96
Phytotechnology with Biomass Production
biological (e.g., rhamnolipids) origins. Gonzalez et al. (2010) reported that
adding Tween 80 (nonionic) to contaminated soils effectively enhanced p,pDDT, p,p-DDE, and α-cypermethrin solubility while adding sodium dodecyl
sulfate (anionic) increased the solubility of two other pesticides (α-endosulfan
and endosulfan sulfate).
Rhamnolipids, also called biosurfactants, are glycolipids produced by
Pseudomonas, Burkholderia, and other genera (Abdel-Mawgoud et al., 2010).
Amendment of soil contaminated with p,p′-DDE by adding biosurfactants
increased accumulation of pesticides in roots, leaves, and fruits of Cucurbita
pepo ssp. Pepo (hyperaccumulator) and C. pepo ssp. Ovifera (nonaccumulator)
mainly by reducing its net hydrophobicity (White et al., 2006).
Carbon-rich materials. Application of carbon-rich materials (biochar, activated carbon, lignite, etc.) in a phytoremediation process aims to stabilize
organic pollutants by reducing their bioavailability (Denyes et al., 2012). A
comparative study on potential of biochar and activated carbon to decrease
the bioavailability of polychlorinated dibenzo-p-dioxins and -furans showed
reduction of their bio-uptake in earthworms by 51.6%–90.3% (Chai et al.,
2012). In the Chai et al. (2012) research, contaminant reduction was higher in
soil treated by activated carbon whereas in Denyes et al. (2013) it was almost
the same. The effectiveness of carbon-rich materials also depends on the way
they were added to the system. In a mechanically mixed system (24 hours,
30 rpm rotation in a drum) activated carbon reduced polychlorinated biphenyl levels 1.7 and 1.4 times more efficiently in the plant Cucurbita pepo and
earthworm Eisenia fetida, respectively, while the effectiveness of biochar was
higher by 2.0 and 1.7 times, respectively, as compared to simply digging the
material into soil at a contaminated site (Denyes et al., 2013). Contact of contaminant and sorbent is slow in natural systems.
Nanoparticles. Nanoremediation is a relatively new area of environmental
biotechnology, based on the ability of Ag, Au, Mg, and Fe nanoparticles to
facilitate dehalogenation of halocarbon pesticides. Nanoparticles can either
directly react with contaminant or participate in its conversion into less toxic
forms (Adeleye et al., 2013). Nanoparticles have been shown to be an efficient
amendment able to degrade 100% of DDT in various matrices (Tian et al.,
2009). Applying zero-valent iron nanoparticles (nZVIs) for DDT dechlorination in water and soil systems showed that the potential of nZVIs to decompose DDT was higher (92%) in water than in soil (22.4%) over the same time
(El-Temsah et al., 2016). Unfortunately, different modes of preparation of the
nZVI yield different eco-toxicity, which is nontrivial when it is applied in
large amounts to obtain effective degradation of POPs such as DDT. The
nZVIs were able to degrade lindane (γ-HCH (hexachlorohexane)) within 24
hours to γ-3,4,5,6-tetrachlorocyclohexane (an unstable intermediate) (Elliott
et al., 2009). The high rates were largely driven by the very high surface area
of nanoparticles, compared to larger ZVI particles.
Initial research combining nano- and phytotechnology to restore soil polluted by a chlorinated pesticide (endosulfan) included three tropical plant
Phytotechnology with Biomass Production
biological (e.g., rhamnolipids) origins. Gonzalez et al. (2010) reported that
adding Tween 80 (nonionic) to contaminated soils effectively enhanced p,pDDT, p,p-DDE, and α-cypermethrin solubility while adding sodium dodecyl
sulfate (anionic) increased the solubility of two other pesticides (α-endosulfan
and endosulfan sulfate).
Rhamnolipids, also called biosurfactants, are glycolipids produced by
Pseudomonas, Burkholderia, and other genera (Abdel-Mawgoud et al., 2010).
Amendment of soil contaminated with p,p′-DDE by adding biosurfactants
increased accumulation of pesticides in roots, leaves, and fruits of Cucurbita
pepo ssp. Pepo (hyperaccumulator) and C. pepo ssp. Ovifera (nonaccumulator)
mainly by reducing its net hydrophobicity (White et al., 2006).
Carbon-rich materials. Application of carbon-rich materials (biochar, activated carbon, lignite, etc.) in a phytoremediation process aims to stabilize
organic pollutants by reducing their bioavailability (Denyes et al., 2012). A
comparative study on potential of biochar and activated carbon to decrease
the bioavailability of polychlorinated dibenzo-p-dioxins and -furans showed
reduction of their bio-uptake in earthworms by 51.6%–90.3% (Chai et al.,
2012). In the Chai et al. (2012) research, contaminant reduction was higher in
soil treated by activated carbon whereas in Denyes et al. (2013) it was almost
the same. The effectiveness of carbon-rich materials also depends on the way
they were added to the system. In a mechanically mixed system (24 hours,
30 rpm rotation in a drum) activated carbon reduced polychlorinated biphenyl levels 1.7 and 1.4 times more efficiently in the plant Cucurbita pepo and
earthworm Eisenia fetida, respectively, while the effectiveness of biochar was
higher by 2.0 and 1.7 times, respectively, as compared to simply digging the
material into soil at a contaminated site (Denyes et al., 2013). Contact of contaminant and sorbent is slow in natural systems.
Nanoparticles. Nanoremediation is a relatively new area of environmental
biotechnology, based on the ability of Ag, Au, Mg, and Fe nanoparticles to
facilitate dehalogenation of halocarbon pesticides. Nanoparticles can either
directly react with contaminant or participate in its conversion into less toxic
forms (Adeleye et al., 2013). Nanoparticles have been shown to be an efficient
amendment able to degrade 100% of DDT in various matrices (Tian et al.,
2009). Applying zero-valent iron nanoparticles (nZVIs) for DDT dechlorination in water and soil systems showed that the potential of nZVIs to decompose DDT was higher (92%) in water than in soil (22.4%) over the same time
(El-Temsah et al., 2016). Unfortunately, different modes of preparation of the
nZVI yield different eco-toxicity, which is nontrivial when it is applied in
large amounts to obtain effective degradation of POPs such as DDT. The
nZVIs were able to degrade lindane (γ-HCH (hexachlorohexane)) within 24
hours to γ-3,4,5,6-tetrachlorocyclohexane (an unstable intermediate) (Elliott
et al., 2009). The high rates were largely driven by the very high surface area
of nanoparticles, compared to larger ZVI particles.
Initial research combining nano- and phytotechnology to restore soil polluted by a chlorinated pesticide (endosulfan) included three tropical plant