INTERNATIONAL CENTRE FOR SCIENCE AND HIGH TECHNOLOGY

Transcription

1 INTERNATIONAL CENTRE FOR SCIENCE AND HIGH TECHNOLOGY Technologies for PTSs contaminated soils: decision support tools for technology evaluation and selection Workshop on Persistent Toxic Substances Contamination of the European Region Brno, Czech Republic November 2003 Andrea Lodolo ICS-UNIDO, Italy

2 Technologies for PTSs contaminated soils: decision support tools for technology evaluatio and selection A review of established and emerging technologies for the treatment of soils contaminated with Persistent Toxic Substances (which include the Persistent Organic Pollutants) is presented. Technologies are classified as biological, physico-chemical and thermal treatments. Advantages and limitations of each technology are also presented in order to assess their applicability in specific site conditions. The MCA based DST software prototype for technology evaluation and selection DARTS, being developed at ICS, is presented.

3 Persistent Toxic Substances Persistent Toxic Substances (PTS s) is a group of substances with specific characteristics of persistence, bioaccumulation and toxicity. The group of PTSs is integrated by the POPs (Persistent Organic Pollutants) and some inorganic compounds (mercury, cadmium, lead and compounds). POPs are highly stable organic compounds used as pesticides, herbicides, fungicides, or in chemical industry. They are also generated as the byproduct of combustion and industrial processes. They are classified through lipophilicity, persistence (resistance to photolytic, chemical and biological degradation) and toxicity.

4 Persistent Toxic Substances Persistent Toxic Substances Aldrin Dieldrin Hexachlorobenzene, HCB Chlordane Endrin Mirex Chlordecone Heptachlor Polychlorinated biphenyls (PCBs) DDT Hexabromobiphenyl Toxaphene Dioxins and Furans Polychlorinated Napthalenes Polycyclic Aromatic Hydrocarbons (PAHs) Polychlorinated benzenes Polychlorinated Paraffins Kepone (chlordecone) Polychlorinated phenols Polybrominated compounds Lindane Isodrin Parathion Malathion Alkyl-lead Mercury and compounds Octachlorostyrene Dinitropyrene Cadmium and compounds Benzopyrene

5 Investigated: Soil contamination Soil contamination ~100 million hectars of contaminated soil in the world ~ 20 million hectars of contaminated soil in Western Europe ~ contaminated sites in USA ~ contaminated sites in E.U.: ~ sites require urgent interventions > 1 billion cubic meter of contaminated soil Estimates (*): sites in E.U.; 85 billion (*) European Topic Centre Soil, 1998

6 Soil recovery annual market Soil recovery annual market Year 1990 Year 2000 (billion US$) (billion US$) E.U. ~ 3.5 ~ 9.0 Japan ~ 1.5 ~ 4.0 USA ~ 6 ~15.5 Total ~ 10 ~ 28.5 Increasing technological demand Fast technological development Fast market development Many remedial options available

7 Contaminated Land Management Contaminated Land Management Source Pathway Receptor Source Removal Pathway Control Protection Remediation Remediation Regulation Destruction Extraction Stabilization Immobilization Land use limitations

8 Breaking the Chain Breaking the Chain Source removal includes technologies aiming towards treatment of the source of pollution Breaking the pathway includes technologies hindering leakage and further spreading of pollutants Hindering a contaminant to reach a receptor could mean changing the land-use by regulation

9 Remediation a treatment that permanently and significantly reduces the volume, toxicity or mobility of hazardous substances, pollutants and contaminants as a principal element (U.S. EPA)

10 Remediation technologies Remediation technologies Established Established treatment technologies are those which have been widely applied in full-scale interventions. Efficiency, process parameters and costs are well known.

11 Remediation technologies Remediation technologies Innovative Innovative treatment technologies can achieve the same results as established technologies at a lower cost, or they can be more effective than established technolgies at the same costs. Efficiency, process parameters and costs must be further assessed.

12 Remediation Technologies Remediation Technologies Type of application In-situ no escavation Ex-situ on site off site escavation escavation + transportation

13 Remediation Technologies Remediation Technologies Biological Process involved Physical, Chemical, Physico-Chemical Thermal Combinations (treatment trains)

14 Biological Processes Biological Processes Biological treatment is a process whereby contaminants in soil, sediments, sludge or groundwater are transformed or degraded into innocuous substances such as carbon dioxide, water, fatty acids and biomass, through the action of microbial metabolism...

