Page 109 - Industrial Wastewater Treatment, Recycling and Reuse

Advanced Physico-chemical Methods of Treatment for Industrial Wastewaters 83

Treated gas emission

Recycle S Recovery
Separation zone
Pollutant removal Recycle

Raw Materials, Process Products
solvents, Pretreatment, Product &
catalyst impurities Products + Wastes purification byproducts
Waste for treatments
removal

Recovery of chemicals/ energy

Water recycling & reuse

Treated effluents for
discharge
Figure 2.1 Schematic representation of chemical industry and processing.

This interrelationship is extremely important in defining the industrial
wastewater treatment problem. Overall, the problem in definition originates
at the reaction step and is most critical: a core issue. Often, there are changes
in the reaction zone from time to time (especially in manufacturing of fine
and specialty chemicals), subsequently requiring modifications in the sepa-
ration zone. As a consequence, the industrial wastewater treatment method-
ology inherently requires flexibility to absorb these changes in the processing
without affecting the efficiency and final goals of pollution control. Thus,
the following points highlight the need for and the extent of environmental
pollution control for industrial wastewater treatment:
1. Replace/substitute for hazardous and toxic chemicals in reaction, if
possible.
2. Separation often requires the most effort and cost.
3. Effluent treatment can get complicated because of the presence of toxic
pollutants and/or number of pollutants such as metals and organics
existing at the same time, requiring multiple solutions, sequential
solutions, or parallel solutions.
4. Failure to control pollution can even threaten the existence of the
industry at times.