SUSTAINABLE INNOVATION
Cost-neutral replacement of
surfactants with enzymes - a short-cut
to environmental improvement for laundry washing
Replacing surfactants with enzymes in detergents helps reduce the environmental impact of laundry washing
without compromising the total wash performance or increasing detergent costs. Detergent enzymes can make
this happen because they are efficient in low concentrations and ensure satisfactory cleaning at low temperatures.
INTRODUCTION
The growing awareness of the vulnerability of our
environment is putting pressure on all players in the
detergent value chain. This increasing pressure from
legal institutions and end consumers is causing
detergent manufacturers to develop products that are
efficient, and have a reduced impact on the
environment before, during, and after the wash
process. Energy consumption to heat wash water is a
major source of environmental impact in laundry
washing. Novozymes has always had a strong focus
on sustainability and has been developing new and
efficient enzyme systems that are effective at low wash
temperatures. These enzyme systems meet the
demand in Asia where cold washes are standard, and
enable wash temperature reduction in Europe and the
United States where clothes are traditionally washed at
elevated temperatures. Enzymes are natural
substances, efficient at low concentrations, readily
degradable in the environment, delivering low toxicity
levels, and most importantly, efficient at low
temperatures. Novozymes' enzymes helps detergent
formulators meeting the requirements of tomorrow.
Novozymes offers documentation to its partners about
the environmental effects of detergent formulation
changes that lead to increased enzyme use.
This paper shows the benefits of replacing surfactants
with enzymes in a standard laundry detergent (IEC-A
bleach), assessed through wash experiments, life
cycle assessments (LCA), and toxicity screenings.
The screenings are in accordance with the European
Eco-labelling system.
METHOD
Fifty percent of surfactants in a standard laundry
detergent (IEC-A bleach) were replaced with enzymes
on a cost-neutral basis and the effect on both wash
performance and environment was evaluated.
Wash performance was tested in Miele Softtronic
W2245 washing machines (front-loaded) at wash
temperatures ranging from 20°C to 60°C. The stain set
consisted of eight stains adopted from the European
Eco-labelling
system.
After wash, all
swatches were
dried at 30°C
for 12 hours and
the reflectance
of the dry swatches measured
with a ColorEye
reflectometer at
460 nm.
Total laundry
load (1) was 3.0
kg, while water
(2) consumption
was 14 L for the
main wash and
38 L for the
rinse.
Wash
experiments
were repeated
five times.
Table 1. Compositions of the conventional and the enzyme-rich detergents. One half gram of enzyme replaced
50% of each of three surfactants in the enzyme-rich detergent, while all other ingredients remain unchanged.
The composiAll ingredients are quantified in g per 14 L wash water and refer to a laundry load of 3.0 kg
tions of the con-
Household and Personal Care Today • nr. 4/2007
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SUSTAINABLE INNOVATION
ventional detergent without enzymes and
the enzyme-rich detergent, where 50%
of each surfactant was replaced with
enzymes, are shown in Table 1.
The cost of the two detergents is the
same.
ENVIRONMENTAL ASSESSMENT
The production of enzymes, surfactants,
and heat impacts the environment
because energy, water, and raw
materials are used in their production.
Additionally, production results in
undesirable substances being released
via smoke stacks and drains. Using life
cycle assessment, the environmental
impact of additional enzyme production
is compared with the reduced impacts
realized by using less surfactant and
using less electricity for heating wash
water (see Box 1).
