Page 159 - Industrial Wastewater Treatment, Recycling and Reuse

Advanced Physico-chemical Methods of Treatment for Industrial Wastewaters 133

not just because of the cost of membrane material, but also because of asso-
ciated costs of operation, and in such cases, these processes no longer remain
a competitive option. Cavitation, in general, is a low-cost operation both in
terms of device cost and cost of operation. Further, cavitation can be satis-
factory as a single technology for effluent treatment, or it can be employed
efficiently in hybrid combinations with most other conventional separations,
thereby proving to be potentially cost-effective and thus techno-
economically feasible option for industrial wastewater treatment.
In most cases, two or more processes can provide techno-economically
feasible options. An appropriate combination of treatment methods com-
bined with process integration often leads to effective water treatment solu-
tions (not just meeting the regulatory norms, but even adding to the
profitability of the overall process).

2.7 SUMMARY

Physico-chemical methods have important role to play in today’s industrial
wastewater treatment scenario and will continue to have increased use
because of established practice and continued improvisation. Although some
methods, such as adsorption, ion exchange, and coagulation, have been con-
sidered relatively matured over the years, they will still continue to dominate
the wastewater treatment mainly through improved materials, devices, and
practices. Further, new emerging technologies such as membrane separa-
tions and cavitation will have to compete with the existing established pro-
cesses, especially through improved process efficiencies and economics.
However, the most challenging aspect for industrial wastewater treatment
in the future will be process integration, which can bring out intelligent
combinations of different physico-chemical processes as well as physico-
chemical processes coupled with biological processes. The application of
physico-chemical methods is not just relevant from the point of view of
industrial wastewater treatment for meeting pollution control norms but also
relevant from the point of view of water recycling and reuse. This is espe-
cially important in view of the scarcity of water resources in several parts of
the world that would demand water conservation, quite apart from environ-
mental pollution control.

Nomenclature
1
a L Constant in Langmuir equation (mg g )
a R Constant in Redlich-Peterson equation