57    ZEOLITE: A NATURALLY OCCURRING MINERAL
FOR THE TREATMENT OF METALS CONTAMINATED
WATER AND WASTE STREAMS
Trudy J. Olin, Research Civil Engineer
R. Mark Bricka, Research Chemical Engineer
U.S. Army Engineer Waterways Experiment Station
Vicksburg, Mississippi 39180
ABSTRACT
This chapter presents the results of a research effort to identify and evaluate an economical,
single-use sorbent for treatment of metals contaminated water and waste streams.
INTRODUCTION
Heavy metals contamination is an environmental problem at U.S. Army installations engaged
in firearms training and munitions production. Weathering and corrosion of expended munitions
and leaching from wastewater lagoons, landfills, and burn pits, has resulted in heavy metals contamination of the soil at these facilities. Transport of metals to the groundwater has been confirmed in some locations, requiring treatment of the groundwater at the site. Certain treatment
processes for contaminated soil produce metals-laden extracts, which also require treatment before reuse or disposal.
The principal metals encountered in firing range soils are lead, copper, and zinc. Cadmium and
other metals, such as antimony, incorporated in the munitions are sometimes seen in lesser concentrations. Chromium is primarily associated with plating operations. Mercury is associated
with various propellants and, while present in much smaller concentrations, is of concern because of its acute toxicity.
Conventional treatment technologies for metals contaminated groundwater and waste streams
include ion exchange and activated carbon. While ion exchange is generally quite effective for
the removal of metals from aqueous streams, resins are expensive and must be regenerated at additional expense. Activated carbon is not as effective for most metals, and also requires regeneration. Alternative sorbents are therefore needed that are effective and economical. In Phase I, an
extensive literature search was conducted to identify low cost sorbents with potential for treatment of metals contaminated water and waste streams. Most sorbents requiring modification
were eliminated from further consideration because of the additional cost introduced by the required chemical modifications. Twelve sorbents were screened in batch testing, including: activated carbon, bark, chitosan, crown ether, corn cob, xanthate, clay (kaolinite and montmoril-
lonite), peat moss, seaweed, and reagent grade zeolite. Of these, zeolite demonstrated the highest
capacity for Pb, Cr, and Cd, and was selected for Phase II testing in batch, kinetic, and column
studies.
MATERIALS AND METHODS
Characterization
The zeolite used in the batch and column studies was provided to the Waterways Experiment
Station (WES) by the United States Geological Service (USGS). The zeolite was obtained from a
natural deposit of clinoptilolite-rich rock located in South Dakota (Rocky Ford SDH). Large
52nd Purdue Industrial Waste Conference Proceedings. 1997, Ann Arbor Press. Chelsea, Michigan 48118. Printed in
U.S.A.
575