Treatment of phenol in synthetic saline wastewater by solvent extraction and two-phase membrane biodegradation

Phenol in synthetic saline (100 g L−1 NaCl) and acidic (pH 3) wastewater was treated by a hybrid solvent extraction and two-phase membrane biodegradation process at 30 °C. Kerosene was adopted to be the organic solvent because it was biocompatible and had a suitable partition coefficient for phenol. Phenol in water was first extracted by kerosene in a batch stirred vessel and the loaded solvent was passed through the lumen of a polyvinylidene fluoride (PVDF) hollow-fiber membrane contactor; in the meantime, Pseudomonas putida BCRC 14365 in mineral salt medium was flowed across the shell, to which tetrasodium phyophosphate (1 g L−1) was added as a dispersing agent. The effect of the initial phenol level in wastewater (110-2400 mg L−1) on phenol removal and cell growth was experimentally studied. At a cell concentration of 0.023 g L−1, it was shown that the removal of phenol from saline wastewater was more efficient at a level of 2000 mg L−1 when 0.02-m2 membrane module was used. The effects of bigger membrane module size (0.19 m2 area) and higher initial cell concentration (0.092-0.23 g L−1) on the performance of such a hybrid process for the treatment of higher-level phenol in saline wastewater was also evaluated and discussed.