Environmental Engineering Reference
In-Depth Information
Pseudomonas sp., Alicaligens sp., and Terrabacter sp. grown on biphenyl has been
reported; however, not all bacterial species that produce biphenyl dioxygenase
degraded DDE. Arsenic and copper inhibit DDE degradation by aerobic microor-
ganisms. Similarly, metal chelates such as EDTA inhibit the breakdown of DDE by
the extracellular lignolytic enzymes produced by white rot fungi. The addition of
adjutants such as sodium ion, surfactants, and cellulose increased the rate of DDT
aerobic or anaerobic degradation but did little to enhance the rate of DDE
disappearance under anaerobic conditions. Only in the past decade has it been
demonstrated that DDE can undergo reductive dechlorination under methanogenic
and sulfidogenic conditions to form the degradation product DDMU, 1-chloro-2,2'-
bis-(4'-chlorophenyl)ethane. The only pure culture reported to degrade DDE under
anaerobic conditions was the denitrifier Alcaligens denitrificans . The degradation
of DDE by this bacterium was enhanced by glucose, whereas biphenyl fumes had
no effect.
Abiotic remediation by DDE volatilization was enhanced by flooding and irriga-
tion and deepplowing inhibited the volatilization. The use of zero-valent iron and
surfactants in flooded soils enhanced DDT degradation but did not significantly alter
the rate of DDE removal. Other catalysts (palladized magnesium, palladium on car-
bon, and nickel/aluminum alloys) degraded DDT and its metabolites, including DDE.
However, these systems are often biphasic or involve explosive gases or both. Safer
abiotic alternatives use UV light with titanium oxide or visible light with methylene
green to degrade DDT, DDD, and DDE in aqueous or mixed solvent systems.
Remediation and degradation of DDE in soil and water by phytoextraction, aer-
obic and anaerobic microorganisms, or abiotic methods can be accomplished.
However, success has been limited, and great care must be taken that the method
does not transfer the contaminants to another locale (by volatilization, deep plow-
ing, erosion, or runoff ) or to another species (by ingestion of accumulating plants
or contaminated water). Although the remediation of DDT-, DDD-, and DDE-
contaminated soil and water is beset with myriad problems, there remain many
open avenues of research.
References
Ahuja R, Awasthi N, Manickam N, Kumar A (2001) Metabolism of 1,1-dichloro-2,2-bis(4-
chlorophenyl)ethylene by Alicaligenes denitrificans . Biotech Lett 23:423-426.
Aigner E, Leone A, Falconer R (1998) Concentrations and enantiomeric ratios of organochlorine
pesticides in soil from the U.S. corn belt. Environ Sci Technol 32:1162-1168.
Aislabie J, Richards N, Boul H (1997) Microbial degradation of DDT and its residues: a review.
N Z J Agric Res 40:269-282.
Aislabie J, Davison A, Boul H, Franzmann P, Jardine D, Karuso P (1999) Isolation of Terrabacter
sp. DDE-1, which metabolizes 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene when induced by
biphenyl. Appl Environ Microbiol 65:5607-5611.
Atlas E, Foster R, Glam C (1982) Air-sea exchange of high molecular weight organic pollutants:
laboratory studies. Environ Sci Technol 16:283-286.
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