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contaminated areas. Further, among these three plants, the biomass produced by
cock’s comb (14.7 kg dw m 2 per year) was the highest followed by sunflower
(8.3 kg dw m 2 per year) and marigold (4.1 kg dw m 2 per year). Hence, for
the purpose of phytoremediation, the option might be to use high biomass
producing plants that were also useful for economy of the area (Prasad 2006;
Chatterjee et al. 2012).

7.12 Concluding Remarks

In a wetland, vegetative mass provided by the growing plants redirect flow of water
and its rhizosphere region stabilizes substrates and provides attachment sites for
microbial development. Rhizosphere in association with decaying plant biomass
generates litter and liberates organic carbon to stimulate microbial metabolism.
Potential conversion of the waterweeds harvested from the area may be used for the
production of fuel, paper, fiber, and energy (Curtis and Duke 1982). Utilizing the
plants at the wetlands for heavy metal remediation, persistent emergent plants like
common reed (Phragmites sp.), bulrushes (Scirpus sp.), spikerush (Efeocharis sp.),
sedges (Cyperus sp.), rushes (Juncus sp.), and cattails (Typha sp.) are suitable.
These species are suitable for wastewater treatment as they are habituated to
tolerate continuous flooding and exposure to wastewater containing relatively
high and often variable concentrations of pollutants. Further, any local species
can also be taken into consideration as those are adapted to the local climate,
soils, contaminants, and surrounding plant and animal communities. Treating
diverse contaminants including metals by a wetland, diverse assemblages of wet-
land plants is probably the best suitable option that usually recovers faster from
sudden anthropogenic disturbances like rapid inputs of varied contaminants. These
native plant assemblages are aesthetically pleasing and may perform well in
resisting invasive species and pests. However, the evolutionary significance of the
trends on metal-specific accumulation among plant species occupying the same
general habitat is an interesting area for future research.
Handling and disposal of the contaminated plant waste is the major concern with
the application of phytotechnology. Periodic harvesting of metal accumulated
biomass and disposing as hazardous waste, involve added cost. However, a number
of options are available like landfills, production of fuel, fiber, and energy for
proper disposal of metal-rich plants. Thus phytoremediation, in combination with
burning the biomass to produce electricity and heat, could become a new environ-
mentally friendly form of pollution remediation (Peuke and Rennenberg 2005).
Further, metals can be recovered from the ash (bio-ore) produced by incineration. It
was reported that Zn and Cd recovered from a typical contaminated site could have
a resale value of more than one thousand US dollar per hectare (Watanabe 1997).
Nicks and Chambers (1998) reported that using the nickel (Ni) hyperaccumulator
Streptanthus polygaloides, a yield of 100 kg ha 1 of sulfur-free Ni could be
produced. Thus, phytomining is a potential technology, however, has only limited