SOLIDIFICATION, ENCAPSULATION AND STABILIZATION
OF INDUSTRIAL WASTES
James E. Alleman, Assistant Professor
Neil A. Berman, Graduate Student
Department of Civil Engineering
University of Maryland
College Park, Maryland 20742
Mark F. Prouty, Environmental Engineer
Tatman & Lee Associates, Inc.
Wilmington, Delaware 19803
Although the emotional issue of industrial waste disposal has recently drawn considerable
national attention, the basic problem has been recognized and pondered since the preceding
century. Indeed, many of the earliest pioneers in environmental engineering gave serious
consideration to the fate and effect of industrially related contaminants [1,2J. Yesteryear
disposal practices (i.e., unconfined land burial, ocean disposal and incineration) must now,
however, be reassessed critically, particularly in light of several recent calamitous failures.
Aside from the technical shortcomings of these simplistic disposal options, the magnitude
and complexity of contemporary industrial wastes demands expedient innovation and
improvement.
To a great extent, the problem of industrial waste disposal is aggravated by the basic
characteristics of the involved material. Generally semiliquid in form, these wastes are
unfortunately susceptible to leachate effects and subsequent mobilization of their noxious
constituents within the surrounding environment. Given the apparent engineering preference
for land disposal, considerable effort has therefore been directed toward development of
site containment measures incorporating various surface and subsurface liners. This approach
specifically attempts to establish an impervious barrier around the waste disposal.
Several alternative strategies have, however, been promoted whereby the waste itself
is stabilized. These latter procedures involve either a chemical treatment that yields a solidified waste material or an incorporation of the waste into a receptive solid matrix. These
techniques include:
• fixation/microencapsulation,
• macroencapsulation,
• cement kiln incineration, and
• brick process incorporation.
The first two procedures both employ chemical additives, either mixed within the waste
to promote stabilization and constitutive microencapsulation or wrapped about a waste
aliquot as a macroencapsulating jacket or binder. With the latter two options, waste materials are blended into conventional manufacturing processes for cement or brick. These
operations both employ high-temperature kilns, which serve to combust waste organics,
enmeshing residual ash within the finished product.
Each of the four identified stabilization strategies will be reviewed, providing a related
discussion of generic technology, apparent application conditions and perceived resource
recovery possibilities. Brick production will be emphasized because of its unusual, emerging
status.
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