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 consta nts of the model were estimated from the results of initial rate exper iments with the mixed culture obtained from a continuous-flow reactor (CFR) at steady state. The suggested model was useful to predict the i nteractions of substrates on the growth of a mixed culture. In the lon g-term study using three CFRs with internal cell recycle, 748 to 810 m g/L of influent phenol were completely degraded (hydraulic retention t ime = 36 hours). The addition of dichlorophenol (DCP) and/or pentachlo rophenol (PCP) into the phenol feed caused system fluctuation. In a re actor fed phenol and DCP, both compounds were consumed completely, whe reas the addition of PCP resulted in incomplete biodegradation of all phenolic compounds. However, the presence of DCP in a feed increased t he 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 decre ased maximum growth rates and increased substrate inhibition, perhaps caused by a loss in bacterial species diversity in the mixed culture.