15 Physico-Chemical Processes Physico-Chemical Processes Physical/chemical treatment uses the physical and/or chemical properties of the contaminants or of the contaminated medium to destroy (i.e., chemically convert), separate, or contain the contamination. Physical processes: the phase transfer of pollutants from the matrix is induced. Chemical processes: the chemical structure (and then the behaviour) of pollutants is changed by means of chemical reactions to produce less toxic or better separable compounds from the matrix.

16 Thermal Processes Thermal Processes Thermal processes use heat to increase the volatility, to burn, decompose, destroy or melt the contaminants...

17 Classification of Remediation Classification of Remediation Effect on Contaminant Destruction as a result of a complete biological and/or physicochemical degradation of contaminants (e.g. at high temperatures by thermal treatments); Removal of contaminants by (a) some process of phase transfer/ mobilisation and recapture (e.g. leaching and sorption); (b) some process of concentration and recovery / harvesting (e.g. by physical separation), or (c) a combination (e.g. via hyper-accumulator plants); Recycling might be the "ultimate" form of removal;

18 Classification of Remediation Classification of Remediation Effect on Contaminant Stabilization: where a contaminant remains in situ but is rendered less mobile and or less toxic by some combination of biological, chemical or physical processes. For most practical site remediatio some combination of these outcomes is achieved (treatment trains Containment: where the contaminated matrix is contained in a wa which prevents exposure of the surrounding environment. Immobilisation: where contaminants are changed into less available constituents by some transportation process or by adding immobilizing agents. (need of long term performance assessment)

19 Classification of Remediation Classification of Remediation Ranking in order of preference (environmental benefit of permanently removing a contamination problem): Recycling > destruction > removal > stabilization > immobilization > containment Wider environmental effects, costs and other benefits must also be considered.

20 Remediation Technologies Remediation Technologies Biological Physical Chemical Physico-chemical Thermal

21 Biodegradation or Bioremediation Biodegradation or Bioremediation Metabolic activity is key to biodegradation Accomplish complete mineralization or partial degradation in both aerobic and anaerobic environments Stimulate indigenous microbes to enhance biodegradation

22 Biological Processes Biological Processes Advantages Treat wide range of organics Are applicable to all media Generate little to no residuals Offer flexibility in system design Cost less than other technologies

23 Biological Processes Biological Processes Limitations Not generally applicable to inorganics Slow treatment time Requires extensive site characterization Limited by site characteristics

24 Bioremediation Technologies Bioremediation Technologies Biopiles (ex) Slurry-phase bioremediation - Bioslurry (ex) Bioventing (in) Composting (ex) Enhanced bioremediation (in) Solid-phase bioremediation - Landfarming (ex) Monitored natural attenuation - Intrinsic bioremediation (in) Phytoremediation (in)

25 Bioremediation Technologies Bioremediation Technologies Technology Main Target Contaminants Biopiles (ex) SVOCs, VOCs, X-SVOCs, X-VOCs, PAHs Bioslurry (ex) SVOCs, VOCs, X-SVOCs, X-VOCs, PAHs, Diox./Fur., Pest. Bioventing (in) SVOCs, VOCs, X-SVOCs, X-VOCs, PAHs Composting (ex) SVOCs, VOCs Enh. bioremediation (in) SVOCs, VOCs, Pest. Landfarming (ex) SVOCs, VOCs, X-SVOCs, X-VOCs, PAHs, Pest. Natural attenuation (in) SVOCs, VOCs, Phytoremediation (in) SVOCs, VOCs, Inorg., Heavy metals

26 Bioremediation Technologies Bioremediation Technologies Technology Cost (US$/ton) Clean-up time* Biopiles (ex) < 6 months Bioslurry (ex) to 12 months Bioventing (in) < 6 months Composting (ex) to 12 months or > Enh. bioremediation (in) to 12 months Landfarming (ex) to 12 months or > Natural attenuation (in) 10,000/year > 12 months Phytoremediation (in) > 12 months (*) Time referred to a standard mass of about tons

27 Remediation Technologies Remediation Technologies Biological Physical Chemical Physico-chemical Thermal

28 Physical Processes Physical Processes Physical properties of the contaminants or of the contaminated medium are used. By means of a physical mechanism the phase transfer of contaminants is induced. No modification of the chemical structure of contaminants occurs.

