Typically, during the anaerobic stage, the carbon source is taken up and phosphate is released by the bacteria, then in the subsequent aerobic phase the phosphate is taken up by the bacteria, over and above that which was released in the anaerobic phase (Seviour et al., 2003). Before dosing of pharmaceuticals the SBR was performing good EBPR for more than 6 months. During dosing, the reactor operation did not change, except that the principal carbon source in the reactor feed was no longer alternated between acetate

and propionate, but rather only acetate was used in order to reduce the number of variables. OC and antibiotics were added as detailed below. The OC and antibiotic dosing for the SBR mirrored projected usage in the United Kingdom, as per A.C. Singer

et al. (unpublished data), with a stepwise selleck dosing up to the pandemic peak. OC and antibiotics were dissolved in sterile distilled water and added to autoclaved acetate feed. The maximum amount of www.selleckchem.com/products/byl719.html each antibiotic and OC in the reactor influent was: 36 μg L−1 OC, 70 μg L−1 amoxicillin, 30 μg L−1 erythromycin and 10 μg L−1 levofloxacin. During the 14-day OC-only dosing period, the reactor influent contained 360 μg OC L−1 (see Supporting Information, Table S1). At the peak of the simulated pandemic, the concentration of antibiotics and OC were ∼2 to 20 × projected mean concentrations in WWTPs as per A.C. Singer et al. (unpublished data), during a moderate pandemic (R0=2.3, where R0 indicates the average number of infections generated by an infectious individual in a

fully susceptible population) PIK3C2G with conservative estimates of Tamiflu® use within the populations (30% of infected people utilize OC). Although the experimental concentrations of pharmaceuticals in the reactor were above the mean projected levels (A.C. Singer et al., unpublished data), they reflect a realistic worst-case scenario. OC was quantified from the influent and effluent during a single cycle of the SBR on the final day of each dosing regime. Approximately 10 mL of each sample was filtered through a 0.22 μm disposable filter (Millipore, Billerica, MA) into glass GC vials and kept at −20 °C until measurement. OC concentrations were measured by direct aqueous injection of the sample into an Agilent 6410B Triple Quad LC MS at the National Laboratory Services (Wales) (see Supporting Information for further details). Mixed liquor suspended solids (MLSS), effluent suspended solids (effluent SS) and mixed liquor volatile suspended solids (VSS) were measured according to standard methods (APHA, 1998). Ammonium (N-NH4+), nitrate (N-NO3−), nitrite (N-NO2−), orthophosphate (P-PO43−) and acetate concentrations in the liquid phase were analysed at the AWMC Analytical Laboratory (Brisbane, Qld, Australia) (see Supporting Information for further details). Visual inspections of whole granules were performed using an Olympus SZH10 stereomicroscope with a DP70 digital camera.