the pH value.
Thus, there is a considerable need for the development of new methods of removing heavy metals from soil, sludge, compost and similar materials.
The object of the present invention is to provide a method of removing heavy metals from soil, sludge, compost and similar mate¬ rials, whereby the heavy metals are concentrated to a larger extent than is the case in connection with the known methods.
This object is obtained according to the invention by a method which is characterized in that the heavy metal containing material is treated with an agent forming a complex with heavy metal ions so as to form a product consisting of a solid phase and a liquid phase containing a heavy metal complex, in that the liquid phase is separated off, in that the liquid phase separated off is treated with an ion exchanger so as to bond heavy metals onto the ion exchanger, and in that the heavy metals are optionally removed from the ion exchanger by eluation.
It has surprisingly been found that by using the method of the invention both an efficient removal of heavy metals from the star¬ ting material and a very substantial concentration of the heavy metals removed can be obtained, whereby the final disposal of the extracted heavy metals is considerably facilitated.
By practicing the method of the invention it has e.g. been possible to remove up to 60% of the heavy metals and to obtain an end product having a concentration of heavy metals which is 800 times that of the starting material.
In a preferred embodiment of the method of the present invention, whereby the heavy metal containing material is aqueous, the heavy metal containing material is treated with a solid complex bonding agent in order to avoid an increase of the volume of the treated material. If the starting material is too dry the complex bonding agent is added as an aqueous solution. The pH value of the mixture of the heavy metal containing material and the complex bonding agent should preferably be in the range of about 3 to 5.5 and if necessary an adjustment of the pH value is carried out by using e.g. nitrous acid or sulphuric acid. However, the starting material will often have a pH value of about 5. When treating sludge which is subjected to a dewatering process using e.g. a sieve diaphragm press/plate and frame filter or a centrifuge the complex bonding agent may advan¬ tageously be added in solid form before the dewatering. The treatment with the complex bonding agent may optionally be repeated one or more times in order to obtain a desired degree of removal of heavy metals.
In connection with the present invention EDTA or a mixture of EDTA and pyrophosphate is preferably used as complex bonding agent. When using EDTA as a complex bonding agent it is preferably used in a concentration of from about 5 to about 50 mmol per litre of heavy metal containing material. When using pyrophosphate it is preferably used in a concentration in the range of about 1 to about 50 mmol per litre of heavy metal containing material.
Subsequently, the solid matter is separated from the liquid, which separation may be carried out by e.g. sedimentation, centrifugation or filtration.
The separated liquid is then treated on an ion exchanger. Preferab¬ ly, an ion exchanger based on bark is used, such as a sulphonated bark ion exchanger, as such ion exchangers are inexpensive. A sulphonated bark ion exchanger is capable of specifically absorbing about 0.3 equivalent heavy metal per litre. By "specifically" is meant that the absorption can take place without the influence of other ions possibly present, such as sodium ions and calcium ions. The overall capacity of the bark ion exchanger corresponds to about 1 equivalent per litre, but only about 30% of the ionic groups of the ion exchanger are specific to the absorption of heavy metals. The duration of the treatment on the ion exchanger is preferably in the range of about 30 to about 120 minutes.
Finally, the collected heavy metals may optionally be eluted from the ion exchanger by e.g. acid so as to obtain the heavy metals. Alternatively, the bark ion exchanger may be burnt using an exhaust gas filter whereby the heavy metals are further concentrated in the ashes.
