Di Fabio S., Malamis S., Katsou E., Vecchiato G., Cecchi F., Fatone F., 2013, Optimization of Membrane Bioreactors for the Treatment of Petrochemical Wastewater under Transient Conditions, Chemical Engineering Transactions, 32, 7-12.
The main objective was to study the appropriateness of membrane bioreactor (MBR) technology in treating petrochemical wastewater under the variable conditions of the petrochemical industry. Five experimental periods were carried out; in the first period the operating conditions of the full scale MBR were examined, and then changes were introduced, such as the addition of more external carbon source, the decrease of the anoxic compartment volume, alternations in configuration and an increase of the influent load. Laboratory batch experiments were conducted in order to assess the impact of spent caustic soda on nitrification. Finally, the impact of fouling and clogging layers on the removal of trace metals/metalloids was studied during the long-term operation of the MBR. The results showed that the composition of petrochemical wastewater affected the biological processes. Specifically, in the pre-denitrification configuration ammonification was not effective, while ammonium oxidation was high. The addition of higher concentration of acetic acid compared to the one added to the full scale plant increased the denitrification rate and the organic carbon oxidation. The decrease in the volume of the anoxic compartment and the abolition of internal recycling reduced the rate of denitrification. Doubling the influent wastewater flow did not significantly affect the quality of the treated effluent. The unwanted biofilm layer was more effective than activated sludge in the uptake of certain metals/metalloids.
