INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

CASE STUDY # 147

1.   Headline:  Recovery of chromium from plating bath at
     Industrial Electroplaters eliminates need for chemical
     treatment.

2.   Background:  See below.

3.   Cleaner Production Principle:  internal recycling

4.   Description of Cleaner Production Application:  The Model
     C12-X Chromic Acid Recovery Unit operates as a closed-
     loop system to recover chromic acid from plating baths.
     The rinsewater is filtered to remove solids and then
     pumped through three reciprocating-flow ion-exchange
     columns.  An anion-exchange resin removes the chromate and
     polychromate ions, and the water is then reused for
     rinsing.  The effluent passes through a second
     cation-exchange bed, where a concentrated chromic acid
     solution is collected.  The cation and anion resins are
     regenerated with sulfuric acid and sodium hydroxide,
     respectively.

     Material/Energy Balance and Substitution

     FEEDSTOCKS:  Spent electroplating bath

     WASTES:  Contaminated rinsewater

     MEDIUM:  Water

5.   Economics:

     CAPITAL COST:  Not reported

     OPERATION/MAINTENANCE: $8,055/yr for materials

     DISPOSAL & FEEDSTOCK:  $11,000/yr in recovered chromic
     acid $5400/yr in chemical treatment eliminated, $400/yr in
     sludge disposal, $6,980/yr in water consumption.

6.   Advantages

     FEEDSTOCK REDUCTION: 2300 kg/yr chromic acid recovered,
     water consumption reduced by 2.4 million gals/yr

     WASTE PRODUCTION: 2300 kg/yr chromic acid not disposed as
     waste, large volumes of wastewater eliminated

     IMPACT/PROBLEMS: The rinsewater used to be diluted at a
     rate of 10 gallons per minute to reduce the chromium
     content to 5 ppm to meet local effluent regulations.
     Chromium in the plant effluent is now less than 2.0 ppm,
     eliminating the need for chemical treatment.  Rinsing of
     the plated parts is also more efficient.


7.   Constraints:  No information provided.

8.   Contact and Citation: "Catalogue of Successful Hazardous
     Waste Reduction/Recycling Projects", Energy Pathways Inc.
     and Pollution Probe Foundation, prepared for Industrial
     Programs Branch, Conservation & Protection Environment
     Canada,  March, 1987, page .

9.   Keywords:  United States, USA, metal, electroplating,
     recycling, ISIC 3000, chrome, acid, ion exchange, rinsing,
     chromic acid.

10.  Reviewer's Comments:  This case study was originally
     abstracted for the US EPA's Pollution Prevention
     Information Clearinghouse from the Canadian publication
     "Catalogue of Successful Hazardous Waste
     Reduction/Recycling Projects."  It underwent a UNEP IE
     funded technical review in 1994 for quality and
     completeness.  It was edited for the ICPIC diskette in
     July 1995.

( Docno unep05: 450-003-A-348 )