Page 58 - Energy from Toxic Organic Waste for Heat and Power Generation

46 Energy from Toxic Organic Waste for Heat and Power Generation

4.4 TOXIC OR HAZARDOUS WASTES
A toxic or hazardous waste is a waste with properties that make it dangerous
or capable of having a harmful effect on human health or the environment.
Toxic or hazardous waste is generated from many sources, ranging from in-
dustrial manufacturing process wastes to batteries, and may come in many
forms, including liquids, solids gases, and sludges [12].
The toxic wastes that are contained mainly in the effluents of textile in-
dustry are classified in this section. The hazardous and toxic nature of these
substances are described in the following subsections.

4.5 CONTAMINATED TEXTILE EFFLUENTS WITH
CHEMICALS
The effluent from the textile industry contains chemicals which are used
during the various stages of processing. The toxic chemicals present in the
textile effluent are listed and discussed later.

4.6 CHLORINATED SOLVENTS
Chlorinated solvents are used for a number of operations in the textile
manufacturing industry such as scouring, desizing, dyeing, and cleaning.
[2]. Chlorinated solvents are a large family of chemical compounds that
contain chlorine. The commonly used chlorinated solvents in the tex-
tile industry [13] are carbon tetrachloride (CCl 4 ), chloroform (CHCl 3 ),
methylene chloride or dichloromethane (CH 2 Cl 2 ), tetrachloroethylene
(C 2 Cl 4 ), trichloroethane (C 2 H 3 Cl 3 ), and trichloroethylene (C 2 HCl 3 ).
Chlorinated solvents, in general, are harmful to human and ecological
health. They can cause or are suspected of causing cancer and are toxic
or harmful to aquatic organisms. Spills and leaks of chlorinated solvents
have caused widespread subsurface contamination in the environment.
Commonly, these contaminants are present in the subsurface in the form
of nonaqueous phase liquids, as dissolved contaminants in ground water,
associated with aquifer sediments, and as vapors in the unsaturated zone.
Because the density of these nonaqueous phase liquids is greater than wa-
ter, they tend to sink in ground water systems, which results in a com-
plex dispersal and plume patterns, long-term sources in the subsurface, and
difficult cleanup [14].