Among known microbial species, Arthrobacter
chlorophenolicus A6 has shown very good
potential to treat phenolic wastewaters. In this study,
the levels of various culture conditions, namely initial
pH, agitation (rpm), temperature (C), and inoculum age
(h) were optimized to enhance 4-chlorophenol (4-CP)
biodegradation and the culture specific growth rate. For
optimization, central composite design of experiments
followed by response surface methodology (RSM) was
applied. Results showed that among the four independent
variables, i.e., pH, agitation (rpm), temperature
(C), and inoculum age (h) investigated in this study,
interaction effect between agitation and inoculum age as
well as that between agitation and temperature were
significant on both 4-CP biodegradation efficiency and
culture specific growth rate. Also, at the RSM optimized
settings of 7.5 pH, 207 rpm, 29.6C and 39.5 h inoculum
age, 100% biodegradation of 4-CP at a high initial
concentration of 300 mg l-1 was achieved within a
short span of 18.5 h of culture. The enhancement in the
4-CP biodegradation efficiency was found to be 23%
higher than that obtained at the unoptimized settings of
the culture conditions. Results of batch growth kinetics
of A. chlorophenolicus A6 for various 4-CP initial
concentrations revealed that the culture followed substrate
inhibition kinetics. Biokinetic constants involved
in the process were estimated by fitting the experimental
data to several models available from the literature.