title: Analysis of phosphorus removal and anaerobic selector performance in a full-scale activated sludge process in Singapore.
abstract: This paper analyses the performance of the anaerobic selector (A/O process) in a full-scale activated sludge process receiving mostly industrial sewage discharge (> 60%) in Singapore. In addition to the sludge settleability, enhanced biological phosphorus removal (EBPR) was studied. The sludge volume index (SVI) reduced from 200 to 80 ml g(-1) and foaming was suppressed significantly, indicating the effectiveness of the anaerobic selector in improving sludge settleability. The phosphorus removal efficiency was 66%, and 7.5 mg HAc-COD was consumed per mg PO4(3-) -P removed. In the anaerobic compartment, 31% of the SCOD and 73% of the acetic acid in the settled sewage were removed with PO4(3-) -P release of 14.1 mg PO4(3-)-P l(-1). The linear correlation between PO4(3-) -P release in the anaerobic compartment and PO4(3-) -P uptake in the aerobic compartment indicates that there is about 0.8 mg PO4(3-) -P release in the anaerobic compartment per mg PO34(3-) -P uptake in the aerobic compartment. The fates of volatile fatty acids (VFAs) and its short chain acids (SCAs) in the process were studied and discussed.
authors.affiliation: Centre for Advanced Water Technology (CAWT), A Division of Singapore Utilities International Pte Ltd (SUI), Innovation Centre (NTU), Block 2, Unit 241, 18 Nanyang Drive, Singapore 637723. yscao@cawt.sui.com.sg
authors.forename: Y S
authors.initials: YS
authors.lastname: Cao
authors.forename: C M
authors.initials: CM
authors.lastname: Ang
authors.forename: K S
authors.initials: KS
authors.lastname: Raajeevan
authors.forename: A K
authors.initials: AK
authors.lastname: Kiran
authors.forename: K C
authors.initials: KC
authors.lastname: Lai
authors.forename: S W
authors.initials: SW
authors.lastname: Ng
authors.forename: I
authors.initials: I
authors.lastname: Zulkifli
authors.forename: Y L
authors.initials: YL
authors.lastname: Wah
mesh_terms: D019342:Acetic Acid / Q000378:metabolism; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D019149:Bioreactors; D005232:Fatty Acids, Volatile / Q000378:metabolism; D010758:Phosphorus / Q000737:chemistry / Q000302:isolation & purification*; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D012846:Singapore; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D005232:Fatty Acids, Volatile; D012722:Sewage; D010758:Phosphorus; D019342:Acetic Acid