Two-phase biodegradation of phenol in trioctylphosphine oxide impregnated hollow fiber membrane bioreactor

Abstract

A hollow fiber membrane bioreactor using trioctylphosphine oxide (TOPO) impregnated in polypropylene hollow fiber membranes was developed for two-phase biodegradation of phenol using Pseudomonas putida ATCC 11172. Scanning electron microscopy revealed white deposits of TOPO impregnated non-uniformly within the cross sections and surfaces of the membranes. The extractant impregnated membranes exhibited high adsorption capacity and rates, whereas biodegradation of 800–2500mg/L phenol at 200mL volume in the extractant impregnated hollow fiber membrane bioreactor (EIHFMB) was characterized by high cell growth and biodegradation rates. For example, 1000mg/L phenol was completely degraded within 12h at a specific growth rate of 0.73h−1 while the biomass yield and average biodegradation rate were 0.31g/g and 86mg/Lh, respectively. The biodegradation capacity and rate in the EIHFMB were improved by increasing the effective length of the fibers by 50%, as demonstrated during the biodegradation of 3000mg/L phenol. The adsorption/desorption rates were also enhanced with increasing aqueous phase flow rate. EIHFMB performance remained unchanged over 400h of operation under various operating conditions suggesting the stability of TOPO impregnation within the membrane. These results indicate the use of EIHFMB as a promising technology in solvent-free two-phase biodegradation of phenolic compounds.