Kinetics Modelling of the Biodegradation of Benzene, Toluene and Phenol as Single Substrate and Mixed Substrate by Using Pseudomonas putida

A. K. Mathur and C. B. Majumder

Abstract
In the present work, kinetics of the biodegradation of benzene, toluene and phenol by using a pure culture of Pseudomonas putida (MTCC 1194) was determined by measuring the specific growth rate and degradation rate with substrate concentration as a function of time in a batch reactor. In general, the degradation rate of benzene, toluene and phenol increased with the increase in the initial substrate concentration and then decreased after reaching a maximum, showing substrate inhibition kinetics. The degradation rates of benzene, toluene and phenol were highest, 0.108, 0.133, and 0.0705 mg L–1 h–1 at γ = 148.2, 202.6, and 97.8 mg L–1 initial substrate concentration, respectively. Toluene degradation rate was highest, followed by benzene and phenol at the optimum temperature and pH. In the mixtures of benzene, toluene and phenol, toluene was the preferred substrate, but degradation of each compound was competitively inhibited by other compounds. This paper also deals with the study of Haldane, Andrews and Noack, and Han and Levenspiel model equations for substrate inhibition. An attempt has been made to study the applicability of three model equations for substrate inhibition systems by fitting their experimental data. It was found that the Han and Levenspiel model is best suited to the system.

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Keywords
Benzene, toluene, phenol, Pseudomonas putida, growth kinetics