Marine Macrophytes: Biosorbents 24.3 Biosorption 601
Part D | 24.3
for the transportation of nutrients, water, and gases.
Overall all species of marine angiosperms have developed a similar habit, characterized by a prostrate
stem (rhizome) supporting bundles of ribbon-like leaves
with parallel veins connected by short transversal veins
(Fig. 24.7, Cymodocea nodosa (Ucria) Asch.).
24.2 Heavy Metals: Definition and Toxicity
Heavy metals such as arsenic (As), cadmium (Cd),
chrome (Cr), copper (Cu), nickel (Ni), lead (Pb), and
zinc (Zn), have a specific gravity (i. e., measure of
density) at least five times that of water. Because of
their solubility in the water environments, heavy metals can be absorbed by living organisms [24.13–15]. It
is known that in small quantities heavy metals are essential for human nutrition, however, when consumed
in high amounts they can cause health problems. Indeed, elements like iron, copper, nickel, manganese,
selenium, and zinc are common in nature and are normally ingested with food (foodstuffs, fruits, vegetables,
multivitamin products) [24.16–18]. The anthropogenic
impact on the environment has increased the presence
of heavy metals, which is of major concern because of
their toxicity and threat to plant and animal life. The
main anthropogenic sources of heavy metals released
into the environment are:
a) Acid mine drainage (AMD), caused by mining operations
b) Electroplating industry waste solutions (e.g., zinc
plating, nickel plating, chrome plating, oxidation)
c) Coal-burning applications for power generation
and
d) Nuclear technology for power generation (uranium
mining/processing and special waste generation).
Moreover, heavy metals are common in industrial applications like the manufacture of batteries,
textile dyes, pesticides, alloys, steel, and others. The
risks for human health and the toxicity associated
with heavy metals are now well known [24.19–21].
Heavy metals in significant quantities are released into
freshwater bodies and seas. These substances can be
accumulated and biomagnified along sediment, water, and aquatic food chains, resulting in fatal effects in fish populations, and for humans. They become toxic when they are not metabolized by organisms and accumulate in the soft tissues [24.19, 20].
The Agency for Toxic Substances and Disease Registry (ATSDR), based in Atlanta (Georgia), is one
of the largest federal public health agencies of the
USA. It provides trusted health information to prevent harmful exposures and diseases related to toxic
substances.
24.3 Biosorption
Biosorption is a method that can be used for the removal of pollutants from wastewater, especially those
that are not easily biodegradable like heavy metals and
industrial dyes. Furthermore, this process can remove
low heavy metal concentrations as an inexpensive,
simple and effective alternative to conventional methods like activated carbon [24.22–26]. The recapture of
heavy metals from industrial wastewater is of dual interest: (i) the prevention of threats to health (metal
toxicity) [24.19–21], and (ii) society is realizing the
importance of recycling these substances for metal
costs [24.27–29]. When the concentrations of wastewater contaminants are above 100 mg=L, the biological
treatment processes for removing heavy metals are the
most effective [24.30]. The treatments used are precipitation, electrodialysis, and reverse osmosis, which
become costly and difficult to manage at low metal concentrations (< 100 mg=L) [24.31, 32]. The potential of
metal biosorption by biomass materials has been well
established in the last 15 years. This technique uses
a variety of biological materials for binding of these
pollutants, including fungi [24.33], bacteria [24.34–
36], plants [24.37], macroalgae [24.24–26, 38], microalgae [24.39, 40], and agricultural and industrial
wastes [24.41–43]. For economic reasons, particular
interest must be given to large biomass types, either
generated as a waste by-product of large-scale industrial
fermentations or certain metal binding macrophytes
found in large quantities in the sea. Recent studies
showed that aquatic macrophytes (i. e., seaweeds and
seagrasses) can be used as potential biosorbents for the
removal of heavy metals [24.24–26, 38, 44–46]. This is
considered one of the most promising types of biosorbents in view of its high capacity for uptake, its low
Part D | 24.3
for the transportation of nutrients, water, and gases.
