THE EFFECTIVENESS OF LAND TREATMENT
FOR REMOVAL OF HEAVY METALS
Robert S. Reimers, Assistant Professor
Andrew J. Englande, Associate Professor
Department of Environmental Health Sciences
Tulane University
New Orleans, Louisiana 70112
Peter A. Krenkel, Director
Division of Environmental Planning
Tennessee Valley Authority
Chattanooga, Tennessee 37402
Richard A. Danforth, Research Associate
Dennis B. Leftwich, Research Associate
Chongi Paul Lo, Research Associate
Department of Environmental Health Sciences
Tulane University
New Orleans, Louisiana 70112
INTRODUCTION
Consideration of land disposal as an alternative for tertiary treatment and/or ultimate
disposal of wastewaters has increased due to the enactment of the 1972 Federal Water
Pollution Control Act.   In many instances effluent classifications have dictated qualities
that are economically feasible only through land application methods.   Traditionally,
effluent application to land has been employed to enhance the removal of certain nutrients.
As emphasis in this type of treatment method increases it becomes important also to
estimate the efficiency of land treatment in removing other types of contaminants, including heavy metals.
The objective of this investigation was to determine the effectiveness of the removal of
selected trace heavy metals from wastewater effluents subject to land treatment. Cadmium
(cationic metal), mercury (nonionic metal) and arsenic (anionic metal) were selected as
trace metals for evaluation owing to their varying reactive natures in an aqueous soil milieu.
Fate of these three metals after application to soil was estimated after considering several
factors affecting transport.   These factors are as follows:   (a) changes in solubility, (b) formation of complexes, (c) affects of dissolved oxygen, (d) oxidation-reduction potential
fluctuations, and (e) soil pH variability and biotic transformations.
BACKGROUND LITERATURE
The following is a synopsis of the literature concerned with the efficiency of heavy
metal removal by secondary or biological treatment methods; expected concentrations of
heavy metals in secondary municipal effluents; and potential accumulation of heavy metals
in soils and plants in areas affected by land application.
Secondary treatment has been found to effectively reduce heavy metal concentrations.
Cohen[l] reported a highly variable removal of metals by biological treatment, as shown
in Table I.
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