Enhancement of Remediation Technologies with Biosurfactants - Biosurfactants: Research Trends and Applications - page 266

TABLE 10.3 (continued)
Summary of Soil Washing or Flushing Studies with Biosurfactants

Biosurfactant Medium Contaminant References

Rhamnolipid Soil PCP Mulligan and Eftekhari (2003)

Soil Cd, Ni Mulligan and Wang (2004)

Oil Chakrabarty (1985)

Rhamnolipid Sediments PAH, Pb, Zn, Ni Alavi and Mulligan (2011)

Clay PAHs Shafeeq et al. (1989)

Water Oil Holakoo and Mulligan

(2002)

Water Cu, Zn, Ni, Pb, Cd El Zeftawny and Mulligan

(2011)

Glycolipid Water Cu, benzene Ridha and Mulligan (2011)

Soil PCBs Golyshin et al. (1999)

situations is needed, particularly in light of the potential for remediation of metal
contamination by the biosurfactants.
More information is required concerning the interaction of the biosurfactants and
the contaminant, relationship of biosurfactant structure and contaminant removal
and the soil, scale-up and cost reduction for ex situ production, and understanding of
the factors influencing the bioremediation of the compounds by enhanced bioavail-
ability. Methods to enhance the economics of biosurfactant utilization will need to
be developed further. For example, ultrafiltration (Mulligan and Gibbs, 1990) can
be used to concentrate the biosurfactants for recovery and subsequent reuse, thus
decreasing the amount of biosurfactant required.
The effects of soil components such as hydroxides, oxides, and organics on metal
desorption by biosurfactants have been initiated in sediments, mining residues, and
soil (Dahrazma and Mulligan, 2004; Mulligan and Dahr Azma, 2003; Mulligan
et al. 1999). These types of studies provide clues into how difficult it will be to
remove the metals from the soil by the biosurfactant. Further methods will need to
be developed to enable one to predict and model the efficiency of the enhanced bio-
degradation, washing or flushing processes with biosurfactants under various hydro-
logical and soil conditions.
Rhamnolipids and other biosurfactants including saponin have shown their
potential for remediation of contaminated soil and water. More biosurfactants need
to be investigated. Both organic and inorganic contaminants can be treated through
desorption or biodegradation processes. The biosurfactants seem to enhance biodeg-
radation by influencing the bioavailability of the contaminant through solubiliza-
tion and emulsification of the contaminants. Due to their biodegradability and low
toxicity, biosurfactants such as rhamnolipids are very promising for use in reme-
diation technologies. In addition, there is the potential for in situ production, a dis-
tinct advantage over synthetic surfactants. This needs to be studied further. Further
research regarding prediction of their behavior in the fate and transport of contami-
nants will be required. More investigation into the solubilization mechanism of both