Pollution and Pollution Control 79However, perhaps the most fitting example of environmental biotechnology in
the textile industry, though not really in a ‘clean technology’ role, is the incorpo-
ration of adsorbers and microbes within a geotextile produced for use in land man-
agement around railways. Soaking up and subsequently biodegrading diesel and
grease, the textile directly reduces ground pollution, while also providing safer
working conditions for track maintenance gangs and reducing the risk of fire.
Leather industry
The leather industry has a lengthy history of using enzymes. In the bating process,
residual hair and epidermis, together with nonstructural proteins and carbohy-
drates, are removed from the skins, leaving the hide clean, smooth and soft.
Traditionally, pancreatic enzymes were employed. Moreover, something in the
region of 60% of the input raw materials in leather manufacturing ultimately ends
up being discarded and enzyme additions have long been used to help manage
this waste. Recent advances in biotechnology have seen the upsurge in the use of
microbially-derived biological catalysts, which are cheaper and easier to produce,
for the former applications, and the possibility of converting waste products into
saleable commodities, in the latter.
As well as these improvements on existing uses of biotechnology, new areas
of clean application are emerging for tanners. Chemical methods for unhairing
hides dissolve the hairs, making for efficient removal, but adding to the treat-
ment cost, and the environmental implications, of the effluents produced, which
are of high levels of COD and suspended solids. Combining chemical agents
and biological catalysts significantly lessens the process time while reducing the
quantities of water and chemicals used. The enzymes also help make intact hair
recovery a possibility, opening up the prospect of additional income from a cur-
rent waste. It has been estimated that, in the UK, for a yearly throughput of
400 000 hides, enzymatic unhairing offers a reduction of around 2% of the total
annual running costs (BioWise 2001). While this may not seem an enormous
contribution, two extra factors must be borne in mind. Firstly, the leather indus-
try is very competitive and, secondly, as effluent treatment becomes increasingly
more regulated and expensive, the use of clean manufacturing biotechnology will
inevitably make that margin greater.
Degreasing procedures are another area where biotechnological advances can
benefit both production and the environment, since conventional treatments pro-
duce both airborne volatile organic compounds (VOCs) and surfactants. The use
of enzymes in this role not only gives better results, with a more consistent qual-
ity, better final colour and superior dye uptake, but also considerably reduces
VOC and surfactant levels. The leather industry is also one of the places where
biosensors may have a role to play. With the ability to give almost instanta-
neous detection of specific contaminants, they may prove of value in giving early
warning of potential pollution problems by monitoring production processes as
they occur.