title: Removal of colloidal biogenic selenium from wastewater.
abstract: Biogenic selenium, Se(0), has colloidal properties and thus poses solid-liquid separation problems, such as poor settling and membrane fouling. The separation of Se(0) from the bulk liquid was assessed by centrifugation, filtration, and coagulation-flocculation. Se(0) particles produced by an anaerobic granular sludge are normally distributed, ranging from 50 nm to 250 nm, with an average size of 166±29 nm and a polydispersity index of 0.18. Due to its nanosize range and protein coating-associated negative zeta potential (-15 mV to -23 mV) between pH 2 and 12, biogenic Se(0) exhibits colloidal properties, hampering its removal from suspension. Centrifugation at different centrifugal speeds achieved 22±3% (1500 rpm), 73±2% (3000 rpm) and 91±2% (4500 rpm) removal. Separation by filtration through 0.45 μm filters resulted in 87±1% Se(0) removal. Ferric chloride and aluminum sulfate were used as coagulants in coagulation-flocculation experiments. Aluminum sulfate achieved the highest turbidity removal (92±2%) at a dose of 10(-3) M, whereas ferric chloride achieved a maximum turbidity removal efficiency of only 43±4% at 2.7×10(-4) M. Charge repression plays a minor role in particle neutralization. The sediment volume resulting from Al2(SO3)4 treatment is three times larger than that produced by FeCl3.
authors.affiliation: UNESCO-IHE Institute for Water Education, PO Box␣3015, 2601 DA Delft, The Netherlands; Université Paris-Est, Laboratoire Géomatériaux et Environnement, EA 4508, UPEM, 5 bd Descartes, 77454 Marne-la-Vallée Cedex 2, France.
authors.forename: Lucian C
authors.initials: LC
authors.lastname: Staicu
authors.affiliation: Université Paris-Est, Laboratoire Géomatériaux et Environnement, EA 4508, UPEM, 5 bd Descartes, 77454 Marne-la-Vallée Cedex 2, France. Electronic address: Eric.vanHullebusch@u-pem.fr.
authors.forename: Eric D
authors.initials: ED
authors.lastname: van Hullebusch
authors.affiliation: Université Paris-Est, Laboratoire Géomatériaux et Environnement, EA 4508, UPEM, 5 bd Descartes, 77454 Marne-la-Vallée Cedex 2, France.
authors.forename: Mehmet A
authors.initials: MA
authors.lastname: Oturan
authors.affiliation: Department of Chemistry, Colorado State University, Fort Collins, CO 80521, United States.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Ackerson
authors.affiliation: UNESCO-IHE Institute for Water Education, PO Box␣3015, 2601 DA Delft, The Netherlands.
authors.forename: Piet N L
authors.initials: PN
authors.lastname: Lens
mesh_terms: D000534:Alum Compounds; D002498:Centrifugation; D002712:Chlorides; D005290:Ferric Compounds; D005374:Filtration / Q000379:methods; D005427:Flocculation; D009391:Nephelometry and Turbidimetry; D012643:Selenium / Q000032:analysis / Q000302:isolation & purification*; D012722:Sewage / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D000534:Alum Compounds; D002712:Chlorides; D005290:Ferric Compounds; D012643:Selenium; D012722:Sewage; D062065:Wastewater; C041524:aluminum sulfate; C024555:ferric chloride
keywords: Aluminum sulfate; Centrifugation; Coagulation–flocculation; Colloids; Elemental selenium; Filtration