Microbial Removal of Phenol and P-Chlorophenol from Industrial Waste Water Using Rhodococcus sp.RSP8 and Its Growth Kinetic Modeling

Abstract

A phenol-degrading microorganism, Rhodococcus sp.RSP8, was used to study the substrate interactions during cell growth on phenol and p-chlorophenol dual substrates. Both phenol and p-chlorophenol could be utilized by the bacteria as the sole carbon and energy sources. When cells grew on the mixture of phenol and p-chlorophenol, strong substrate interactions were observed. The p-chlorophenol inhibited the degradation of phenol, on the other hand, phenol also inhibited the utilization of p-chlorophenol. The overall cell growth rate depends on the co-actions of phenol and p-chlorophenol. In addition, the cell growth and substrate degradation kinetics of phenol, p-chlorophenol as single and mixed substrates for Rhodococcus sp.RSP8 in batch cultures were also investigated over a wide range of initial phenol concentrations (5-1600 mg.L^–1) and initial p-chlorophenol concentrations (5 – 250 mg.L^–1). The single-substrate kinetics was described well using the Haldane-type kinetic models, with model constants of µ_m1 = 0.15 h^–1, K_S1 = 2.22 mg.L^–1 and K_i1 = 245.37 mg.L^–1 for cell growth on phenol and of µ_m2 = 0.0782 h^–1, K_S2 = 1.30 mg.L^–1 and K_i2 = 71.77 mg.L^–1, K′_i2 = 5480 (mg.L^–1)² for cell growth on p-chlorophenol. Proposed cell growth kinetic model was used to characterize the substrates interactions in the dual substrates system.