SiO 2 + Al 2 O 3 + Fe 2 O 3 . It is also named as Class F Fly ash and has less than 10%
CaO (Table 17.1). This chapter deals with the various types of earthworm-assisted
technologies that help to mitigate the toxic effects of fly ash (the toxic waste product
of thermal power plant).
The waste stabilization and management of various industries are highlighted in
this chapter, and it is fully focused on the management of the end product of thermal
power plant, i.e., coal fly ash. The heavy metal removal from the fly ash is done with
the help of the vermicomposting process that involves earthworms, which focuses on
proper utilization and conversion of the nutrient contents of fly ash into high-quality
manure.
Coal
Source
Coal pulverizer
Boiler
Electrostatic precipitator
Transfer System
Pond
Ponded
ash
Fly ash Storage
Wet
Dry
Fig. 17.1 Generation of fly
ash in power plant
Table 17.1 Fly ash classification on the basis of different sources of coal
Types of
coal
Mineral contents
(SiO 2 + Al 2 O 3 + Fe 2 O 3 )
Content of CaO
Classes of fly ash
Bituminous
coal
70%
<10%
Class C (Grade I)
Lignite coal 50%
>10%
Class F (Grade II)
284
B. Sohal and A. P. Vig