Page 99 - Industrial Wastewater Treatment, Recycling and Reuse

74 Industrial Wastewater Treatment, Recycling, and Reuse

facilitate transmission and assimilation of the most suitable technologies in
the industries, which will impact positively and reduce environmental pol-
lution apart from helping water conservation.
In view of the above analysis on various methods of wastewater treat-
ment, their characteristics, advantages and disadvantages, and costs of oper-
ations, and on the basis of commercial acceptance, a qualitative analysis of
major commercial physico-chemical and biological methods is presented
in Table 1.6. The analysis represents a 5-point rating for each of these pro-
cesses on different aspects pertaining to economic, environmental, technical,
and sociocultural issues. The status indicated by 4- and 5-open circle sym-
bols represent the developed nature of the process, while the 3-star black
status indicates considerable room for further development. Filled circle
symbols indicate status where the application requires significant efforts to
make it commercially attractive. It appears that hybrid processes combining
two or more processes would have significant potential from a commercial
viewpoint. While processes such as coagulation and adsorption are well
placed in the overall scheme of wastewater treatment, oxidation and cavi-
tation need efforts to increase their commercialization and acceptance. Sim-
ilarly, biological processes need improvements in final effluent quality, quite
apart from the land requirement factor. Membrane separations, though, look
excellent from a separation point of view, but they need a lot of effort in
treatment of wastewaters in real-life situations.

1.9 SUMMARY
Industrial wastewater treatment, recycling, and reuse is an important theme
in today’s context, not just to protect the environment from pollution, but
also to conserve water resources so that water stress is reduced. A number of
technologies are available to treat industrial wastewaters, and judicious deci-
sion making is required for selecting appropriate technologies. The selection
depends on the desired goals of wastewater treatment: recovery of valuable
chemicals from wastewater, possible water recycling and reuse, complying
with the statuary norms for discharge into water bodies, and economics of
the treatment process. The number and diverse nature of pollutants in waste-
water makes the task of selection rather difficult. The overview presented
here should be useful in identifying key issues and facilitating selection of
appropriate processes for treating wastewater. Various technologies are dis-
cussed in detail in the chapters following.