Arsenic Speciation of CCA-Treated Wood

1. Arsenic Speciation of CCA-Treated Wood Bernine Khan University of Miami May 6th, 2002

2. Purpose of Study Purpose: Speciation analysis - to identify & quantify the arsenic species leaching from CCA-treated wood Interest of individual arsenic species? Arsenic toxicity varies with each species Species of interests to this study: Inorganic - As(III) & As(V) Organic – MMAA & DMAA

3. Speciation Arsenic Valence -3 0 +1 +3 +5 Arsine (g) Inorganic Inorganic Organic As(V) MMAA DMAA As(III) Various forms of an element that make up the total concentration of that element

4. Speciation Arsenic Valence -3 0 +1 +3 +5 Arsine (g) Inorganic Inorganic Organic As(V) MMAA DMAA As(III) Various forms of an element that make up the total concentration of that element

5. Toxicity of Arsenic SpeciesDependent on chemical form • AsH3 - arsine (gas) – most toxic (formed under reduced conditions eg. landfills) • As(III) - arsenite • As(V) - arsenate • MMAA - monomethylarsonic acid • DMAA - dimethylarsinic acid • TMAO - trimethylarsine oxide • AsB - arsenobetaine (marine) * • AsC - arsenocholine (marine) *

6. Toxicity of Arsenic SpeciesDependent on chemical form • AsH3 - arsine (gas) • As(III) - arsenite – inorganic (more toxic) • As(V) - arsenate – inorganic - CCA • MMAA - monomethylarsonic acid • DMAA - dimethylarsinic acid • TMAO - trimethylarsine oxide • AsB - arsenobetaine (marine) * • AsC - arsenocholine (marine) *

7. Toxicity of Arsenic SpeciesDependent on chemical form • AsH3 - arsine (gas) • As(III) - arsenite – inorganic • As(V) - arsenate – inorganic • MMAA - monomethylarsonic acid • DMAA - dimethylarsinic acid • TMAO - trimethylarsine oxide • AsB - arsenobetaine (marine) * • AsC - arsenocholine (marine) * bacteria

8. Toxicity of Arsenic SpeciesDependent on chemical form • AsH3 - arsine (gas) • As(III) - arsenite – inorganic • As(V) - arsenate – inorganic • MMAA - monomethylarsonic acid • DMAA - dimethylarsinic acid • TMAO - trimethylarsine oxide • AsB - arsenobetaine (marine) * • AsC - arsenocholine (marine) *

9. To Study Arsenic Leaching From CCA-Treated Wood Study Setup: Group 1 -Controlled Laboratory Batch Experiments Group 2 -Controlled Field-Scale Experiments Group 3 -Uncontrolled Field-Scale Experiments

10. Group 1 - Controlled Laboratory Batch Experiments • pH Stat – Leaching of As species under different pH conditions (similar to TCLP) • TCLP – Should treated wood waste be considered hazardous • SPLP – Should treated wood waste be land applied • Solvent-Extraction – Leaching characteristics from Deionized Water, Rainwater, & Seawater

11. Group 2 - Controlled Field-Scale Experiments • Lysimeter Study – Leaching of As species under simulated MSW and C&D landfill conditions using field columns • Deck Study – Leaching of As species from a field built treated deck

12. Group 3 - Uncontrolled Field-Scale Experiments • Testing of Groundwater & Landfill Leachate – Identify & quantify As species found at MSW and C&D landfills

13. Group 1 - Controlled Laboratory Batch Experiments pH Stat • Unburned CCA-treated wood subjected to leaching solvent (HNO3 or NaOH – to obtain desired pH) pH 1 2 3 4 5 6 7 8 9 10 11 12 New (0.4 pcf) CCA-treated wood measured at 0.214 pcf Used (0.4 pcf) CCA-treated wood measured at 0.386 pcf

14. Environmental pH Results of pH Stat New Wood TCLP 5 mg/L • As(V) was the only specie detected • Highest concentration at extreme pH • Environmental pH range – As(V) ~ 5mg/L

15. As(III) As(V) Total Environmental pH Results of pH Stat Used Wood TCLP 5 mg/L • Both As(III) & As(V) detected • As(III) up to pH 8.5 • Environmental pH range – Total As increase • Total As > 5 mg/L

16. New (0.214 pcf) Used (0.386 pcf) – 14 yrs Environmental pH Results of pH Stat Total Arsenic Total arsenic conc. (mg/L) TCLP 5 mg/L • More As from new wood – pH 1 - 3 (40 – 9 mg/L) • More As from used wood – pH 3 - 12 (9 – 27 mg/L)

17. Summary of Results pH Stat • Species - New – As(V), Used - As(V) & As(III) • pH significant in As leaching • As(III) due to biological factors • More As leaching from new wood at pH 1 to 3 – more As on new wood surface • – easily released under acidic conditions • More As from used wood at pH 3 to 12 • - Higher retention • - Age of wood – weakening release more As • - As(III) - more mobile specie & may not bind • as strongly as As(V) to the wood

