Environmental Engineering Reference
In-Depth Information
where
n
is the number of responses and
w
i
are weighting functions ranging
from 0 to 1.
These desirability functions can also be expressed mathematically as well.
For example, a linear desirability function where minimum is best would be
expressed as:
B
i
- Y
i
d i
B
i
-A
i
for the range
A
i
B
i
with w
i
1
Once the desirability functions are defined for each response, then the
optimization can proceed. As an alternative to rigorous numerical methods,
desirability can be evaluated by superimposing a grid of points at equal
spacing over the experimental region and evaluating desirability at each point.
The point(s) of maximum desirability can be found by sorting the results or by
creating contour plots of desirability over the grid area.
2.
M
ATERIALS AND
M
ETHODS
This section describes the sources of raw materials such as hazardous
jarosite waste, CCRs and clay obtained / collected to conduct the experiment.
Details about the methodology adopted in characterising the waste materials
and conducting the experimental program is also discussed. Further, the
standard testing procedure in evaluating jarosite waste composites and
statistical techniques adopted using response surface methodology to
maximise the use of different waste materials and optimise the response
variables/products properties are also described.
2.1. Raw Materials
Jarosite waste from Hindustan Zinc limited (HZL) as well as clay soils
were collected from the local area of Rajasthan, India. CCRs (Coal
Combustion Residues, so called flyash) were collected from a ash pond of
Satpura Thermal Power Station, Sarni, Central India. Figure 3 (a) shows the
collected jarosite waste and (b) CCRs storage pond from where CCRs were
collected. Hereafter, especially in the statistical analysis and modeling section,
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