The Fate of 17 β-Estradiol and 17 α-Ethinylestradiol in a Laboratory-Scale Anaerobic-Anoxic-Oxic Activated Sludge System

摘要

Laboratory-scale experiments were carried out to investigate the fate of17β-estradiol (E2) and 17α-ethinylestradiol (EE2) in an anaerobic-anoxic-oxic (AAO)activated sludge system. E2 and EE2 of μg/l levels were added to the wastewater obtainedfrom a local municipal wastewater treatment plant. E2 and EE2 concentrations in the aqueousand solid phases were analyzed separately. The operational parameters were as follows:hydraulic retention time (HRT) was 8 h, sludge retention time (SRT) was 20d, sludge recycleratio was 100%, recycle ratio of mixed liquor was 300 %. Under the above conditions, theremoval efficiencies of Total nitrogen (TN), TP and COD were 81%, 91% and 86%,respectively. E2 was completely transformed since E2 was not detected in the outlet samples.The anaerobic, anoxic and oxic reactors were responsible for 71%, 7% and 22% of the overallE2 removal, respectively. EE2 removal efficiency was about 80%. The anaerobic, anoxic andoxic reactors were responsible for 35%, 7% and 38 % of the overall EE2 removal,respectively. Both these two estrogens were easily sorbed onto the activated sludge.Distribution coefficient (Kd) of EE2 on the anaerobic activated sludge was greater than thoseon the anoxic and aerobic activated sludges. Mass balance calculation indicated that about97% of E2 was transformed by the activated sludge process, 3% remained in the waste sludge;for EE2, about 81% was transformed by the activated sludge process, 16% was released in theeffluent, and 3% remained in the waste sludge.