form of an NPK (nitrogen, phosphorus, and potassium) fertilizer (32% vs. 26% of
degraded oil in 90 days, respectively). Similarly to those results, a significant improvement was observed for the rhamnolipids + bacterial consortium treatment compared to
the rhamnolipids + nutrients addition (53% vs. 36% of degraded oil in 90 days,
respectively). As expected, the combined rhamnolipids + nutrients + bacterial consortium treatment led to an even greater efficiency, degradation of oil by 77% in 90 days.
Besides petroleum contamination, PAHs are among the most common toxic soil
contaminants. Because the environmental PAHs usually occur as a mixture, the
biosurfactants’ specificity must be taken into account. Portet-Koltalo et al. (2013)
conducted a comparative study on the removal of seven PAHs from contaminated
soil by either SDS (a synthetic surfactant) or two cyclolipopeptide-based
biosurfactants (amphisin and viscosin-like mixture), both produced by two Pseudomonas fluorescens strains. SDS was able to release all the studied PAHs while both
biosurfactants were only effective toward the desorption of the lowest molecular
weight PAHs (naphthalene to fluorene). This selectivity was confirmed by Bezza and
Chirwa (2015) when they reported a higher efficiency and faster kinetics of the threering phenanthrene desorption from soil in comparison to four-ring pyrene by a
lipopeptidal biosurfactant produced by Paenibacillus dendritiformis.
Pesticides are widespread, dangerous, and persistent pollutants that tend to be
strongly adsorbed in contaminated soils. A glucolipid-based biosurfactant produced
by Burkholderia cenocepacia BSP3 noticeably enhanced the pesticide solubilization
making it available for either washing or bioremediation treatments (Wattanaphon
et al. 2008). Also an in situ release of a rhamnolipid produced by Pseudomonas
aeruginosa CH7, a β-cypermethrin-degrading bacterium, has the potential for enhancing the degradation of pesticides by increasing their bioavailibility (Zhang et al. 2011).
24.2.4.2 Treatment of Sites Contaminated with Heavy Metals
Heavy metals can be efficiently removed from contaminated water, sludge, and soils
by a biosurfactant action. Das et al. (2008) reported an efficient chelation of Pb and
Cd followed by precipitation by an anionic lipopeptide biosurfactant of a marine
origin. Tang et al. (2017) applied saponin, which is an anionic plant biosurfactant
having carboxyl groups at the hydrophilic end of its molecule, and showed its ability
to bind heavy metals (Zn, Ni, Cu, Mn, Cr, and Pb) for their ultimate removal from
water sludge. A specific feature of this surfactant is that its metal binding facilitates
the micelle formation by saponin molecules. It was shown that Cr exhibits the
highest (65%), while Pb and Mn the lowest (25–35%) extraction efficiency.
Luna et al. (2016) described an efficient treatment of soil and aqueous solutions
contaminated from the automotive battery industry using an anionic biosurfactant
from Candida sphaerica. The results showed the removal rates of 95%, 90%, and
79% for Fe, Zn, and Pb, respectively. The addition of HCl increased the metal
removal rate. Additionally, the re-use of a recycled biosurfactant after metal precipitation yielded a reduced but still suitable removal efficiencies of 70%, 62%, and
45% for Fe, Zn, and Pb, respectively.
24 Modern Bioremediation Approaches: Use of Biosurfactants, Emulsifiers. . .
503
degraded oil in 90 days, respectively). Similarly to those results, a significant improvement was observed for the rhamnolipids + bacterial consortium treatment compared to
the rhamnolipids + nutrients addition (53% vs. 36% of degraded oil in 90 days,
respectively). As expected, the combined rhamnolipids + nutrients + bacterial consortium treatment led to an even greater efficiency, degradation of oil by 77% in 90 days.
Besides petroleum contamination, PAHs are among the most common toxic soil
contaminants. Because the environmental PAHs usually occur as a mixture, the
biosurfactants’ specificity must be taken into account. Portet-Koltalo et al. (2013)
conducted a comparative study on the removal of seven PAHs from contaminated
soil by either SDS (a synthetic surfactant) or two cyclolipopeptide-based
biosurfactants (amphisin and viscosin-like mixture), both produced by two Pseudomonas fluorescens strains. SDS was able to release all the studied PAHs while both
biosurfactants were only effective toward the desorption of the lowest molecular
weight PAHs (naphthalene to fluorene). This selectivity was confirmed by Bezza and
Chirwa (2015) when they reported a higher efficiency and faster kinetics of the threering phenanthrene desorption from soil in comparison to four-ring pyrene by a
lipopeptidal biosurfactant produced by Paenibacillus dendritiformis.
Pesticides are widespread, dangerous, and persistent pollutants that tend to be
strongly adsorbed in contaminated soils. A glucolipid-based biosurfactant produced
by Burkholderia cenocepacia BSP3 noticeably enhanced the pesticide solubilization
making it available for either washing or bioremediation treatments (Wattanaphon
et al. 2008). Also an in situ release of a rhamnolipid produced by Pseudomonas
aeruginosa CH7, a β-cypermethrin-degrading bacterium, has the potential for enhancing the degradation of pesticides by increasing their bioavailibility (Zhang et al. 2011).
24.2.4.2 Treatment of Sites Contaminated with Heavy Metals
Heavy metals can be efficiently removed from contaminated water, sludge, and soils
by a biosurfactant action. Das et al. (2008) reported an efficient chelation of Pb and
Cd followed by precipitation by an anionic lipopeptide biosurfactant of a marine
origin. Tang et al. (2017) applied saponin, which is an anionic plant biosurfactant
having carboxyl groups at the hydrophilic end of its molecule, and showed its ability
to bind heavy metals (Zn, Ni, Cu, Mn, Cr, and Pb) for their ultimate removal from
water sludge. A specific feature of this surfactant is that its metal binding facilitates
the micelle formation by saponin molecules. It was shown that Cr exhibits the
highest (65%), while Pb and Mn the lowest (25–35%) extraction efficiency.
Luna et al. (2016) described an efficient treatment of soil and aqueous solutions
contaminated from the automotive battery industry using an anionic biosurfactant
from Candida sphaerica. The results showed the removal rates of 95%, 90%, and
79% for Fe, Zn, and Pb, respectively. The addition of HCl increased the metal
removal rate. Additionally, the re-use of a recycled biosurfactant after metal precipitation yielded a reduced but still suitable removal efficiencies of 70%, 62%, and
45% for Fe, Zn, and Pb, respectively.
24 Modern Bioremediation Approaches: Use of Biosurfactants, Emulsifiers. . .
503