Handbook of Solvents - George Wypych - ChemTech - Ventech!

1036 Mohamed Serageldin, Dave Reeves
ties will first mix their waste solvents with unused coating. Incineration is generally
selected as the disposal method when it is determined to be less expensive than recycling.
The type of solvent waste generated from shipbuilding and ship repair facilities does
not vary much. Surface preparation and cleaning operations following application of coatings
does not represent the most significant part of the organic solvent waste. Certain coatings,
such as antifouling coatings, contain toxic pigments (metals) such as chromium, lead,
and tributyltin. The waste will likely be hazardous waste if the waste material contained
coating residues or other materials that are toxic. Solvents used in cleaning are often mixed
with other waste fuels such as hydraulic fluids, waste fuels, and other maintenance by-products.
Some of the larger shipyards segregate the solvent waste or recycle it for re-use.
14.26.9 REDUCING SOLVENT USAGE, EMISSIONS, AND WASTE
The amount of organic solvent usage for cleaning operations makes up about 20 percent of
the total solvent usage in cleaning operations and coating operations at shipyards. The waste
from solvent cleaning represents a major portion of the waste in a plant that has surface
coating operations. Line cleaning, gun cleaning, and tank cleaning are three operations that
utilize most of the cleaning solvents. There are many steps that a facility can undertake to reduce
the use of solvent for cleaning. It can reuse some of the solvent, scrape off the paint left
on the inside of a mix tank, or modify existing cleaning practices and procedures. 5,30 Some
shipyards have modified their coating operations to use less solvent. For planning purposes,
a facility needs to know where the major solvent usage, emissions, and waste occur in the
facility. This may be achieved by:
• Developing a solvent accounting system for tracking the usage, fate, and costs of
organic solvents in coating operations and cleaning operations;
• Identifying actions management will take to reduce solvent content in coatings and
reduce usage of cleaning materials containing organic solvents. 5,31
The steps are not mutually independent and require full management support and financial
backing. Obtaining reliable data is one of the major problems that a manager or supervisor
involved in pollution reduction faces. Any program adopted should be one that can
identify accurate and specific material usage, emission data, and waste data that will be useful
for evaluating pollution cost and risk. 32 The “unit operation system” (UOS) approach
was used to categorize the universe of cleaning into nine main categories equivalent to those
identified here in the section discussing cleaning operations. The concept of a UOS provides
the foundation for a standardized material accounting method that provides transportable
data, that a secondary user can understand, for setting up a material balance, for
comparing alternatives, or evaluating risk. The visual representation of a set up, as was done
in Figure 14.26.1, is an essential component of this approach.
When facility managers and operators are able to identify with some confidence, at the
source, final solvent disposition and cost of cleaning, they are in a better position to make
informed decisions and take the necessary actions for reducing solvent usage. Facilities
have the added incentive to reduce worker exposure to toxics contained in solvents because
of OSHA requirements. 33 The facility owners and operators also have to abide by state, local,
and federal regulations that limit the amount of VOCs and HAPs emitted to the air and
water streams. Facilities that generate large amounts of solvent waste streams will have to
deal with RCRA hazardous waste regulations. 34