Guidelines For Landfill
Of Toxic Industrial Sludges
NOLAN A. CURRY, Senior Sanitary Engineer
Division of Pure Waters, Bureau of Industrial Wastes
New York State Department of Environmental Conservation
Albany, New York 12201
INTRODUCTION
Sludges, slurries, or dewatered solids containing toxic materials present an ever
increasing problem of disposal. To many, any solid represents material that can be safely
landfilled and forgotten. On the contrary, such solids may present potential sources of
highly toxic pollution.
If pollution of the environment is to be controlled, it is essential not only to remove the
toxic materials from industrial wastewaters before discharge, but also to insure that, once
removed, they are prevented from reaching ground or surface water by another path.
Most reactions, by which insoluble sludges are formed, are reversible if the conditions
in the water in contact with the sludge change sufficiently. Variations in pH, in the
concentration of ammonia (which can dissolve most toxic metals by forming water soluble
complexes), in temperature or in the presence of oxidizing compounds are some of the
parameters that can produce toxic concentrations of metals in the leachate.
These possibilities require that sludges be segregated by class, that close control of
landfill conditions be practiced and that adequate surveillance of the leachate be
maintained. Treatment of toxic leachate may be required if the precautions taken are not
adequate.
The preferred disposition from the viewpoint of mineral conservation and pollution
abatement is to reclaim minerals for reuse. These guidelines are intended for use only where
reclaiming is not practical and disposition to a landfill is the best remaining method
available.
To do an adequate job in landfilling requires: 1) detailed knowledge of the sludges;
2) precautions to insure continued insolubility of pollutants; 3) maintenance of surveillance to check efficacy of handling; and 4) treatment of leachate, if contaminated.
Since the various sludge encountered become soluble under different and sometimes
conflicting conditions, no one universal procedure will suffice.
DETAILED KNOWLEDGE OF THE SLUDGES
To store solid wastes properly with the necessary safeguards to prevent leaching, the
composition and properties of each waste must be known. It preferrable that each type of
waste be kept segregated from point of origin, through scavenger handling and to delivery
at the landfill site. In case of doubt, all sludges should be kept separate until properly
classified for landfilling. Premature mixing at point of production may be cause for its
rejection when delivered to a landfill.
In general, it is desirable to know the details of the process producing each sludge and
the conditions required by the process to produce acceptable effluent concentrations at
the wastewater treatment plant. Maintenance of similar conditions in the landfill should
help to insure leachate of acceptable quality from the landfill.
In addition to the amount and kind of toxic material, it is necessary to know all of the
information that could affect its reaction with other sludges and its behavior in the landfill.
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