Prior to the treatment with the complex bonding agent the heavy metal containing material may be aired, whereby a considerably improved extraction of the heavy metals from the heavy metal con¬ taining material is obtained. The further treatment of the extract on an inexpensive bark ion exchanger in addition to the above discussed substantial concentration provides the advantage that the problem of the expensive treatment or depositing of the environmen¬ tally harmful extract is avoided and that the liquid used for the extractions may be regenerated and recycled, whereby the expenses for chemicals for the extraction are reduced considerably.
The invention will now be described in further detail with reference to the following examples.
Example 1
1 kg matured compost (wet basis) was aired for 30 minutes, and 20 mmol EDTA, 5 mmol pyrophosphate and 100 ml water were then added to reduce the content of dry matter to 60 % by weight. The compost contained 105 ppm lead and 4 ppm cadmium (wet basis), which it was desired to reduce to 40 ppm lead and 1 ppm cadmium (dry matter basis). After 15 minutes a pH value of 5.0 was measured. Then the compost was sedimented, and the supernatant was removed and centri- fuged thereby obtaining 110 ml clear liquid which contained 77 mg lead and 2.4 mg cadmium corresponding to a reduction of the content of the compost to 28 ppm lead and 1.6 ppm cadmium on a wet basis. To obtain the desired reduction it was thus necessary to perform a further extraction resulting in an additional 100 ml of clear liquid containing 17 ppm lead and 1.0 ppm cadmium, and the content of lead and cadmium of the compost had then been reduced to the desired level.
The 210 ml of extract were then treated on a sulphonated bark ion exchange column having a total volume of 100 ml. The period of treatment was about 2 hours the calculated residence time in the column being about 1 hour. The concentration of the extract of 52 ppm lead and 1.7 ppm cadmium was reduced to 1 ppm lead and 0.02 ppm cadmium by the treatment.
In order to determine the compost treatment capacity of the bark ion exchanger a total of 12 kg of compost were treated on the ion exchange column without it showing any sign of saturation. The ion exchanger was then saturated using water containing lead and cadmium in the same concentration as the compost extract (52 ppm lead and 1.7 ppm cadmium), and it was found that 100 ml of bark ion exchanger is capable of retaining heavy metals from about 20 kg of compost, which corresponds to a concentration of heavy metals from the compost to the bark ion exchanger of about 800 times.
Example 2
1.2 kg of harbour sludge having a content of dry matter of 32% was aired for 2.5 hours. 50 mmol EDTA and 1.5 ml concentrated sulphuric acid were then added, and the sludge was then centrifuged. The clear supernatant had a volume of 350 ml and a pH value of 4.3 and con¬ tained 1840 ppm lead, 23 ppm cadmium, 560 ppm chromium and 1230 ppm copper. Before the extraction the harbour sludge contained 2100 ppm lead, 41 ppm cadmium, 760 ppm chromium and 1450 ppm copper on a dry matter basis, and after the extraction it contained 235 ppm lead, 17 ppm cadmium, 184 ppm chromium and 210 ppm copper.
The extract was treated on a 200 ml bark ion exchange column having a residence time of 45 minutes, whereby the heavy metal content of the extract was reduced to 12 ppm lead, 2 ppm cadmium, 12 ppm chromium and 2 ppm copper. The bark ion exchanger was saturated by treatment with a total of 8 times 1.2 kg harbour sludge correspond¬ ing to a concentration of 48 times.
Example 3
200 g of soil was treated with 50 ml 30 mM EDTA plus 10 ml 25 mM pyrophosphate. Following 10 minutes of aeration and subsequent sedimentation the clear aqueous phase of 55 ml in all was separated off. In the extraction the lead content of the soil was reduced from 97 ppm to 31 ppm (dry matter basis).
The extract, which contained 208 ppm lead, was treated on a 100 ml bark ion exchange column having a residence time of 1 hour. By use of a liquid having the same heavy metal concentration as the extract it was determined that a total of 60 soil samples of 200 g each can be treated on the ion exchange column before it shows any sign of saturation. This corresponds to a concentration of 120 times.

