ION EXCHANGE/METAL PRECIPITATION WASTEWATER
TREATMENT SYSTEM: CASE HISTORY
James C. North, President
Resource Consultants, Inc.
Brentwood, Tennessee 37027
William G. Russell, Plating Superintendent
Park Sherman Company
Murfreesboro, Tennessee 37130
Rudolf F. Mathis, Technical Services Representative
Polymetron AG
Hombrechtikon, Switzerland
This paper describes the application of the ion exchange process to recover valuable
process water in a pollution control project at the Park Sherman Company, Murfreesboro,
Tennessee. Ion exchange was considered by the metal-finishing industry to have limited
application in water pollution control projects until the last few years. Formerly, the application consisted of selected use in waste treatment as a final polishing step or in limited
chemical recycling situations (e.g., the recovery of copper). However, over the last two
decades the European metal-finishing industry has applied ion exchange to an exciting
plant-wide water recycling concept that has considerably broadened the future for the
process.
Most metal-finishing plants that have significant electroplating, etching and/or paint
preparation operations can apply the technology. The concept is very simple, experiences
low operating costs, reduces water consumption 80 to 90% which results in a much smaller
wastewater stream and has a longer life than conventional chemical destruct systems. Park
Sherman started its system in late 1978 and has been very pleased with the system's effectiveness and utility.
COMPANY BACKGROUND
Park Sherman Company is a medium-sized industrial plant in Murfreesboro, Tennessee,
primarily involved with various metal plating, anodizing, etching, fabrication, embossing
and assembly operations. The principal product is cigarette lighters, but metal plating of
parts for other local manufacturers is also an important aspect of the business. Process
wastewater is discharged to the municipal sewer system.
In 1972, Park Sherman retained Resource Consultants, Inc. to perform an engineering
study to develop an economical solution to the problem of its wastewater discharge. Wastewater is generated from the continuous rinses and batch dumps of seven process lines. By
transporting the material on racks, and dipping it manually into tanks, one line plates
nickel and chromium onto the metal, and another line plates zinc. Other lines convey the
material in barrels automatically: one line plates zinc and one line plates brass. In addition,
there is one line each for anodizing, etching and zinc phosphate coating. After a thorough
wastewater sampling and analytical program, several treatment and recovery techniques
were evaluated as to the feasibility of reducing hexavalent chromium, concentrating metals,
and recycling wastewaters. Several years lagged before compliance was initiated. The chosen
treatment scheme consisted of an ion exchange system to treat and recycle dilute rinsewaters and a chemical precipitation system to remove the metals from the spent baths and
miscellaneous wastewaters as well as the regenerant wastes from the ion exchange system.
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