Page 555 - Industrial Wastewater Treatment, Recycling and Reuse

Industrial Wastewater Treatment, Recycling, and Reuse—Past, Present and Future 525

industry (low to medium volumes of water, generally biodegradable and
non-toxic). The diverse nature of these industries demands effluent treat-
ment in similarly diverse forms, employing a variety of technologies and
for small to very large scale operations. Typically, present day wastewater
treatment activities involve initial pH adjustment; particulate removal;
oil and grease removal; removal of metals; removal of biodegradable pollut-
ants using biological processes (if the ratio of BOD to COD is favorable);
chemical treatment of wastewaters for removal of organics, acids, non-
biodegradable pollutants, and toxic pollutants, among other substances;
and finally, polishing of treated water to make it reusable. This book con-
siders a variety of conventional, advanced, and specialized forms of industrial
wastewater treatment methods in Chapters 1–13, with a specific focus on
industrial case studies and applications.
Present day industrial wastewater treatment emphasizes the drastic
reduction of pollutant levels, and each pollutant class often has its own dis-
charge limits specified by the respective government or pollution control
agencies, with an eye towards minimizing the cost of treatment. Interest-
ingly, most of the present day operations do not specifically intend to recycle
or reuse wastewater unless faced with severe constraints. The likelihood of
water scarcity in many regions in the near future, combined with the esca-
lating cost of water, is driving many industries to adopt industrial wastewater
treatment, recycling, and reuse.
The discussion of various treatment technologies in the previous chapters
can be used to identify present day wastewater treatment needs, as well as
treatment guidelines for the future. For a quick analysis, these needs and
guidelines can be summarized as follows.

14.3.1 Overall Effluent Treatment Plant

• Proper sequencing of different technologies and distribution of the
pollutant load
• Optimization of the cost of overall effluent treatment plant (ETP) oper-
ations with recovery or recycling options
• Increased flexibility to handle different effluents, loads, and process
variations
• Less space requirement
• Reducing the cost of water treatment technologies and plant operation
through recycling, reuse, and novel energy generation methods.