title: Anaerobic digestibility of estrogens in wastewater sludge: effect of ultrasonic pretreatment.
abstract: BACKGROUND
  Estrogenic compounds have been detected in the secondary effluents and in the biosolids from conventional wastewater treatment plants, which are not designed for their removal. Furthermore, existing limited studies on anaerobic digestibility of estrogens report conflicting results. The objective of the present work was to determine the fate and anaerobic digestibility of estrogenic compounds in various types of sludge including primary sludge (PS), waste activated sludge (WAS), and anaerobically digested sludge (seed).
  
  
  METHODS
  Estrone (E1) and 17-β estradiol (E2) were chosen as the model estrogenic compounds. Initially batch adsorption was conducted to determine the extent of adsorption and isotherm of E1 on various sludge. Thereafter, batch anaerobic digestion of E1 and E2 was conducted in various sludge using So/X ratio of 4 gCOD/gVSS in 250 ml bottles. The effect of earlier optimized ultrasonication dosage on the anaerobic digestion of E1 and E2 was also characterized. Estrogenicity of the digested samples was determined by the YES assay.
  
  
  RESULTS
  Most of E1 and E2 was adsorbed on the biosolids and the Freundlich isotherm fitted the experimental data well. No anaerobic digestion of E1 and E2 was found in any of the sludge tested, and the estrogenicity of the sludge measured by YES assay increased during digestion due to the formation of E2 from E1 in a reduced environment. Ultrasonication decreased the initial mass of E1 and E2 by 20% in the sonicated digester as compared to control digester, however, there was no further decrease in E1 and E2 during digestion.
  
  
  CONCLUSIONS
  Most of the estrogenic compounds partitioned onto the solids and remained there during digestion. Ultrasonication pretreatment reduced the estrogen burden for the digester due to advance oxidation, but no further removal of the estrogens occurred in the digester.
authors.affiliation: Department of Chemical and Biochemical Engineering, The University of Western Ontario, London N6A5B9, Canada.
authors.forename: Charu
authors.initials: C
authors.lastname: Chawla
authors.affiliation: Department of Chemical and Biochemical Engineering, The University of Western Ontario, London N6A5B9, Canada.
authors.forename: Shubhajit
authors.initials: S
authors.lastname: Sarkar
authors.affiliation: Department of Chemical and Biochemical Engineering, The University of Western Ontario, London N6A5B9, Canada.
authors.forename: Sura
authors.initials: S
authors.lastname: Ali
authors.affiliation: Department of Chemical and Biochemical Engineering, The University of Western Ontario, London N6A5B9, Canada.
authors.forename: Lars
authors.initials: L
authors.lastname: Rehmann
authors.affiliation: Department of Chemical and Biochemical Engineering, The University of Western Ontario, London N6A5B9, Canada.
authors.forename: George
authors.initials: G
authors.lastname: Nakhla
authors.affiliation: Department of Chemical and Biochemical Engineering, The University of Western Ontario, London N6A5B9, Canada. Electronic address: mray@eng.uwo.ca.
authors.forename: Madhumita B
authors.initials: MB
authors.lastname: Ray
mesh_terms: D000327:Adsorption; D000693:Anaerobiosis; D004958:Estradiol / Q000032:analysis / Q000737:chemistry; D004967:Estrogens / Q000032:analysis* / Q000737:chemistry; D004970:Estrone / Q000032:analysis / Q000737:chemistry; D010084:Oxidation-Reduction; D012722:Sewage / Q000737:chemistry*; D013016:Sound; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D004958:Estradiol; D004967:Estrogens; D004970:Estrone; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Anaerobic digestion; Estrogens; Primary sludge; Ultrasonication; WAS; YES assay