title: Effect of temperature & salt concentration on salt tolerant nitrate-perchlorate reducing bacteria: Nitrate degradation kinetics.
abstract: The sustainability of nitrate-contaminated water treatment using ion-exchange processes can be achieved by regenerating the exhausted resin several times. Our previous study shows that the use of multi-cycle bioregeneration of resin enclosed in membrane is an effective and innovative regeneration method. In this research, the effects of two independent factors (temperature and salt concentration) on the biological denitrification rate were studied. The results of this research along with the experimental results of the previous study on the effect of the same factors on nitrate desorption rate from the resin allow the optimization of the bioregeneration process. The results of nitrate denitrification rate study show that the biodegradation rate at different temperature and salt concentration is independent of the initial nitrate concentration. At each specific salt concentration, the nitrate removal rate increased with increasing temperature with the average value of 0.001110 ± 0.0000647 mg-nitrate/mg-VSS.h.°C. However, the effect of different salt concentrations was dependent on the temperature; there is a significant interaction between salt concentration and temperature; within each group of temperatures, the nitrate degradation rate decreased with increasing the salt concentration. The temperature affected the tolerance to salinity and culture was less tolerant to high concentration of salt at low temperature. Evidenced by the difference between the minimum and maximum nitrate degradation rate being greater at lower temperature. At 35 °C, a 32% reduction in the nitrate degradation rate was observed while at 12 °C this reduction was 69%. This is the first published study to examine the interaction of salt concentration and temperature during biological denitrification.
authors.affiliation: Biological Solutions Laboratory, School of Engineering, University of British Columbia, 3333 University Way, Kelowna, BC V1V 1V7, Canada.
authors.forename: Shelir
authors.initials: S
authors.lastname: Ebrahimi
authors.affiliation: Biological Solutions Laboratory, School of Engineering, University of British Columbia, 3333 University Way, Kelowna, BC V1V 1V7, Canada.
authors.forename: Thi Hau
authors.initials: TH
authors.lastname: Nguyen
authors.affiliation: Biological Solutions Laboratory, School of Engineering, University of British Columbia, 3333 University Way, Kelowna, BC V1V 1V7, Canada. Electronic address: Deborah.roberts@ubc.ca.
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Roberts
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors; D058440:Denitrification; D004305:Dose-Response Relationship, Drug; D007474:Ion Exchange; D008954:Models, Biological; D009566:Nitrates / Q000378:metabolism*; D010084:Oxidation-Reduction; D010472:Perchlorates / Q000378:metabolism; D012965:Sodium Chloride / Q000378:metabolism*; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D018508:Water Purification / Q000379:methods*
chemical_list: D009566:Nitrates; D010472:Perchlorates; D014874:Water Pollutants, Chemical; D012965:Sodium Chloride; C494474:perchlorate
keywords: Biological treatment; Denitrification; Ion exchange; Kinetics; Resin regeneration