Characterization of bacterial isolates from rubber dump site and their use in biodegradation of isoprene in batch and continuous bioreactors

• Five bacterial isolates have been isolated from isoprene contaminated soil.
• Pseudomonas sp. have been found to degrade up to 83% isoprene in batch mode.
• Kinetic constants have been used to explain the efficiency of isolates.
• Degradation is better (71–100% RE) in continuous mode.
• Use of bioscrubber enhances the performance of biofilter.

Bacterial isolates from contaminated soil of a waste rubber dumping site were isolated and characterized using biochemical and molecular approaches. Isoprene degradation kinetics in batch mode (isoprene concentration: 100–1000 ppm) revealed the degradation efficiency of isolates as: Pseudomonas sp. (83%) > Alcaligenes sp. (70%) > Klebsiella sp. (68.5%). The most efficient isolate Pseudomonas sp. was finally inoculated in a specifically designed bioreactor system comprising a bioscrubber and a biofilter packed with polyurethane foam connected in series. The bioscrubber and biofilter units when operated in a series showed more than 90% removal efficiency up to the inlet loading rate (IL) of 371.1 g/m3/h. Maximum elimination capacity (EC) of biofilter was found to be an order of magnitude greater than that for bioscrubber. Oxidative cleavage of the double bond of isoprene has been revealed through IR spectra of the leachate.

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