243
17 Phytoremediation Systems for the Recovery of Nutrients from Eutrophic Waters
production owing to shading by floating plants (Feuchtmayr
et al. 2009).
17.5.6 pH
It has been found that Lemna minor performs better at low
pH for phytoremediation of eutrophic waters (Ansari and
Khan 2008) and for increased treatment efficiencies in duckweed-covered wastewater, pH values should be decreased
(Ansari and Khan 2009b; Ansari et al. 2011b).
17.5.7 Light
Recently, it has been shown that light is the significant factor
controlling plant growth in a eutrophic lake (Karlsson et al.
2009). Various treatments of light showed a significant effect
on photosynthesis and acclimation in aquatic macrophytes. It
was found that in eutrophicated coastal waters seagrass decline is largely owing to low light intensity because of high
biomass of algal overgrowth as epiphytes and macroalgae in
shallow coastal areas, and phytoplankton in deeper coastal
waters (Burkholder et al. 2007).
17.5.8 Seasonal Variations
In addition to more favorable temperatures during a particular
season, there is some phenological specificity in developing
plant biomass, which is contributing to higher plant growth
during the season and therefore contributing to higher nutrients removal efficiency. Nutrient removal exhibited a typical
seasonal pattern in microcosms with planted Carexla custris,
Scirpus validus, Phalarisa rundinacea,and Typha latifolia,
with higher removal rates in the growing season and lower
rates in the winter months (Picard et al. 2005). During the
autumn season, Phragmites spp. and Typha latifolia reached
their optimum growth rate, followed by a dormant phase,
which affected their nutrient removal efficiency (Kouki et al.
2009). Wetlands vegetated by Pennisetum purpureum significantly outperformed wetlands with other plants in May and
June, whereas wetlands vegetated by Phragmites communis
and Canna indica demonstrated higher removal efficiency
from August to December (Yang et al. 2007).
17.6 Phytoremediation of Eutrophic Water
Using Aquatic Macrophytes
The growth response of common duckweed Lemna minor
was studied at various temperature and pH levels for its
possible application for remediating eutrophic waters. The
dry weight, chlorophyll a, nitrogen, phosphorus, potassium,
peroxidase (POD), catalase (CAT), and malondialdehyde
(MDA) levels were determined. While optimum growth was
recorded at between 20 and 30 °C, reduced growth and an
increase in protective enzymes were noted at both lower and
higher temperatures. There was oxidative damage at temperatures less than 10 °C and greater than 40 °C. The pH of the
growth medium was inversely related to the growth responses of Lemna minor. At acidic pH and at temperatures between
20 and 30 °C, the environmental conditions were most suitable for phytoremediation of eutrophic waters. Under these
conditions, and when harvested regularly, Lemna minor was
found to be useful in counteracting eutrophication (Ansari
and Khan 2008). The range of pH from 6.5 to 6 and temperature of 25–30 °C were found to be the most suitable environmental condition for remediation of eutrophic water using
giant duckweed. When harvested regularly duckweed plants
were suggested to be useful in counteracting eutrophication
in affected water bodies (Ansari and Khan 2009a).
Phytoremediation potential of duckweed Lemna minor
L. was studied in vitro for the period of 7 days to investigate the removal of pollutants in domestic wastewater with
special reference to nutrients. The study was conducted in
plastic tubs of 6 inches deep and of 175 cm diameter. Twenty
liter domestic wastewater was used in tubs for the culture
of duckweed. The domestic wastewater quality was assessed
by analyzing physicochemical characters and the resulting
data were indicated as initial value. 1Hundred grams of fresh
weight of Lemna minor L was cultured for the period of 7
days and again domestic wastewater was analyzed for the
same physicochemical parameters and obtained values were
indicated as final value. Net primary productivity (NPP) of
duckweed was also determined by Harvest method for the
period of culture. The study revealed that pH, dissolved oxygen and percentage oxygen saturation value had increased,
while the values for other studied physico chemical parameters decreased significantly after seven days of culture of
Lemna minor L. An increase in value of pH, dissolved oxygen, percentage oxygen saturation and decrease in value of
alkalinity, carbon di oxide concentration, chloride, COD,
hardness, nitrogen, and phosphorus value indicated an improvement in water quality. An increase in fresh weight of
Lemna minor L. and NPP value have suggested its great potential in Phytoremediation for removal of pollutants with
special reference to nutrients like nitrogen and phosphorus
from domestic wastewater (Patel and Kanungo 2010).
The potential of Eichhornia crassipes was tested at various temperature and pH levels for its application for remediation of eutrophic water. The dry weight, chlorophyll-a, nitrogen, phosphorus, potassium, POD, CAT, and MDA levels
were determined. Optimum growth of plant was recorded at
pH levels 6 to 7 and between 20 and 30 °C temperatures. A
significant reduction in growth and an increase in protective
17 Phytoremediation Systems for the Recovery of Nutrients from Eutrophic Waters
production owing to shading by floating plants (Feuchtmayr
et al. 2009).
