Paints and Coatings - P2 InfoHouse

132 Paints & Coatings
chronic and cumulative threats to
health as solvents, their caustic
nature dictates use of proper
safety equipment mch as goggles,
face masks and protective cloth-
ing.
Industry spokesmen suggest
that caustic cleaning solution is
recycled among many of those
plants that use this cleaning
method. Waste rinsewater, on the
other hand, is typically sewered.
Some paint formulators success-
fully muse waste rinsewater in
the production of water-based
paints without impairing paint
quality.! Such water recycling
applications are rare.
H Accordrng to a study of the
United States paint mandactur-
ing industry by Burns and Roe
Industrial Services Corp.
(Paramus, New Jersey), if the
s00,OOO gallons of wastewater
produced daily by the entire paint
mandacturing industry in the
United Stah were treated by
conventional chemical precipita-
tion and settling, it would yield a
sludge volume of 120,OOO gallons
per day.I5
On the other hand, if8096 of the
wastewater generated is recycled
industry-wide, this would shrink
the total wastestream to 160,000
gallons per day.15 This assumes
that 20% of the total wastewater
volume would be incompatible for
reuse because of colour and for-
mulation restrictions.
Recycling wastewater is antici-
pated to be the cheapest treatment
option because it greatly reduces
the volume of wastewater requir-
ing costly chemical precipitation
and sludge disposing procedures.
Flgure 2
Caustic Recycling During Equipment
Clean-Out
Hot caustic cleaning solutlon Is pumped under pressure to the tank to be
cleaned, where a spray system shoots the cleaning solution against the
walls of the mixlng tank. When the cleaning operation is complete, the
dirty caustic solutlon Is flitamd and mtumed to the storage tank for
"e.
Sou~:"ATankCleanlngSystemforthe Small Pain!Piant,"Joumddcodnga Tecdmibgy, September 1979.
II fr \\
II II
Paint Application
It has been decades since in-
dustrial painters foresook the
paint brush for more modern
methods such as spray painting.
Although the development of the
spray gun did much to escalate
productivity and enhance the
quality of painted finishes, it also
unleashed a Pandora's box of prob-
lems. In addition to potential
health hazards posed by inhala-
tion of atomized paint, the ques-
tion of what to do with the millions
of gallons of paint siudge gener-
ated annually continues to plague
the paint industry.
By spraying paint onto an ob
ject, as little as 30% of the spray
reaches the target object. The rest,
known as overspray, commonly
ends up in a barrel at a landfill
site. This dilemma has the indus-
try pursuing several strategies to
minimize the quantity of waste
paint requiring disposal. The
major thrust is in improving the
efficiency of paint application.
Another strategy is to maximize
the re-use of paint overspray and
wastewater.
,
A third direction is to substitute
less hazardous materials, namely
to reduce or eliminate the solvent
component of paints. It must be
recognwd, however, that some of
the non-solvent coating systems
contain potentially hazardous
components such as isocyanates
which are considered to be of even
greater hazard than conventional
solvent-borne systems.16.17 Re-
search into substitution of less
hazardous pigments and other
cuiiyiitilents is atill in its infancy,
but can be expected to accelerate
as health hazards associated with
existing components are iden-
tified.
Although technological innova-
tion in the paint industry has come
a long way, it still has some way to
go. In the meantime, however,
pollution reduction and company
profits can be maximized by im-
plementing some of the proven
technologies now commercially
available.
One thing is clear. Unlike the
1940s and 1950s when solvent-
borne alkyd resins ruled supreme,