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CHAPTER 9

Hazardous Waste and Its

Treatment Process

R. Prakash, M. Gowtham
School of Mechanical Engineering, Vellore Institute of Technology (VIT), Vellore, India

9.1 INTRODUCTION
There are numerous ways of extracting energy from scrap materials. These
ways comprise of thermochemical and biological means. It can demon-
strate the various pathways for extracting energy, most of which are in
their early developmental stages. These ways come under waste to energy
technologies (WTE). The only WTE technology that is commercially
available in the United States uses municipal solid waste (MSW) feedstock
for combustion. MSW has a high ratio of food wastes, which results in
high-moisture content and a comparatively low calorific value (3–5 MJ/kg
on average, compared to that of 8–11 MJ/kg in Europe). The waste also
has seasonal variations, exhibiting its complicated heating properties
(Fig. 9.1) [1].
There are several other processes which hold high potential for utiliz-
ing MSW feedstock, but must overcome various technical or procedural
challenges at the initial stage before they hit the commercial market. The
prime challenge facing these technologies is the heterogeneous behavior
of MSW, which crafts a widely erratic chemical constituency of the energy
products generated from these processes [2]. This alteration affects the fa-
cility to extract energy efficiently. The solutions have been pursued from
two different views:
1. Clean-up and maintaining of syngas material of thermochemical con-
version and biogas materials of biological translation—These efforts are
aimed at making the gases more usable as a direct fuel in internal com-
bustion engines or gas turbines.
2. Feedstock preparation, shredding and mixing of MSW to make the
feedstock much homogeneous—This homogeneity in the feedstock
will be reflected in the energy products and will help in improving its
service (Fig. 9.2).

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