69    MAXIMUM REMOVAL OF HEAVY METALS FROM THE
WASTEWATER OF A PROPOSED COPPER
PROCESSING FACILITY
Karen B. Thomas, Graduate Student
Jack V. Matson, Associate Professor
Zu-Mo Wang, Visiting Scholar
Department of Civil and Environmental Engineering
University of Houston, Houston, Texas 77204
BACKGROUND
In 1988 Mitsubishi Metals, through its subsidiary Texas Copper Corporation (TCC), proposed to
build a $200 million copper smelter in Texas City, Texas near Houston. The smelter would be located
on Galveston Bay. A productive estuary as a source of seafood and recreation, the Bay contributes
immensely to the economy of the area. However, due to contamination from chemical and sewage
plant discharges, roughly half of the Bay is currently closed to oystering and health advisories have
been issued for north bay fish and crabs.
In the wastewater permit application to the Texas Water Commission, TCC proposed to limit the
release of heavy metals to the Bay to approximately two thousand pounds per year. The-specific
treatment was a four stage lime neutralization process. Environmentalists objected to the application
on the basis that additional heavy metal removal was possible with the incorporation of advanced
metal removal processes such as sulfide precipitation. The hearings concluded with TCC receiving a
permit without consideration of advanced treatment.
The environmental community continued to protest and fight against the other required permits.
TCC reversed its position and cooperated by funding a project to determine if advanced wastewater
treatment could be effective. TCC also agreed to install an advanced treatment system if the results
were positive. This paper delineates the results of that study.
INTRODUCTION
In the Mitsubishi process, concentrated copper ore is converted to blister copper in a series of three
furnaces. The off-gases from the furnaces contain sulfur dioxide and metals in the fume and particulate matter. Before the sulfur dioxide can be oxidized and used to concentrate sulfuric acid, it must be
cleaned. The wastewater resulting from the cleaning process has high concentrations of a mixture of
metals and their removal is the subject of this study. The effluent stream was permitted for 98,000 gpd
and metal contents limits as shown in Table I. The treated effluent was to be combined with once
through cooling water, cooling tower blowdown, domestic wastewater and stormwater prior to release
to Galveston Bay.
The primary goal of the cooperative effort was to determine the treatment process which would
maximize the metal removal from the wastewater stream. The important metals were copper, cad-
Table I.    Permit Effluent Limits
Daily Avg Daily Max Single Grab
Metal lb/day lb/day mg/L
4.0 7.5
0.41 0.9
0.52 1.0
0.82 1.6
3.7 6.0
47th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
643
Arsenic
2.0
Cadmium
0.082
Copper
0.41
Lead
0.33
Zinc
1.4