The environmental impact of enzyme
Box 1. Principle of life cycle assessment (LCA)
production refers to Novozymes'
production records in 2007. All
processes in the product chain from
resource extraction through material
production and production at
Novozymes are included. See Nielsen et
al, 2007 (3). The avoided environmental
impact obtained by reduced electricity
and surfactant production is derived from
the public database Ecoinvent (2005)
(4), which includes all processes in a
Figure 1. Main changes when enzymes replace surfactants in the detergent and
similar way. This study focuses on
the wash temperature is reduced. Life cycle assessment is used to compare the
laundry washing in Northern Europe. We
environmental impact of enzyme production with the avoided impacts obtained by
surfactant saving and reduced electricity production for heating wash water. A
assume that wash water for laundry
screening method from the European Eco-label scheme is used to compare ecowashing is heated with electricity and
toxicity of added enzymes and saved surfactants
that
the
electricity
s a v i n g s
obtained
by
w
a
s
h
temperature
reduction
p r i m a r i l y
influences coalfired
power
plants
(the
marginal power
suppliers).
Electricity
savings
by
r e d u c i n g
laundry wash
temperature is
estimated at
16.2 Wh per °C
(5). Electricity
consumption for
maintaining the
w
a
s
h
temperature
during the wash
process
is
disregarded.
Surfactants and
Figure 2. Wash performance measured as total reflectance when the laundry is washed with the conventional
and the enzyme-rich detergent at various wash temperatures. Arrows indicate the changes which have been
e n z y m e s
subjected to environmental assessments.
present in the
See Figure 3 and 4 for environmental assessment details
wash
water
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Household and Personal Care Today • nr. 4/2007
Figure 3. Added (brown bars) and saved (dark and pink bars) environmental impacts when enzymes replace 50% of the surfactants
in the detergent and wash temperature is reduced from 40°C to 30°C. Data reflect additions and savings per 3.0 kg laundry
after use are undesirable substances in the aquatic
environment because they may have a negative
influence on flora and fauna. A screening method
adopted from the European Eco-labeling system
(Madsen and Stranddorf, 2003) (6) is used to assess the
changes in eco-toxicity of the wash water after use and
cleaning in waste water treatment plant.
A brief overview of the most important changes
considered in the study is shown in Figure 1.
RESULTS
The results show that total wash performance
measured as total reflectance increases when
enzymes replace surfactants in the detergent and that
wash temperature can be reduced to a lower level with
almost the same or better total wash performance
(Figure 2). Table 2 shows the changes in wash
performance on specific types of stains when changing
from the conventional detergent to the enzyme-rich
detergent and reducing the wash temperature. Wash
performance changes of two units or more are usually
visible. The results show that switching to the enzymerich detergent and reduced washing temperatures
improves wash performance on stains caused by milk,
cocoa, egg yolk, and grass. Wash performance on red
wine stains and to a lesser extent oil/carbon black
stains is reduced. The reduced performance of
bleaching agents at reduced wash temperature
Household and Personal Care Today • nr. 4/2007
explains the declining wash efficiency on the red wine
stain.
THE ENVIRONMENTAL IMPACT
The positive environmental effects of replacing
surfactants with enzymes and of reducing wash
temperature from 40ºC to 30°C are shown in figure 3
for a broad range of impact categories. Our results
show that the additional environmental impact caused
by enzyme production is generally quite small
compared to the environmental impact savings
obtained by the wash temperature reduction and the
reduced use of surfactants. The overall reduced
environmental impact reflects the use of a small
amount of enzyme having a relatively small impact on
the environment as opposed to a much larger amount
of surfactants and a relatively large amount of
electricity. Sugar is used to feed microorganisms in
enzyme production and vegetable oil is used as raw
material for surfactant production (soap and
ethoxylated alcohol); both lead to use of agricultural
land. However, the amount of sugar used for enzyme
production is small compared with the amount of
vegetable oil saved in surfactant production and this in
turn results in a net saving of agricultural land. Palm oil
is often used in surfactant production so reducing the
use of surfactants can help alleviate the pressure on
the nature in the tropics where palm oil plantations
5
SUSTAINABLE INNOVATION
Table 2. Changes in wash performance for specific types of stains (change in reflectance)
that 150-450 g of carbon dioxide
(CO 2 ) can be saved per wash
when
the
detergent
is
reformulated with enzymes and
the wash temperature is reduced.
