Loss of bisphenol A removal ability of activated sludge in semi-continuous reactors (SCR)

Since its recognition as an endocrine disrupting chemical, bisphenol A (BPA) removal processes became not only an engineering issue but also a public health concern. In actual biological treatment systems, alternating periods of presence and absence of BPA may cause a decrease of the BPA degradation ability of activated sludge (AS). The objective of this work was to study the effect of alternating periods of presence and absence of BPA in the BPA degradation ability of AS. Two semi-continuous reactors, with partial (SCR1) or total (SCR2) biomass recycling, were used. In SCR1, five feeding phases were tested, being dehydrated cheese whey (DCW) the carbon source. During phases I, III, and V, BPA was also added. In SCR2, seven feeding phases that consisted of the alternation between DCW and BPA as the sole carbon sources were studied. For both SCRs, specific dissolved organic carbon (q(DOC)), and BPA (q(BPA)) removal rates, and metabolic measurements (qO(2)) were performed. Obtained results demonstrated that q(DOC) and qO(2) values were not affected by the alternation between feeding with and without BPA. Conversely, a noticeable deterioration of BPA values was observed. Thus, BPA degradation ability of AS would not be stable in actual treatment systems.