Recent Developments for the Remediation of Contaminants.

Cesar M. Lozano, Ph. D.Chair Department of Chemistry – Physics,

Universidad del Turabo, PR

Presentation at CIEMADeS, Santo Domingo, D. R.

August 12, 2005

REMEDIATION

• Process or series of processes designated to eliminate or reduce the threaten of contaminants toward humans and/or the environment with the minimum possible impact.

• Why to remediate?

– Probability of Contamination is everywhere.– Many players– $ $ $– Contaminants could be destroyed or

degraded before discarding.

• Contaminants could be separated into eight contaminant groups as follows:

– Nonhalogenated volatile organic compounds (VOCs). – Halogenated volatile organic compounds. – Nonhalogenated semivolatile organic compounds

(SVOCs). – Halogenated semivolatile organic compounds – Fuels. – Inorganics. – Radionuclides. – Explosives.

• Remediation can be accomplished by:– Complete destruction of contaminants

(mineralization).– Partial decomposition of contaminants to less

toxic or dangerous materials.– Extraction of contaminants.– Reduction of mobility of contaminants.

• Classification of treatment technologies according to the process:

– Chemical– Physical– Biological

• Techniques to achieve complete degradation of contaminants:– Chemical Oxidation and Reduction– Incineration– Bioremediation– Electrochemical oxidation– High Temperature Decomposition– Wet Air Oxidation

• Techniques for partial decomposition of contaminants:

– Bioremediation– Chemical processes

• Techniques for extraction of contaminants:– Chemical extraction– Acid leaching– Adsorption/Ionic exchange– Destilation– Filtration– Chemical precipitation– Soil Vapor Extraction

• Techniques for reducing mobility of contaminants:

– Encapsulation– Stabilization– Vitrification– Calcination– Reactive barriers– Phytoremediation– Bioremediation

Factor affecting applicability of a remediation technology

• Applicability– Objective of the technology

– Type of contaminants susceptible to the technology

– Type of site (water, soil, on site, off site, in situ, ex situ)

• Description of the technology– Underlying principles for the operation of the technology.

• Performance of the technology– Is a valid technology? Has been demonstrated?

Factor affecting applicability of a remediation technology

• Limitations of the technology:– WCAP– Design parameters– Site characteristics

• Economic factors– Capital (equipment, design)– Operational (how long?, mano de obra)– Maintenance

• Status of the technology– Experimental– Small-scale operation– Full-scale operation– Field study– patented

• DOE SITE REMEDIATION TECHNOLOGIES BY WASTE CONTAMINANT

Technology Media Waste Contaminant Description

Arc Melter Vitrification Soil Toxic metals Vitrification

Bio-Immobilization of Heavy Metals Ground water, surface water, aqueous streams

Toxic metals Uses bacteria to transform heavy metal ions to an insoluble, less toxic form

Biological Destruction of Tank Waste Supernatants, aqueous streams

Toxic metals Biosorption

Electrokinetic Remediation of Heavy Metals and Radionuclides Soil Heavy metals Electrical current is supplied between two electrodes, ions of contaminant will be attracted to one of the electrodes

Encapsulation of Hazardous Wastes Liquid, slurry, solid waste Metals, inorganics Encapsulation of wastes

In Situ Ground Water Remediation Using Colloid Technology Ground water Heavy metals absorbed on clay and silica

In situ colloid immobilization of contaminants

In Situ Vitrification of Contaminated Soils Soil Heavy metals Immobilization

Mitigation Barrier Covers Arid soils Soluble metals Containment/ Treatment

Polyethylene Encapsulation of Radionuclides and Heavy Metals Aqueous salt and concentrate, saltcake, sludge, ash, ion exchange resin in tanks

Toxic metals (e.g., Cr, Pb, Cd) Encapsulation

Remediation of Metals Contaminated Soils Using Ligand-Based Extraction Technology

Soil Pb, Hg, Cr Density classification followed by extraction to remove metals from soil

OPERATING PARAMETERS AFFECTING TREATMENT COST OR PERFORMANCE System Parameter Biological Activity

