Removal of endocrine disrupter compounds from municipal wastewater using an aerobic granular biomass reactor

Abstract

The removal of selected endocrine disrupter compounds (EDCs), namely estrone (E1), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), bisphenol A (BPA) and 4- tert-octylphenol (4t-OP) from municipal wastewater was investigated using a sequencing batch biofilter granular reactor (SBBGR), a new technology for biological treatment based on aerobic granular biomass. This new biological treatment is characterized by high biomass concentration (up to 40 g L −1), high sludge retention times (up to 6 months) and low sludge production (i.e., an order of magnitude lower than commonly reported for conventional biological technologies). The investigation was carried out comparing both a lab-scale SBBGR system and a demonstrative unit with a conventional full-scale activated sludge process. Results showed that the SBBGR, beside its already known benefits (removal efficiencies around 90% COD even at a high organic load (i.e., 5.7 kg COD m −3 d −1) and a sludge production value of around 0.06 kg TSS kg −1 COD removed), performed better than a conventional activated sludge process in removing E1, E2, BPA and 4t-OP. The average removal percentages of the above-mentioned EDCs, obtained during a 4-month operating period, were 60, 69, 93, 81% and 53, 41, 72, 67% for the demonstrative SBBGR system and the conventional activated sludge process of the municipal sewage treatment plant, respectively. In addition, lab-scale and demonstrative SBBGR systems showed similar efficiency for the removal of the investigated EDCs.