Page 77 - Industrial Wastewater Treatment, Recycling and Reuse

54 Industrial Wastewater Treatment, Recycling, and Reuse

Overall, industrial wastewater effluents usually contain mixtures of var-
ious toxic metals. It is indeed a huge task to eliminate the pollution effects of
these toxic heavy metals by bringing down concentrations to desired levels.
A process integration approach by combining various conventional as well as
newly developed technologies, especially nanotechnology, can help sub-
stantially in pollution control and recovery of metals, quite apart from bring-
ing down the cost of operation.

1.5.2 Dye Wastewater Treatment
1.5.2.1 Indian Scenario
The dye sector in India has major contributions from the dyes/dye
intermediates-producing industry and the pigment industry as well as from
end user industries that are closely associated with this entire sector, such as
textiles, paint/ink, paper, and leather, and polymers and plastics. It is reported
that 70% of dyestuff gets consumed in textiles alone. In India, the dyestuff
industry is fragmented, where most of the units belong to the small-scale
industry sector, which is a major concern from the environmental pollution
controlpointofviewbecausesmallindustrieshavealimitedcapacityforefflu-
ent treatment. Most of the dye industries are concentrated in western India,
and over 80% of the total capacity comes from the state of Gujarat, which
housesabout750units.Thecapacityandproductionvolumesofdyesandpig-
ment, put together, are well above several thousand tons per annum, contrib-
uting to a 12% share in the world market. In the last few years, although the
growth of dye industry has been 6% on an average, production of some of
the dyes such as acid and direct dyes and reactive and vat dyes has remained
nearly constant. Dyes such as sulfur dyes have shown over a 100% increase in
the 5 years from 2002 to 2007. The organic pigment sector has also shown an
increase of 100% in production in this period (DCPC, Annual Report,
2011–12; CPCB, 2004; 2007a, 2009–10a; Department of Chemicals and
Petrochemicals, Annual Report 2011–12; Performance of Chemical and
Petrochemical Industry at a glance- 2001–2007).

1.5.2.2 Global Scenario
The dyestuff industry is one of the larger polluting industries, which has led
to the closing down or shifting of units to emerging economies. For exam-
ple, a majority of the international producers have shifted technology to
developing nations such as China, India, Indonesia, Korea, Taiwan, and