CHARACTERISATION OF COAL FLY ASH LEACHING IN RELATION TO LONG TERM RELEASE BEHAVIOR AND JUDGMENT OF ITS USE IN CONSTRUCTION APPLICATIONS

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1 CHARACTERISATION OF COAL FLY ASH LEACHING IN RELATION TO LONG TERM RELEASE BEHAVIOR AND JUDGMENT OF ITS USE IN CONSTRUCTION APPLICATIONS H.A. van der Sloot, D.S. Kosson 2, O. Hjelmar 3 Energy Research Centre of The Netherlands, P.P. Box, 755 ZG, Petten, The Netherlands vandersloot@ecn.nl; 2 Vanderbilt University, Box 83 Station B, Nashville, Tennessee 37235, USA david.kosson@vanderbilt.edu 3 DHI Water Environment Health, Agern Allé 5, DK 2970 Hørsholm, Denmark oh@dhigroup.com International Workshop on Environmental Aspects of Coal Ash Utilization Tel Aviv, Israel, December 5 to 6, 2009

2 Existing policy framework with many sources in EU PROTECTED AREAS CEN CEN TC 230 RESEARCH POLICY 76/60/EEC (BWD) POLICY 79/409/EEC (birds) 92/43/EEC (habitat) DRINKING WATER RESEARCH POLICY 85/337/EEC (impact assessment) POLICY 98/83/EC (DWD) URBAN SECTOR POLICY 9/27/EEC (UWW) 89/06/EEC (CPD) AGRI- CULTURE CEN CEN TC 308 & 345 CEN CEN TC 35 POLICY 86/278/EEC (sludge) 99/3/EC (landfill) POLICY 96/82/EC (seveso) 96/6/EC (IPPC) INDUSTRY CEN CEN TC 292 POLICY POLICY 9/44/EEC (pesticides) 2000/60/EC (Water Framework Directive) 9/276/EEC (nitrates) From a presentation by Philippe Quevauviller at a CEN Workshop on , Coimbra 98/8/EC - Portugal (biocides) Modified from a presentation by Philippe Quevauviller at a CEN Workshop on , Coimbra - Portugal RESEARCH POLICY 80/68/EEC (groundwater) Very similar patch work in other jurisdictions around the globe REACH POLICY In preparation (End of Waste)

3 DIFFERENT IMPACT SCENARIOS.. 6 Dec DG ENV Landfil l Drinking water well Contaminated soil Drinking water pipes Mining Road base Coastal protection Roof runoff Construction Plant Industrially contaminated soil Agriculture sewer

4 . SIMILAR PROBLEM Key issue is the source term = leaching information [conc] Roadbase L/S SOURCE TERM TRANSPORT IMPACT Different for each scenario - material, changes over time (carbonation, redox), etc. Transport in unsaturated zone and saturated zone to point of compliance - Similar for each scenario Point of compliance In first instance a generic sensitive soil system is assumed, which can later be adapted to the actual situation

5 Characterisation leaching tests GRANULAR MATERIALS or MONOLITHIC MATERIALS Same as granular + Chemical speciation aspects ph DEPENDENCE TEST: BATCH MODE ANC, CEN/TS 4429, or EPA Draft method 33 or, COMPUTER CONTROLLED CEN/TS 4997 PERCOLATION LEACHING TEST CEN TS 4405 or EPA Draft method 34 Standardisation: CEN/TC292, ISO/TC90, CEN/TC345, CEN/TC35, SW846 (US EPA) TANK LEACH TEST MONOLITH CEN/TS 5863 and EPA Draft method 35 and COMPACTED GRANULAR LEACH TEST (NEN 7347 and EPA method 33). Time dependent aspects of release This set of tests covers almost any practical condition for any material

