Low Temperature Thermal Aeration (LTTA®) Technology
SMITH ENVIRONMENTAL TECHNOLOGIES CORPORATION
(formerly CANONIE ENVIRONMENTAL SERVICES CORPORATION)
(Low Temperature Thermal Aeration [LTTA®])
TECHNOLOGY DESCRIPTION:
The Low Temperature Thermal Aeration (LTTA®) technology is a low-temperature de-sorption process (see figure below). The tech-nology removes organic contaminants from contaminated soils into a contained air stream, which is extensively treated to collect or thermally destroy the contaminants.
A direct-fired rotary dryer heats an air stream which, by direct contact, desorbs water and organic contaminants from the soil. Soil can be heated to up to 800 °F. The processed soil is quenched to reduce temperatures and mitigate dust problems. The processed soil is then discharged into a stockpile. The hot air stream that contains vaporized water and organics is treated by one of two air pollution control systems. One system removes the organic contaminants from the air stream by adsorption on granular activated carbon (GAC) and includes the following units in series: (1) cyclones and baghouse for particulate removal; (2) wet scrubber for acid gas and some organic vapor removal; and (3) GAC adsorption beds for organic removal.
The second air pollution control system can treat soils containing high concentrations of petroleum hydrocarbons. The system includes the following units in series: (1) cyclones for particle removal; (2) thermal oxidizer-afterburner for destruction of organics; (3) quench tower for cooling of air stream; (4) baghouse for additional particle removal; and (5) wet scrubber for acid gas removal.
The LTTA® technology generates no wastewater or waste soils. Cyclone fines and baghouse dust are combined with treated soil and quenched with treated scrubber water. The treated soil, once verified to meet the treatment criteria, is backfilled on site without restrictions. GAC beds used for air pollution control are regene-rated or incinerated when spent.
WASTE APPLICABILITY:
LTTA® can remove volatile organic compounds (VOC), semivolatile organic compounds (SVOC), organochlorine pesticides (OCP), organophosphorus pesticides (OPP), and total petroleum hydrocarbons (TPH) from soils, sediments, and some sludges. LTTA® has been used at full scale to remove VOCs such as benzene, toluene, tetrachloroethene, trichloro-ethene, and dichloroethene; SVOCs such as ace-naphthene, chrysene, naphthalene, and pyrene; OCPs such as dichlorodiphenyltrichloroethane (DDT), DDT metabolites and toxaphene; OPPs such as ethyl parathion, methyl parathion, merphos, and mevinphos; and TPHs.
STATUS:
The LTTA® technology was accepted into the SITE Demonstration Program in summer 1992. LTTA® was demonstrated in September 1992 on soils contaminated with OCPs during a full-scale remediation at a pesticide site in Arizona. The Demonstration Bulletin (EPA/540/MR-93/504) and Applications Analysis Report (EPA/540/AR-93/504) are available from EPA.
The full-scale LTTA® system has remediated contaminated soils at six sites, including three Superfund sites. The system has treated more than 117,000 tons of soil.
DEMONSTRATION RESULTS:
Key findings from the demonstration are summarized below:
· The LTTA® system achieved the specified cleanup criteria for the site, a sliding scale correlating the concen-trations of DDT family compounds (dichlorodiphenyldichloroethylene [DDE], tetrachlorodiphenylethane [DDD], and DDT) with concentrations of toxaphene. The maximum allowable pesticide concentrations in the treated
soil were 3.52 milligrams per kilogram (mg/kg) of DDT family compounds and 1.09 mg/kg of toxaphene.
· Residual levels of all the pesticides in the treated soil were generally below or close to the laboratory detection limit, with the exception of 4,4'-DDE, which was found at residual concentrations of 0.1 to 1.5 mg/kg. Removal efficiencies for pesticides found in the feed soil at quantifiable concentrations are summarized below:
Compound Efficiency
4,4'-DDD >99.97%
4,4'-DDE 90.26%
4,4'-DDT 99.97%
Endrin >99.85%
Toxaphene >99.83%
Endosulfan 1 >99.98%
· The LTTA® process did not generate dioxins or furans as products of incomplete combustion or thermal transformation.
FOR FURTHER INFORMATION:
EPA PROJECT MANAGER:
Paul dePercin
U.S. EPA
National Risk Management Research
Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7797
Fax: 513-569-7620
TECHNOLOGY DEVELOPER CONTACT:
Douglas Anderson
Smith Environmental Technologies Corporation
800 Canonie Drive
Porter, IN 46304
219-926-8651
Fax: 219-926-7169