Leaching Environmental Assessment Framework Pre-Method 1313: Liquid-Solid Partitioning as a Function of Eluate ph using a Parallel Batch Procedure

Transcription

1 Leaching Environmental Assessment Framework Pre-Method 1313: Liquid-Solid Partitioning as a Function of Eluate ph using a Parallel Batch Procedure Andrew C. Garrabrants 1 Rossane DeLapp 1 Florence Sanchez 1 Hans A. van der Sloot 2 David S. Kosson 1 1 Civil & Environmental Engineering, Vanderbilt University, Nashville, TN 2 Energy Research Center of The Netherlands, Petten, The Netherlands Revision 1 March 2010

2 Leaching Controlling Factors H + CO 2 O 2 Chemical Factors Equilibrium or kinetic control Liquid-solid ratio Potential leachability ph Complexation Redox Sorption Biological activity Physical Factors Particle size Flow rate of leachant Rate of mass transport Temperature Porosity Geometry Permeability Hydrological conditions Release Mechanisms Wash Off Dissolution Diffusion Erosion Trace elements Soluble salts TOC (@ high ph) DOC 2

3 Leaching Environmental Assessment Framework Kosson, van der Sloot, Sanchez & Garrabrants (2002) Environ. Engr. Sci., 19(3) Goal to provide improved leaching test methods and interpretation for a wide range of waste, construction and other materials. Collaborative Effort Vanderbilt University and ECN (the Energy Center of the Netherlands) USEPA Office of Resource Conservation and Recovery USEPA Office of Research and Development Pathway Preliminary versions of methods formatted for SW-846 Background theory and interpretation documents Lab-to-field verification (document pending) Inter-lab testing of standard materials ( ) USEPA review by SW-846 personnel USEPA Science Advisory Board approval Incorporate into SW-846 3

4 Preliminary Versions of EPA Methods Pre-Method 1313: Liquid-Solid Partitioning as a Function of Eluate ph using a Parallel Batch Procedure Equilibrium data over broad ph range Basis for geochemical speciation modeling Pre-Method 1314: Liquid-Solid Partitioning as a Function of Liquid-Solid (LS) Ratio using an Up-flow Percolation Column Equilibrium-based release under percolation conditions Estimate of pore solution concentration at low LS ratio Pre-Method 1315: Mass Transfer Rates in Monolithic and Compacted Granular Materials using a Semi-dynamic Tank Leaching Procedure Rate of diffusion/mass transfer from less permeable material Pre-Method 1316: Liquid-Solid Partitioning as a Function of Liquid-Solid Ratio using a Parallel Batch Procedure Equilibrium data over similar LS ratio range as Method

5 Pre-Method 1313 Overview Equilibrium Leaching Test Parallel batch as function of ph Example parallel batch test n samples Specifications 9 parallel batch extractions Particle size-reduced material LS ratio of 10 ml/g-dry material Leachant: DI water plus HNO 3 to lower ph NaOH to raise ph Contact time based on particle size hours Measure and record Equivalents of acid/base added Eluate ph and conductivity Eluate constituent concentrations S 1 n chemical analyses A L A S 2 S n B n L B L n titration curve & liquid-solid partitioning curve for each constituent of concern 5

6 Pre-Method 1313 Procedure Sample Preparation Particle size distribution Air drying (as needed) Particle size reduction (as needed) Pre-test Titration Extraction procedure Schedule of acid/base additions Extraction Extraction Set-up Tumbling Eluate Processing ph, conductivity, Eh (optional) Filtration Preservation 6

7 Granular Sample Preparation Sieve Analysis Particle size distribution Air Drying As appropriate for handling Particle Size Reduction Related to contact time < 5 mm < 2 mm < 0.3 mm Gross reduction (e.g., rock hammer, hydraulic press) Fine reduction (e.g., grinder, mortar and pestle) > 85% of total mass EXTRACTION PARAMETERS AS FUNCTION OF MAXIMUM PARTICLE SIZE Particle Size (85 wt% less than) [mm] US Sieve Size Minimum Dry Mass [g-dry] Contact Time [h] Suggested Vessel Size [ml] ± ± ± ± ± ±

8 Moisture/Solids Content Record mass Moisture/Solids Content as tested - M test oven dried (105 C) - M dry Moisture Content (wet basis) Solids Content Mass of Dish + Sample [g] Mass of Dish + Dry Sample [g] Required to calculate as tested mass equivalent to dry mass Moisture Content Data Entry with LeachXS Lite Template 8