Claims

C l a i m s
1. A method of removing heavy metals from soil, sludge, compost and similar materials, c h a r a c t e r i z e d in that the heavy metal containing material is treated with an agent forming a complex with heavy metal ions so as to form a product consisting of a solid phase and a liquid phase containing a heavy metal complex, in that the liquid phase is separated off, in that the liquid phase separa¬ ted off is treated with an ion exchanger so as to bond heavy metals onto the ion exchanger, and in that the heavy metals are optionally removed from the ion exchanger by eluation.
2. A method according to claim 1, c h a r a c t e r i z e d in that the heavy metal containing material is aired prior to the treatment with the complex bonding agent.
3. A method according to claim 1 or 2, c h a r a c t e r i z e d in that EDTA is used as complex bonding agent.
4. A method according to claim 3, c h a r a c t e r i z e d in that EDTA is used as complex bonding agent in a concentration ranging from about 5 to about 50 mmol per litre of heavy metal containing material.
5. A method according to claim 3 or 4, c h a r a c t e r i z e d in that additionally pyrophosphate is used as complex bonding agent.
6. A method according to claim 5, c h a r a c t e r i z e d in that pyrophosphate is used as complex bonding agent in a concentration ranging from about 1 to about 50 mmol per litre of heavy metal containing material.
7. A method according to any of the preceding claims, c h a r a c ¬ t e r i z e d in that a bark ion exchanger is used as ion exchan- ger.
8. A method according to claim 7, c h a r a c t e r i z e d in that a sulphonated bark ion exchanger is used as bark ion exchanger.
9. A method according to any of the preceding claims, c h a r a c ¬ t e r i z e d in that the pH value of the mixture of the heavy metal containing material and the complex bonding agent is adjusted from about 3 to about 5.5.
10. A method according to any of the preceding claims, c h a r ¬ a c t e r i z e d in that the liquid separated off is treated on the ion exchanger for a period of from about 30 to about 120 mi¬ nutes.
EP19900916713 1989-11-07 1990-11-07 A method of removing heavy metals form soil, sludge, compost and similar materials Withdrawn EP0500657A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK5538/89 1989-11-07
DK553889A DK553889A (en) 1989-11-07 1989-11-07 PROCEDURES FOR THE REMOVAL OF HEAVY METALS FROM EARTH, SLAM, COMPOSITION AND SIMILAR MATERIALS

Publications (1)

Publication Number Publication Date
EP0500657A1 true EP0500657A1 (en) 1992-09-02

Family

ID=8143305

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900916713 Withdrawn EP0500657A1 (en) 1989-11-07 1990-11-07 A method of removing heavy metals form soil, sludge, compost and similar materials

Country Status (3)

Country Link
EP (1) EP0500657A1 (en)
DK (1) DK553889A (en)
WO (1) WO1991006343A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5051191A (en) * 1990-10-31 1991-09-24 Green Environmental Systems Ltd. Method to detoxify sewage sludge
BG856Y1 (en) * 2004-02-02 2007-01-31 Институт По Инженерна Химия При Бан Means of rendering harmless of heavy metals, pesticides and organic pollutantsin the soil
NL2001725C2 (en) * 2008-06-26 2009-12-29 Miguel Angel Aguilera Zayas Method for removing heavy metals from composted organic waste used as horticultural substrate in potting soil for growing trees, involves sieving composted organic waste through sieve bodies that are provided with apertures

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4267159A (en) * 1980-08-08 1981-05-12 Crane Co. Cyanide recovery
CS245861B1 (en) * 1984-06-01 1986-10-16 Zdenek Matejka Method of heavy metals separation from aminocarboxyl complexing substances
NL8403683A (en) * 1984-12-04 1986-07-01 Tno Recovering heavy metals from sediments and sludges - by acidifying and adjusting chloride ion content to solubilise the metals as chloride complexes, and passing over anion exchanger
DE3545321C2 (en) * 1985-12-20 1995-07-20 Gfs Ges Fuer Flugaschenverwert Process for the treatment of sludges containing heavy metals
DE3617848A1 (en) * 1986-05-27 1987-12-03 Hoelter Heinz Process for removing heavy metals from sewage sludges or any type of sludges
DD252180A1 (en) * 1986-08-18 1987-12-09 Univ Schiller Jena METHOD FOR REMOVING HEAVY METALIONS FROM SOLIDS AND WASTE CLAUSE

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9106343A1 *

Also Published As

Publication number Publication date
DK553889A (en) 1991-05-08
WO1991006343A1 (en) 1991-05-16
DK553889D0 (en) 1989-11-07

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