VOLUME 84, AUGUST 2006 THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING 501 INTRODUCTION T he removal of polyaromatic hydrocarbons (PAHs) from diesel is an essential requirement since they have a very harmful effect on living organisms due to their carcino- genic, tetragenic and toxic nature (Zhang et al., 2004). Biodegradation of PAH and bioremediation of PAH contaminated soil, therefore, are one of the main targets of scientists at present (Ashok et al., 1995; Bouchez et al., 1999; Gallego et al., 2001; Ghazali et al., 2004; Hanson et al., 1997; Kanaly and Harayama, 2000; Lal and Khanna, 1996; Lotfabad and Gray, 2002; Rahman et al., 2002; Richard and Vogel, 1999 and Saadoun, 2002). There are several factors that directly and indirectly affect the rate of biodegradation of the hydrocarbons, the main factors being pH, availability of nutrients, oxygen (for aerobic) and water (consid- ered as the most important) (Peressutti et al., 2003). In the case of the soil remediation system, maintenance of moisture level is an essential factor since it ensures not only the availability of water to the micro-organisms but also oxygen and nutrients dissolved in water (Admon et al., 2001; Filonov et al., 1999). Reaction Engineering Studies on the Biodegradation of Anthracene on Bioremediation of Diesel Contaminated Soil Using Acinetobacter sp. (ATCC No. 14293) Ruma Roy, Pinaki Bhattacharya and Ranjana Chowdhury* Jadavpur University, Chemical Engineering Department, Kolkata, West Bengal 700 032 India In the present investigation an attempt has been made to carry out a systematic and programmed bioprocess study of the monoculture system capable of decomposing anthracene from its simulated mixture in methanol and total aromatics from diesel contaminated soil through bioremediation, a technique that is not only simple but also cost-effective in cleaning up chemically contaminated soil. A pure bacterial strain, Acinetobacter sp. (ATCC No. 14293), has been used to carry out these studies. The main emphasis of the present investigation is to understand the complex reaction engineering behaviour of the biodegradation of anthracene as well as bioremediation of diesel contaminated soil by reducing total aromatic content. Anthracene has been chosen as a model PAH as it represents a typical polyaromatic hydrocar- bon, present in diesel, with three benzene rings fused together. The selected micro-organism has been adapted to anthracene in In the present investigation bio-degradation of anthracene, a polyaromatic hydrocarbon, from its simulated mixture in methanol, has been studied using a monoculture strain, (Acinetobacter sp. (ATCC No. 14293)), within the concentration range 500–800 mg/dm 3 . In a separate attempt bioremediation of diesel contaminated soil to reduce total aromatic content using the same bacterial strain has been carried out. The main emphasis of this investigation is to understand the complex reaction engineering behaviour involved in both the above bioprocess systems. It is observed that while Monod’s classical substrate uninhibited model can be used for simulation purpose for the biodegradation of anthracene, the reaction engineering behaviour of the bioremediation of soil can be expressed by coupling Monod’s classical equation with first order cell decay rate. In both the cases the concerned intrinsic kinetic parameters have been evaluated. Dans la présente étude, la biodégradation de l’anthracène, un hydrocarbure polyaromatique, venant d’un mélange simulé avec du méthanol, a été étudiée à l’aide d’une souche de monoculture (Acinetobacter sp. (ATCC No 14293)), pour une gamme de concentrations de 500 à 800 mg/dm 3 . Dans un essai distinct, on a procédé à la bioremédiation de sol contaminé par du diesel pour réduire la teneur aromatique totale à l’aide de la même souche bactérienne. Cette recherche a pour but principal de comprendre le comportement complexe du génie réactionnel associé à ces deux bioprocédés. On observe qu’alors que le modèle non inhibé de substrat classique de Monod peut être utilisé à des fins de simulation pour la biodégradation de l’anthracène, le comportement réactionnel de la bioremédiation de sol peut s’exprimer en couplant l’équation classique de Monod avec une cinétique de dégradation des cellules au premier ordre. Dans les deux cas, les paramètres de cinétique intrinsèques concernés ont été évalués. Keywords: biodegradation, anthracene, bioremediation of soil, growth kinetics, modelling * Author to whom correspondence may be addressed. E-mail address: ftbe_bon@yahoo.com