Date of Award

Fall 1993

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering - (Ph.D.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Piero M. Armenante

Second Advisor

Gordon Lewandowski

Third Advisor

David Kafkewitz

Fourth Advisor

Basil Baltzis

Fifth Advisor

Ching-Rong Huang

Abstract

The present work was aimed at determining the effect of the main operating parameters on the performance of an anaerobic-aerobic reactor system to degrade toxic chlorinated compounds. In previous work conducted in the Biological Treatment Lab at NJIT it was shown that this system is capable of achieving the complete degradation of chlorophenols. In that system, reductive dehalogenation took place in the first anaerobic reactor, which was followed by a second aerobic reactor in which the degradation products of the first reactor were mineralized. In the present work the role of a number of parameters that can have a significant impact on the performance of the anaerobic reactor, namely, pH, temperature, concentration of pollutants, and residence time were examined.

The medium pH appears to have a very significant impact on the ability of the anaerobic organisms to dechlorinate. Experiments were conducted using a novel, chloride-free, completely defined medium in which the buffering agent was one of several non-fermentable buffering agents (MOPS, TRICINE, BICINE, CHES). The results indicate that the dechlorination process occurs only if the pH is within the range 8.0-8.8. In addition, stoichiometric amounts of chloride ion were produced during the process. The dechlorination process was also studied at different temperatures. It was found that the data could be interpreted assuming an Arrhenius kind of dependence for the degradation reactions on temperature.

The overall dechlorination reaction was mathematically modeled assuming that the degradation process is constituted of a series of single dechlorination steps. Rate constants for each step were obtained in independent experiments. The resulting model was then used to predict the rate of degradation in both batch and continuous reactors. The prediction of the model matched closely the experimental results obtained in such systems, thus confirming the validity of the kinetic mechanisms postulated in the development of the model.

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