VOLUME REDUCTION AND DETOXIFICATION OF
HAZARDOUS WASTES BY ENCAPSULATION
IN AN ASPHALT BINDER
Richard D. Doyle, Manager
Hazardous Waste Treatment Systems
Werner & Pfleiderer Corporation
Ramsey, New Jersey 07446
Every week, the newspapers feature articles on the problems of waste disposal. Only a
few areas in the country can categorically state that they are not affected by waste disposal
problems. Problems can initiate from local generators, illegal dumping, well contamination,
plans to locate a disposal site within the area, or a myriad of other reasons. In our high
technology society, hazardous and toxic wastes are the inevitable by-products of this technology. With the wastes being produced, industry only has control of the amounts and
types, and their ultimate disposal.
Industry has responded to these waste problems by controlling or modifying their processes and returning to the basic 3R's of waste treatment; Reduce volumes at the source,
Recycle all wastes possible, and Recover all that is economically beneficial. However, even
with maximum use of these techniques, it is estimated that between 30-50 million tons of
wet slurry and sludge type hazardous wastes will be generated this year. This large volume of
waste generation, with disposal costs escalating, available secured disposal space decreasing,
and the emotional aspects of waste disposal becoming increasingly more prominent, require
that improvements in waste volume reduction and stabilization be utilized if our nation's
production is to maintain continued growth. The utilization of an asphalt binder with a
simple, one-step, extruder-evaporator process for encapsulation of sludges and slurries containing hazardous materials is one method of meeting the requirements to provide volume
reduction and improved end-product leachabdity.
This process has undergone considerable evolution since its inception in the 1960s. This
evolution has allowed the full development of a well proven and safe system that has over
70 unit operating years. The system as developed by Werner & Pfleiderer Corporation
(WPC) is a Volume Reduction and Solidification (VRS™) System that is appicable to many
wet slurry and sludge wastes. In addition to its proven record of reliable operation and the
production of a very stable end product, the VRS system also provides the operator with a
significant annual cost savings when compared with most nonvolume reducing methodologies. In addition to having 14 units in routine operation for hazardous waste treatment,
new applications and waste encapsulations are being continually demonstrated on one of
the production sized extruders in the WPC development laboratory. Detads of the VRS
process and its evolution are described in detail in the following sections.
WPC-VRS PROCESS EVOLUTION
In the early 1960s, the nuclear industry in Europe was experiencing problems analogous
to the current hazardous waste disposal problems in the U.S. They were producing significant and ever-increasing volumes of slurry and sludge waste that required disposal at secured
sites. These disposal sites were very limited in avadable space. With limited space, the cost
of the disposal was very significant and generators were looking for ways of acceptably
reducing the volume. In addition, most ultimate disposal sites were located in close proximity to high population areas or on the generators own property and therefore very strict
end-product criteria were imposed. The major criterion imposed was the requirement that
the end-product stabdity had to be maximized for long term storage. Stability was defined
in terms of a monolithic solid, with no free moisture, environmental stabdity, and high
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