Environmental Engineering Reference
In-Depth Information
but not in the quantities discarded by today's society. The overload that
results, called pollution, eventually puts the ecosystem out of balance. Most
often our waterways are being polluted by municipal, agricultural and
industrial wastes, including many toxic synthetic chemicals, which can-
not be broken down at all by natural processes. Thus, the environmental
threat posed by contamination in water has to be lessened for a healthy and
disease-free life, and for this to happen united efforts have to be made for
effectual wastewater treatment and recycling technologies [8,9].
Water pollution is even a greater problem in the Third World, where
millions of people obtain water for drinking and sanitation from unpro-
tected streams and ponds that are contaminated with human waste. This
type of contamination has been estimated to cause more than three mil-
lion deaths annually from diarrhea in Third World countries, most of them
children. Clearly, the problems associated with water pollution have the
capability to disrupt life on our planet to a great extent [3].
It can definitely be said that one of the major causes of water pollution
is rapid industrialization. Chief sources contributing to this contamina-
tion are mining and smelting, disposal of municipal industrial wastes, use
of fertilizers, pesticides, chemicals and automobiles [10]. In view of the
volume discharged and effluent composition, the wastewater generated by
the textile industries is rated as the most polluting among all industrial
sectors. In 1980, Clark and Anliker [11] reported that world production of
dyes in 1978 were estimated at 640,000 tons. By now, surely this figure must
have grown up to 100 million tons per year. The majority of this quantity is
used in the textile and dying industries, which includes many types of dif-
ferent compounds, and their environmental behavior is largely unknown.
Industries discharge massive amounts of the most toxic pollutants into
the water system. There are various industries like nuclear power projects,
petroleum refineries, chemical fertilizers, pesticides, pharmaceuticals, syn-
thetic rubber, etc., that are put in the red category, and the dye industry is
also one of them.
Dyes, the most impending material used in the industrial sector as col-
oring material, are synthetic organic aromatic compounds that are molec-
ularly dispersed and bound to the substrates by intermolecular forces. The
textile industry ranks first in the consumption of the dyes and effluents
released from textile dyeing, which is intensely colored and poses serious
problems to various segments of the environment. The global production
of these dyes is about 7 × 10 5 tons per annum. There are no reliable pub-
lished statistics on the financial size of the color market, however, on the
universal scale a reasonable guesstimate would be 940 million dollars  [12].
Zollinger [13] revised the synthesis, properties and applications of organic
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