18. Group 1 - Controlled Laboratory Batch Experiments TCLP & SPLP • Unburned CCA-treated wood & CCA-treated wood ash subjected to leaching solvent & rotated for 18  2 hrs. TCLP Unburned CCA-treated wood Untreated 0.25 pcf 0.6 pcf Weathered (0.6 pcf) 2.5 pcf C&D 1 C&D 3 SPLP TCLP CCA-treated wood ash SPLP

19. Results of TCLP Unburned Wood As(III) As(V) Total TCLP 5 mg/L C&D 3 untreated C&D 1 0.25 pcf 0.6 pcf 2.5 pcf weathered • As(III) highest - weathered wood • As(V) highest - 2.5 pcf • Total As increased with increasing retention • As from 0.6 pcf weathered > 0.6 pcf new wood

20. Results of TCLP Wood Ash As(III) As(V) Total TCLP 5 mg/L C&D 3 untreated C&D 1 0.25 pcf 0.6 pcf 2.5 pcf weathered • As(III) highest – 2.5 pcf • As(V) highest - 2.5 pcf • Total As increased with increasing retention • As from 0.6 pcf weathered > 0.6 pcf new wood

21. Results of SPLP Unburned Wood As(III) As(V) Total SPLP 0.05 mg/L C&D 3 untreated C&D 1 0.25 pcf 0.6 pcf 2.5 pcf weathered • As(III) highest - weathered wood • As(V) highest – 0.6 pcf • Total As increased to 0.6 pcf & decline at 2.5 pcf • As from 0.6 pcf weathered > 0.6 pcf new wood

22. Results of SPLP Wood Ash As(III) As(V) Total SPLP 0.05 mg/L C&D 3 untreated C&D 1 0.25 pcf 0.6 pcf 2.5 pcf weathered • As(III) highest – 2.5 pcf • As(V) highest - 2.5 pcf • Total As increased with increasing retention • As from 0.6 pcf weathered < 0.6 pcf new wood

23. Results of TCLP & SPLP Sample Untreated 0.25 pcf 0.6 pcf Weathered 2.5 pcf C&D 1 C&D 3 TCLP (U) 0.02 3.9 5.4 8.3 9.0 1.3 0.2 TCLP (A) 0.08 126 217 224 386 9.2 11.2 SPLP U) 0.03 3.7 6.7 10 5.7 0.5 0.03 SPLP (A) 0.02 56.2 179 128 325 0.5 2.5 Total As – mg/L Fail TCLP – 5mg/L U – unburned wood Fail SPLP – 0.05 mg/L A - ash

24. Summary of Results TCLP & SPLP • Ash samples leached considerably more As • Ash (new) ~118 to 245 mg/L (TCLP) • ~ 53 to 330 mg/L (SPLP) • Unburned (new) ~3 to 10 mg/L (TCLP) • ~ 3 to 6 mg/L (SPLP) • As(III) predominant in weathered than new • Overall As leaching for SPLP < TCLP • SPLP (pH ~4.22) & TCLP (pH ~4.93) • As release sensitive to small pH changes • All failed TCLP & SPLP regulatory limit set forth for other arsenic-containing wastes

25. Group 1 - Controlled Laboratory Batch Experiments Solvent-Extraction – Deionized Water • Unburned CCA-treated wood subjected to deionized water & rotated for 18  2 hrs. Untreated 0.25 pcf 0.6 pcf Weathered (0.6 pcf) 2.5 pcf C&D 1 C&D 2 Unburned CCA-treated wood

26. As(III) As(V) Total Results of Deionized Water (Hypothetical Scenario) C&D 3 untreated C&D 1 0.25 pcf 0.6 pcf 2.5 pcf weathered • As(III) highest - weathered wood • As(V) highest – 0.6 pcf • Total As increased to 0.6 pcf & decline at 2.5 pcf • As from 0.6 pcf weathered > 0.6 pcf new wood

27. Summary of Results of Deionized Water • Unburned (new) ~2.5 to 4.5 mg/L • Unburned (weathered) ~ 5 mg/L • As(III) predominant in weathered • pH of deionized water ~ 6.27 • pH of new wood sample ~4.3 • pH of weathered sample ~5.2 • DI water -no buffering capacity • CCA chemical caused acidic leachate • One factor that drives As leaching - pH

28. Group 2 - Controlled Field-Scale Experiments Lysimeter Study - to be discussed by Jenna Jambeck (University of Florida) Deck Study – to be discussed by Dr. Helena Solo-Gabriele (University of Miami)

29. Tasks to be Completed Group 1- Controlled Lab Batch Expt - Rainwater & Seawater Extraction Group 2 - Controlled Field-Scale Expt - Lysimeter study – awaiting rainfall - Deck study – deck completion (end of May) Group 3 - Uncontrolled Field-Scale Expt - Re-collect & re-analyze groundwater & landfill leachate in Florida

30. Questions ? ? Questions Questions Questions Questions