Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


ucin1054223125.pdf (1.2 MB)

ETD Abstract Container

Abstract Header

BIODEGRADATION AND BIOAVAILABILITY STUDIES ON AGED PAH-CONTAMINATED SEDIMENT

LEI, LI
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054223125

Abstract Details

2003, PhD, University of Cincinnati, Engineering : Environmental Engineering.
The degradation of PAHs by bacteria indigenous to chronically field-contaminated sediment was investigated, where the sediment served as both the inoculum and the medium containing PAHs. Microbial composition and dynamics under representative conditions were characterized by Denaturing Gradient Gel Electrophoresis (DGGE).Due to the high content of reduced sulfur compounds in the sediment, rapid oxygen depletion and severe acidification resulted from intensive activities of sulfur-oxidizing bacteria affiliated with the genus Thiovulum . Proper use of crushed limestone and an oxygen delivery protocol successfully avoided acidification and satisfied the oxygen demand of the system. With sufficient oxygen, substantial biodegradation of 2-, 3-, 4-, and 5-ring PAHs was achieved, while no appreciable degradation of 6-ring compounds was observed. Phylogenetic analysis of the microbial communities in various aerobic slurries with different additives revealed the selection of species associated with genera Cytophaga and Sphingomonas .Only phenanthrene showed a significant degradation coupled to sulfate reduction. Two dominant species grouped with the genus Bacteroides were probably involved in the degradation. They related to clones involved in the degradation of aromatic hydrocarbons with sulfate as the electron acceptor.Under denitrifying conditions, no appreciable PAH degradation was observed, while the reduction of nitrate to nitrogen occurred stoichiometrically with the production of sulfate. This was due to the absolute dominance of an autotrophic, Thiomicrospira denitrificans -like denitrifier. The addition of ethanol or acetate, as applied, was unable to encourage the dominance of heterotrophic denitrifiers, which was necessary for PAH biodegradation.An XAD-2 assisted desorption assay was developed for assessing the bioavailability of PAHs in the sediment. Its promise was demonstrated by the strong agreement between final residual levels of all the 2-, 3-, and 4-ring PAHs after biodegradation and desorption. This suggests that bioavailability was the factor limiting the biodegradation of these PAHs, and explains why addition of nutrients, co-substrates, or surfactants, as practiced, did not improve the extent of degradation in aerobic systems, although different dominant species resulted in response to these amendments. Mild extractions using certain isopropanol- or ethanol-water solutions could also approximate the bioavailability of PAHs, which, however, require intensive studies of extraction parameters.
Dr. Makram T. Suidan (Advisor)
177 p.
PAHs (polycyclic aromatic hydrocarbons); biodegradation; bioavailability; sediment; XAD-2 assisted desorption

Recommended Citations

Citations

  • LEI, L. (2003). BIODEGRADATION AND BIOAVAILABILITY STUDIES ON AGED PAH-CONTAMINATED SEDIMENT [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054223125

    APA Style (7th edition)

  • LEI, LI. BIODEGRADATION AND BIOAVAILABILITY STUDIES ON AGED PAH-CONTAMINATED SEDIMENT. 2003. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054223125.

    MLA Style (8th edition)

  • LEI, LI. "BIODEGRADATION AND BIOAVAILABILITY STUDIES ON AGED PAH-CONTAMINATED SEDIMENT." Doctoral dissertation, University of Cincinnati, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054223125

    Chicago Manual of Style (17th edition)

ucin1054223125
2,290
© 2003, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.