Overall all species of marine angiosperms have developed a similar habit, characterized by a prostrate
stem (rhizome) supporting bundles of ribbon-like leaves
with parallel veins connected by short transversal veins
(Fig. 24.7, Cymodocea nodosa (Ucria) Asch.).
24.2 Heavy Metals: Definition and Toxicity
Heavy metals such as arsenic (As), cadmium (Cd),
chrome (Cr), copper (Cu), nickel (Ni), lead (Pb), and
zinc (Zn), have a specific gravity (i. e., measure of
density) at least five times that of water. Because of
their solubility in the water environments, heavy metals can be absorbed by living organisms [24.13–15]. It
is known that in small quantities heavy metals are essential for human nutrition, however, when consumed
in high amounts they can cause health problems. Indeed, elements like iron, copper, nickel, manganese,
selenium, and zinc are common in nature and are normally ingested with food (foodstuffs, fruits, vegetables,
multivitamin products) [24.16–18]. The anthropogenic
impact on the environment has increased the presence
of heavy metals, which is of major concern because of
their toxicity and threat to plant and animal life. The
main anthropogenic sources of heavy metals released
into the environment are:
a) Acid mine drainage (AMD), caused by mining operations
b) Electroplating industry waste solutions (e.g., zinc
plating, nickel plating, chrome plating, oxidation)
c) Coal-burning applications for power generation
and
d) Nuclear technology for power generation (uranium
mining/processing and special waste generation).
Moreover, heavy metals are common in industrial applications like the manufacture of batteries,
textile dyes, pesticides, alloys, steel, and others. The
risks for human health and the toxicity associated
with heavy metals are now well known [24.19–21].
Heavy metals in significant quantities are released into
freshwater bodies and seas. These substances can be
accumulated and biomagnified along sediment, water, and aquatic food chains, resulting in fatal effects in fish populations, and for humans. They become toxic when they are not metabolized by organisms and accumulate in the soft tissues [24.19, 20].
The Agency for Toxic Substances and Disease Registry (ATSDR), based in Atlanta (Georgia), is one
of the largest federal public health agencies of the
USA. It provides trusted health information to prevent harmful exposures and diseases related to toxic
substances.
24.3 Biosorption
Biosorption is a method that can be used for the removal of pollutants from wastewater, especially those
that are not easily biodegradable like heavy metals and
industrial dyes. Furthermore, this process can remove
low heavy metal concentrations as an inexpensive,
simple and effective alternative to conventional methods like activated carbon [24.22–26]. The recapture of
heavy metals from industrial wastewater is of dual interest: (i) the prevention of threats to health (metal
toxicity) [24.19–21], and (ii) society is realizing the
importance of recycling these substances for metal
costs [24.27–29]. When the concentrations of wastewater contaminants are above 100 mg=L, the biological
treatment processes for removing heavy metals are the
most effective [24.30]. The treatments used are precipitation, electrodialysis, and reverse osmosis, which
become costly and difficult to manage at low metal concentrations (< 100 mg=L) [24.31, 32]. The potential of
metal biosorption by biomass materials has been well
established in the last 15 years. This technique uses
a variety of biological materials for binding of these
pollutants, including fungi [24.33], bacteria [24.34–
36], plants [24.37], macroalgae [24.24–26, 38], microalgae [24.39, 40], and agricultural and industrial
wastes [24.41–43]. For economic reasons, particular
interest must be given to large biomass types, either
generated as a waste by-product of large-scale industrial
fermentations or certain metal binding macrophytes
found in large quantities in the sea. Recent studies
showed that aquatic macrophytes (i. e., seaweeds and
seagrasses) can be used as potential biosorbents for the
removal of heavy metals [24.24–26, 38, 44–46]. This is
considered one of the most promising types of biosorbents in view of its high capacity for uptake, its low