Reagents.

ETL 1110-1-158

28 Feb 95

hazardous wastes unless they still exhibit a hazardous

characteristic.

(2) The Comprehensive Environmental Response, Compensation,

and Liability Act (CERCLA). CERCLA established a procedure for

responding to releases of hazardous substances which ultimately

involves site remediation actions potentially utilizing the S/S

technology. CERCLA requires contaminated sites to be

investigated, prioritized, and remediated. Requirements of other

regulations such as RCRA, Clean Air Act, and Clean Water Act are

integrated into the CERCLA process when evaluating alternative

remedial actions by identification of what are referred to as

Applicable or Relevant and Appropriate Regulations (ARARS). The

Superfund Amendments and Reauthorization Act (SARA) was enacted

in 1986. SARA reauthorized and further defined the CERCLA

regulations. SARA strongly recommends remedial actions involving

on-site treatment methods which reduce the toxicity, mobility or

volume of hazardous substances. S/S is an applicable treatment

technology based on these criteria since it reduces the mobility

of contaminants.

c. Reagents. Reagents are the materials which are mixed

with contaminated soils, sludges, and liquids to reduce the

mobility of the contaminants by chemical and physical reactions.

There are two basic types of S/S reagents, organic and inorganic.

Organic reagents have rarely been used for the cleanup of

hazardous waste sites. Therefore, this ETL will focus on the use

of inorganic reagents. The normal processing steps when using

inorganic reagents are to 1) chemically react with all the water

present, 2) chemically react with the contaminants to render them

insoluble, and then 3) encapsulate the products.

(1) Inorganic Reagents. Inorganic reagents most often used

for S/S include portland cement, fly ash, lime, phosphates, and

kiln dust from lime and cement production. All of these reagents

have basically the same general types of active ingredients as

far as S/S reactions are concerned. These active ingredients

include SiO2, CaO, MgO, Al2O3, and Fe2O3.

(2) Organophillic Clay. Organophillic clay has been

proposed for use to adsorb organic contaminants so that they can

be trapped in a solidified matrix. Lab tests have indicated that

some organophillic clays chemically bond to organics. However,

the strength of this bond is of concern. In most cases, the

mechanism by which the organics are trapped is merely physical

adsorption. Organophillic clays show some promise in combination

with other reagents for the treatment of organics.

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