1.2 Phytoremediation: Present Outcomes
Phytoremediation is a flourishing field of active research with its novelty and costeffectiveness; being eco-friendly, aesthetic, and efficient, phytoremediation can be
applied onsite, with remediation by solar-driven technology (Ali et al. 2013). The
phytoremediation concept, first coined by Chaney (1983), includes phytoextraction,
phytofiltration, phytostabilization, phytoevaporation, and phytodegradation. Over
the past 20 years, phytoremediation has been widely used to remove contaminants
(i.e., HMs, organic and inorganic substrates) from polluted soil or water by
rhizofiltration and accumulation in the aboveground biomass (Ali et al. 2013;
Rezania et al. 2016). Many kinds of hyper-accumulator were found; Brassica spp.,
a bioenergy crop, is found to be efficient in accumulating HMs in their tissues and
recovering the contaminants (Wu et al. 2010). To date, many researchers have used
plant-assisted biosolids or microbes to enhance the efficacy of the phytoremediation
process in removing HMs from contaminated sites (Kim et al. 2010; Rajkumar et al.
2012). The addition of these organic substrate and microbes could possibly assist the
plants in their growth and their HM adsorption capacities (Gao et al. 2010). Other
than natural plants, genetically engineered plants with expected outcomes improve
the remediation of HMs from contaminated soil (Chanu and Gupta 2016; Gomes
et al. 2016).
1.3 Market Demand for Phytoremediation
Soil remediation is a difficult task because of current technical and financial limitations. Phytoremediation is a useful technology to harvest HMs from polluted soil and
has been certified as an effective and economical method (Figs. 4.1 and 4.2).
Compared to other technologies, phytoremediation is more suitable for market
demand, having low installation and maintenance costs at less than 5% of the cost
required for alternative methods (Prasad 2003). The plants remediated the contaminants without affecting the topsoil, consequently conserving the utility and fertility
of the soil. Also, HMs with market value (e.g., Ni, Tl, Au) could be retrieved by
plants. Furthermore, rapidly growing plants with high biomass yield, such as poplar,
willow, and Jatropha, not only remediate the soil but can also produce energy
(Prasad 2003; Abhilash et al. 2012). Therefore, employing phytoremediation could
reduce HM pollution and create economic benefits.
1.4 Global Overview of Toxic Metals Phytoremediation
In the development of phytoremediation in HM-polluted soil, many plants and toxic
metals have been widely investigated (Prasad 2003; Kim et al. 2010; Ali et al. 2013;
80
M. K. Awasthi et al.
Phytoremediation is a flourishing field of active research with its novelty and costeffectiveness; being eco-friendly, aesthetic, and efficient, phytoremediation can be
applied onsite, with remediation by solar-driven technology (Ali et al. 2013). The
phytoremediation concept, first coined by Chaney (1983), includes phytoextraction,
phytofiltration, phytostabilization, phytoevaporation, and phytodegradation. Over
the past 20 years, phytoremediation has been widely used to remove contaminants
(i.e., HMs, organic and inorganic substrates) from polluted soil or water by
rhizofiltration and accumulation in the aboveground biomass (Ali et al. 2013;
Rezania et al. 2016). Many kinds of hyper-accumulator were found; Brassica spp.,
a bioenergy crop, is found to be efficient in accumulating HMs in their tissues and
recovering the contaminants (Wu et al. 2010). To date, many researchers have used
plant-assisted biosolids or microbes to enhance the efficacy of the phytoremediation
process in removing HMs from contaminated sites (Kim et al. 2010; Rajkumar et al.
2012). The addition of these organic substrate and microbes could possibly assist the
plants in their growth and their HM adsorption capacities (Gao et al. 2010). Other
than natural plants, genetically engineered plants with expected outcomes improve
the remediation of HMs from contaminated soil (Chanu and Gupta 2016; Gomes
et al. 2016).
1.3 Market Demand for Phytoremediation
Soil remediation is a difficult task because of current technical and financial limitations. Phytoremediation is a useful technology to harvest HMs from polluted soil and
has been certified as an effective and economical method (Figs. 4.1 and 4.2).
Compared to other technologies, phytoremediation is more suitable for market
demand, having low installation and maintenance costs at less than 5% of the cost
required for alternative methods (Prasad 2003). The plants remediated the contaminants without affecting the topsoil, consequently conserving the utility and fertility
of the soil. Also, HMs with market value (e.g., Ni, Tl, Au) could be retrieved by
plants. Furthermore, rapidly growing plants with high biomass yield, such as poplar,
willow, and Jatropha, not only remediate the soil but can also produce energy
(Prasad 2003; Abhilash et al. 2012). Therefore, employing phytoremediation could
reduce HM pollution and create economic benefits.
1.4 Global Overview of Toxic Metals Phytoremediation
In the development of phytoremediation in HM-polluted soil, many plants and toxic
metals have been widely investigated (Prasad 2003; Kim et al. 2010; Ali et al. 2013;
80
M. K. Awasthi et al.