Biodegradation of high phenol concentration in a membrane bioreactor

Phenol biodegradation by mixed culture was studied in a membrane bioreactor (MBR) over a period of 285 days. Activated sludge was used as the MBR biomass, after controlled acclimation to high phenol concentrations. The MBR permeate flux was stabilized quickly (in a few hours) and always maintained above 90 L.h(-1).m(-2).bar(-1). The acclimatized activated sludge allowed significant phenol degradation (95% average COD removal efficiency and greater than 99% phenol removal efficiency) without supplemental reagent addition. After sludge acclimatization, the Haldane kinetics model for a single substrate was used to obtain the maximum specific growth rate (mu m = 0.438 h(-1)), the half saturation coefficient (Ks = 29.54 mg.L-1) and the substrate inhibition constant (Ki = 72.45 mg.L-1). Biodegradation experiments were conducted at different phenol concentrations (4.9 - 8.5 g.L-1 d(-1)). Although the phenol concentration was high, the Haldane model was still acceptable, and removal capacities were in agreement with literature. Excellent effluent quality was obtained regardless of the extremely short SRT (5 - 17 days). This work shows the potential of MBR for toxic chemical elimination, charged effluents treatment and process stability.