title: Novel technique for phosphorus recovery from aqueous solutions using amorphous calcium silicate hydrates (A-CSHs).
abstract: A novel technique for phosphorus (P) recovery from aqueous solutions was developed using amorphous calcium silicate hydrates (A-CSHs). A-CSHs, which have a high Ca/Si molar ratio of 2.0 or greater, could be synthesized using unlimitedly available, inexpensive materials such as siliceous shale and calcium hydroxide. A-CSHs showed high performance for P recovery from an anaerobic sludge digestion liquor (ASDL) and the synthetic model liquor (s-ASDL) containing 89 mg PO4-P/L. After 20 min mixing, 1.5 g/L A-CSHs could remove approximately 69 and 73% PO4-P from ASDL and s-ASDL, respectively. By contrast, autoclaved lightweight concrete particles, which contained crystalline calcium silicate hydrates as a principal component, removed only 10 and 6% PO4-P from ASDL and s-ASDL, respectively, under the same experimental conditions. When A-CSHs were washed with deionized water to remove free Ca(OH)2, P removability was significantly improved (up to 82%) despite the reduction in the amount of Ca(2+) released. Unlike in the case of Ca(OH)2, no significant carbonate inhibition was observed with P removal by A-CSHs. Moreover, P removed by A-CSHs showed better settleability, filterability, and dewaterability than P precipitated with conventional CaCl2 and Ca(OH)2. The present study demonstrated that A-CSHs have great potential as a novel, beneficial material for P recovery and recycling.
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan. okano@bio.eng.osaka-u.ac.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Okano
authors.forename: Masahide
authors.initials: M
authors.lastname: Uemoto
authors.forename: Jumpei
authors.initials: J
authors.lastname: Kagami
authors.forename: Keiichi
authors.initials: K
authors.lastname: Miura
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Aketo
authors.forename: Masaya
authors.initials: M
authors.lastname: Toda
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Honda
authors.forename: Hisao
authors.initials: H
authors.lastname: Ohtake
mesh_terms: D000327:Adsorption; D000693:Anaerobiosis; D002118:Calcium / Q000032:analysis; D017610:Calcium Compounds / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry; D011232:Chemical Precipitation; D005374:Filtration; D046529:Microscopy, Electron, Transmission; D010758:Phosphorus / Q000302:isolation & purification*; D059027:Recycling; D012722:Sewage / Q000737:chemistry; D017640:Silicates / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D017610:Calcium Compounds; D002254:Carbonates; D012722:Sewage; D017640:Silicates; D014867:Water; D010758:Phosphorus; C031293:calcium silicate; D002118:Calcium