title: Effects of solid retention time on the performance of submerged anoxic/oxic membrane bioreactor.
abstract: In this study, four similar bench-scale submerged Anoxic/Oxic Membrane Bioreactors (MBR) were used simultaneously to investigate the effects of solids retention time (SRT) on organic and nitrogen removal in MBR for treating domestic wastewater. COD removal efficiencies in all reactors were consistently above 94% under steady state conditions. Complete conversion of NH(4+)-N to NO(3-)-N was readily achieved over a feed NH(4+)-N concentration range of 30 to 50 mg/L. It was also observed that SRT did not significantly affect the nitrification in the MBR systems investigated. The average denitrification efficiencies for the 3, 5, 10 and 20 days SRT operations were 43.9, 32.6, 47.5 and 66.5%, respectively. In general, the average effluent nitrogen concentrations, which were mainly nitrate, were about 22.2, 27.6, 21.7 and 13.9 mg/L for the 3, 5, 10 and 20 days SRT systems, respectively. The rate of membrane fouling at 3 days SRT operation was more rapid than that observed at 5 days SRT. No fouling was noted in the 10 days and 20 days SRT systems during the entire period of study.
authors.affiliation: Water and Biotreatment Group, Centre for Water Research, Division of Environmental Science and Engineering, National University of Singapore. Block EA, #07-23, 9 Engineering Drive 1, Singapore 117576. esenghy@nus.edu.sg
authors.forename: H Y
authors.initials: HY
authors.lastname: Ng
authors.forename: T W
authors.initials: TW
authors.lastname: Tan
authors.forename: S L
authors.initials: SL
authors.lastname: Ong
authors.forename: C A
authors.initials: CA
authors.lastname: Toh
authors.forename: Z P
authors.initials: ZP
authors.lastname: Loo
mesh_terms: D019149:Bioreactors; D004867:Equipment Design; D008566:Membranes; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D011312:Pressure; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012722:Sewage; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000379:methods*
chemical_list: D000644:Quaternary Ammonium Compounds; D012722:Sewage; D009584:Nitrogen; D010100:Oxygen