17.5.6 pH
It has been found that Lemna minor performs better at low
pH for phytoremediation of eutrophic waters (Ansari and
Khan 2008) and for increased treatment efficiencies in duckweed-covered wastewater, pH values should be decreased
(Ansari and Khan 2009b; Ansari et al. 2011b).
17.5.7 Light
Recently, it has been shown that light is the significant factor
controlling plant growth in a eutrophic lake (Karlsson et al.
2009). Various treatments of light showed a significant effect
on photosynthesis and acclimation in aquatic macrophytes. It
was found that in eutrophicated coastal waters seagrass decline is largely owing to low light intensity because of high
biomass of algal overgrowth as epiphytes and macroalgae in
shallow coastal areas, and phytoplankton in deeper coastal
waters (Burkholder et al. 2007).
17.5.8 Seasonal Variations
In addition to more favorable temperatures during a particular
season, there is some phenological specificity in developing
plant biomass, which is contributing to higher plant growth
during the season and therefore contributing to higher nutrients removal efficiency. Nutrient removal exhibited a typical
seasonal pattern in microcosms with planted Carexla custris,
Scirpus validus, Phalarisa rundinacea,and Typha latifolia,
with higher removal rates in the growing season and lower
rates in the winter months (Picard et al. 2005). During the
autumn season, Phragmites spp. and Typha latifolia reached
their optimum growth rate, followed by a dormant phase,
which affected their nutrient removal efficiency (Kouki et al.
2009). Wetlands vegetated by Pennisetum purpureum significantly outperformed wetlands with other plants in May and
June, whereas wetlands vegetated by Phragmites communis
and Canna indica demonstrated higher removal efficiency
from August to December (Yang et al. 2007).
17.6 Phytoremediation of Eutrophic Water
Using Aquatic Macrophytes
The growth response of common duckweed Lemna minor
was studied at various temperature and pH levels for its
possible application for remediating eutrophic waters. The
dry weight, chlorophyll a, nitrogen, phosphorus, potassium,
peroxidase (POD), catalase (CAT), and malondialdehyde
(MDA) levels were determined. While optimum growth was
recorded at between 20 and 30 °C, reduced growth and an
increase in protective enzymes were noted at both lower and
higher temperatures. There was oxidative damage at temperatures less than 10 °C and greater than 40 °C. The pH of the
growth medium was inversely related to the growth responses of Lemna minor. At acidic pH and at temperatures between
20 and 30 °C, the environmental conditions were most suitable for phytoremediation of eutrophic waters. Under these
conditions, and when harvested regularly, Lemna minor was
found to be useful in counteracting eutrophication (Ansari
and Khan 2008). The range of pH from 6.5 to 6 and temperature of 25–30 °C were found to be the most suitable environmental condition for remediation of eutrophic water using
giant duckweed. When harvested regularly duckweed plants
were suggested to be useful in counteracting eutrophication
in affected water bodies (Ansari and Khan 2009a).
Phytoremediation potential of duckweed Lemna minor
L. was studied in vitro for the period of 7 days to investigate the removal of pollutants in domestic wastewater with
special reference to nutrients. The study was conducted in
plastic tubs of 6 inches deep and of 175 cm diameter. Twenty
liter domestic wastewater was used in tubs for the culture
of duckweed. The domestic wastewater quality was assessed
by analyzing physicochemical characters and the resulting
data were indicated as initial value. 1Hundred grams of fresh
weight of Lemna minor L was cultured for the period of 7
days and again domestic wastewater was analyzed for the
same physicochemical parameters and obtained values were
indicated as final value. Net primary productivity (NPP) of
duckweed was also determined by Harvest method for the
period of culture. The study revealed that pH, dissolved oxygen and percentage oxygen saturation value had increased,
while the values for other studied physico chemical parameters decreased significantly after seven days of culture of
Lemna minor L. An increase in value of pH, dissolved oxygen, percentage oxygen saturation and decrease in value of
alkalinity, carbon di oxide concentration, chloride, COD,
hardness, nitrogen, and phosphorus value indicated an improvement in water quality. An increase in fresh weight of
Lemna minor L. and NPP value have suggested its great potential in Phytoremediation for removal of pollutants with
special reference to nutrients like nitrogen and phosphorus
from domestic wastewater (Patel and Kanungo 2010).
The potential of Eichhornia crassipes was tested at various temperature and pH levels for its application for remediation of eutrophic water. The dry weight, chlorophyll-a, nitrogen, phosphorus, potassium, POD, CAT, and MDA levels
were determined. Optimum growth of plant was recorded at
pH levels 6 to 7 and between 20 and 30 °C temperatures. A
significant reduction in growth and an increase in protective