29 Physical Processes Physical Processes Advantages Fast treatment Treats variety of contaminants Applicable to all media Less site characterization required Lower relative cost

30 Physical Processes Physical Processes Limitations Often do not treat but only transfer the contaminant Residuals require treatment Limited by site characteristics

31 Chemical Processes Chemical Processes The chemical structure (and then the behaviour) of the pollutant is changed by means of chemical reactions

32 Chemical Processes Chemical Processes Advantages Fast treatment Treat variety of contaminants Applicable to all media

33 Chemical Processes Chemical Processes Limitations Require extensive site characterization Limited by site characteristics Residuals require treatment

34 Physical and Chemical Technologies Physical and Chemical Technologies Landfill cap systems (in or ex) Chemical Dehalogenation (ex) Electrokinetic (in) Soil vapour extraction (SVE) (in or ex) Soil Flushing (in) Soil Washing (ex) Supercritical water oxidation (ex) Solvent extraction (ex) Solvated electron (ex) Solar detoxification (ex) Solidification/stabilization (in or ex)

35 Physical and Chemical Technologies Physical and Chemical Technologies Technology Main Target Contaminants Landfill cap systems (in or ex) Chemical Dehalogenation (ex) Electrokinetic (in) Soil vapour extraction (SVE) (in or ex) Soil Flushing (in) Soil Washing (ex) Supercritical water oxidation (ex) Solvent extraction (ex) Solvated electron (ex) Solar detoxification (ex) Solidification/stabilization (in or ex) all kind of contaminants X-VOCs, X-SVOCs, PCBs, Diox/Fur. Heavy Metals X- (VOCs, SVOCs) X- (VOCs, SVOCs), PAHs, H.M. X- (VOCs, SVOCs), PAHs, H.M., PCBs, Pest. X- (VOCs, SVOCs), PCBs, Pest. X- (VOCs, SVOCs), PAHs, H.M., PCBs, Pest., Diox/Fu X-VOCs, X-SVOCs, PCBs, Diox/Fur., Pest. X- (VOCs, SVOCs), PAHs, H.M., PCBs, Pest., Diox/Fu Heavy metals, PAHs, PCBs, Inorg.

36 Physical and Chemical Technologies Physical and Chemical Technologies Technology Cost (US$/ton) Clean-up time Landfill cap systems (in or ex) N. A. N. A. Chemical Dehalogenation (ex) < 6 months Electrokinetic (in) to 12 months Soil vapour extraction (SVE) (in or ex) to 12 months or Soil Flushing (in) to 12 months Soil Washing (ex) to 12 months Supercritical water oxidation (ex) < 6 months Solvent extraction (ex) to 12 months Solvated electron (ex) < 6 months Solar detoxification (ex) N. A. 6 to 12 months Solidification/stabilization (in or ex) to 12 months or (*) Time referred to a standard mass of about tons

37 Thermal Processes Thermal Processes Advantages Fast treatment Applicable to organics Applicable to solid media Significant reduction in volume

38 Thermal Processes Thermal Processes Limitations Not applicable to inorganics Not applicable to liquid or gaseous media Residuals require treatment Efficiency controlled by contaminant Higher relative cost

39 Thermal Technologies Thermal Technologies Combustion systems (ex) Thermal desorption systems (in or ex) Pyrolysis (ex) Plasma Arc Systems (ex) Vitrification (in or ex)

40 Thermal Technologies Thermal Technologies Technology Main Target Contaminants Combustion systems (ex) Thermal desorption systems (in or ex) Pyrolysis (ex) Plasma Arc Systems (ex) Vitrification (in or ex) X- (VOCs, X-SVOCs), PAHs, PCBs, Pest., Diox/Fur. VOCs, SVOCs, PAHs, PCBs, Pest., Diox/Fur. X- (VOCs, SVOCs), PAHs, PCBs, Pest., Diox/Fur. PCBs, Pest., Diox/Fur. X- (VOCs, SVOCs), PAHs, H.M., PCBs, Pest., Diox/Fur., Inorg

41 Thermal Technologies Thermal Technologies Technology Cost (US$/ton) Clean-up time* Combustion systems (ex) < 6 months Thermal desorption systems (in or ex) to 12 months Pyrolysis (ex) 300 < 6 months Plasma Arc Systems (ex) to 12 months Vitrification (in or ex) < 6 months (*) Time referred to a standard mass of about tons

42 Remediation technology assessmen Remediation technology assessmen Many technologies available Many ratable and non ratable parameters must be considered Assessment of remediation technology is a difficult process

