Adsorption kinetics Fig xA Kinetic
Small scale continuous flow systems were installed and operated in the laboratory (Fig. S1), under constant room temperature controlled by central air-conditioning system. The AS system consisted of an aerobic bioreactor (AB), with MK-0518 working volume of 4.5 L, and a settling tank with a working volume of 1 L, from which sludge was recirculating to the bioreactor (Solid Retention Time, SRT: 18 d; HRT: 26.4 ± 2.4 h; organic loading: 0.25 ± 0.16 kg m−3 d−1). The AS for AB start-up was taken from a nitrifying municipal STP (Mytilene, Greece), operating at a SRT of 18 d; the laboratory scale system operated in summer 2014. The MBBR system consisted of two aerobic bioreactors (BC1 and BC2) connected in series, with a working volume of 4.5 L each. Each bioreactor contained biocarriers (type K3, AnoxKaldnes) at a filling ratio of 30%. The biocarriers were moving due to aeration in all parts of the reactor. The MBBR system was operated at two HRTs, in two different experimental cycles during summer and autumn 2014. A HRT of 26.4 ± 3.6 h (for each reactor) was applied in the first experimental cycle, providing a low substrate organic loading (MBBR-low) equal to 0.25 ± 0.16 kg m−3 d−1 for BC1 and 0.05 ± 0.03 kg m−3 d−1 for BC2. A lower HRT of 10.8 ± 1.2 h (for each reactor) was applied in the second experimental cycle in order to provide higher substrate organic loading (MBBR-high), equal to 0.60 ± 0.40 kg m−3 d−1 for BC1 and 0.17 ± 0.11 kg m−3 d−1 for BC2. All systems were fed with raw wastewater collected from the STP of the University Campus in Mytilene, Greece (Table S1). In all bioreactors, the conservation of aerobic conditions and adequate mixing of biomass were achieved by using porous ceramic diffusers, while dissolved oxygen concentration (DO) was higher than 4 mg L−1. In order to develop a stable biofilm onto the carriers, the MBBR system was operated for 5 months with domestic wastewater before starting the experiments with micropollutants.