Biomedical Engineering Reference
In-Depth Information
Therefore, despite the large amount of research on dispersants, there is very little on
the use of biosurfactants as biodispersants despite their potential benefits, particu-
larly for enhancing oil biodegradation and solubilization.
Simultaneous removal of metals and organic pollutants from water is challeng-
ing. Although ultrafiltration can remove high molecular weight molecules, it is not
effective for removal of low molecular weight pollutants. Rhamnolipid biosurfactant
(Elzeftawny and Mulligan, 2011) was utilized in micellar-enhanced ultrafiltration
(MEUF) of heavy metals from contaminated waters. The effects of different major
operating conditions on the MEUF system performance were investigated for cop-
per, zinc, nickel, lead, and cadmium using two membranes. The optimal conditions
were successfully applied to treat six contaminated wastewaters from metal refining
industries using the two membranes (>99% rejection ratio). To efficiently choose the
most influential factors to the MEUF system, optimization by the response surface
methodology approach was utilized and data quality was examined. Optimization
by the response surface methodology and validation experiments determined that
the best operating conditions were a transmembrane pressure of 69 ± 2 kPa, bio-
surfactant-to-metal MRs of approximately 2:1, a temperature of 25°C ± 1°C, and
pH of 6.9 ± 0.1. The rhamnolipid-enhanced ultrafiltration system was also shown to
treat samples of six contaminated wastewaters from metal refining industries using
membranes with molecular weight cutoffs (MWCO) of 10,000 and 30,000 Da. The
resulting heavy-metal concentrations in the permeate were all significantly reduced
to be in accordance with the federal Canadian regulations.
Micellar-enhanced ultrafiltration (MEUF) can be a more effective technique to
remove contaminants as it makes use of the micellar properties of surfactant solu-
tions to remove low molecular weight dissolved ions and/or organics. Compared to
chemical surfactants, biosurfactants are less toxic. This is advantageous as they may
create a secondary problem due to some leakage into the permeate. Therefore, the
objective of this study was to evaluate the effect of a rhamnolipid biosurfactant on
mixed contaminant removal from aqueous solutions (Ridha and Mulligan, 2011).
The required quantity of rhamnolipid to remove the copper ions as a heavy-metal
pollutant and benzene molecules as an organic pollutant separately was determined
for different concentrations of pollutants. This quantity, indicated by the MR of bio-
surfactant to contaminant was 6.25 to obtain a 100% rejection for the copper ions
and 1.33 to obtain the same rejection for benzene molecules. When copper and ben-
zene were cocontaminants in the water, the MRs improved for benzene from 1.33 to
0.56 but remained the same for copper. In all cases, rhamnolipid proved excellent for
the removal of contaminants and a rejection of 100% has been obtained for copper
and benzene either separately or simultaneously, which indicates the potential of this
approach for wastewater treatment.
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oPhoroliPiDs
Although sophorolipids have been used to release bitumen from oil sands (Cooper
and Paddock, 1984), few applications of these biosurfactants have been reported so
far. High yields of the sophorolipid make this a potentially useful and economic bio-
surfactant. A crude preparation of biosurfactants from
Candida bombicola
was able
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