INTERNATIONAL
CLEANER
PRODUCTION
INFORMATION
CLEARINGHOUSE
INTERNATIONAL
CLEANER
PRODUCTION
INFORMATION
CLEARINGHOUSE
CASE STUDY 228
1. Headline: The use of the enzyme Terminox Ultra in the
textile finishing industry to neutralize the fabric after
bleaching and before dyeing.
2. Background: See below
3. Cleaner Production Principle: Material substitution. The
water and reducing agent normally used in the rinsing
process to remove hydrogen peroxide from the fabric before
dyeing is replaced by the enzyme Terminox Ultra.
4. Description of Cleaner Production Application:
Process and Waste Information
Original process
Natural fabrics such as cotton are normally bleached with
hydrogen peroxide before dyeing. Bleaching agents are
highly reactive chemicals and even very small amounts of
hydrogen peroxide can interfere with the dyeing process.
That is why thorough 'bleach cleanup' is necessary. Bleach
Cleanup is a term chosen by Novo Nordisk to describe this
process of removing residual hydrogen peroxide after
bleaching and prior to dyeing [1].
The traditional method is to remove the bleaching agent by
rinsing the fabric with large quantities of water several
times. Alternatively a reducing agent like thiosulfate can
be used to neutralize the bleach but the dose has to be
controlled precisely. Also a higher temperature is
required in order to react efficiently with hydrogen
peroxide. After the reduction the remaining reducing agent
has to be rinsed out. In either case, large amounts of
water are required for rinsing: up till 40 litres per kg
of fabric.
New process
Enzymes provide a more convenient alternative because they
are easier and quicker to use. A small dose of Catalase is
capable of decomposing hydrogen peroxide to water and
oxygen. Compared with the traditional clean-up method, the
enzymatic process results in a reduced water consumption
and a reduced energy consumption. The enzyme can be
applied directly after the bleaching stage. The Terminox
Bleach Cleanup process recommended for batch processing in
e.g. Yarn dyeing equipment, Jet dyers and winches is as
follows [2]:
1. Drain the bleaching liquor
2. Fill with fresh cold water
3. Adjust pH as for dyeing
4. Add 0.5-1.0 g/l Terminox
5. Check hydrogen peroxide after 10 - 15 min.
6. Start dyeing in same liquor
The rinsing step is not required when using the enzyme
because the bleaching agent is decomposed and the residues
of the enzyme have no effect on textile fibres or
dyestuffs. In cases where the fabric is very dirty it is
recommended to include a rinsing step between bleaching
and dyeing.
Terminox Ultra (commercial name of the Novo enzyme) is a
stabilized liquid catalase, found in nature and produced
by submerged fermentation of a non-pathogenic microorg
anism. The enzyme specifically breaks down hydrogen
peroxide into non-active oxygen and water under mild tem
perature conditions.
cat.
2 H2O2 ----> O2 + 2 H2O
The activity of the enzyme is 10 KCIU/g. One KCIU activity
unit ( Kilo Catalase International Unit) is the amount of
enzyme that breaks down one millimole of hydrogen peroxide
per minute under standard conditions ( 25 C, pH 7.0, 10
millimole H2O2)[2]. Under industrial conditions, Terminox
Ultra takes 10 to 15 minutes to breakdown the hydrogen
peroxide completely and then the dye can be added. This
also means that time can be saved.
Saving energy ( thereby preventing the associated
emissions ) and saving water are the main environmental
benefits compared to conventional bleach clean up,
especially in developing countries where water is usually
a scarce resource. In industrialized countries, water is
often more readily available but water charges are usually
high for both fresh water and for treating waste water.
The advantages of the enzyme are:
- No adverse effect on dyestuffs
- No need for heating
- No need for rinsing prior to dyeing
- No risk of harmful overdosing
- No formation of by products in waste water
A thorough economic and environmental analysis of the
enzyme treatment has been made in full-scale trials at
Skjern Tricotage Farveri, a dyehouse in Denmark. Until
recently, the company used thiosulfate for Bleach Cleanup
but switched to Terminox Ultra in 1994. Existing equipment
could be used and there was no need to make any new
investment[1,3].
TABLE 1: Savings when using the enzyme instead of a
reducing agent.
savings
quantity/year
water 13,500 m3
energy 2,780 GJ
natural gas 70,800m3
CO2 emissions 160 ton
reducing agent
10-15
Terminox Ultra
consumption 5-
10 ton
The quantity of gas is converted to the quantity of energy
in GJ. The basic heating value of natural gas is assumed
to be 39.1 MJ/m3.
The natural gas is used for the steam generation at the
dyehouse. As no heating is required when the enzymatic
treatment is used, considerable amounts of gas can be
saved giving reductions in carbon dioxide emissions of an
estimated 160 tons per year. This is the main advantage
from the environmental point of view. However, from the
economical point of view, the savings in water charges are
most significant. Instead of 19 litres per kg of fabric,
only 10 litres were required for the Bleach Clean up stage
[1].