9 Method 1313 Test Equilibrium at specific ph targets Trial Extraction Process Mimics extraction procedure Define titration curve Natural ph (no acid/base) Buffering zones Overlay target ph values Select acid/base additions to reach ph targets Pre-test Titration Titration Curve with ph Targets Selecting Acid/Base Additions 9

10 Column B Select target phs Schedule of Acid/Base Additions Column C Determine equivalents of acid or base from titration curve Column D and E Calculate volume of acid or base Column F Calculate volume of moisture in as tested sample Defining a Schedule of Acid/Base Additions (manual method) Test Position EXAMPLE SCHEDULE OF ACID AND BASE ADDITIONS A B C D E F G Target Equivalents Volume of Volume of Volume of Extract of Acid 2N HNO 3 1N KOH moisture in ph [meq/g-dry] [ml] [ml] sample [ml] Volume of DI water [ml] T T T T T05 Natural T T T B01 QA/QC B02 QA/QC B03 QA/QC Column G Volume of make up deionized water 10

11 Schedule of Acid/Base Additions LeachXS TM Lite Data Template 1) Enter Particle Size and Solids Content 4) Follow Set-up Recipe 2) Enter Acid & Base Normality 5) Record Eluate ph, Conductivity, Eh (optional) 3) Enter Target Equivalents from Titration Curve 6) Verify Final ph in Acceptable Range 11

12 Extraction Set-Up Label Twelve Extraction Bottles Nalgene I-Chem certified N311 series 9 Test positions T01 through T09 3 QA/QC samples (no solid sample) B01 Reagent Water B02 Reagent Water + Acid B03 Reagent Water + Base 125 ml bottles shown Add Solid Sub-sample to Each Test Position Mass adjusted for moisture in as tested material Example 40 g-dry minimum sample 90% Solid Content Add g as tested sample 12

13 Add Make-up Deionized Water Example Extraction Set-Up Required LS ratio of 10 ml/g-dry (LS) 40 g-dry sample (M dry ) 400 ml total liquid includes: Acid/base (V a/b ), moisture in solid (V w,sample ), DI (V DI ) Add Acid or Base Based on equivalents from titration curve Concentrated solutions added volumetrically Dilute solutions may be added gravimetrically 13

14 Extraction Set-Up Tumble for Required Contact Time Contact time depends on particle size End-over-end for best liquid-solid contact 30±2 RPM (i.e., standard TCLP rotators) EXTRACTION PARAMETERS AS FUNCTION OF MAXIMUM PARTICLE SIZE Particle Size (85 wt% less than) [mm] US Sieve Size Minimum Dry Mass [g-dry] Contact Time [h] Suggested Vessel Size [ml] ± ± ± ± ± ± Environmental Express LE Series Rotator 14

15 Eluate Processing Same Process for: All Methods (e.g., 1313, 1314, 1315, 1316) All Test Position Extracts All QA/QC Solutions Method 1313 samples in 50-mL tubes prepared for ICP and TOC/IC Eluate ph and Conductivity Standard SW-846 method 5-10 ml aliquot 15

16 Eluate Filtration Vacuum for non-volatiles Pressure (~1 psig) for Hg & PAHs 0.45-µm pore size membrane Nalgene polycarbonate holders Standard TCLP filtration apparatus may be used Eluate Processing Nalgene Filter Holder 16

17 Save Samples for Analysis 50-mL (min) for metals 50-mL (min) for anions and dissolved carbon Eluate Processing Analytical Sample Preservation Metals: ph < 2 with HNO 3 Anions: none Hg: depends on analytical lab PAHs: depends on analytical lab IC samples: no additives ICP samples: Optima-grade nitric acid to ph < 2 (usually final 1%) 17

18 Processing Schedule Approximate Materials Processing Schedule Schedule Cases: Green case (hatched) Air drying 2 rounds of pre-test titration Red case (solid) Air drying not required Blue case (dotted) Prior titration knowledge Method 1313 Schedule Notes: 1) Schedule is based on workdays (i.e., weekends will add time to total). 2) Air drying of "as received" materials for processing may not be necessary. 3) Particle-size reductions assumes a relatively easy material to reduce via mechanical grinder or light hand grinding with mortar/pestle. 18

19 Acknowledgments Financial and Technical Support CRESP - Consortium for Risk Evaluation with Stakeholder Participation (US Department of Energy-funded research consortium) USEPA Office of Research and Development USEPA Office of Resource Conservation and Recovery 19