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Environmental Technology Listing
Title of Listing:
CHEMICAL TREATMENT - OTHER
Category:
Treatment Technologies
Subcategory:
*Soil, All Listings
Media:
Soil
Contaminants:
Heavy Metals
Web Site:
http://www.rmtinc.com/
Email:
Technology Description:

RMT has developed four processes for ex situ and in situ treatment of heavy metals. These proprietary chemistries and methods focus on lead, cadmium, chromium, arsenic, copper, and zinc.

          Our principal process involves the use of a buffering agent with phosphate compounds to render lead- and cadmium-bearing waste, soil, and contaminated media nonhazardous over a wide range of disposal conditions. This is accomplished by converting the hazardous metals into forms of the metals which are less hazardous and more stable in the environment.

          Some metals, such as lead, exhibit amphoteric solubility characteristics; that is, they become very soluble at low and high pHs. Since acid is used to leach metals in the TCLP test, lime or lime-based product such as Portland cement or cement kiln dust (CKD) may be used to neutralize the acid in the leaching test and maintain the pH in a range where lead is relatively insoluble.

          However, when the lime-treated waste is disposed in a nonacidic environment, such as a monofill or industrial landfill, the treated waste may actually leach higher concentrations of metals in the real environment than the untreated waste would have. Therefore, site owners who believe they have solved a RCRA or CERCLA waste problem may actually have created a far worse problem than existed with the untreated waste.

          To avoid the high pH caused by Portland cement or lime, RMT uses buffering agents which do not raise the pH as high as lime does. These buffers are used in combination with an acid or salt containing an anion that chemically bonds with and forms substantially nonleachable forms of metals.

          RMT's treatment processes satisfy leaching requirements under both acidic and nonacidic conditions (for example, ASTM water leach test).

          Significant advantages in leaching characteristics have been demonstrated over more traditional methods like lime stabilization and Portland cement solidification. Other advantages may include cost savings for the reagents, material handling, transportation, and disposal.
Performance Status/
Limitations:

Performance Status:

          RMT's heavy metal treatment process has been utilized on over 200 bench-scale treatability studies, and has been successfully implemented on 20 full-scale projects, including one Superfund site. USEPA and State agency approval has been obtained on each of these projects, many times with permission to leave the treated soil on site.

          RMT has been developing chemical treatment solutions for heavy metal problems since the early 1980s, and has patented some of the most effective ones. The current technologies can reduce the leaching of lead, cadmium, zinc, copper, arsenic, and chrome when present in soil, sludge, ash, slag, or some mixture of the above items.

          Limitations:

          RMT's process can reduce the hazard due to leachable metals, but it does not reduce the concentrations of total metals present. Treated soil and materials must still be landfilled, although they no longer need to be treated as hazardous waste.

          Very high (greater than 10 percent) zinc concentrations impair the ability of the process to effectively treat cadmium, and may result in high dosages of required treatment chemicals.
Topics
Chemicals, Inorganics/Metals, Technologies, Treatment/Remediation
Additional Topics/Tags/Keywords
Stabilization, Soil, Heavy Metals


Organization:
RMT, INC.
Address:
744 Heartland Trail
Phone:
DescriptionNumber
City:
Madison
1.
Primary (608) 831-4444
State/Province/Territory:
WI
2.
Zip/Postal Code:
53717-1934
3.
Country:
United States
4.
Fax:(608) 831-3334
Branch Locations: