title: Novel regeneration method for phosphate loaded granular ferric (hydr)oxide--a contribution to phosphorus recycling.
abstract: At a progressive rate, small wastewater treatment plants in rural areas need to be equipped with an additional phosphorus removal stage in order to achieve a good chemical status in the receiving natural water bodies. A conventional regeneration method for ferric (hydr)oxides such as phosphate specific adsorbents, which can be applied to remove and recover phosphorus in fixed bed filters, was investigated and improved. It was shown that a loss of up to 85% of the initial capacity can be observed when regeneration with 1 M NaOH is implemented. The losses are caused by surface blocking with different calcium-containing compounds as revealed by an EDX analysis. These blocking compounds could be removed completely with an additional acidic regeneration step at pH = 2.5. During the alkaline desorption that followed, complete phosphorus removal and a full recovery of the adsorption capacity were achieved for goethite-rich Bayoxide(®) E 33 HC (E33HC) and akaganéite-rich GEH(®) 104 (GEH). The regeneration procedure was repeated up to eight times without any signs of further decline in the phosphate adsorption capacity or any changes in the specific surface area or pore size distribution of the adsorbent. In contrast to GEH and E33HC, ferric hydroxide- and calcite-rich FerroSorp(®) Plus (FSP) was partly dissolved during acid treatment.
authors.affiliation: Institute of Water Chemistry, Technische Universität Dresden, D-01062 Dresden, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Kunaschk
authors.affiliation: Institute of Water Chemistry, Technische Universität Dresden, D-01062 Dresden, Germany.
authors.forename: Viktor
authors.initials: V
authors.lastname: Schmalz
authors.affiliation: VKTA Nuclear Engineering and Analytics Inc., P.O. Box 510119, D-01314 Dresden, Germany.
authors.forename: Norman
authors.initials: N
authors.lastname: Dietrich
authors.affiliation: Institute of Water Chemistry, Technische Universität Dresden, D-01062 Dresden, Germany. Electronic address: Thomas.Dittmar@tu-dresden.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dittmar
authors.affiliation: Institute of Water Chemistry, Technische Universität Dresden, D-01062 Dresden, Germany.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Worch
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry* / Q000302:isolation & purification; D005374:Filtration; D006863:Hydrogen-Ion Concentration; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D017610:Calcium Compounds; D005290:Ferric Compounds; D014874:Water Pollutants, Chemical; C021024:ferric hydroxide
keywords: Adsorption; Granular ferric hydroxide; Phosphate; Phosphorus recycling; Regeneration