The dye house tested the color shade and fastness, and
found no difference between the processes. The bursting
strength of samples were tested internally, and again no
difference could be found between the two samples [3].
Neither terminox, nor the reducing agent applied as
alternative, had any significant impact on the waste water
quality. Impurities from the cotton fabric (pectines and
spinning oil) were the main contributors to BOD5 and COD.
Scale of operation
Skjern Tricotage-Farveri at Skjern in Denmark is a modern
dyehouse with an annual production of around 5000 tons of
fabric. 225 employees are working at the company. The
annual turnover is about 115 million DDK. The company has
a stated policy of reducing water and air pollution risks
[4]. This dyehouse is a major supplier to Novotex, a
Danish company that sells ecologically sound cotton under
the brand name "Green Cotton". The fabric volume dyed is
roughly 1500 tons per year. In this case study the figures
are based on this quantity of 1500 tons per year.
Terminox Ultra is manufactured and marketed by Novo
Nordisk. The company manufactures a variety of enzymes,
pharmaceuticals and biotech products. It employs 11,600
people and is headquartered in Denmark.
Stage of development
The cleaner production technique is fully implemented this
summer (1994). The data given in this case study are based
on a full-scale trial at Skjern Tricotage-Farveri. The
trial is done with 470 kg knitted 100% cotton fabric with
a machine capacity of 500 kg. The results of this test are
passed on to the 1500 tons dyed in a year to calculate the
yearly savings [3].
Level of commercialization
The enzyme is on the market from end 1993. Currently there
are already a few big customers.
Material/Energy Balances and Substitutions
TABLE 2: material/energy balance
material category quantity before Quantity
After
(per kg
fabric)
(per kg
fabric)
water use
19 L
10 L
energy use
1.89 MJ
0.04 MJ
5. Economics
Investment Costs
There are no investment costs. The same machine is used
and no further equipment is necessary.
Operational and Maintenance Costs
There are no additional operational and maintenance costs.
The difference in price of terminox and thiosulfate
depends on the supplier ( of thiosulfate) as well as the
geographical market. The cost savings in a particular
country will depend on local water charges and the costs
for energy. To calculate the cost savings for a hypo
thetical case the following assumptions for energy and
water costs have been made. Natural gas: 1 DKK/m3 and
water 15 DKK/m3. Using these assumptions the cost savings,
as a result of the use of Terminox, are 27500 DKK per
year, based on the reductions in water and energy
consumptions indicated in table 1.
Payback Time
While the investment cost are zero the payback time is
also zero. The new process starts to give benefits as soon
as it is used.
6. Advantages
- Reduced water consumption
- Reduced energy consumption
- Reduced process time
- Easy to implement and control
- No need for reducing chemicals
7. Constraints
The company did not experience any problem when using the
enzyme. There are no technical constraints to change over
to the biotechnological process by applying Terminox
Ultra.
8. Contacts and Citations
Type of Source Material: Leaflet of the company,
organization report, interviews.
Citation:
1. Gitte Pedersen," Enzymatic treatment of residual
bleach in cotton dyeing",draft UNEP Cleaner
Production Worldwide publication, 1994.
2. Product sheet Terminox 10 L, Novo Nordisk, March
1993.
3. Gitte Pedersen,"Terminox Trial at Skjern Tricotage-
Farveri", confidential report, 1994.
4. Leaflet Skjern Tricotage-Farveri A/S, 1993.
5. Interview Gitte Pedersen, Novo Nordisk.
Level of detail of the Source Material
Some more detail about the tests done at the company can
be found in the confidential report.
Industry/Program Contact and Address
Per Hans Jakobsen
Industry Manager
SBU 1/Textile Group
Enzyme Process Division
Novo Nordisk A/S
Kroegshoejvej 36
2880 Bagsvaerd
Denmark
Tel:+45-4444 8888
Fax:+45-449 1050
Abstractor Name and Address
Annelies den Braber
TME, Institute for Applied Environmental Economics
Grote Marktstraat 24
2511 BJ The Hague
Netherlands
tel:+31-70-3464422
fax:+31-70-3623469
Name and Location of Company
Skjern Tricotage-Farveri A/S
Farverivej 1
DK-6900 Skjern
Denmark
tel: + 4597350811
fax: + 4597353392
9. Keywords: Denmark, textile finishing, material
substitution, new technology, ISIC I2242,
biotechnology, enzyme, bleaching, dyeing,
neutralizing, bleaching agent, water saving, energy
saving, Terminox Ultra, textile, energy.
10. Abstractors Comments:
Assumptions
Basic heating value natural gas: 39.1 MJ/m3
Specific CO2-emission factor natural gas: 57 kg/GJ
Energy efficiency: 70 %
Price natural gas: 1 DKK/m3
Price water: 15 DKK/m3
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.