43 Process to assess remediation technologies Process to assess remediation technologies Collect information Identify common parameters between different technologies Define criteria to assess information Define criteria to compare common parameters between different technologies Screen and evaluate information Define ranking criteria for each common parameter Create data bases Give a ranking to each technology for each parameter

44 Some elements to assess remediation technologie Some elements to assess remediation technologies Applicability (target contaminants) Minimum achievable concentration Clean-up time required Reliability and maintenance Decontaminated soil quality Residuals produced (by-products post treatment needed) Site data needed Overall cost Public acceptability Safety Development status Environmental impacts Performance dependency on site characteristics

45 Process to select remediation technologies Process to select remediation technologies Select specific common parameters between different technologies Rank technologies on the basis of their performance in each weighted criteria Selected parameters become criteria for technology comparison Choose the best ranked technology Weight each criteria

46 Remediation technology selection Remediation technology selection Many technologies available Many ratable and non ratable criteria must be considered Selection of remediation technology is a difficult process Need of decision support tools

47 Decision Support Tools Decision Support Tools Nature of Support Tools that help to solve the problems involved in decision making Tools that facilitate knowledge management capabilities Tools that help to coordinate distributed decision making process Tools that offer advice, expectations, facts, analyses, etc may play a stimulative role

48 Decision Support Tools Decision Support Tools Computer-Based Decision Support purposes: Improve decision making ability of managers (and operating personnel) by allowing more or better decisions within constraints of cognitive, time, economic limits Increase productivity of decision makers Supplement one or more of a decision maker s abilities Facilitate one or more of the decision-making phases Aid decision maker in addressing unstructured or semistructured decisions

49 Decision Support Tools Decision Support Tools Limitations: unable to replicate some human DM skills/talents may be too specific (i.e., many DSTs needed in course of working on a single decision - how to coordinate them?) may not match DM s mode of expression or perception constrained by the knowledge it possesses (to what extent can a DST learn and is its knowledge at any moment sufficient for DM s needs?) > need of continuous improvement

50 AIMS: Remediation technology selection Remediation technology selection Decision Aid for Remediation Technology Selection DARTS a software tool being developed at ICS To identify and sistematically compare information about conventional and innovative remediation technologies to meet remediation goals To esthablish a structured evaluation and selection process To define consistent and measurable criteria for technology evaluation and selection To provide documented and reproducible evaluation wich can be updated as needed information become available To provide flexible optimized approach for technology evaluation and selection To fasten preliminary steps in feasibility studies To provide a tool for the evaluation of remediation interventions

51 Decision Aid for Remediation Technology Selection DARTS DARTS key elements Technologies database Contaminants database Set of selected criteria Multi Criteria Analysis system

52 Decision Aid for Remediation Technology Selection DARTS Contaminant classes (US-EPA) Nonhalogenated VOCs (Volatile Organic Compounds) Halogenated VOCs Nonhalogenated SVOCs (Semi-Volatile Organic Compounds) Halogenated SVOCs Fuels Heavy metals Explosives Radionuclides Inorganics

53 Decision Aid for Remediation Technology Selection DARTS Criteria to assess remediation technologies being considered in present DARTS version: applicability minimum achievable concentration clean-up time required reliability and maintenance data needs overall cost safety public acceptability development status stand alone character residuals produced DARTS future development Criteria to be included in the next DARTS version Performance dependency on site characteristics: Geology/hydrogeology, Soil characteristics, Pollutant characteristics and behaviour etc...

54 Decision Aid for Remediation Technology Selection DARTS The user selects one or more target contaminants The program displays the available technologies for the specific contaminants The user then selects the criteria according to contaminant type and parameter rating The user sets criteria importance (weight ranges between 0 and 100%) MCA is performed and recommended technologies are shown and sorted (together with ranked alternatives) Yes Want to iterate again? No The user selects a remediation technology

55 DARTS prototype

56 DARTS prototype

57 DARTS prototype

58 Decision Aid for Remediation Technology Selection DARTS DARTS future development Acquire and assess further information on emerging technologies Implement technologies database Add more evaluation criteria Test and validate DARTS Make DARTS accessible through Internet

59 ICS-UNIDO Pure and Applied Chemistry Stanislav Miertus - Area Director Andrea Lodolo - Scientific Advisor ICS-UNIDO AREA Science Park, Building L2 Padriciano, Trieste, Italy tel /12 fax e.mail: andrea.lodolo@ics.trieste.it