Ecology, Environment and Conservation Paper

KINETIC MODELING OF GROWTH ON BIODEGRADATION OF NAPHTHALENE USING RHODOCOCCUS SP.

J. Jegan, T. Bhagavathi Pushpa, S. Praveen and B. Nithyalakshmi

Abstract

The naphthalene biodegradation by Rhodococcus sp. isolated from the tannery industry effluent was studied. The influence of various operational parameters like pH, glucose concentration and inoculum concentrations on the growth and naphthalene degradation potential of the species were investigated. The naphthalene degradation and microbial growth was higher at optimum pH (pH7), glucose concentration (500 mg/L) and inoculum concentration (3%). The non-ionic surfactants were used in very high concentrations of naphthalene (1000–5000 mg/L) to investigate the maximum naphthalene tolerance potential of Rhodococcus sp. The surfactants used are Triton X-100 and Tween-80. These surfactants enhanced the availability of naphthalene to the microbes. The naphthalene was degraded by Rhodococcus sp. upto the initial concentration of 4000 mg/L without microbial inhibition. Beyond that when the naphthalene concentration increases, the degradation potential of the microbes decreases. The inhibition characteristics of substrate was described using four kinetics models (Haldane, Webb, Edward and Aiba). These kinetics models fitted very well and it describes the dynamic behavior of naphthalene biodegradation by Rhodococcus sp.