In Situ Soil Remediation

Bioventing X X X X X X X X Soil Flushing X X X Soil Vapor Extraction X X

Ex Situ Soil Remediation Land Treatment X X X X X X X Composting X X X X X X X X X X Slurry Phase Bioremediation X X X X X X X X X X Soil Washing X X X Thermal Desorption X X X Incineration X X X X Stabilization*see footnote at bottom X

Ground Water Remediation In Situ Bioremediation X X X X Air Sparging X X Ground Water Pumping X

CLASSIFICATION OF REMEDIAL TECHNOLOGIES BY FUNCTION*

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Treatment Technologies by Type (Vendor Supplied Data)(as of June 8, 2004)

Technology Category No. of Technologies Bioremediation (in situ) - Groundwater 54

Chemical Treatment - Oxidation/Reduction 38

Bioremediation (in situ) – Other 32

In Situ Thermal Treatment 28

Soil Vapor Extraction 25

Thermal Desorption (ex situ) 22

Solidification/Stabilization 21

Passive Treatment Wall (Permeable Reactive Barrier) 18

Flushing (in situ) 15

Off-Gas Treatment 12

Soil Washing 12

Phytoremediation 11

Bioremediation (ex situ) - Solid Phase 10

Multi-Phase Extraction 10

Pump and Treat (perchlorate treatment only) 10

Vitrification 10

Air Sparging (in situ) – Groundwater 8

Bioremediation (ex situ) – Other 8

Bioremediation (ex situ) - Slurry Phase 8

Treatment Technologies by Type (Vendor Supplied Data)(as of June 8, 2004)

Technology Category No. of Technologies Bioventing 8

Chemical Immobilization 8

Bioremediation (in situ) – Lagoon 7

Chemical Treatment – Groundwater 7

Solvent Extraction 7

Bioremediation (in situ) - Biosparging 5

Chemical Treatment – Other 5

Decontamination of Debris 5

In Well Air Stripping 5

Delivery/Extraction Systems 3

Materials Handling/Physical Separation 4

Electrical Separation/Electrokinetics 3

Pyrolysis 2

Acid Extraction 1

Adsorption (in situ) 1

Bioremediation (ex situ) – Biopile 2

Bioremediation (ex situ) - Composting 2

Bioremediation (ex situ) - Land Treatment 2

Dechlorination 2

Fracturing – Hydraulic: Fracturing – Pneumatic 2 : 2

Magnetic Separation 1

Mechanical Soil Aeration 1

Treatment Technologies by Contaminant Group (Vendor Supplied Data) (as of June 8, 2004)

Contaminant Group No. of Technologies Nonhalogenated Volatiles 187 Halogenated Volatiles 184 Nonhalogenated Semivolatiles 143 Solvents 126 Benzene-Toluene-Ethylbenzene-Xylene (BTEX) 125 Halogenated Semivolatiles 118 Polynuclear Aromatic Hydrocarbons (PAHs) 92 Heavy Metals 86 PCBs 74 Explosives/Propellants 65 Organic Pesticides/Herbicides 65 Radioactive Metals 32 Organic Acids 26 Dioxins/Furans 23 Organometallic Pesticides/Herbicides 23 Inorganic Corrosives 16 Inorganic Cyanides 16 Acetonitrile (organic cyanide) 14 Nonmetallic Toxic Elements 10 Chemical/Biological Warfare Agents 6 Asbestos 4 Medical Wastes 4

Our Project

• Chemical/Physical degradation of hazardous compounds– Most compounds are wastes produced in our

research and teaching laboratories– Reduce possibilities of accidents and

contamination– Recuperate solvents from wastes– Reduce cost of disposal of chemical wastes

Current study:

Chemical Oxidation of Coumarin 47• Comparison between several oxidant agents:

permanganate, hydrogen peroxide, and persulfate salts

• Obtain optimal conditions for oxidation: pH, T, Time of reaction

• Detect and characterize possible degradation

by-products (TLC, HPLC, GC-MS, NMR)• Mutagenic studies of residues

• Results:– Oxidation with KMnO4 is the fastest even a

low temperature and at different pH. Concern: subproducts: manganese (II) salts or oxide.

– Oxidation with Persulfate salts is accomplished in about two hours at 50 oC. No subproducts of concern.

– Other oxidants were too slow, but further studies needed.