Technology Limitations

Tables 11.16.4 and 11.16.5 summarize factors that interfere with stabilization and solidification processes.

TABLE 11.16.3 COMPATIBILITY OF WASTE CATEGORIES WITH SOLIDIFICATION/STABILIZATION TECHNIQUES

Waste Component

Cement-Based

Treatment Type

Organic

Lime- Polymer

Based Thermoplastic (ÜF)a

Surface Self-

Encapsulation Cementing

Classification and Synthetic Mineral Formation

Organics

1. Organic solvents and oils

2. Solid organics (e.g., plastics, resins, tars)

Inorganics

1. Acid wastes

2. Oxidizers

3. Sulfates

4. Halides

Many impede setting, may escape as vapor

Good-often increases durability

Cement will neutralize acids

Compatible

May retard setting and cause spall-ing unless special cement is used

Easily leached from cement, may retard setting

Many impede Organics may May retard Must first be

5. Heavy metals Compatible setting, may escape as vapor

Good-often increases durability

Compatible

Compatible

Compatible

May retard setting, most are easily leached vaporize on heating

Possible use as binding agent

Can be neutralized before incorporation

May cause matrix breakdown, fire

May dehydrate and rehydrate, causing splitting set of polymers

May retard set of poly-

absorbed on solid matrix

Compatible-many encapsulation materials are plastic

Compatible Can be neutralized before incorporation

May cause May cause matrix deteriora-

break- tion of en-

down capsulating materials

May dehydrate Compatible Compatible

Compatible Compatible

6. Radioactive materials

Compatible

Compatible Compatible

Acid pH Compatible solubil-

izes metal hydroxides

Compatible Compatible

Fire danger on heating

Fire danger on heating

May be neutralized to form sulfate salts

Compatible if sulfates are present

Compatible Compatible Compatible

Compatible if sulfates are also present

Compatible if sulfates are present

Compatible if sulfates are present

Wastes decompose at high temperatures

Wastes decompose at high temperatures

Can be neutralized and incorporated

High temperatures may cause undesirable reactions

Compatible in many cases

Compatible in many cases

Compatible in many cases

Compatible

Source: Reprinted, from U.S. EPA, 1980. aUrea-formaldehyde resin.

mers

Physical mechanisms that interfere with the S/S process include incomplete mixing due to high moisture or organic chemical content. This results in only partial wetting or coating of particles with stabilizing and binding agents, and the aggregation of untreated waste into lumps (EPA 1986). Chemical mechanisms that interfere with S/S of cement-based systems include chemical adsorp tion, complexation, precipitation, and nucleation (Conner 1990).

Environmental conditions must be considered in determining whether and when to implement S/S process technology. Extremes of heat, cold, and precipitation can adversely affect S/S applications. For example, the viscosity of one or more of the materials may increase rapidly with

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