title: Settleability and kinetics of a nitrifying sludge in a sequencing batch reactor.
abstract: A physiological study of a nitrifying sludge was carried out in a sequencing batch reactor (SBR). Pseudo steady-state nitrification conditions were obtained with an ammonium removal efficiency of 99% +/- 1% and 98% +/- 2% conversion of NH4+-N to NO3 - -N. The rate of biomass production was negligible (1.3 +/- 0.1 mg microbial protein-N.L(-1).d(-1)). The sludge presented good settling properties with sludge volume index values lower than 20 mL.g(-1) and an exopolymeric protein/carbohydrate ratio of 0.53 +/- 0.34. Kinetic results indicated that the nitrifying behavior of the sludge changed with the number of cycles. After 22 cycles, a decrease in the specific rate of NO3- -N production coupled with an increase in the NO2- -N accumulation were observed. These results showed that the activity of the nitrite oxidizing bacteria decreased at a longer operation time. Ammonia oxidizing bacteria were found to exhibit the best stability. After 4 months of operation, the specific rates of NH4+-N consumption and NO3- -N production were 1.72 NH4+-N per microbial protein-N per hour (g.g(-1).h(-1)) and 0.54 NO3- -N per microbial protein-N per hour (g.g(-1).h(-1)), respectively.
authors.affiliation: Universidad Autónoma Metropolitana-Iztapalapa, Div. CBS, Departamento de Biotecnología, Av. San Rafael Atlixco 186, Col. Vicentina, CP 09340, México D.F. actx@xanum.uam.mx
authors.forename: A-C
authors.initials: AC
authors.lastname: Texier
authors.forename: J
authors.initials: J
authors.lastname: Gomez
mesh_terms: D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism*; D019149:Bioreactors; D003470:Culture Media; D007700:Kinetics; D009573:Nitrites / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D012722:Sewage / Q000382:microbiology*
chemical_list: D003470:Culture Media; D009573:Nitrites; D000644:Quaternary Ammonium Compounds; D012722:Sewage