CASE STUDY # 162
1. Headline: Meeting Clean Water Standards by In-line
Measures in an Electroplating Shop
2. Background: See below.
3. Cleaner Production Principle: Process modification
4. Description of Cleaner Production Description:
Technology Principle: This technology involves use of in-
process measures, such as static and spray rinsing, and
neutralization of wastewater from plating baths.
Case Study Summary
Process and Waste Information: The plant operates four
plating lines: an automated chrome-nickel line with one
chrome and three nickel plating baths, a silver line with
a cyanide containing pre-silver plating bath and a
cyanidic silver plating bath, a bath for bright nickel
plating, and a hard chrome plating bath. Before 1978,
none of the lines contained static or spray rinse baths.
These have now been installed and a chemelec cell was
installed in 1980. The chrome rinse is followed by a
static rinse and a reduction tank for chrome (VI). Water
from the static rinse is returned to the nickel bath at a
rate of 200 liters/day and to the chrome bath at a rate of
50 liters/day. All rinse water comes together in a final
stream for neutralization and is then sewered. In the
original process, wastewater was sewered without
treatment.
The small quantities of cyanides are not detoxified, but
the Cr (VI) is detoxified with caustic soda and bisulfite.
No new waste products are generated. Due to spray
rinsing, water consumption has decreased about 5,000
m3/yr. The chemelec cell recovers about 80 kg/yr of
nickel and spray rinsing results in 80 kg/yr less of
nickel and chromium being released to the sewer system.
Scale of Operation: The production capacity is 9,000
m2/yr and employs 12 people, 9 of them in the
electroplating shop. The shop operates 12 hours/day, 360
days/yr.
Stage of Development: The technology is fully
implemented.
Level of Commercialization: All components needed are
widely available.
Material/Energy Balances and Substitutions: No data was
provided for the process before 1978. In 1986, 16-20
kg/yr of heavy metals are lost in the wastewater.
5. Economics
Investment Costs: Investment costs were Dfl 22,000 for
rinse tanks and Dfl 75,000 for the chemelec cell. Capital
costs were reported as Dfl 19,400 per year.
Operational & Maintenance Costs: Chemicals for the
measures cost Dfl 5,000 per year.
Payback Time: Payback time could not be calculated.
6. Advantages
Savings were reported as follows for 1986:
Water 3,000 Dfl/yr
Process chemicals 1,200
Pollution taxes 12,000
Total 16,200
The measures were probably implemented in an attempt to
meet water regulatory limits. The shop meets the present
and proposed future demands. The relationship with water
regulation authorities is good. A Roska filter has been
ordered to reduce water consumption from some 20,000 m3/yr
to 10,000 m3/yr by reusing the water from the filter. The
water authorities would like the water consumption to be
reduced further to 5,000 m3/yr.
7. Constraints
8. Contacts and Citation
Type of Source Material: Reports based on interviews with
companies
Citation: Wastewater problems in the metal industry. Dr
Ir W. H. Rulkens, TNO, Maatschappelijke Technologie,
Postbus 342, 7300 AH Apeldoorn, the Netherlands. Phone
+31-(0)55-773-344.
Industry/Program Contact and Address
H.W. du Mortier
VOM
Jan van Eycklaan 2
Postbus 120
3720 AC Bilthoven
Netherlands
TEL: 31-30-287111
FAX: 31-30-287674
9. Keywords: the Netherlands, metal, electroplating, process
modification, rinsing, plating, chrome, nickel, ISIC 3471.
10. Reviewer's Comments: This case study was originally
compiled by the UNEP IE Working Group on Metal Finishing.
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 10-04)