1. 2005 TAG Meeting
Evaluation of Thermal Processes for CCA Wood Disposal in Existing Facilities
Anadi Misra1, Brajesh Dubey1, Chang-Yu Wu1, Timothy Townsend1, Helena Solo-Gabriele2
1University of Florida 2University of Miami
Aerosol and Particulate Research Laboratory
November 8, 2018

2. Aerosol and Particulate Research Laboratory
Overview
Background
Methodology
Task 1: Inventory of Combustion Facilities
Task 2: Survey of Arsenic air pollution control technologies
Task 3: Screening of potential materials for minimizing leaching
Results and Discussions
Summary and Future Work
Why is the disposal of CCA wood through thermal processes an issue ?
Proposed solution
Aerosol and Particulate Research Laboratory
November 8, 2018

3. Aerosol and Particulate Research Laboratory
Background: CCA Wood
Currently not considered hazardous under Resource Conservation & Recovery Act (RCRA) which monitors hazardous waste
Disposed alongside other wood waste in Construction & Demolition (C & D) debris landfill
~ 60% is burned to produce energy
Aerosol and Particulate Research Laboratory
November 8, 2018

4. Background: Problems with incineration of CCA Wood
Heavy Metal Emissions from combustion
Leaching of Heavy Metals from Ash into Groundwater
Rain
Volatilization and entrainment, metals in submicron range, difficult to capture,
Contaminated Soil
Ground Water
National Physical Lab:
Aerosol and Particulate Research Laboratory
November 8, 2018

5. Aerosol and Particulate Research Laboratory
Proposed Solution
Use mineral sorbents (e.g. lime) for
Preventing emission of metals
Preventing leaching of metals from incinerator ash
Many sorbents have good capture efficiency with respect to metal emissions ( Venkatesh et al, 1996, Kenjiro et al, 2004)
 so we have focused on the leaching behavior of CCA metals on interaction with sorbents
Activated Carbon Injection :
Aerosol and Particulate Research Laboratory
November 8, 2018

6. Aerosol and Particulate Research Laboratory
Methodology
Task 1: Inventory of Existing Major Wood-Fired Capable Facilities
Task 2: Survey of Available Arsenic Air Pollution Control Technologies
Task 3: Screening of Potential Materials for Preventing Heavy Metal Leaching from Incineration Product
Task 1 was reported in the last TAG meeting too. Thanks to FDEP officials.
As is much more volatile and has been reported to be the main metal in leaching. Then state that there is limited resource and time for this project. So, we only focus on As for this project.
Aerosol and Particulate Research Laboratory
November 8, 2018

7. Task 1: Inventory of Combustion Facilities in Florida
Type
Max. Heat input rate
Types of fuels used
Air pollution control devices
Cement
Kiln
(7)
MMBtu/hr
Coal (bituminous usually), whole
tires, propane, natural gas,
petroleum coke, propane, No. 2
fuel oil, residual fuel oil, No. 6 fuel
oil
Baghouses, ESPs
Coal
Fired
(14)
Coal (bituminous , pulverized,
latex coated, mixed with
petroleum coke), natural gas,
Nos.1,2 & 6 fuel oil, carbonaceous
fuel, Briquette Mixture, refuse
derived fuel (RDF)
Cold side & Hot side ESP, flue gas desulphurization (FGD) unit, wet caustic scrubber , Selective Non Catalytic Reduction system (SNCR)
, spray dryer absorber, and fabric filter baghouse
The details are available on our website
Aerosol and Particulate Research Laboratory
November 8, 2018

