Nature Environment and Pollution Technology

R. Manikandan ¹, H. J. Prabhu ¹, P. Sivashanmugam ¹

Affiliations
1 Deptt. of Chemical Engineering, National Institute of Technology, Tiruchirappalli-620 015, T.N., IN

Abstract

In this work Nocardia hydrocarbonoxydans has been identified as potential organism to decompose chlorobenzene by its crude extract through immobilization technique. Nocardia hydrocarbonoxydans was grown on chlorobenzene as a sole source of carbon and energy. Chlorobenzene was used as an inducer to develop specific intracellular enzymes which will decompose chlorobenzene to nontoxic substance. Crude extracts of the cell contain intracellular enzyme, which were immobilized on sodium alginate beads. The beads were mixed with different concentrations (200, 250, 300 ppm) of chlorobenzene to study the kinetics of degradation of chlorobenzene. The rate of decomposition of chlorobenzene by immobilized crude extracts was measured at different time intervals and it was found that 86 to 96 percent of chlorobenzene can be decomposed in less than ten minutes. The immobilized crude extracts were reused for all other experiments and found that immobilization technique can be used for higher capacity conversion for scale up process.

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R. Manikandan ¹, H. Janardhana Prabhu ¹, P. Sivashanmugam ¹

Affiliations
1 Deptt. of Chemical Engineering, National Institute of Technology, Tiruchirappalli-620 015, T.N., IN

Abstract

Microorganisms have the ability to conform to a variety of environmental conditions. Their versatility makes them useful for various biotechnological applications. One such application is the use of microorganisms for removal of pollutants from the environment, called bioremediation. The first goal of the present work was to identify a microorganism which could grow on the model pollutant monochlorobenzene. The microbes used for degradation are Pseudomonas aeruginosa, Nocardia hydrocarboxydanse, and Mycoplana dimorpha.The batch-wise degradation is carried out on a laboratory scale using monochlorobenzene (MCB) as a substrate. The pH and temperature were maintained at 7.0 and 30°C throughout the experiment. The degradation was studied at various substrate concentrations (100, 200, 500 ppm.). Following a 2-5 hr post-treatment lag phase, degradation of the substrate occurred within 48 h.Various factors such as inocula, concentration of chlorinated aromatic hydrocarbons (CAHs), pH, temperature, presence of co-substrates and the type of carbon source used influenced the degradation of CAHs in shake flasks. Results show that the degradation was highest at an initial concentration of 200 ppm of MCB by Pseudomonas aeruginosa. Results also show that when the substrate concentration was increased to 500 ppm, the degradation became slower.

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