INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

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)