INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

Case STUDY #230

1.  Headline:   The use of the enzyme Greasex, a lipase, for
    the degreasing of skins and hides.

2.  Background:  See below.

3.  Cleaner Production Application:  Material substitution.
    Instead of surfactants to degrease the leather, enzymes
    are used. The process stays the same for bovine hides. For
    pigs- and sheep skins the process is more complicated.

4.  Description of Cleaner Production Application:

    Process and Waste Information

    Original process

    In the original process the degreasing of skins or hides
    is only a separate process for pig- and sheep skins.

The standard Pig Skin Recipe [1].

Soaking including non ionics ending with a wash            3
                                                       hours
First liming incl. non ionics and sulphide
                                                       overnigh
                                                       t
Washes
Second liming including non ionics
                                                  2 days
Washes
Deliming
                                        30 minutes
Bating including non-ionics
                                                  2 hours
Washes
Degreasing
Pickling and following processes

In the degreasing process for sheep- and pigskins the chemicals
mentioned below are used [3]. The solvents are recirculated:
trichlorethylene, white spirit, marlophen 89 and salt.
The output is BOD, COD and fat.

For bovine hides the degreasing is not a process on its own.
                              Surfactants for degreasing are
                              used in many steps like the
                              liming, washing or bating
                              process. These surfactants can be
                              Nonyl Phenol Ethoxylate
                              (forbidden in many European
                              countries) or Alkyl Alcohol
                              Ethoxylate.
Novo Nordisk introduced the enzyme Greasex in the world in
1990. Greasex is a lipase without any proteolytic side
activities. Greasex is not able to influence the fibrillar
structure of the hide. Greasex is rather specific in the way
that it only hydrolyses triglyceridic fats (or neutral fats or
tricylglycerols).


                       C-O-C-R1

             R2-C-O-C

                       C-O-C-R3


Figure 1: Structure of triglyceride.

Greasex then removes one or more of the fatty acids from the
glycerol molecule and a mixture of mono and diglycerides is
left. The mono- and diglycerides are emulgators themselves and
in that way the emulgation of non-hydrolysed fats is adding to
the effect of the enzyme.

The degreasing process must be carried out on fleshed
hides/skins with the structure of the hide beginning to open at
pH values beyond 8 and sufficient calcium and time available.
The addition of tensides should preferably be postponed until
Greasex has had the time to get into contact with the fat in
the skin/hide. High pH means that the fatty acids are not
protonated. The pH optimum is 9-11. Experiments have shown that
the enzyme is also active when the starting pH in liming is
12,5 [1].

Trials have been carried out on Danish salted pig skins in
which the basic recipe was a standard pigskin tanning recipe
with all tenside treatment included. This recipe is given in
the conventional process (page before). Greasex  was applied in
the second liming, alternatively in the bating step [4].

TABLE 1: Results from the Greasex degreasing trials on danish
pig skins

  parameters     reference  0.1% Greasex  applied in
             process     bating      liming

Extractable fat            5,3%          3,4%         1,8%
Tear strength (N)          41                         49
                                                  48
Color uniformity
of wet blue       Many stains
    (Cr-soaps)     no stains     no stains
Total results      Mediocre        Good        Very good


Novo Nordisk claims that degreasing with Greasex provides the
following advantages [2]:

-   Reduces the amount of natural fat
-   Reduces requirement for non-ionics
-   Organic solvents in the degreasing can be avoided
-   Increases tear strength
-   Improves uptake of chemicals in the succeeding processes
-   Improves color uniformity of wet blue and finished leather

In another article Novo Nordisk is speaking about tannery
experience [2].
Improvements by using the lipase that are observed on all
different types of skin include:
-   More homogeneous degreasing
-   Application of the non biodegradable Nonyl Phenol
    Ethoxylate (NPE) can be substituted by a treatment with
    the lipase, followed, when necessary, by an addition of
    Alkyl Alcohol Ethoxylate (AAE).
-   The dosage of the lipase can be reduced if the hides/skins
    are fleshed before degreasing.

In this article other positive effects are mentioned which
depend on the kind of skin. The dosage of lipase is in between
0,01 to 0,2 %. For bovine hides the enzyme has the best effect
when added in the liming step.
It is very difficult to give guidelines for lipase treatment.
The treatment temperature should be as high as possible, taking
in account that it is possible in the given process step. Novo
Nordisk says that lipase does not accentuate irregularities.

Scale of operation
Not known, because a user is not known.

Stage of development
The enzyme is developed by Novo Nordisk, a lot of research is
still to be done.

Level of commercialization
Novo Nordisk introduced the enzyme in the market by the end of
1990. There are some tanneries using this enzyme.

Material/Energy Balances and Substitutions
Maybe the use of enzymes saves some dyestuff. No more water or
energy or time is used.


5.  Economics

Investment Costs
There are no investment costs.

Operational and Maintenance Costs
The costs of the enzyme are around the 29 pounds (GB) per kilo.
Other costs are not known yet.

Payback Time
No payback time

6.  Advantages

-   Reduces requirement for non-ionics.
-   Organic solvent in the degreasing can be avoided.
-   Improves uptake of chemicals in the succeeding processes.
-   Application of the non biodegradable Nonyl Phenol
    Ethoxylate (NPE) can be substituted by a treatment with
    the lipase, followed, when necessary, by an addition of
    Alkyl Alcohol Ethoxylate (AAE).
-   The lipase does not, as surfactants do, counteract the
    effects of chemicals used to produce hydrophobic leather.

7.  Constraints

Many different chemicals are used in the beamhouse processes.
The performance of the lipase, in connection with these
chemicals, must be considered.


September 1994.


Contacts and Citations

Type of source Material
Articles, Interviews.

Citation
1.  Niels Henrik Sorensen, Novo Nordisk A/S "Novo Nordisk
    enzymes for the leather industry", presented in Poland and
    Czechoslovakia, April 1991.

2.  H. Svanholm et al "Enzymatic degreasing of skins and
    hides", Novo Nordisk A/S, Denmark, 1994.

3.  UNEP/IEO "Tanneries and the Environment, a technical
    guide", technical report series Nø 4, United Nations
    Publication, 1991.

4.  Application sheet Novo Nordisk A/S "Enzymatic degreasing
    of hides and skins with Greasex", Denmark, nov. 1990.

5.  JÆrgen Christner, Rohm Tech Inc." The use of lipases in
    the beamhouse processes", JALCA, vol 87, 1992.

Level of detail of the Source Material
More information is available but is not very clear.


Industry/Program Contact and Address
Not available. No permission is asked to or given by the
contact.

Abstractor Name and Address
Annelies den Braber
TME, Institute for Applied Environmental Economics
Grote  Marktstraat 24
2511 BJ The Hague
Netherlands
tel: 3170-3464422
fax: 3170-3623469


9.  Keywords: Novo Nordisk; ISIC code I2411, surfactant,
    tenside, organic solvent, tannery, degreasing, liming,
    biotechnology, enzyme, biological degreasing, leather, the
    Netherlands, material substitution, lipase, skins, hides,
    solvent, BOD, COD, trichloroethylene, white spirit, pig
    skins, Greasex.

10. Reviewer's Comments:  This case study was submitted to
    UNEP IE by the Institute for Applied Environmental
    Economics (TME) of the Netherlands on the part of the UNEP
    IE working group on Biotechnology.  The case study was
    edited for the ICPIC diskette in August 1995.  It has not
    undergone a formal technical review.