Thermochemical Conversion (thermal treatment)
- Wood waste processed at three different scales: small, intermediate, and large
- Small scale-test conducted in a tube furnace (a horizontal electrically heated chamber that houses a refractory tube in which the sample is placed)
- 2 series of tests conducted, the first on wood shavings, and the second on ash produced from the intermediate-scale processing of wood shavings to test the sintering properties of the fluxed ash
- Intermediate scale test conducted in a 4.7 ft2-area rotary hearth furnace.
- Four of five burners operated during the test, with the hearth maintained at a negative pressure via an induced draft fan
- Large-scale test conducted at contractors test facility; operating temperature of hearth was about 1500°F
- Following system shutdown, ash samples from various parts of hearth and off-gas system collected and analyzed
- Leach performance of ash produced from test was evaluated including ash as-produced, fluxed and sintered ash, and ash to which Portland cement and water had been added
Commanding Officer (specific name not provided)
Naval Facilities Engineering Service Center
1100 23rd Avenue
Port Hueneme, CA 93043
Heavy Metals (lead) (evaluated for recycling or stabilization after thermal treatment of debris)
Demolition of 26 World War II-era wooden military building located at Fort Ord
Type/Quantity of Media Treated:
- Wood siding coated with lead-based paint (LBP)
- Wood shavings and LBP generated from attempts to remove LBP and recycled lumber
Purpose/Significance of Application:
Field demonstration of thermochemical conversion to treat demolition debris
Regulatory Requirements/Cleanup Goals:
- Conduct a series of thermal treatment tests to collect data that would facilitate designing and estimating capital/operational costs for a transportable treatment system that could process such waste on site during demolition activities at current and former military installations
Toxicity Characteristic Leaching Procedure (TCLP) target for lead: 5.0 parts per million (ppm)
- 97% volume reduction and 90% reduction in mass of waste
- Over 99.9% of lead released to off-gas system during processing was in particulate form >0.7 microns in effective diameter
- Concentrations of lead in residual ash ranged from about 7 - 12% from the processing of whole boards to about 25% from the processing of wood and paint shavings.
- Data collected from off-gas monitoring and sampling suggest that emission control for processing lead-based pain (LBP) waste will be relatively simple and consist of a dry filtration system. There will not be a need for a wet off-gas system thus eliminating issues surrounding management of wastewater.
- Data produced from the tests facilitated development of a design for a transportable processing system for LBP-coated materials.
Estimated capital cost: $1,950,000
Estimated average annual operating costs - $987,000 (for a system with capacity to process 1.5 tons/hour)
Estimated unit cost - $117/ton (based on the processing of 8,450 tons/year)
Fort Ord, located near Monterey, California, is a former military facility that has undergone decommissioning and demolition. Due to the application of LBP on many of the buildings at the site, the demolition debris has been shown to exhibit hazardous properties. A series of in situ thermal desorption tests (at three different scales) was conducted on debris from the site, to collect data that would facilitate the design and capital/operational cost estimates for a transportable treatment system that could process such wastes on site during demolition activities at current and former military installations. The large-scale test was performed at a test facility in Tacoma, Washington. Leach performance of ash produced from the tests were evaluated, including ash as-produced, fluxed and sintered ash, and ash to which Portland cement and water had been added.
The results showed that the technology was able to effect a 97% reduction in volume and a 90% reduction in mass of waste. Analyses of the chemistry and recyclability of the ash showed that concentrations of lead ranged from about 7-12% from the processing of whole boards, to about 25% from the processing of wood and paint shavings. Data collected from off-gas monitoring and sampling suggest that a combination of a bag house and HEPA filter in a dry off-gas system will be capable of meeting regulatory standards. Based on these tests, a design for a transportable processing system for LBP-coated materials was developed. The estimated unit cost for a system that can process 8,450 tons of waste per year at the rate of 1.5 tons/hour is $117/ton.
The tests also showed that hearth ash typically passed leach tests for lead, while bag house ash did not, and the addition of Portland cement tended to improve leach characteristics but relatively large quantities of cement will be required to immobilize lead in bag house ash. Fluxing and sintering of ash impaired leach performance because of the lack of glass forming ions in the ash