EFFECT OF CARBONATE ION ON PRECIPITATION TREATMENT
OF CADMIUM, COPPER, LEAD AND ZINC
James W. Patterson, Professor
Pritzker Department of Environmental Engineering
Illinois Institute of Technology
Chicago, Illinois 60616
Considerable effort is being expended to control heavy metals discharges to the nation's
waters. Metals sources include treated and untreated municipal and industrial waste effluents, and geological sources. The quality and quantity of metal-bearing industrial effluents
depend upon their industrial source and the degree of treatment imposed. Table I illustrates
example sources and concentration ranges of several heavy metals in industrial wastewaters.
Under the authority of the Clean Water Act of 1977, the U.S. Environmental Protection
Agency has recently promulgated or proposed a number of BATEA and Pretreatment
effluent limitations guidelines to be met by industry. An evaluation of these guidelines
indicates that, for like pollutants, there are major differences in the effluent quality required
for different categories of industrial dischargers [2]. Table II presents example BATEA
effluent limitations guidelines for the four metals discussed in this article, on an equivalent
concentration basis. The range of BATEA guidelines for cadmium is near 4-fold, for copper
200-fold, for lead 28-fold, and for zinc 30-fold. Similar guidelines variability is observed
among subcategories within industrial categories, such as inorganic chemicals or iron and
steel.
Effluent limitations guidelines are normally derived from performance data obtained
from field monitoring of highly efficient industrial wastewater treatment plants. Differences
in limitation guidelines between industrial categories or subcategories are usually explained
as resulting from variations in category or subcategory wastewater characteristics, and the
Table I. Range of Heavy Metals Concentrations in Wastewater [ 1 ]
Metal
Typical Industrial
Sources
Concentration Range
Reported (mg/1)
Cadmium
Electroplating, metallurgical alloying,
ceramics
0-5,000
Copper Copper wire mills, metal process pickling
baths, plating
Storage battery industry, printing, paint,
explosive materials, pigment manufacture,
plating
Nickel Metal processing industries, plating
Zinc Zinc smelting, steel works with galvanizing
lines, plating
0-800
0-843
0-900
0-48,000
579