that have emerged during paper production processes, which are a major concern for
the environment. Bleached effluents may contain chloroform and carbon tetrachloride, which are classified as carcinogens. The hypochlorite stage is the major
producer of chloroform. In pulp and paper mill wastewater, many compounds
such as phenols, chlorinated benzenes, epoxy stearic acid, and dichloromethane
are found, which act as carcinogens.
4.3 Chlorophenolics
The chlorophenolics are toxic, persistent, and bioaccumulative which emerged from
pulp bleaching process. These compounds are formed due to the use of large amount
of chlorine compounds. Chlorophenolics, such as chloroguaiacols, chlorophenols,
and chlorocatechols, and some chloroaliphatics are extremely toxic and recalcitrant
compounds. These compounds accumulate in sediments or at different levels of the
trophic chain causing detrimental effects toward all life forms.
4.4 Dioxins (Polychlorinated Dibenzodioxins) and Furans
(Polychlorinated Dibenzofurans)
It is well known that dioxins and furans are persistent in nature and reported as potent
carcinogenic agent. Chemical structures of furans are similar with dioxins but of less
magnitude. These two toxic compounds are found in sludge after the wastewater
treatment and cause serious concern. Chemicals, such as chloroform,
chloroacetones, aldehydes, and acetic acid, are formed during bleaching process,
but in lower concentrations than chlorophenolics. Generally these compounds are
nonpersistent and non-bioaccumulative, but some of these are moderately toxic,
mutagenic, and suspected carcinogens.
5 Environmental Contamination and Toxicity
Toxic effect of paper mill effluent to fish has been well documented since long back
(Johnston et al. 1997; Mishra et al. 2011). Water bodies receiving paper mill effluent
were observed with reduced oxygen levels, eutrophication, and deposition of sludges
and accompanying microbial growth. Highly toxic chlorinated compounds identified
in paper mill effluent during 1980 included phenolics, organic acids (fatty acids and
resin acids), and highly toxic dioxins and furans (Ali and Sreekrishnan 2001). These
compounds are bioaccumulative and mutagenic in exposed flora and fauna in
respective environment (Ali and Sreekrishnan 2001; Hewitt et al. 2006; Dey et al.
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the environment. Bleached effluents may contain chloroform and carbon tetrachloride, which are classified as carcinogens. The hypochlorite stage is the major
producer of chloroform. In pulp and paper mill wastewater, many compounds
such as phenols, chlorinated benzenes, epoxy stearic acid, and dichloromethane
are found, which act as carcinogens.
4.3 Chlorophenolics
The chlorophenolics are toxic, persistent, and bioaccumulative which emerged from
pulp bleaching process. These compounds are formed due to the use of large amount
of chlorine compounds. Chlorophenolics, such as chloroguaiacols, chlorophenols,
and chlorocatechols, and some chloroaliphatics are extremely toxic and recalcitrant
compounds. These compounds accumulate in sediments or at different levels of the
trophic chain causing detrimental effects toward all life forms.
4.4 Dioxins (Polychlorinated Dibenzodioxins) and Furans
(Polychlorinated Dibenzofurans)
It is well known that dioxins and furans are persistent in nature and reported as potent
carcinogenic agent. Chemical structures of furans are similar with dioxins but of less
magnitude. These two toxic compounds are found in sludge after the wastewater
treatment and cause serious concern. Chemicals, such as chloroform,
chloroacetones, aldehydes, and acetic acid, are formed during bleaching process,
but in lower concentrations than chlorophenolics. Generally these compounds are
nonpersistent and non-bioaccumulative, but some of these are moderately toxic,
mutagenic, and suspected carcinogens.
5 Environmental Contamination and Toxicity
Toxic effect of paper mill effluent to fish has been well documented since long back
(Johnston et al. 1997; Mishra et al. 2011). Water bodies receiving paper mill effluent
were observed with reduced oxygen levels, eutrophication, and deposition of sludges
and accompanying microbial growth. Highly toxic chlorinated compounds identified
in paper mill effluent during 1980 included phenolics, organic acids (fatty acids and
resin acids), and highly toxic dioxins and furans (Ali and Sreekrishnan 2001). These
compounds are bioaccumulative and mutagenic in exposed flora and fauna in
respective environment (Ali and Sreekrishnan 2001; Hewitt et al. 2006; Dey et al.
344
I. Haq and A. Raj