Biodegradation of bisphenol A and its metabolic intermediates by activated sludge: Stoichiometry and kinetics analysis

• The biodegradation of BPA and its metabolic intermediates was analyzed.
• Different conditions affected the kinetics of the biodegradation of the compounds.
• Regardless of the conditions, the stoichiometry of the reactions was constant.
• The aerobic biodegradation pathway of BPA by activated sludge was discussed.

Bisphenol A (BPA) has been described as a estrogenic compound. However, it is used in the production of polycarbonate, epoxy resins and other plastics. Mixed microbial cultures, such as activated sludge, have been proposed as a feasible methodology to achieve the decontamination of wastewater containing BPA. Several studies on the biodegradation of BPA have demonstrated the presence of 4-hydroxyacetophenone (4HAP), 4-hydroxybenzaldehyde (4HB) and 4-hydroxybenzoic acid (A4HB) as the main metabolic intermediates. The objective of the present work was to study the kinetics and stoichiometric characteristics of the aerobic degradation of BPA and its metabolic intermediates by activated sludge. The effect of the sludge age (SA), and the concentration of each compound was analyzed. The biodegradation of the compounds was analyzed by an open respirometer. The kinetics of the biodegradation of all the tested compounds was influenced by the SA, the acclimation process, and the concentration of the tested compound. The stoichiometry of the reactions was not affected by the studied conditions. The oxidation coefficient (YO/S) was 10.0 ± 0.5, 5.2 ± 0.2, 3.7 ± 0.2, and 3.0 ± 0.1 molO2 molS−1 for BPA, 4HAP, 4HB, and 4HBA, respectively. Based on the obtained YO/S values, the aerobic biodegradation pathway of the tested compounds by BPA-acclimated activated sludge is discussed.