6 Development of Standards and Range of Materials Covered European: Percolation test TS 4405 CEN TC 292 WG6 Leaching of waste Granular waste compliance leaching test EN validated CEN TC 292 WG2 or first fraction(s) of percolation test TS5863 and 5864 Dynamic monolith leach test CEN TC 292 WG6 ph dependence leaching test TS 4429 and TS4997 CEN TC 292 WG6 CEN/TC 35 Dangerous substances from construction products Percolation test (TS3), tank test + CGLT (TS2), ph dependence test based on CEN/TC 292 methods Above mentioned tests are suitable for wastes from the extractive industry Further needs: Redox capacity test (starting point NEN 7348; ARD evaluation (CEN TC 292 WG8) International (ISO): Batch tests, percolation test and ph dependence test for soil, sediments and soil like materials ISO 2268 series - 4 (based on CEN TC 292 procedures) ISO TC 90 SC7 WG6 (includes leaching of organic contaminants) to be adopted by CEN/TC 345 Soil. Model parameters: DOC fractionation and quantification of sorptive surfaces (Fe-oxides, Al oxides, clay) in preparation ISO-CD 2782 parts -5. US-EPA: Adoption of tank leach (Draft EPA 35) test for monolithic materials, percolation test (Draft EPA 34), compacted granular leach test and ph dependence (Draft EPA 33) test for implementation in SW 846 (wide range of materials). Conclusion: Harmonisation of leaching tests across fields is feasible and cost effective

7 Leaching Framework Kosson, van der Sloot, Sanchez & Garrabrants (2002) Environ. Engr. Sci., 9(3) Status of adoption of characterisation leaching tests by US EPA Goal to incorporate improved leaching test methods and interpretation guidance into 4 th edition of SW-846. Collaborative Effort Vanderbilt University (with ECN) USEPA Office of Resource Conservation and Recovery USEPA Office of Research and Development Pathway Draft method formatted for SW-846 Background theory and interpretation documents Lab-to-field verification (document pending) Inter-lab testing of standard materials (200) USEPA review by SW-846 personnel USEPA Science Advisory Board approval Coal ash data obtained in US on > 70 CCR s with the specified methods available in LeachXS Lite (free) by January 200

8 Essential Requirement 3 in the Construction Products Directive (CPD) states that construction products shall not lead to environmental and health risks Question: How to satisfy this requirement for the wide variety of construction products covered by over 60 Technical Committees in the European standardisation organisation? Approach : horizontal harmonised test methods covering release of dangerous substances from construction products Aim in CE Marking : Construction products in their normal intended use CEN TC 35 (Construction products: Assessment of release of dangerous substances) works on mandate M/366 to develop tools for release

9 Tiered approach in testing - Different users of the release information have different needs. Both regulators and industry need information with sufficient detail to allow proper judgment of the materials in their intended use scenario. - Once the release characteristics of a product type or class are established much simpler conformity testing will suffice for potentially critical parameters only at a frequency consistent with the risk of approaching/ exceeding set limit values by notified regulations. Level of detail Initial type testing/ characterization Characterisation testing compliance Factory production testing control Frequency of testing

10 JUDGEMENT OF ENVIRONMENTAL IMPACT ON TOTAL COMPOSITION OR ON LEACHING? AND THEN JUST SINGLE POINT OR FULL BEHAVIOUR 00 "Total" Total (HF, HClO4) Le ache d (mg/kg) Ni Log-scale ph Relevant ph domain Le ache d (mg/kg) Total (A qua Regia) Ni Linear-scale Total (HNO3,tef lonbomb) Total (HNO3, HClO4) ph PrEn4429 PrEN 4429 EN CaCl2 SCE Contaminated harbour sediment (Rhine) Different digestion methods for total composition hardly relevant for environmental judgement. Leaching by far more important for environmental impact assessment and for bioavailability. Use of log scale crucial. Single point insufficient

11 Relationships between characterisation test results Emission (mg/kg) , ph dependent Emission of Cl Coal_fly_ash NL TS 4405 Coal_fly_ash_NL TS ph dependent Concentration of Cl , ph Cumulative release (mg/kg) , , Cumulative release of Cl Coal_fly_ash NL TS 4405 slope=.0 0,0 0, 0 Cl concentration as function of L/S Coal_fly_ash NL TS4405 0,0 0, 0 L/S (L/kg) Internal consistency and coherence of test data for ph dependence test and percolation test. Different modes of data presentation provide different answers. Here for Cl: clear washout maximum release reached at L/S=. Higest concentration at Low L/S

