INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

CASE STUDY # 172

1.   Headline:  Membrane Electrolysis Results in almost
     Complete        Recovery of Nickel from Electroplating
     Wastewaters

2.   Background:  See below.

3.   Cleaner Production Principle:  process modification

4.   Description of Cleaner Production Application:

     This technology involves in-process modifications using
     membrane electrolysis to recover nickel and reduce rinse
     water flow from electroplating processes.

     Case Study Summary

     Process and Waste Information:  Water purification was
     previously accomplished in a DND installation. For the new
     process, membrane electrolysis was selected because the
     high iron concentration in the solution can impair
     electrolysis operation.  The wastewater is sent to ion
     exchangers where the stream of 4 m3/hr with 0.5 g/l of
     nickel is concentrated to 10 m3/week with a concentration
     of about 12 g/l.  The wastestream is then passed to a
     membrane electrolysis cell where 99.8% or 5000 kg/yr of
     nickel is reclaimed through batch treatment.  The nickel
     content in the stream is reduced to less than 6 mg/l.  The
     membrane in the cell is composed of perfluorinated PTFE.
     The cell operates at 7 V and with 900 A 4 days/week.

     The new technology reduces the rinse water flow,
     eliminates chlorine and sludge production, and recovers
     nickel for sale or reuse.  There is no effect on the final
     product.

     Stage of Development:  The technology is fully
     implemented.

     Level of Commercialization:  From the case study, it was
     not clear whether the equipment was purchased or developed
     in the plant itself.  On further inquiry, it became
     apparent that the equipment comes from Esmil, Diemen in
     the Netherlands.

     Material/Energy Balances and Substitutions:  5000 kg/yr of
     nickel are reclaimed from the rinsewater.

6.   Economics

     Investment Costs:  Investment costs for the electrolysis
     system were reported as Dfl 715,000. Capital costs were
     reported as Dfl 100,000.  No further breakdown was
     provided.

     Operational & Maintenance Costs:  Operating and
     maintenance costs were reported to be Dfl 5,000 for
     energy, Dfl 15,000 for labor, and Dfl 14,000 for
     maintenance.

     Payback Time:  Nickel savings can be estimated to be about
     Dfl 100,000 since 5000 kg/yr of nickel are recovered at a
     rate of Dfl 20/kg.  Savings on sludge hauling were not
     specified, however, the amount of sludge not produced was
     indicated as "tens of tons" and hauling rates are
     estimated at Dfl 300 to 500.

6.   Advantages:  This process recovers nickel for sale or
     reuse, reduces the quantity of wastewater requiring
     further treatment, and eliminates chlorine and sludge
     production.  Benefits from improved public relations,
     reduced liabilities, and changes in regulatory compliance
     were not discussed.

7.   Constraints

     One problem which arose during implementation of the
     technology was the plugging of anode compartments with
     iron sludge from steel anodes.  This was solved by using
     activated titanium anodes with a layer or iridium oxide
     which also increased efficiency.

     At the end of the process, a basic mist was produced above
     the anode compartments.  This problem was eliminated by
     placing mist filters above the anode compartments.

     It was found that removal of nickel from the electrodes
     took about 5 to 6 hours.  Using cathode cylinders treated
     with a contact oil before starting the process decreased
     the time to about 2 hours.

     The problem of the control of the voltage rectifier being
     destroyed frequently was corrected by using oil cooling
     instead of air cooling.

8.   Contacts and Citations

     Membrane electrolysis in practice.
     J. Manders.  Tijdschrift voor oppervlaktetechnieken en
     corrosiebestrijding.
     Vol. 34, No. 1, January 1990,  p.14-16.

     Level of Detail of the Source Material:  Schematic
     diagrams of plating and membrane electrolysis
     processes, including additional efficiency and mass
     balance data, are available in source document.

     Industry/Program Contact and Address

     Egidius Jansen
     Witveldweg 14
     5951 AV Belfeld
     The Netherlands
     TEL: 31-4705-1444

9.   Keywords:  the Netherlands, metal, electroplating, process
     modification, ISIC 3471, nickel, electrolysis, ion
     exchange, iron, PTFE, chlorine, sludge.

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: DOCUMENT NOT AVAILABLE *****10-19