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Index >> Biodegradation of Pesticides and Pollutants >> Acceleration of Biodegradation

Acceleration of Biodegradation

Acceleration of Biodegradation
Three methods by which biodegradation can be augmented have been ex­plored. They are (1) addition of surfactants, (2) supplementation with inorganic nutrients and (3) inoculation with biomass of enriched bacterial species known to degrade a specific compound, the method referred to as bioaugmentation. The enzymes responsible for biodegradation are genetically encoded in bacterial plasmids. These plasmids possess broad host range and can be transferred within the same species or genera. They have been identified in species of Pseudomonas, Alcaligenes, Acinetobacter, Flavobacterium, Beijerinkia, Klebisella, Moraxella and Arthrobacter. Most of the novel strains have been genetically engineered from the genus Pseu­domonas and have been patented for cleaning up oil spills.

Some surfactants such as Surgee 2 and Corexit in combination with bacteria have been marketed to clean up crude oil spills. Since the volume of carbon to be degraded in crude oil is large, there is obviously, a need for replenishing or reinforcing the surroundings of NAPLs with nitrogen and phosphorus for faster biodegradation. This strategy has met with success in the case of phenanthrene degradation in an hexane NAPL.

Where normal microflora cannot take care of the degradation processes, inoculation with specific microorganisms becomes necessary and intact reduces the acclimation period. Success appears to be the rule in closed bioreactors designed for specific pollutants when bioaugmented with biomass of known microorganisms capable of degrading the pollutant in question. Industrial waste treatment systems use immobilized microbial cells (cells trapped in an inert matrix) or biofilms carrying the desired microbes in bioreactors. The substrates used for immobilization of desired bacteria have been alginate diatomaceous earth, activated carbon and nylon membrane, powder or tubes. However, success as well as failures have been encountered in in situ clean ups of aquifers, surface water and soils contaminated with pollutants. Some instances of successes have been listed in.

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