12 Relationships between characterisation test results from ph dependence and percolation test 00 0, 0,0 ph dependent Concentration of Al 0 ph dependent Concentration of Sb 0, 0,0 0,00 0,000 0, 0,0 0,00 0,000 Coal_fly_ash TS 4405 Coal_fly_ash NL TS ph dependent Concentration of Zn ph Cumulative release (mg/kg) Cumulative release (mg/kg) Cumulative release (mg/kg) 0 0, 0,0,0E-0,0E-02,0E-03,0E-04,0E-05 0, 0,0 0,00 0,000 Cumulative release of Al Coal_fly_ash NL TS 4405 slope=.0 0,0 0, 0 Cumulative release of Sb 0,0 0, 0 Cumulative release of Zn 0,0 0, 0 L/S (l/kg) 0,0 Al concentration as function of L/S 0 0, Sb concentration as function of L/S 0,0 0,00 0,000 0,0 0,00 0,000 Coal_fly_ash NL TS4405 0,0 0, 0 0,0 0, 0 Zn concentration as function of L/S 0,0 0, 0 L/S (l/kg) Internal consistency and coherence of test data for ph dependence test and percolation test. Solubility control by mineral and sorptive phases. Release mainly controlled by ph change

13 , 0,0 Ca COMPARISON DATA FROM 982 WITH RECENT COAL FLY ASH DATA Mg 0, 0,0 0,00 0,000 0, 0,0 0,00 W Zn Column leaching data from alkaline coal fly ash (ECN20) with percolating acid match well with ph dependence test data illustrating local equilibrium to be a reasonable assumption. Geochemical modelling is in progress 0, ph 0, ph

14 Eluate concentration (mg/l) Eluate concentration (mg/l) , 0,0 0,00 Comparison of laboratory column test data and lysimeter leachate Lysimeter-4 Lysimeter-9 Lysimeter-4 Column-4 0,00 0,0 0, L/S (L/kg) 0,00 0,0 0, L/S (L/kg) Na Data from Ole Hjelmar DHI As Eluate concentration (mg/l) Eluate concentration (mg/l) , 0 0, 0,0 0,00 0,0 0, L/S (L/kg) 0,00 0,0 0, L/S (L/kg) Ca Cr Eluate concentration (mg/l) Eluate concentration (mg/l) , 0,0 0,00 0,0 0, L/S (L/kg) 0,00 0,0 0, L/S (L/kg) Sulfate Presenting data from lab and field as a function of L/S leads to consistent and comparable results Mo

15 Leaching of B as a function of ph 0 0, 0,0 ph dependent Concentration of B CFA NL CFA NL col CFA India CFA various NL CFA IS RU CFA IS OR ph Many oxyanions show similar release behaviour as ph decreases leachability increases. When fly ash is mixed with cement for concrete applications, the effect only shows at longer term. By mixing fly ash with soil, the effect is immediate.

16 ROLE OF DOC IN COAL FLY ASH LEACHING ph dependent Concentration of DOC DOC concentration as function of L/S , Coal_fly_ash_NL - TS4405 Coal_fly_ash_NL - TS ph 00 0 Coal_fly_ash_NL - TS4405 0, 0,0 0, 0 L/S (l/kg) Conclusion: not negligible

17 Statistical evaluation for WFT classification and test frequency in case of FT k-value = (log (regulatory limit) Y average of log normal data )/ Stdev log normal data K-value K-value Chance of Risk of non- Testing Parameter N=5 N=0 compliance compliance frequency # relevance > 6.2 > 4.63 > 99.9 % < 0.% WFT % -99.9% 0.% -% Every year FT % -99% % -0% Every 0 batches FT % -90% 0% -30% Every 4 batches FT % -70% 30% -50% Every other batch FT < 0.69 < 0.44 < 50% > 50% Every batch FT Integration of statistics, leaching behaviour, parameter selection based on WFT and FT classification of substances (CEN/TC35 ER 3 of CPD) Recent Dutch Soil Protection Law data used for comparison # Example of testing frequency (not fixed; to be decided)

