1 Introduction
Water pollution is a worldwide problem that leads to the cause of death and disease.
According to researchers, the improper disposal of waste causes contamination of
groundwater. The strongest water pollutants are insecticides, pollutants from livestock operations, volatile organic compounds, food processing waste, and chemical
waste. Heavy metals are the most dangerous type of chemicals since they impose
serious health hazards in all living organisms. The most common heavy metal
contaminants are Cadmium (Cd), Chromium (Cr), Copper (Cu), Mercury (Hg),
Lead (Pb), Nickel (Ni), and Zinc (Zn) (Lasat 2002). The heavy metal pollution in
the environment is presently a global challenge. Heavy metal toxicity and the threat
of their bioaccumulation in the food chain is one of the major environmental
problems faced by our modern society. The noteworthy reason for heavy metal
pollution is a discharge of contaminated sewage and effluents from industries
(Prasannakumari et al. 2014).
In recent years the studies related to pollutant uptake and degradation are being a
subject of interest. Many scientist are working hard towards decreasing the level of
heavy metal pollution. Some of the most used methods of removal of contaminants
are chemical precipitation, adsorption, ionic exchange, and electrochemical filtration. Most of these methods are costly and inefficient at low concentrations. These
drawbacks in these methods demand the development of new low-cost water
treatment methods. Therefore for the removal of heavy metal contaminants from
the environment, the most preferred method is phytoremediation. Phytoremediation
is defined as the capability of plants to degrade and reduce the pollutant from the
environment. These plants can accumulate the toxic contaminants within themselves
and also capable to destroy them (Dipu 2013).
Phytoremediation uses specific plants that can accumulate various heavy metals
like lead, chromium, arsenic, etc., and its radioisotopes, which helps in cleaning soil
and water contaminated with heavy metals. The recent work on the capability of
certain chelating agent that helps in the removal of heavy metal by the plant is highly
promising for commercial use in the future (Ghosh and Singh 2015). Aquatic ferns
have the capability of degradation of contaminants.
Among various species, Salvinia, a free-floating aquatic fern holds a distinct
position because of high productivity and tolerance to a wide range of temperatures
(Olguin et al. 2003). Salvina Molesta is a free-floating weed that is native to SouthEastern Brazil. It is a highly accelerated vegetative reproduction and has earned the
title of various serious weed in most regions outside its natural habitat. It can chock
up the rivers and canals and has both direct and indirect effects on the aquatic
ecosystem (Sreerama Kumar et al. 2005). It grows in the slow-moving water (or) still
water like ponds, lakes, rivers, and prefers nutrient-rich water such as eutrophic
water and polluted water. It grows best at pH less than 7.5 (Arzani et al. 2007) and
the optimum temperature range is 25–36
C (Lesniewicz et al. 2006). Salvina
molesta can be used for the treatment of blackwater effluent in an eco-friendly
sewage system (Moore and Ramamoorthy 1984; Prichard et al. 1984).
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T. G. Nithya et al.
Water pollution is a worldwide problem that leads to the cause of death and disease.
According to researchers, the improper disposal of waste causes contamination of
groundwater. The strongest water pollutants are insecticides, pollutants from livestock operations, volatile organic compounds, food processing waste, and chemical
waste. Heavy metals are the most dangerous type of chemicals since they impose
serious health hazards in all living organisms. The most common heavy metal
contaminants are Cadmium (Cd), Chromium (Cr), Copper (Cu), Mercury (Hg),
Lead (Pb), Nickel (Ni), and Zinc (Zn) (Lasat 2002). The heavy metal pollution in
the environment is presently a global challenge. Heavy metal toxicity and the threat
of their bioaccumulation in the food chain is one of the major environmental
problems faced by our modern society. The noteworthy reason for heavy metal
pollution is a discharge of contaminated sewage and effluents from industries
(Prasannakumari et al. 2014).
In recent years the studies related to pollutant uptake and degradation are being a
subject of interest. Many scientist are working hard towards decreasing the level of
heavy metal pollution. Some of the most used methods of removal of contaminants
are chemical precipitation, adsorption, ionic exchange, and electrochemical filtration. Most of these methods are costly and inefficient at low concentrations. These
drawbacks in these methods demand the development of new low-cost water
treatment methods. Therefore for the removal of heavy metal contaminants from
the environment, the most preferred method is phytoremediation. Phytoremediation
is defined as the capability of plants to degrade and reduce the pollutant from the
environment. These plants can accumulate the toxic contaminants within themselves
and also capable to destroy them (Dipu 2013).
Phytoremediation uses specific plants that can accumulate various heavy metals
like lead, chromium, arsenic, etc., and its radioisotopes, which helps in cleaning soil
and water contaminated with heavy metals. The recent work on the capability of
certain chelating agent that helps in the removal of heavy metal by the plant is highly
promising for commercial use in the future (Ghosh and Singh 2015). Aquatic ferns
have the capability of degradation of contaminants.
Among various species, Salvinia, a free-floating aquatic fern holds a distinct
position because of high productivity and tolerance to a wide range of temperatures
(Olguin et al. 2003). Salvina Molesta is a free-floating weed that is native to SouthEastern Brazil. It is a highly accelerated vegetative reproduction and has earned the
title of various serious weed in most regions outside its natural habitat. It can chock
up the rivers and canals and has both direct and indirect effects on the aquatic
ecosystem (Sreerama Kumar et al. 2005). It grows in the slow-moving water (or) still
water like ponds, lakes, rivers, and prefers nutrient-rich water such as eutrophic
water and polluted water. It grows best at pH less than 7.5 (Arzani et al. 2007) and
the optimum temperature range is 25–36
C (Lesniewicz et al. 2006). Salvina
molesta can be used for the treatment of blackwater effluent in an eco-friendly
sewage system (Moore and Ramamoorthy 1984; Prichard et al. 1984).
338
T. G. Nithya et al.