Phenol and 4-chlorophenol biodegradation by yeast Candida tropicalis in a fluidized bed reactor

The objective of this work was to evaluate (i) the hydrodynamics and oxygen transfer characteristics of a fluidized bed reactor (FBR) and (ii) their performance in the continuous biodegradation of a phenol (Phe) and 4-chlorophenol (4-CP)-containing influent when the FBR was loaded with Candida tropicalis yeast immobilized onto granular activated carbon (GAC) particles. The first part was carried out in terms of the behavior of mixing time (t(m95)), bubble diameter (d(B)), gas hold-up (epsilon(G)), gas-liquid interfacial area (a') and oxygen transfer coefficient (k(L)a) in biphasic (gas-liquid) and triphasic (gas-liquid-carbon) systems, both batch-wise operated in pseudohomogeneous regime at superficial gas flow rates UG below 1.72 cms(-1). Mixing time was determined using a tracer technique, epsilon(G) was measured by the volume expansion method; (d(B)) was determined by the procedure reported by Poulsen and Iversen and k(L)a was determined by a transient gassing-in technique. It was found that hydrodynamic variables were severely influenced by GAC particles. The dB values were smaller in triphasic than in biphasic system, with the consequent increase in the epsilon(G), a' and k(L)a values.