Page 235 - Industrial Wastewater Treatment, Recycling and Reuse

Advanced Treatment Technology and Strategy 209

using these seven steps, the right questions can be asked, more ideas can be cre-
ated, and the best answers can be chosen. The steps are not sequential; they can
occur simultaneously and can be repeated.
Besides design thinking, it is important to clearly understand the nature
of a wastewater and the pollutants in it. Typically, COD and BOD levels are
considered as key deliverables of the treatment. However, parameters like
COD and BOD may be just the tip of the iceberg. The real problem in
wastewater treatment can be anything from pH, ineffective primary treat-
ments, biorefractory compounds, presence of solvents, heavy metals, phe-
nols, lack of space, or other issues. Unless the nature of problem is clearly
defined, the correct AOP can never be selected.
For example, textile-processing industries are well known for being asso-
ciated with wastewater with high volume and low COD. It is also well
known that wastewater from textile processing is readily treatable biologi-
cally, but the real problem is availability of space for putting a biological
treatment system in place. Thus the right solution for such an industry
can be an AOP, which can handle a huge volume of wastewater of low
COD value. Fluidized-bed Fenton can serve the purpose in this case.
Another example is the case of an SME dyestuff industry that
manufactures a broad range of products/dyestuffs that generate wastewater
whose nature is difficult to predict. In this scenario, the Fenton and electro-
Fenton (Fered Fenton) processes can be the right technology for treatment
because they can address a wide variety of wastewater characteristics.
After defining the problem, the next task is to select an appropriate com-
bination of treatment technologies. Figure 4.14 shows the available spec-
trum of treatment technologies for wastewater treatment, mainly
from the point of view of advanced oxidation processes. It is important
to know the appropriate technology for application to wastewater treatment
for technoeconomic selection. Figure 4.14 indicates one extreme techno-
logical selection in the form of biological treatment, while the other extreme
is incineration. The pollutants that are most refractory in nature cannot be

Advanced treatment technologies
Novel coagulants, Electro-coagulation, Electro-oxidation,
Biological Advanced electrochemical oxidation process (AEOP), Evaporation,
treatment Fenton oxidation, Electro-Fenton, incineration
Sludgeless Fenton, Nano-Fenton, etc.

Figure 4.14 Spectrum of wastewater treatment technologies.