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THE unprecedented increase in population, and the even
greater increase in the scale of human activity, largely in this
century, have been brought about by the growing mastery of
science and its applications.
This has led to prosperity,
improved standards of life,
and opportunities have
expanded beyond anything
that the previous generations
could have imagined. But
these developments have
damaged and deteriorated
the ecological systems and
caused widespread destruction of the natural resourcebase on which human life
and well-being depends.
One such class of products, indispensable from our
kives, are detergents. By definition, a detergent is anything that cleans. Although
the origin of soap detergents
ts shrouded in the mists of
antiquity, it is generally
accepted that some form of
primitive saponification was
developed in prehistoric
ames in the eastern shores of
at Mediterranean. -Soap
daergents (using natural
Astsi contain a sodium or
lum salt of a fatty acid, d
or oil. This serves as a
c detergent the surfacl
alattiiiy derived, like the line
A surfactant, or a surface a
in turn perowr the
s dirt particles to be lifted or floated off the article, then to
ned by water. Another distinction between soap and
bttk detergents is that the latter contains a lower percent unfactants, but higher levels of phosphates, which helps
w the water.
Swe the early '60s, the sale of synthetic detergents (with
Md names like Surf or Sunlight) has surpassed the sale of
pArtergents. The popularity of synthetic detergents stems
ponh- from their superior cleaning efficiency, particularly
mtd in hard water areas, or under other unfavorable
The production of synthetic detergents has shot
up from 3.8 lakh tonnes in 1982 to approximately 18 lakh
tonnes in 1992, a near-five-time jump.
About 15-35 per cent of a detergent comprises of a surfactant, such as LAS, and the remaining is of substances known as
fillers. These include phosphates, optical brighteners, bleaches
and perfumes. LAS does not
show any buildup in waterbodies (where they eventually flow out after washing)
over some years, as it is
biodegradable. Thus, LAS
residues do not constitute a
The problem caused by
LAS, however, is one of foaming. Foam is visible and is
aesthetically unacceptable in
sewage treatment plants, and
in rivers and streams receiving their outflows. As these
compounds are able to
reduce foam even in very low
concentrations, aeration of
water (in sewage treatment
plants, to increase the rate of
organic matter degradation)
is nQt possible, since it tends
to increase the amount of
foam once again. Hence, the
rate of recreation of river
water is reduced, along with
the efficiency of sewage
aquatic flora and fauna are
to foaming. If the surface-active
i detergent is not biodegradable,
I as industrial effluents would be
ose a hazard to the environment.
Concern for the environment was
of the list of
right at the bottom
ities. Due to increasing environmental awareness, there is an
increasing emphasis on the use of ecofriendly products for
various domestic purposes.
The criteria for detergents being considered environment
friendly are described in the Gazette 6fIndia, (April 1992). The
product should not contain any phosphate, because sudden
increases in phosphate levels causes eutrophication of water
bodies. It can contain environment-friendly substitutes, but
should be used in sufficient quantities to ensure a similar performance of the product as compared to the phosphates. The
active ingredients used must have a biodegradability of 97 per
cent. The detergent should also not cause skin irritation.
According to the Industrial Toxicology Research Centre
(ITRC), Lucknow, detergent particles destroy the natural, thin
layer of protective oil on the skin. Also, nearly 80 per cent of
skin problems among infants are caused by clothes washed
According to The phosphate Report, published recently by
the Landbank Consultancy of London, phosphate-free detergents are no better for the environment either. There are alternatives, such as zeolites, which are essentially minerals or synthetic compounds characterized by an aluminosilicate tetrahedral framework (which could also be used as water softeners).
But these can do just as much harm to the environment.
Phosphates, however, have the enormous advantage over
zeolites, and over all detergent builders, in that they can be
easily and cheaply recovered from wastewater for recycling.
The Netherlands is already operating 2 sewage treatment
plants which have phosphate recovery units.
However, detergents generally contain a fair percentage of
sodium tripolyphosphate (STPP). This STPP may be partly
replaced by enzymes. The use of enzymes in detergent formulations is now common in the developed countries, with over
half of all detergents presently available containing these. In
fact, in the West the detergent industry is the single largest
market for enzymes, grabbing 25-30 per cent of the total sales.
Some Indian brand-namcs also use enzymes.
Dirt comes in many forms and includes proteins, starches
and lipids. It is possible to remove most types of dirt by using
synthetic detergents in water at high temperatures (50-60oc)
and through vigorous mixing. But the cost of heating the
water is high, and prolonged mixing or beating shortens clothlife.
The problem of staining of clothes is more serious for
those working in kitchens, and in industries such as fish processing, poultry and meat etc. However, enzyme-rich detergents arc able to remove not only the obvious stains, such as
blood, but also other less obvious materials, including proteins from body secretions, milk, egg, fish and meat.
Enzymes are of different kinds, depending on the
als (substrate) they degrade. For instance, the In
degrade proteins, amylases degrade starch, lipases
hpids, and the celluloses degrade cellulose. A feature c
to all enzymes is that they convert their substrates in
and readily soluble fragments which can be casil r
from the fabrics. These enzymes are produced by m
For instance, the alkaline protease is obtained from a
um, Bacillus licheniformis.
Soil is absorbed with sweat and sebum (secretions of
ceious glands, which contain fatty acids, cholesterol an
cells) in the network of cotton fibres of the fabrics whi
made of cellulose. Alkaline celluloses partly modif 'v the
lose and subsequently, the solid is removed by deter
Similarly, alkaline lipases act on oil spots as well as an C
adsorbed on them.
Alkaline proteases remove stains like blood and pre
ceous materials which come through handling food itei
the absence of proteases, proteinacei
coagulates on the fabric as a result
washing conditions. Higher temper;
and PH, and the action of the surf;
and sequestering agents dissolve in
the dirt components, and the blea
agent decomposes the undissolved
The process, however, causes the
tem material to precipitate onto the
This precipitate also retains other dirt cc
ponents and is subsequently diffic4
remove. Failure to remove the prota
ceous dirt results in the fabric appe4
grey and unclean after several washings.
An enzyme should have certain pr-4
ties to be able to function under varN
washing conditions. The PH of laul
detergents is generally alkaline, and te
perature requirements can be as hi
Detergents also contain oxich
bleaching and chelating agents whid
hinder the activity of certain enzymes. Some surfactants
denature the enzymes. Hence, an ideal detergent enzyme
be stable in alkaline conditions, have stability over a wide
perature range, be compatible with the oxidizing, blea,
and chelating agents and perfumes, and should no( re,
metal ions for their own activity.
We have developed microbial processes for
production of bacterial alkaline protease and ft
alkaline lipase, in the Department of Microbiology a
University of Delhi's South Campus. With the incre
use of washing machines and the availability of enzym
a safe, encapsulated form, there exists a tremen
market potential for enzyme detergents. The us
enzymes will contribute to environmental safet,
decreasing the use of more toxic detergents, conserVJ
of energy due to washing at relatively low temperat,
and also help in keeping clothes in better health I