In this work, the implementation and competitiveness of a continuous coupled wet oxidation/biological
process for the treatment of four different phenolic compounds of a pharmaceutical wastewater are evaluated
according to removal efficiency of each compound, sensitivity to feed perturbations and robustness.
Efficiencies of wet oxidation pretreatment for each compound rose to 95%, whereas an important part
of the initial COD remained in the medium. In the case of the biotreatment, phenolic compounds were
practically eliminated and COD reductions up to 95% were achieved. These values are higher than those
obtained by means of the majority of the coupled processes.
The wet oxidation also showed relatively low sensitivities in front of perturbations on the feed composition
for compounds with kinetic constants during the wet oxidation process higher than 8.4 h_1. Sensitivity
studies indicated that the system is stable to changes in the flow rate for residence times in the
bioreactor lower than 25 days. Perturbations of the oxygen flow rate had no effect on the removal of the
phenolic compounds, in accordance with the fact of calculated Hatta numbers lower than 0.015, indicating
a kinetically controlled regime in the range assayed (4—10 kgO2=m3
wastewater).
Additionally, during the evaluation of the robustness of the process, ‘‘dampening factors’’ near of 1
were obtained for the removal of phenolic compounds, corroborating the excellent behavior of the coupled
wet oxidation/biological system when fast and continuous changes in the pollutant load were
assayed.