Section Two
POLLUTION PREVENTION
3    REVIEW, ASSESSMENT, AND TRANSFER OF
POLLUTION PREVENTION TECHNOLOGY IN
PLASTIC AND RFC INDUSTRIES
C. B. Roth, Graduate Research Assistant
R. A. Greenkorn, Professor
School of Chemical Engineering
Purdue University
West Lafayette, Indiana 47907
INTRODUCTION
Pollution Prevention options are available for all the types of waste associated with this industry. The availability of these options to a company varies throughout the industry. There are four
major areas a company should analyze to determine the appropriate strategy in starting its pollution prevention program: Product design, necessary materials, manufacturing technology and
methods, and workforce ability. These four areas should be addressed equally when trying to develop a strategy. It is unreasonable to purchase a new spray coating system that requires more
operator skills than employees have. At the same time evaluations are being made, the cost of the
change should also be considered. The costs that need to be evaluated can usually be broken
down into four areas. They are the tooling cost (the cost of new molds, if necessary, for process
change), the equipment cost (cost of resin application system and support equipment), the waste
and scrap cost (cost of waste inherent in each system), and the workplace and environmental cost
(cost of dealing with waste and scrap generated from each technology). The pros and cons of
each cost for each technology should play as important a role in the evaluation of new technology as materials needed or workforce ability.
EQUIPMENT CLEANING
Many of the options for equipment cleaning are relatively inexpensive. Most of these options
only require better operating practices or very minor in-plant modification of techniques and
equipment. In general, by either a process modification or a change to a different cleaning material, these options reduce the amount of solvent lost due to evaporation.
A change of cleaning methods from solvent based to water based reduces solvent loss to zero
because solvents are never used. The most widely used change presently is the change to a water
based emulsifier or dibasic ester. These cleaning agents work especially well with a combined
use of hot water as a carrying agent and increased pressure in the cleaning stream. The cured
resin stream is the waste that this change has problems removing. Emulsifiers are well suited for
cleaning of pipes between production runs and molds to remove excess waxes. This type of
change actually changes the cleaning process. It is based on the principle of cleaning by mechanical action as opposed to solvent cleaning that is based on cleaning by chemical action.'~7
It is not necessary, however, to change from a solvent based system to reduce the amount of
solvent use and still maintain the current level of cleanliness. The reduction in solvent loss can
be realized by better operating practices. A change from large sprayers (spray guns) to smaller
squeeze bottles can obtain the same cleanliness but can also reduce the amount of overspray and
loss because the operator has better control over the solvent stream. Even better for reducing solvent waste is hand cleaning with rags. Care must be taken when examining this option, however.
51st Purdue Industrial Waste Conference Proceedings, 1996, Ann Arbor Press, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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