Even though the amount of CO2
saved per wash is small, it
becomes very substantial when
the effect of all warm laundry
washes are considered.
The current number of 40°C
laundry washes in Denmark is
around 150 per household per
year while the number of 60°C
washes is around 90 (ELMODELbolig, 2004) (7). Using these
averages, the total savings
potential per household and for
the entire nation has been
estimated in Table 3.
Extrapolating these estimates to
Europe, where the number of
households is 180 million
(Eurostat), the total savings have
also been roughly estimated,
though we acknowledge that
regional variation in laundry
washing
behaviour
adds
considerably to the uncertainty.
The total European CO 2
remediation potential if all 60°C
washes were reduced to 30°C or
40°C, and all 40°C washes were
reduced to 20°C or 30°C, is on
the order of 9-15 million tons of
CO 2 per year. With the annual
CO2 emission of a car averaging
at 4 tons (8), the laundry-derived
savings correspond to the annual
emission of about three million
cars.
SENSITIVITY ANALYSIS AND
UNCERTAINTY ASSESSMENT
Uncertainty is an important issue
Figure 4. Added (brown bars) and saved (dark and pink bars) contributions to global warming when enzymes
in environmental assessments
replace surfactants in the considered detergent and wash temperatures are reduced. Data refer to 3.0 kg
and a number of sensitivity
laundry. Avoided contributions to global warming obtained by wash temperature reduction is achieved by
analyses and data quality
reducing electricity production at coal fired power plants
assessments have therefore been
occupy an increasing amount of land. The contribution undertaken to test the robustness of the results
to "toxicity" is expressed as the amount of water in the obtained. Based on these sensitivity analyses and
environment that is required to dilute enzymes and quality assessments, we can say that the
surfactants respectively ("Critical dilution volume", environmental assessments of enzyme production and
CDV tox ). Toxicity screening shows that much less avoided electricity production are considered good
water is needed to dilute the added enzymes than the because these assessments rely on recently updated
saved surfactants, indicating that the eco-toxicity of the and rather detailed studies. The environmental
enzyme-enriched detergent is far less than the assessment of avoided surfactant production is more
conventional detergent. This is because enzymes are uncertain because the data is older, coming from the
readily degradable and have a lower inherent toxicity.
mid nineties. The differences between enzymes and
CDVtox is one of five parameters in the European Eco- surfactants are, however, quite considerable (see
label scheme. Replacement of surfactants with Figure 3) and general observations of environmental
enzymes has a positive influence on other parameters advantages of enzyme use are considered robust.
too, and the increased use of enzymes as alternative Eco-toxicity assessments (CDVtox) of both surfactants
to surfactants can help fulfil the Eco-label criteria.
and enzymes after use are based on a screening
Combating global warming is high on the global method, and the outcomes of toxicity assessments are
agenda right now. The reduction to global warming considered rather uncertain. However, the difference
realized by replacing surfactants with enzymes and between the enzymes and surfactants (see Figure 3) is
reducing wash temperatures is shown for all four enormous and the general observation that enzymes
temperature reductions in Figure 4. Our results show are preferable from an eco-toxicity point of view is also
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Household and Personal Care Today • nr. 4/2007
considered robust. The electricity
production scenario has a
considerable influence on the
results, and outcomes of the
study would have been somewhat
less favourable for lowtemperature washing if, for
example, natural gas had been
the marginal source of electricity
Table 3. Estimation of annual global warming remediation potential for each household, for Denmark, and for
instead of coal. The type of oil
Europe, if all consumers changed from the conventional detergent to the enzyme-rich detergent and reduced
used in ethoxylated fatty alcohol
laundry wash temperatures
production
(vegetable
or
petrochemical) has only a limited
influence on the results except for the savings in
agricultural land use. Less agricultural land is saved if
ethoxylated fatty alcohols are produced from mineral
oil instead of vegetable oil.
