Kinetics of Multiple Phenolic Compounds Degradation with a Mixed Culture in a Continuous-Flow Reactor

A multiple substrate kinetic model was tested to predict the growth of a mixed culture receiving multiple phenolic compounds. Kinetic constants of the model were estimated from the results of initial rate experiments with the mixed culture obtained from a continuous-flow reactor (CFR) at steady state. The suggested model was useful to predict the interactions of substrates on the growth of a mixed culture. In the long-term study using three CFRs with internal cell recycle, 748 to 810 mg/L of influent phenol were completely degraded (hydraulic retention time = 36 hours). The addition of dichlorophenol (DCP) and/or pentachlorophenol (PCP) into the phenol feed caused system fluctuation. In a reactor fed phenol and DCP, both compounds were consumed completely, whereas the addition of PCP resulted in incomplete biodegradation of all phenolic compounds. However, the presence of DCP in a feed increased the removal of PCP up to 43%. The growth of the mixed culture on dual- and triple-phenolic compounds was predicted using the model. The long-term exposure of the mixed culture to DCP and/or PCP resulted in decreased maximum growth rates and increased substrate inhibition, perhaps caused by a loss in bacterial species diversity in the mixed culture.