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Degradation of perchloroethylene and dichlorophenol by pulsed‐electric discharge and bioremediation
Author(s) -
Yee Dennis C.,
Chauhan Sadhana,
Yankelevich Efim,
Bystritskii Vitaly,
Wood Thomas K.
Publication year - 1998
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19980820)59:4<438::aid-bit6>3.0.co;2-h
Subject(s) - 2,4 dichlorophenol , bioremediation , chloride , chemistry , degradation (telecommunications) , nuclear chemistry , phenol , environmental chemistry , contamination , bacteria , organic chemistry , biology , ecology , telecommunications , genetics , computer science
Pulsed electric discharge (PED) and bioremediation were combined to create a novel two‐stage system which dechlorinates the halogenated pollutants, 2,4‐dichlorophenol and perchloroethylene, with repetitive (0.1–1 kHz), short pulse (∼100 ns), low voltage (40–80 kV) discharges and then mineralizes the less chlorinated products with aerobic bacteria. A 6.1 m M aqueous dichlorophenol sample was cycled through the PED reactor (60 kV of applied pulsed voltage and 300 Hz) 6 times, resulting in the release of 55% of the initial dichlorophenol chloride ions (1 m M Cl − removed each cycle). The respective average specific efficiency is 0.4–0.6 keV/(Cl − molecule). Pseudomonas mendocina KR1, which grows in minimal medium supplemented with phenol but not with dichlorophenol, increased in cell density in all cultures supplemented with the PED‐treated DCP samples and yielded a maximum of two‐fold additional Cl − released compared to the PED‐related alone. The number of PED‐treatment cycles, voltage, and frequency were also varied, showing that both cell densities and overall dichlorophenol dechlorination were highly dependent upon the number of PED‐treatment cycles, rather than the tested voltages and frequencies. Using this two‐stage treatment system, PED released 31% of the initial chloride ions from dichlorophenol (after three cycles at 40–45 kV and 1.2 kHz) while P. mendocina KR1 in the second stage increased dechlorination to 90%. These results were corroborated by the 35% additional chloride release found with activated sludge cultures. Perchloroethylene (0.6 m M ) was similarly treated in a first‐stage PED reactor (80% chloride removal after four cycles) followed by biodegradation of the dechlorinated products with a recombinant toluene o ‐monooxygenase‐expressing Pseudomonas fluorescens strain. Gas chromatographic analysis showed that the PED reactor created less‐chlorinated byproducts (i.e., trichloroethylene) that were removed (74%) upon exposure to the recombinant bacterium. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:438–444, 1998.