Finally, the reduced packaging and transport
requirements realized by reducing the amount of
detergent (see Table 1) add to the advantage of
enzyme application, but has not been included in the
study. The avoided environmental impacts obtained by
reduced packaging production and transport are,
however, small compared with avoided environmental
impacts obtained by wash temperature reduction and
surfactant saving.
In summary, uncertainty assessments and sensitivity
analyses reveal that the environmental advantages
observed in the study are robust, although the exact
magnitudes of the results are uncertain and subject to
variation.
CONCLUSIONS AND OUTLOOK
Cost-neutral replacement of surfactants with enzymes
in a standard laundry detergent allows reduction of
laundry wash temperatures without compromising the
total wash performance. Enzyme use is small
compared with surfactant saving and the
environmental impact caused by the extra enzyme use
is insignificant compared with the savings obtained by
reduced use of surfactants and particularly reduced
consumption of energy used to heat wash water.
Data quality assessments and sensitivity analyses
show that exact results are uncertain and depend on
the magnitude of the temperature reduction, the
applied water heating systems, and a range of other
factors, but they also show that the overall conclusions
of the study are robust. The enzyme-rich detergent
examined in this study costs the same as the
conventional detergent and substantial environmental
improvement can be realized while saving on the
consumers' electricity bill. Increased use of enzymes at
the expense of surfactants reduces eco-toxicity of the
detergent after use, and enzymes can help meet the
criteria of European Eco-label. Surfactant saving and
wash temperature reduction can reduce contribution to
global warming by 150-450 g CO2 per wash and the
total annual saving potential for Europe is in the order
of 12 million tons of CO2, corresponding to the annual
emissions from about three million cars.
This is considerable and Novozymes is pleased to join
forces with colleagues in the detergent industry to
realize this potential in the coming years.
ACKNOWLEDGEMENTS
The authors are grateful to Associate Professor Stig
Irving Olsen, Technical University of Denmark, who
reviewed the study according to ISO standards on LCA
(14040 series).
Household and Personal Care Today • nr. 4/2007
Figure 5. The total annual CO2 mitigation potential for Europe of increased enzyme
use and reduced wash temperature is on the order of 12 million tons. This
corresponds to the annual emissions of around three million cars
REFERENCES AND NOTES
1.
2.
3.
4.
5.
6.
7.
8.
9.
Ballast: 10 shirts, 3 T-shirts, 4 pillowcases, 2 bed sheets, 2 tea
towels and socks.
Hardness: 15°dH (Ca:Mg:HCO3- = 4:1:7.5 [molar]).
Nielsen PH, Oxenbøll KM, Wenzel H (2007): Cradle to gate
environmental assessment of enzyme products produced in
Denmark by Novozymes A/S. Int J LCA. 12(6), 432-438.
http://dx.doi.org/10.1065/lca2006.08.265.1
Ecoinvent Database (2005): www.ecoinvent.com
1°C · 14 L · (4.19 kJ · kg-1 · °C-1) · (0.992 kg · L-1) · (0.278 · Wh/kJ-1)
= 16.2 Wh/°C.
Madsen T, Stranddorf H (2003): European Eco-label - Revision of
Eco-label criteria for laundry detergents. Final report. Project no.
51503. www.ecolabel.dk
ELMODEL-bolig (2004): Udbredelse og anvendelse af
husholdningsapparater i boligsektoren. (Distribution and use of
household appliances in households). In Danish.
www.elmodelbolig.dk
Annual CO2 emission from driving 20,000 km (16 km/kg gasoline
(= 12 km/L at density = 0.75 kg/L); 3.2 kg CO2/kg gasoline) ~ 4.0
tons CO2 per car per year.
Wenzel H, Hauschild M and Alting L (1997), Environmental
assessment of products. Volume 1. Methodology, tools and case
studies in product development. Chapman and Hall
PER H. NIELSEN,
PETER SKAGERLIND
Novozymes A/S
www.novozymes.com
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