8. Task 1: Inventory of Combustion Facilities in Florida (cont.)
Type
Max. Heat input rate
Types of fuels used
Air pollution control devices
Wood
Fired
(31)
MMBtu/hr
carbonaceous fuel (bagasse, wood chips, rice hulls), natural gas, bark and primary clarified wood fibers, dry wood waste, combination of waste wood and paper( with some lesser amounts of peanut hulls, lumber, oily rags, oil soaked peat moss) MSW, Coal, No. 2 & 6 fuels, oil soaked paper towels, biomass, sugar mill waste, tires, landfill gas.
fly ash arrestor,
wet caustic scrubber , SNCR, Multicyclone, ESP, venturi scrubber, multiple tube dry collectors, Joy type Impingement Scrubber, spray dryer absorber, fabric filter
WTE
(14)
MMBtu/hr
MSW
fabric filter baghouse, spray dry absorbers, activated carbon injection system, SCNR , dry scrubber, mercury abatement systems, ESP
There are a lot more wood fired boilers, and their capacities are typically smaller.
So, from the data, we can see there are many types of fuels used which will definitely affect the chemistry of CCA metals in the combustion system and therefore their fate. Also, the air pollution control devices are very different from one category to the other.
Aerosol and Particulate Research Laboratory
November 8, 2018
Back

9. Task 2: Arsenic Pollution Control Technologies
Reduction in emissions
Co-incineration along with dilution
Low temperature pyrolysis
Capture of emissions
Combination of filters and scrubbers
Sorbent injection combined with filtration
Briefly discuss the pros and cons of these technologies. Do not just read your text. Ultimately, you want to lead to sorbent injection as the best choice.Also briefly metion other industries that have arsenic as a focus metal to deal with.
Pyrolysis Furnace
Econ Systems:
Baghouse
Aerosol and Particulate Research Laboratory
November 8, 2018
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10. Aerosol and Particulate Research Laboratory
Task 3: Screening of Potential Materials for Preventing Heavy Metal Leaching from Incineration Product
Evaluate Potential mineral sorbents in combustion environments
Analysis of Ash by
Toxicity Characteristic Leaching Procedure (TCLP) for leaching properties
X-Ray Diffraction (XRD) to identify the crystalline composition
Aerosol and Particulate Research Laboratory
November 8, 2018

11. List of Sorbents Used in Experiments
Name of Sorbent
Chemical formula
Alumina
Al2O3
Attapulgite Clay*
Si16Mg H3.6O 5.9
Calcium Hydroxide
Ca(OH)2
Cement*
Si9Al3Ca 29.3 S0.8 H3Fe1O57
Diatomaceous Earth*
Si106Al4.6Ca 0.3 Mg0.5Fe2O229.5
Ferric Oxide
Fe2O3
Kaolin
H2Al2Si2O8-H2O
Magnesium Hydroxide
Mg(OH)2
Silica
SiO2
*Approximate molecular formula based on % composition. Varies according to mineral composition
Aerosol and Particulate Research Laboratory
November 8, 2018

12. Experimental Procedure
Prepared a spike sample of CCA metals having same concentration as that of CCA Type C chemical (47.5% CrO3, 18.5% CuO & 34% As2O5)
Heated sorbent and spike sample at 700oC, 900oC & 1100oC for 30 minutes
Analysis of the residue
TCLP Leaching tests
Speciation characterization by XRD
Aerosol and Particulate Research Laboratory
November 8, 2018

13. Results: Arsenic Retention in Residue
Ca(OH)2 , Cement and Mg(OH)2 show over 98% retention for As at both temperatures
Alumina & Diatomaceous Earth show over 80% retention at 900oC
This is a separate question from the presentation, but related to your study. Will a higher Cu content result in lower As leaching?
Please also check the soluability of CuCr2O4 and Cu3(AsO4)2.
Aerosol and Particulate Research Laboratory
November 8, 2018

14. Results: Arsenic Leaching from Residue
Cement, Ca(OH)2 and Mg(OH)2 leach less than 5 mg/l of arsenic in both cases
All other sorbents exceed the TC limit for leaching
Aerosol and Particulate Research Laboratory
November 8, 2018

15. Results: Chromium Retention in Residue
Alumina, Silica, Kaolin & Diatomaceous Earth show over 90% retention for Cr at both temperatures
Attapulgite Clay shows higher Cr retention at 900oC
Ca(OH)2 and Cement show negligible retention
Aerosol and Particulate Research Laboratory
November 8, 2018

