Stimulation of Phenol Removal Efficiency of Aspergillus versicolor by Surfactants, a Promising Way to Treat Phenol-Containing Waste Waters

Abstract

The effect of the cationic surfactant, dodecyl trimethyl ammonium bromide (DTAB), on phenol bioremoval efficiency of an Aspergillus versicolor strain was examined. The strain was grown in mineral salt (MS) medium and the effect of DTAB was investigated as a function of different pH values, phenol and surfactant concentrations. The effect of pH was tested within the range of 4-7 and the maximum bioremoval was found at pH 4. Initial phenol concentrations investigated ranged from 100 to 600 mg/L, and the effects of surfactant concentrations on the removal were tested with 0, 0.25, 0.5 and 1 mM DTAB, which showed that 0.5 mM surfactant was the most effective concentration. The maximum bioremoval rates found after 72 h incubation were 99.48 and 99.15 % in 100 and 200 mg/L initial phenol-containing samples, respectively, where the phenol removal capacity of the fungus was only 142.373 mg/g in the DTAB blank samples. The maximum phenol uptake capacity of 267.162 mg/g was measured in the presence of 0.5 mM DTAB at 200 mg/L initial phenol concentration. These results showed that DTAB considerably increased the bioremoval efficiency of the strain tested at relatively lower phenol concentrations. The feasibility of this bioremoval method for industrial wastewater treatment is discussed.