Section Six
INDUSTRIAL WASTES-A. METAL FINISHING
WASTES
64    OIL AND GREASE REMOVAL FROM A CONCENTRATED
SOURCE IN THE METAL FINISHING INDUSTRY
Mark A. Westra, Environmental Chemist
Bryan L. Rose, Associate
Fishbeck, Thompson, Carr & Huber, Inc.
Ada, Michigan 49301
INTRODUCTION
The Murray Ohio Manufacturing Company (Murray), a wholly owned subsidiary of Tompkins,
Inc., manufactures bicycles, mopeds, cycles, lawn mowers and garden tillers. The manufacturing
facility, located in Lawrenceburg, Tennessee, discharges treated process wastewater to Shoal Creek.
This discharge is regulated under an NPDES permit. In 1984-85, the wastewater treatment facilities
were expanded to meet more stringent limitations based on water quality criteria presented in Table 1.
Figure 1 presents a schematic of the multi-faceted treatment solution which was designed for the
process waste streams. A portion of the expansion included the pretreatment of concentrated oil and
grease waste streams from several alkaline surfactant cleaner "soaks" used in plating and cleaning
lines. Spent cleaner tanks are discharged (dumped) to treatment when they can no longer satisfactorily
clean parts. The entire tank is usually discharged to waste treatment when spent (4,000- to 10,000-
gallon dumps). The spent dumps are pretreated in batch tanks prior to subsequent treatment. This
chapter deals with the treatment of these alkaline-soak cleaning solutions.
The cleaning solutions are used to prepare parts for plating and painting. These solutions contain
sodium hydroxide to provide a highly alkaline media, nonionic surfactants to remove oil and grease
from the parts, anionic surfactants to emulsify the oil and grease and extend the bath life, and various
other components such as phosphates and silicates that function as "builders" to enhance the performance of the surfacants. The proprietary cleaning solutions used at Murray are formulated to provide
excellent cleaning and an extended bath life. Table II includes a list of components found in a typical
cleaning bath. These properties make the cleaners difficult to treat because they are so effective in
emulsifying the oil and grease. The treatment of these baths is further complicated by the fact that
Murray uses synthetic and semi-synthetic coating oils which are more readily and completely emulsified than natural oils. The use of synthetic oils in combination with highly effective emulsifiers has
Table I.    NPDES Water Quality Based Limitations
Parameter Average (mg/L)                                       Daily Max. (mg/L)
TSS 31 60
Oil and Grease 26 52
Cadmium .26 .69
Chromium 1.71 2.77
Copper 2.07 3.38
Lead .43 .69
Nickel 2.38 3.98
Silver .24 .43
Zinc 1.48 2.61
TTO - 2.13
pH 6.0 to 9.0
44th Purdue Industrial Waste Conference Proceedings, © 1990 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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