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Thermal Metal Treating, Inc. Amplate,
Inc. Quality Rolling
& Deburring Co., Inc
Location: Charlotte, NC (Mecklenburg County)
Industry: Electroplating: (SIC: 3471)
Pollution Prevention Application: Wastewater Reuse, Cleaning/Filtration
Annual Savings: 88% Reduction in Hazardous Waste
Payback Period: Not applicable
Contact: David French, President (704) 597-0688
Amplate, Inc., performs nickel, zinc, and decorative chrome electroplating.
The company also electroplates using heat chemical processes such
as black oxidizing, passivation, and electroless nickel.
Tank Maintenance and Filtration
The company installed a countercurrent system on the rinse tanks
and an ion exchange system to remove contaminants from the chromate
rinse water. Contaminated overflowing rinse water is pumped through
a pre-filter unit, a cation column to remove metals, and then an
anion column to further purify the water. The water is then returned
to the rinse tank for reuse. Once the ion exchange columns are exhausted,
they are shipped off site for regeneration.
The company has been able to increase bath life of the alkaline
cleaning solutions by proper selection of chemicals, in-tank filtration
to remove insoluble contaminants, and treatment of other contaminants.
These practices extended alkaline cleaner bath life from 3 months
to over 18 months. A coagulant (DTC) was used periodically in the
acid pickle tanks to remove metal contamination without the usual
pH adjustment. However, organics would eventually build up and thus
require acid bath disposal.
In the late summer of 2000, Gwen Wagner, President of Wagner Environmental
Technologies, persuaded Amplate to test a new acid bath extender
called, PRO pHx, a decarboxylating agent. After successful test
results on a small scale, the DTC was replaced by PRO pHx late in
the year 2000 and no acids have been disposed of since. Acid addition
is required only to make-up for drag-out and evaporation.
Wastewater Reuse System
Amplate utilizes an electro-coagulation unit to treat and recycle
the rinse water from the alkaline cleaners and the acid pickle rinses
of the plating line. The pH of the wastewater is adjusted, but no
chemicals are used to precipitate contaminates. Treatment is accomplished
with an ionic generator, which utilizes UV light and a small rectifier.
The UV light produces oxygen in the rinse water stream, which then
passes two probes powered by the rectifier. Wastewater floc accumulates
on the probes, which reverse polarity every few minutes. When the
polarity reverses, the floc is released from the probe and captured
downstream by a conventional filter. Final treatment was accomplished
when the water passed through an activated carbon filter to remove
The carbon has since been removed from the system and PRO pHx is
being added at 1/12 of 1% to remove organics during filtration.
Wastewater must be circulated through the system more than once
to achieve desired quality standards, and therefore, a batch approach
is utilized. Treated water is stored in a holding tank and reused
for both alkaline cleaner and acid bath rinses.
In response to more stringent air emission requirements for chromium
electroplaters, Amplate asks customers to consider electroless nickel
as an alternative to hard chrome. Many customers have found electroless
nickel to be a suitable and sometime superior replacement to hard
chrome in some applications.
Waste Reduction and Annual Savings
The shop savings are estimated in excess of $75,000 per year. The
figures below reflect the savings on one line only.
Table1: Amplate Waste Reduction
||Acid Bath Disposal, lbs.
||Hazardous Waste generated, lbs.
||Hazardous Waste Disposed Costs
||Acid and Caustic Purchases
It should be noted that all the reductions in waste generation and
water conservation were achieved despite a fourfold increase in
total production. Cost savings were not calculated for variables
other than hazardous waste disposal costs and purchases of generic
acids and caustic soda.
Amplate was recognized for Outstanding Achievement in the Small
Business Category of the 1994 Governor's Award for Excellence in
Waste Reduction competition.
Submitted by: Ray Guerrein, Consultant, Waste Reduction Partners