Section Three
CHEMICAL STABILIZATION
8    CHEMICAL STABILIZATION -
MORE THAN A FIXATION PROCESS
C. Paul Lo, Director of R&D
Margaret C. Metcalf, Environmental Scientist
Chemfix Technologies, Inc.
Matairie, Louisiana 70001
Robert S. Reimers, Professor
Leslie F. Roberts, Graduate Student
Thomas G. Akers, Professor
Department of Environmental Health Sciences
Tulane University
New Orleans, Lousiana 70112
INTRODUCTION
Recent collaborative studies conducted by Chemfix Technologies, Inc. and Tulane University
researchers revealed that the proprietary process does more than just fix or retard the migration of
toxic constituents. It was observed that the alkaline environment produced by treatment using the
CHEMFIX® process caused chemicals to precipitate as silicate hydroxide complexes, to be entrapped
in a solidified matrix or to be altered to degradable or non-toxic forms. The capability of the
CHEMFIX® process to bind metals, detoxify organics, and inactivate pathogens will be discussed.
The process efficiency can be increased with the use of appropriate additives. It is anticipated that the
CHEMFIX® process can be developed for various industrial wastes using a matrix treatment scheme.
In essence, the CHEMFIX® process is applicable for the treatment of infectious wastes, municipal
sludges, refinery wastes, electric arc furnace dusts, and foundry wastes. Influenced by the pH,
chemicals are precipitated, entrapped, or altered chemically. This paper will discuss the ability of the
following processes to inactivate pathogens, detoxify organics, and bind metals.
Almost fifty percent of the toxic wastes generated commercially in the U.S. are estimated to be
derived from primary metal or electroplating industries.1 A major survey of four Northeastern States
confirmed this by categorizing 41% of all hazardous wastes produced annually as heavy metal
wastes.2 Unquestionably, heavy metals contribute significantly to the environmental liabilities
imposed by toxic wastes.
In contrast to organic compounds, there is presently no economically feasible process for detoxifying heavy metals. Controlling such wastes requires immobilizing the metal which often includes
altering its form. Containment is usually done through the use of some enclosement or fixation
technique. The later has several advantages including a far lower cost. Thus, due to the vast amount
of hazardous metal waste produced each year, solidification is in most cases the most applicable
control method.
In 1984 there were at least 59 commercially available solidification processes being promoted in the
U.S.' These processes included ceramic formation, resin or plastic mixtures and mixtures with industrial by-products such as fly ash, kiln dusts and shales. Of these 59, at least 20 involve the use of
cement and/or fixation processes.3
All of the cement based processes utilize several common phenomena. One is encapsulation in a
solid matrix as a containment vehicle. Another is the formation of insoluble hydroxyl complexes at
high pH's to decrease its intensity. Since the minimum solubility of many metal hydroxides is around