11.4.3 Phytoremediation
Phytoremediation has also been identified as one of the economic and effective
techniques to remove/degrade the toxic HMs from water systems, and several
invasive plants have been used for this purpose. Hyperaccumulators or
hyperaccumulating plants can accumulate higher quantities of HMs in their aboveground tissues and are not sensitive to the HM toxicity and, therefore, used
phytoremediation to treat contaminated water bodies. Water hyacinth (Eichhornia
crassipes) is the commonly tested plant for phytoremediation to uptake several HMs
from water bodies (Schneider et al. 1995). In a study, Goswami and Das (2018)
reported 55–57% of Cu removal from the contaminated water by this plant. In a
laboratory study conducted by Odjegba and Fasidi (2007), they observed the
effective removal of Ag, Cd, Cr, Cu, Hg, Ni, Pb, and Zn from the contaminated
water using water hyacinth. Alshaal et al. (2013) reported removal of Cd and Zn
from water using giant reed (Arundo donax). Bulrush (Typha latifolia) was also
reported to remove Fe, Mn, As, Au, Cu, Hg, and Zn from water (Newete et al. 2016).
Pb from water can also be effectively removed by the water spinach (Ipomoea
aquatica) plant (Bedabati Chanu and Gupta 2016), and Co can be removed by the
Canadian pondweed (Elodea canadensis) plant (Mosoarca et al. 2018). Furthermore,
frogbit (Hydrocharis morsus-ranae) can uptake and accumulate Co, Cu, Hg, K, Mn,
and Ni from water (Polechońska and Samecka-Cymerman 2016).
11.4.4 Microbe-Assisted Bioremediation
Microbe-assisted bioremediation techniques are also adopted to reduce, degrade, or
detoxify the toxic HMs from the contaminated water using different bacteria, fungi,
and algae. Certain bacterial species are tolerant to HMs, and their cells can grow
even at higher concentration of the toxic HMs. Such bacterial cells can uptake heavy
metals by both ATP-dependent and ATP-independent processes and accumulate the
HMs on cell wall, intra- as well as extracellular entrapment or through formation of
complexes and redox reactions (Ahemad 2012). It has been reported that HM
accumulation capability of the gram-positive bacteria is comparatively higher than
the gram-negative bacteria (Rani and Goel 2009). Staphylococcus aureus and
Escherichia coli bacteria can reduce As(V) to As(III) (Rosen 2002). Cyanobacteria
can be used to remove cadmium from wastewater as it is tolerant to cadmium toxicity
(Xu et al. 2018). Furthermore, Pseudomonas (Pepi et al. 2011), Escherichia coli
(Bae et al. 2001; Deng and Wilson 2001; de Luca Rebello et al. 2013; LaVoie and
Summers 2018), and Staphylococcus aureus (Monecke et al. 2016) are resistant to
mercury and can be used to remove mercury from wastewater. Moreover, Pseudomonas stutzeri bacteria can also remove mercury from water systems. In a study,
Zheng et al. (2018) reported that the marine bacterium Pseudomonas stutzeri 273 is
resistant to 50 μM Hg
+2 and removed ~94% Hg
+2 from culture. Escherichia coli
11 An Overview on Heavy Metal Contamination of Water System and Sustainable. . .
269
Phytoremediation has also been identified as one of the economic and effective
techniques to remove/degrade the toxic HMs from water systems, and several
invasive plants have been used for this purpose. Hyperaccumulators or
hyperaccumulating plants can accumulate higher quantities of HMs in their aboveground tissues and are not sensitive to the HM toxicity and, therefore, used
phytoremediation to treat contaminated water bodies. Water hyacinth (Eichhornia
crassipes) is the commonly tested plant for phytoremediation to uptake several HMs
from water bodies (Schneider et al. 1995). In a study, Goswami and Das (2018)
reported 55–57% of Cu removal from the contaminated water by this plant. In a
laboratory study conducted by Odjegba and Fasidi (2007), they observed the
effective removal of Ag, Cd, Cr, Cu, Hg, Ni, Pb, and Zn from the contaminated
water using water hyacinth. Alshaal et al. (2013) reported removal of Cd and Zn
from water using giant reed (Arundo donax). Bulrush (Typha latifolia) was also
reported to remove Fe, Mn, As, Au, Cu, Hg, and Zn from water (Newete et al. 2016).
Pb from water can also be effectively removed by the water spinach (Ipomoea
aquatica) plant (Bedabati Chanu and Gupta 2016), and Co can be removed by the
Canadian pondweed (Elodea canadensis) plant (Mosoarca et al. 2018). Furthermore,
frogbit (Hydrocharis morsus-ranae) can uptake and accumulate Co, Cu, Hg, K, Mn,
and Ni from water (Polechońska and Samecka-Cymerman 2016).
11.4.4 Microbe-Assisted Bioremediation
Microbe-assisted bioremediation techniques are also adopted to reduce, degrade, or
detoxify the toxic HMs from the contaminated water using different bacteria, fungi,
and algae. Certain bacterial species are tolerant to HMs, and their cells can grow
even at higher concentration of the toxic HMs. Such bacterial cells can uptake heavy
metals by both ATP-dependent and ATP-independent processes and accumulate the
HMs on cell wall, intra- as well as extracellular entrapment or through formation of
complexes and redox reactions (Ahemad 2012). It has been reported that HM
accumulation capability of the gram-positive bacteria is comparatively higher than
the gram-negative bacteria (Rani and Goel 2009). Staphylococcus aureus and
Escherichia coli bacteria can reduce As(V) to As(III) (Rosen 2002). Cyanobacteria
can be used to remove cadmium from wastewater as it is tolerant to cadmium toxicity
(Xu et al. 2018). Furthermore, Pseudomonas (Pepi et al. 2011), Escherichia coli
(Bae et al. 2001; Deng and Wilson 2001; de Luca Rebello et al. 2013; LaVoie and
Summers 2018), and Staphylococcus aureus (Monecke et al. 2016) are resistant to
mercury and can be used to remove mercury from wastewater. Moreover, Pseudomonas stutzeri bacteria can also remove mercury from water systems. In a study,
Zheng et al. (2018) reported that the marine bacterium Pseudomonas stutzeri 273 is
resistant to 50 μM Hg
+2 and removed ~94% Hg
+2 from culture. Escherichia coli
11 An Overview on Heavy Metal Contamination of Water System and Sustainable. . .
269