27    MINIMIZATION OF HAZARDOUS WASTE GENERATION:
PRELIMINARY INVESTIGATION OF WASTE
MANAGEMENT PROPERTIES OF A SOLVENT
SUBSTITUTE FOR TCE
Ricardo B. Jacquez, Professor
Meei-Huey Li, Graduate Research Assistant
Department of Civil, Agricultural, and Geological Engineering
Walter H. Zachritz II, Program Manager
Southwest Technology Development Institute
New Mexico State University
Las Cruces, New Mexico 88003-0083
Martha I. Beach, President
N-CON Systems Company, Inc.
Larchmont, New York 10538
INTRODUCTION
Halogenated solvents such as trichlorethylene (TCE), freon, and methylene chloride, are routinely
used in a wide variety of degreasing and cleaning operations.1 These highly volatile solvents remove
unwanted oils, greases, metal residues, and other organic films leaving a clean dry surface. Federal
regulations promulgated over the past ten years have classified many of these substances as hazardous
(Resource Conservation and Recovery Act —RCRA) or toxic (Toxic Substance Control Act —TSCA).
Halogenated solvents release vapors2 that accumulate in the work place and produce acute and
sometimes chronic health effects resulting from continuous exposure through inhalation.3 Spent
halogenated solvents released from process washwater or in concentrate can adversely impact industrial wastewater treatment plants, industrial pretreatment programs and may pose a threat to ground
water.4 Various strategies for minimizing the use and disposal costs of halogenated solvents have been
suggested, including: use of solvent substitutes; recycling through filtration and distillation; or sophisticated vapor containment and recovery systems.1
Non-halogenated solvent substitutes with positive attributes that pose no exposure related health
threats to workers, reduce disposal and treatment costs, eliminate the need for costly equipment to
capture volatile organic compounds (VOC's), and result in the hazardous declassification of some
mixed wastewaters and sludges are being strongly considered for many industrial operations. However, solvent substitutes may suffer from the following disadvantages: increased washwater use due to
decreased rinseability; increased solvent use due to the lower solvent capacity; contaminant carryover;
unknown impact on the industrial wastewater treatment plant such as resistance to biodegradation;
and physical/chemical interaction with waste components. Viable substitutes must also meet the
rigorous manufacturing standards for cleaning effectiveness, material compatibility, component
aging and stress, and cost per solvent capacity, while minimizing environmental impacts.
Several types of solvent substitutes which are now available on the market include: terpene-based
materials containing d-limonene; aqueous-based materials containing monoethanol amines; alkaline
aqueous-based material; and hydrochlorofluorocarbon formulation. Preliminary investigations have
indicated that terpene-based formulations appear to be effective for many industrial cleaning operations. Thus, a typical terpene-based formulation was selected for this study. Terpenes are widely
distributed in nature and occur in nearly all living plants. The two most abundant natural sources of
terpenes are turpentine and other essential oils.5 Terpenes are generally regarded as a derivative of
isoprene (2-methyl-l, 3-butadiene)6. Wood and citrus products are the principal commercial sources
of terpenes. Solvent substitute applications for terpenes have grown substantially in recent years5.
Information obtained from the manufacturer's material safety data sheets indicated that the major
component of the terpene-based solvent selected for the study is d-limonene (Pentone Corporation,
45th Purdue Industrial Waste Conference Proceedings, © 1991 Lewis Publishers, Inc., Chelsea, Michigan 48118.
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