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Rayovac Corporation
Reverse Osmosis to Purify a
By-Product Stream for Reuse |
| Standard Industrial Classification
(SIC) |
Battery Manufacturer/3692 |
| Process |
Battery Chemical Production |
| Type of Waste |
Cadmium and nickel contamination of both
zinc chloride by-product and process wastewater. |
| Strategies |
Process Modification - Reverse Osmosis
Material Recovery/Reuse |
| Background |
Rayovac Corporation is a privately owned
battery manufacturer headquartered in Madison, Wisconsin. Rayovac's Nesbitt Road Facility
produces the contents of a specialty battery cell by combining a zinc metal powder with
the salts cadmium chloride and nickel chloride. The completed reaction produces a cadmium
powder, along with a minor amount of nickel. A significant amount of zinc chloride, a
by-product of the reaction, is also produced. |
| Motivation |
Rayovac originally planned to use the zinc
chloride by-product as a raw material at a sister plant. However, the zinc chloride was
frequently contaminated by nickel and cadmium that remained after the original reaction. The nickel and cadmium contaminants posed two problems. The cadmium and nickel
degraded the value of the zinc chloride as a raw material. Also, the two metals were being
carried over in condensate water after heat treatment. Because the condensate was
discharged to a Publicly Owned Treatment Works (POTW), its contamination with nickel and
cadmium was not tolerable. |
| Changes Implemented |
Rayovac solved the problems by eliminating
the process wastewater and reclaiming the cadmium and nickel for reuse. Rayovac installed
a reverse osmosis (RO) membrane filtration system in place of the heat treatment system to
concentrate the zinc chloride solution. The concentrated zinc chloride is then treated
with zinc metal to precipitate any remaining cadmium or nickel. The
filtered water (permeate) from the reverse osmosis unit is recycled within a closed loop
for reuse in the production process as clean-up water, or it's fed to an air pollution
control scrubber. |
| Problems Encountered |
The major obstacle to implementing this
system was preventing the clogging of the membrane filter of the RO unit with solid
particles. Rayovac prevents the clogging of the membrane by adjusting the pH to levels
that hinder precipitation. |
| Material/Energy Balance |
Original Process Feedstock
Cadmium chloride/nickel chloride
Waste
Cadmium and nickel metal contaminant in by-product and process wastewater
Disposal
Discharged with wastewater to POTW.
Pollution Prevention Approach
Feedstock
Cadmium chloride/nickel chloride
Waste
None: the process wastewater was eliminated by closing the process water loop, and the
metal contaminants in the by-product are now recovered for reuse.
Disposal
No disposal is necessary |
| Economics |
Capital Cost
Under $50,000Operating/Maintenance Cost
Approximately $2,000/year
Payback Period
Six months |
| Company Address |
Rayovac Corporation
601 Rayovac Drive
Madison, WI 53711-0960 |
| Contact Person |
Rod Donaldson
608/275-4739 |
| Additional Publications available
from Pollution Prevention Clearinghouse |
Reverse Osmosis
MnTAP Factsheet MnTAP 10/RO (7/90) |
| Pollution Prevention Resources |
Free, On-site Technical Assistance
University of Wisconsin Extension
Solid and Hazardous Waste Education Center
Milwaukee area: 414/475-2845
Remainder of state: 608/262-0385Pollution Prevention
Clearinghouse
Wisconsin Department of Natural Resources
Hazardous Waste Minimization Program
608/264-8852, 608/267-9523 or 608/267-3763 |
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Bureau of Cooperative Environmental Assistance
Wisconsin Department of Natural Resources
P.O. Box 7921
Madison, WI 53707
608/267-9700
PUBL-SW-160 95 |
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