16. Results: Chromium Leaching from Residue
Alumina and Silica leach less than 5 mg/l of Cr at both temperatures
Kaolin leaches less than 5 mg/l of Cr at 900oC
All other sorbents exceed the TC limit at both temperatures
Diatomaceous Earth doesn’t work well in either case
Aerosol and Particulate Research Laboratory
November 8, 2018

17. Results: Copper Retention in Residue
All sorbents except silica and attapulgite clay show ~80% or greater retention at both temperatures
Cement, Ca(OH)2 , Mg(OH)2 show over 98% retention at both temperatures and Kaolin at 900oC
Aerosol and Particulate Research Laboratory
November 8, 2018

18. Aerosol and Particulate Research Laboratory
Major XRD Results
The major metal-mineral compounds formed in spike samples are
Cu3(AsO4)2 , Ca3(AsO4)2 CuHAsO4, CaCrO4 etc., when Cement and Ca(OH)2 are used
CuCr2O4, ,when Alumina and Silica are used
Cu has high affinity for forming compounds
The difference in efficiency can be due to the different speciation products observed in the residue
It is possible that these compounds have low solubility, hence are less leachable. Remember to point to the symbols when you define the species in the figure to guide your audience.
Aerosol and Particulate Research Laboratory
November 8, 2018

19. Aerosol and Particulate Research Laboratory
Summary
Cement, Ca(OH)2 & Mg(OH)2 are good at retaining and preventing leaching of As & Cu
Alumina & Silica are good at retaining and preventing leaching of Cr
The variation in metal-metal and metal-mineral compounds being formed could be the major reason for different retention capabilities.
Understanding their interaction will provide solution to the challenging issue of CCA wood disposal.
Aerosol and Particulate Research Laboratory
November 8, 2018

20. Aerosol and Particulate Research Laboratory
How can we utilize this study for effective control of heavy metals during combustion of CCA wood?
Provide Ca-based sorbent
A possible strategy involving
Cement, Ca-based sorbents to chemically adsorb arsenic in air stream
Alumina, Silica to retain chromium in feed
As in gas phase
Cr in feed
Provide alumina/silica
Potentially viable option for disposal:
Cement kiln
Coal-fired power plants equipped with SO2 scrubbers
Steel mills
Since, arsenic is the only metal which vaporizes in usual combustion environments (< 1200oC), so, Refresh their memory about the excellent performance of each sorbent with specific metal. 1. The major constituent of coal ash is alumino-silicate. Hence, co-burning with coal has the advantage with no need for extra alumina/silica. 2. The arsenice containing flue gas will pass the kiln where cement material is roasting. Your Phase 1 results clear show its beauty of scrubbing As out of flue gas. There is no need for adding Ca-based sorbent. Cement itself is a Ca-based sorbent. The great thing about the use of the cement process is that essentially you don't need to add anything else; thus, you can reduce the cost and it's really easy to adopt.
Additionally, it will be good to show the flow direction of As and Cr.
Aerosol and Particulate Research Laboratory
November 8, 2018

21. Aerosol and Particulate Research Laboratory
Acknowledgements
Financial Support by Florida Center for Solid and Hazardous Waste Management Grant#
Major Analytical Instrumentation Center, Department of Material Science and Engineering, UF
Particle Engineering Research Center, UF
Officials at Florida Department of Environmental Protection (FDEP)
Mr. Henry Gotsch, Florida Rock Industries Inc.
Sang-Rin Lee, Clarkson University
Aerosol and Particulate Research Laboratory
November 8, 2018

22. Aerosol and Particulate Research Laboratory
Thank You
Aerosol and Particulate Research Laboratory
November 8, 2018

23. Aerosol and Particulate Research Laboratory
Aerosol and Particulate Research Laboratory
November 8, 2018