Based on the RSM results, the optimum NH4Cl, and NaH2PO4 concentrations for each BTEX concentration were determined and the conditions were tested for BTEX degradation (Table 3). The
degradation experiments were conducted in triplicate and the cell mass was set as 3.0 107 cells/L. As seen in Table 3, under the optimized conditions, BETX degradation percentages were 62.8%, 45.5% and 20.1% at 60 h for 120 mg/L, 240 mg/L and 360 mg/L, respectively,
while BTEX degradation percentages were 50.0%, 32.2%, and 11.7% at 60 h for 120 mg/L, 240 mg/L and 360 mg/L, respectively under the conditions without optimization. These results indicated that the process optimization via a statistical experimental design was capable and reliable for optimization of BTEX degradation by strain SB2 in sea-tidal flats.