18 Cu leaching from worldwide MSWI bottom ashes 0000 ph dependent Release of Cu 00 Cumulative release of Cu Release (mg/kg) Cumulative release (mg/kg) ph L/S (l/kg) MSWI bottom ash sources: UK, AT, F, NL, DE, DK, SE, USA, Taiwan Same release controlling mechanisms for Cu worldwide

19 Cu leaching from worldwide MSWI bottom ashes 7 RNC < 0. % 5 RNC 0. - % 9 Cu K-Value RNC - 0 % Relevant ph domain RNC 0-30 % RNC % RNC > 50 % Cu Average k=6.2 k=4.67 k=2.74 k=.46 k= ph K-Value k=6.2 k=2.74 k=0.69 Average One Country k=4.67 k=.46 Average Worldw ide Average One facility Percolation test MSWI bottom ash N= L/S (l/kg) k - value evaluation of characterisation leaching test data provides additional possibilities beyond the frequency of testing, as it provides the means to determine, which substances can be declared WFT. (RNC = risk of non-compliance)

20 LeachXS Structure LeachXS Lite with data viewer function in development (free)

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24 Recent studies in which the new test methodology has been applied Carter, C.M., van der Sloot, H.A. and Cooling D. ph dependent extraction of soils and soil amendments to understand the factors controlling element mobility - New approach to assess soil and soil amendments. European Journal of Soil Science. European Journal of Soil Science, August 2009, 60, Van der Sloot, H. A., van Zomeren, A., Meeussen, J. C. L., Seignette, P., Bleijerveld, R., Interpretation of test method selection, validation against field data, and predictive modelling for impact evaluation of stabilised waste disposal. Journal of Hazardous Materials 4, Postma J.F., van der Sloot, H.A. and van Zomeren A. Ecotoxicological response of three waste samples in relation to chemical speciation modelling of leachates. In : Ecotoxicological characterization of waste Results and experiences from a European ring test. Eds: J. Römbke, R. Becker & H. Moser, Springer Science+Business Media, Inc. Norwell (MA),2009. H. A. van der Sloot, P.F.A.B. Seignettte, J.C.L. Meeussen, O. Hjelmar and D.S. Kosson. A database, speciation modelling and decision support tool for soil, sludge, sediments, wastes and construction products: LeachXS - Orchestra. In: Venice Symposium, Venice To be published in WM.

25 Conclusions - Single step leaching tests alone are absolutely insufficient to address environmental issues related to beneficial uses of coal fly ash. -The characterisation leaching tests (ph dependence, column leaching and monolith leaching) provide a sound basis for evaluating treatment options and beneficial uses of coal fly ash. Part of these tests may be used for QC and compliance testing - These methods are now being recognized as widely applicable tools for leaching assessment and are more and more considered by regulators (e.g. Netherlands, Germany, US EPA, Japan, Australia) - The geochemical modelling capabilities provide insight in the release controlling phases and thus provide means to take control. - LeachXS and LeachXS Lite are designed for data evaluation within a sector and can help to streamline data handling and quality control for coal fly ash.

26 Conclusions The collection of coal ash leaching data from different sources in a unified database will lead to a level of comparability of samples from worldwide sources, which is unprecedented. However, it implies that producers will have to step over their anxiety to share data. For several elements coal fly ash can be shown to fall under the WFT (without further testing) classification. However, a few elements will fall under the FT (further testing) classification with a frequency that through statistical data evaluation can be defined for a given installation. The understanding of the factors controlling release using characterization tests provide a means to modify coal fly ash quality based on a scientifically sound basis rather than trial and error approaches, which may only provide a temporary quality improvement.