INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

CASE STUDY #38
1.  Headline: Recovering metals and reusing wastewater in
electroplating
2.  Background: The Robbins Company electroplates  jewelry,
awards and other promotional items with valuable metals such
as gold and silver. Electroplating entails the passing of
electric current through the object to be plated, while it is
submerged in a bath of chemical solvent that includes the
plating metal. The plating of the object occurs as the current
flowing through the object to be plated attracts the metal in
the solvent bath. This process traditionally amounts uses
significant amounts of chemicals and water, and produces
wastewater carrying toxic residuals.
     In the early 1980s, new, increasingly stringent
     environmental regulations came into application in the
     United States under the Clean Water Act. At this time,
     Robbins was controlling its waste discharge into a
     nearby river with a large holding tank, in which waste
     substances settled out before water was discharged. This
     system was incapable of meeting the new regulations, and
     the company found itself regularly in violation of its
     discharge permits.
     Established in 1892, the Robbins Company located in
     Attleboro, Massachusetts, manufactures jewelry, awards,
     and promotional items. The company employs 350 people.
3.  Cleaner Production Principe: Process modification
4.   Description of Cleaner Production Application: Faced
     with possible closing for environmental violations, the
     company decided to look beyond other short-term end-of-
     pipe control solutions to a closed-loop system, which
     would bring the company into compliance with regulations
     through process modifications that would minimize waste
     generation. The system would purify and recycle water,
     recover plating chemicals, and assure long-term
     environmental and economic benefits for the firm.
    Two subsystems comprise the closed-loop process. In the
wastewater purification subsystem, which returns clean water
to the plating line, hydrogen peroxide destroys cyanide; acid
and caustic from spent baths adjust pH level; particulate
filters remove solids; carbon filters remove organic
compounds; and ion exchange resins remove salts and metals.
(Ion exchange has now been replaced with an improved reverse
osmosis process.) In the metal recovery subsystem, metals
captured in the ion exchange are plated out through
electrolytic recovery. The solution is sent to an atmospheric
evaporator, water is boiled off and metal (without hydroxide
complex) and salt sludge remains -- two gallons per year (gpy)
as compared to 2 600 gpy to the closed-loop system. Base and
precious metals are recovered from all filters, resins and
cathodes from the electrolytic process.
     Enabling technology: Robbins' efforts to minimize waste
did not stop with the closed-loop system. 1993-1994, the
company replaced the ion exchange system with reverse osmosis
membranes. As a result, significant hazardous chemical savings
have been achieved.
5.   Economics:
          Annual savings from closed-loop system:
          Operation                Savings (US$)
          Water usage               22 000
          Chemical use              13 000
          Disposal of sludge as
            hazardous waste          28 000
          Revenue from sale of
            reclaimed metals from
            sludge                 14 000
          Laboratory analysis        40 000
          Total annual savings        117 000
          Capital investment:    US $ 240 000
          Annual savings:        US $ 117 000
          Payback period:             2 years
6.   Advantages: Results of this system have included: a drop
     in water consumption from 500 000 to 500-700 gallons per
     week; chemical savings of 82 per cent; and laboratory
     cost savings of 87 per cent. In addition, toxic sludge
     generation has been replaced by metals recovery.
     The company has also experienced unanticipated benefits.
     Because the water returned to the plating line is cleaner
     than the water platers previously used, quality is higher
     and reject rates have dropped. Moreover, from 1987-1991
     following implementation of the closed-loop system, sales
     increased approximately 14 per cent due to quality
     improvements and favorable publicity from the
     modifications.
7.   Constraints: N/A
8.   Contacts:Mr Robert E. Chatel
                  President and Chief Executive Officer
                  The Robbins Company
                  Post Office Box 2966
                  400 O'Neil Boulevard
                  Attleboro, Massachusetts
                  02703-2966
                  United States
                  Tel: +1 508 222 2900
                  Fax: +1 508 222 7089
9.                  Keywords:USA, metal, metal finishing,
                    electroplating, process modification,
                    reverse osmosis, ion exchange
10.  Reviewer comments: This case study was originally
     published in the UNEP IE document "Cleaner Production
     Worldwide", Volume II. In the process of preparing the
     document the case study underwent a technical review.