title: Influence of operational parameters (sludge retention time and hydraulic residence time) on the removal of estrogens by membrane bioreactor.
abstract: BACKGROUND
  This paper deals with the removal of two natural estrogens, estrone (E1) and 17β-estradiol (E2) and a synthetic one 17α ethinylestradiol (EE2) from wastewater in a laboratory-scale membrane bioreactor (MBR).
  
  
  METHODS
  The effects of both solid retention time (SRT) and hydraulic residence time (HRT) were studied using synthetic wastewater in the MBR. At 35, 45, 60, 75, and 95 days, SRT was studied. The HRT was varied in the range of 7-12 h.
  
  
  RESULTS
  The results showed that the increases in HRT and SRT enhanced the biodegradation process after adaptation to microorganisms. At HRT of 12 h, the estrogen removals were close to 100% in the MBR. The highest estrogen removals were obtained at SRT of 60 days. Continuous tests showed a linear relationship between nitrification and estrogen removal rates.
  
  
  CONCLUSIONS
  The most biodegradable compound was the E2. The membrane fouling rates increased with the decreased of SRT and HRT. Optimal process conditions in this work was obtained at the SRT and HRT of 60 days and 12 h, respectively, with high efficient of estrogen removal, nitrification efficiencies, as well as a minimum membrane fouling rate.
authors.affiliation: National Autonomous University of Mexico, Facultad de Ingeniería, Campus Morelos, Paseo Cuauhnahuac 8532, Col. Progreso, Jiutepec, Morelos, Mexico. edson_tum@yahoo.com.mx
authors.forename: Edson B
authors.initials: EB
authors.lastname: Estrada-Arriaga
authors.forename: Petia N
authors.initials: PN
authors.lastname: Mijaylova
mesh_terms: D000327:Adsorption; D019149:Bioreactors; D004958:Estradiol / Q000302:isolation & purification / Q000378:metabolism; D004967:Estrogens / Q000302:isolation & purification* / Q000378:metabolism; D004970:Estrone / Q000302:isolation & purification / Q000378:metabolism; D004997:Ethinyl Estradiol / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008567:Membranes, Artificial; D058465:Nitrification; D012722:Sewage / Q000032:analysis* / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D004967:Estrogens; D008567:Membranes, Artificial; D012722:Sewage; D014874:Water Pollutants, Chemical; D004970:Estrone; D004997:Ethinyl Estradiol; D004958:Estradiol