Presentation on theme: "Recent Developments for the Remediation of Contaminants. Cesar M. Lozano, Ph. D. Chair Department of Chemistry – Physics, Universidad del Turabo, PR Presentation."— Presentation transcript:
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).Nonhalogenated volatile organic compounds (VOCs) –Halogenated volatile organic compounds.Halogenated volatile organic compounds. –Nonhalogenated semivolatile organic compounds (SVOCs).Nonhalogenated semivolatile organic compounds (SVOCs). –Halogenated semivolatile organic compoundsHalogenated semivolatile organic compounds –Fuels.Fuels. –Inorganics.Inorganics. –Radionuclides.Radionuclides. –Explosives.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 TechnologyMediaWaste ContaminantDescription Arc Melter VitrificationSoilToxic metalsVitrification Bio-Immobilization of Heavy MetalsGround water, surface water, aqueous streams Toxic metalsUses bacteria to transform heavy metal ions to an insoluble, less toxic form Biological Destruction of Tank WasteSupernatants, aqueous streams Toxic metalsBiosorption Electrokinetic Remediation of Heavy Metals and RadionuclidesSoilHeavy metalsElectrical current is supplied between two electrodes, ions of contaminant will be attracted to one of the electrodes Encapsulation of Hazardous WastesLiquid, slurry, solid wasteMetals, inorganicsEncapsulation of wastes In Situ Ground Water Remediation Using Colloid TechnologyGround waterHeavy metals absorbed on clay and silica In situ colloid immobilization of contaminants In Situ Vitrification of Contaminated SoilsSoilHeavy metalsImmobilization Mitigation Barrier CoversArid soilsSoluble metalsContainment/ 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 SoilPb, Hg, CrDensity classification followed by extraction to remove metals from soil
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 KMnO 4 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 o C. No subproducts of concern. –Other oxidants were too slow, but further studies needed.