INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

CASE STUDY #2
1.   Headline: Chrome recovery and recycling in the leather
industry.
2.   Background: The Germanakos SA tannery near Athens in
     Greece was founded in 1978. Today it produces good
     quality upper leather from cattle hides, processing 2200
     tons per year and with an annual turnover of US$8.4m and
     a staff of 65. The Toegepast Natuurwetenschappelijk
     Onderzoek (TNO)is the Netherlands organization for
     applied scientific research, and the project was carried
     out by their Institute of Environmental and Energy
     Technology.
     The Greek and Dutch governments have a framework of
     bilateral collaboration in the field of environmental
     protection. One result of this has been that a clean
     technology developed at TNO has been applied in a full
     scale co-operative R & D project between the two
     countries and the Germanakos tannery. The project was
     carried out from 1988 to 1990 with support of the
     European Union.
     Tanning is a chemical process which converts putrescible
     hides and skins into a stable material. Vegetable,
     mineral and other tanning agents may be used - either
     separately or in combination - to produce leather with
     different qualities and properties. Trivalent chromium
     (Cr3) is the major agent since it produces a modern,
     thin, light leather suitable for shoe uppers, clothing
     and upholstery. However recent limits for discharge to
     the environment have limited Cr3 discharge to levels as
     low as 2mg/liter in waste waters.
3.   Cleaner Production Principle: Internal recycling
4.   Description of Cleaner Production Application: The
     technology developed involves the recovery of Cr3 from
     the spent tannery liquors and its reuse.
     Tanning of hides is carried out with basic chromium
     sulphate, Cr(OH)SO4, at a pH of 3.5-4.0. After tanning
     the solution is discharged by gravity to a collection
     pit. The liquor is sieved during this transfer to remove
     particles and fibers that have come from the hides. The
     liquor is then pumped to the treatment tank and a
     calculated quantity of magnesium oxide is added with
     stirring until the pH reaches at least 8. The stirrer is
     switched off and the chromium precipitates as a compact
     sludge of Cr(OH)3. After settling the clear liquid is
     decanted off. The remaining sludge is dissolved by adding
     a calculated quantity of concentrated sulfuric acid
     (H2SO4) until a pH of 2.5 is reached. The liquor now
     contains Cr(OH)SO4 and is pumped back to a storage tank
     for reuse.
     In conventional chrome tanning processes 20-40% of the
     chrome used is discharged into waste waters. In the new
     process 95-98% of the waste Cr3 can be recycled.
5.   Economics: For the Germanakos tannery, which has a
     chrome recycling capacity of 12m2/day, the approximate
     costs were as follows:
     Cost saving                       US$/year
     Savings                          73,750
     Operating cost                30,200
     Total net savings                  US$43,550
     Capital Investment                 US$40,000
     Payback                          11 months
          Savings can be made with any plant processing more
than 1.7m3/day.
6.   Advantages: Very little change to production     process.
     More consistent product quality. Easier to monitor
     amounts of water and process chemicals used. Much reduced
     chromium content of effluent waters.
7.   Constraints: N/A
8.   Contacts:     Mr D Papakonstantinou
                  General Manager
                  Hellenic Leather Center SA
                  Thiseos 7a Str
                  17676 Kallithea
                  Athens
                                Greece
                  Tel: +30 1 9025 595
                  Fax: +30 1 9025 598
                  Telex: 218819 HMIH GR
                  Mr Rob Glaser
                  Inspector International Affairs
                  Ministry of Housing, Physical Planning and
Environment
                  PO Box 7073 4330 GB
                  Middelburg
                                The Netherlands
                  Tel: +31 1180 33792
                  Fax: +31 1180 38245
                  Telex: 37739 RIVOM NL
                  Mr M van Vliet (Ex TNO)
                  British Leather confederation
                  Kings Park Road Moulton Park
                  Northampton
                                NN3 1JD UK
                  Tel: +44 604 494131
                  Fax: +44 604 648220
9.                  Keywords:Greece, the Netherlands, leather,
                    leather tanning, recycling, chrome
10.  Reviewer comments: This case study was originally
     published in the UNEP IE document, "Cleaner Production
     Worldwide". In the process of preparing the document the
     case study underwent a technical review.