Document Type

Thesis

Date of Award

8-31-1991

Degree Name

Master of Science in Environmental Science - (M.S.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Richard B. Trattner

Second Advisor

David Kafkewitz

Third Advisor

Piero M. Armenante

Abstract

In this thesis I examine the feasibility of using anaerobic microbial consortia from digested anaerobic sludge to degrade Diflufenican, a fluorinated herbicide released into the environment as a result of agricultural usage. The compound is manufactured by Rhone Poulenc and it is an active ingredient of agricultural herbicides. The anaerobic digested sludge served both as a source of microorganisms and as a growth medium. Initial studies were conducted by making a stock solution of 1 ppm concentration of Diflufenican in acetone, the optimal solubility of the compound as suggested in the material safety data sheet is 0.05 ppm in water.

Anaerobic sewage sludge obtained from a neighboring treatment plant was filtered using laboratory filter paper then stored to be used for the preparation of samples and controls. The samples consist of a suspension of Diflufenican in filtered sludge without prior sterilization. The controls consist of a suspension of Diflufenican in sterilized sludge. Anaerobic conditions were obtained in the samples and controls by bubbling nitrogen gas through the sludge for a few minutes and then sealing the bottles. The samples and controls were incubated at room temperature and analyzed every two weeks to check for Diflufenican degradation. Analytical difficulties in detecting Diflufenican were encountered because of its low solubility and its concentration in samples and controls were too low for detection. Preparation of standards for Diflufenican led to precipitation in solution of concentrations that were high enough for detection. Alternate methods of concentrating the target compound in the samples and controls using the Baker analyte column , a column used to concentrate compounds in solution, proved unsuccessful. It was then decided to detect metabolites of the target compound to demonstrate degradation. Chemical analysis of Diflufenican by the department of chemistry of Rutgers University, Newark, revealed that the main metabolites were Niacin, 2,4-Difluoroaniline and Trifluorotoluene. It was decided to look for the metabolite 2,4-Difluoroaniline in the samples based on the hypothesis that the microorganisms would act on Diflufenican and degrade it releasing 2,4-Difluoroaniline. Standards for 2,4-Difluoroaniline were prepared and run on HPLC to obtain chromatograms for comparison.

Samples and controls of 6,8 and 12 weeks were run and chromatograms obtained. Although detection peaks were obtained in all of the above chromatograms, no perfect match was obtained between the peaks of the samples and those of the standards for 2,4-Difluoroaniline. This led to the conclusion that Diflufenican may be degraded by microorganisms to some other compounds other than 2,4-Difluoroaniline as it was not possible to detect this compound in the samples. Also it may be possible that the degradation of diflufenican may take a longer period of time to release the expected metabolites.

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