Approximately 10% to 15% of dyes are released into the environment during the
dyeing process, and many of them are highly colored and aesthetically unpleasant.
Dyes are difficult to remove by conventional water treatment procedures, and they
persist in water because they are highly soluble. Biodegradation is highly applicable
for detoxifying the toxic and carcinogenic components of dyes (Rindle and Troll
1975).
3.2 Inorganic Pollutants
Inorganic pollutants include metals, metal compounds, mineral acids, inorganic
salts, trace elements, organic metal complexes, cyanides, and sulfates, which have
long-term adverse effects on aquatic flora and fauna as well as on terrestrial
organisms. High concentrations of heavy metals and other inorganic pollutants
from various industries contaminate the water. These compounds are
nonbiodegradable and persist in the environment. Metals at concentrations above
the threshold value are toxic to biota; for example, copper is toxic to microbes at
concentrations greater than 0.1 mg/l.
3.2.1 Radionuclides
Radioactive pollutants are toxic to all life forms because they accumulate in the
bones and teeth, causing serious disorders. Radioactive isotopes such as
131
I,
32 P,
60 Co,
45 Ca,
35 S, and
14 C originate from mining and processing of ores, research labs,
agriculture, medical, and industrial activities, and as radioactive discharge from
nuclear power plants and nuclear reactors (
90 Sr,
137 Cs,
248 Pu,
238
U,
235 U) and during
testing of nuclear weapons. The safe concentration for lifetime consumption is 1 Â
10
À7 microcuries per milliliter (μCi/ml).
3.2.2 Heavy Metals
Heavy metals are categorized as environmental pollutants because of their toxic
effects on plants, animals, and humans. Heavy metals belong to a very heterogeneous group of elements that vary widely in their chemical properties and biological
functions. Heavy metal contamination of soil results from both anthropogenic and
natural activities. Anthropogenic activities such as mining, smelting operations, and
agriculture activity increase the levels of heavy metals such as Cd, Co, Cr, Pd, As,
and Ni in soil above the threshold limit. Because heavy metals are persistent in
nature, they are easily accumulated in soils and plants, with long-term detrimental
effects on human health when ingested as a part of the diet when consuming
vegetables and plant foods. The impact of heavy metals on aquatic organisms results
from the movements of pollutants from various diffuse or point sources, giving rise
18 Molecular Technologies for Assessment of Bioremediation and. . .
443
dyeing process, and many of them are highly colored and aesthetically unpleasant.
Dyes are difficult to remove by conventional water treatment procedures, and they
persist in water because they are highly soluble. Biodegradation is highly applicable
for detoxifying the toxic and carcinogenic components of dyes (Rindle and Troll
1975).
3.2 Inorganic Pollutants
Inorganic pollutants include metals, metal compounds, mineral acids, inorganic
salts, trace elements, organic metal complexes, cyanides, and sulfates, which have
long-term adverse effects on aquatic flora and fauna as well as on terrestrial
organisms. High concentrations of heavy metals and other inorganic pollutants
from various industries contaminate the water. These compounds are
nonbiodegradable and persist in the environment. Metals at concentrations above
the threshold value are toxic to biota; for example, copper is toxic to microbes at
concentrations greater than 0.1 mg/l.
3.2.1 Radionuclides
Radioactive pollutants are toxic to all life forms because they accumulate in the
bones and teeth, causing serious disorders. Radioactive isotopes such as
131
I,
32 P,
60 Co,
45 Ca,
35 S, and
14 C originate from mining and processing of ores, research labs,
agriculture, medical, and industrial activities, and as radioactive discharge from
nuclear power plants and nuclear reactors (
90 Sr,
137 Cs,
248 Pu,
238
U,
235 U) and during
testing of nuclear weapons. The safe concentration for lifetime consumption is 1 Â
10
À7 microcuries per milliliter (μCi/ml).
3.2.2 Heavy Metals
Heavy metals are categorized as environmental pollutants because of their toxic
effects on plants, animals, and humans. Heavy metals belong to a very heterogeneous group of elements that vary widely in their chemical properties and biological
functions. Heavy metal contamination of soil results from both anthropogenic and
natural activities. Anthropogenic activities such as mining, smelting operations, and
agriculture activity increase the levels of heavy metals such as Cd, Co, Cr, Pd, As,
and Ni in soil above the threshold limit. Because heavy metals are persistent in
nature, they are easily accumulated in soils and plants, with long-term detrimental
effects on human health when ingested as a part of the diet when consuming
vegetables and plant foods. The impact of heavy metals on aquatic organisms results
from the movements of pollutants from various diffuse or point sources, giving rise
18 Molecular Technologies for Assessment of Bioremediation and. . .
443