title: Prolonged exposure of mixed aerobic cultures to low temperature and benzalkonium chloride affect the rate and extent of nitrification.
abstract: The combined effect of benzalkonium chloride (BAC) and prolonged exposure to low temperature on nitrification was investigated. Ammonia oxidation at 22-24°C by an enriched nitrifying culture was inhibited at increasing BAC concentrations and ceased at 15 mg BAC/L. The non-competitive inhibition coefficient was 1.5±0.9 mg BAC/L. Nitrification tests were conducted without and with BAC at 5mg/L using an aerobic, mixed heterotrophic/nitrifying culture maintained at a temperature range of 24-10°C. Maintaining this culture at 10°C for over one month in the absence of BAC, resulted in slower nitrification kinetics compared to those measured when the culture was first exposed to 10°C. BAC was degraded by the heterotrophic population, but its degradation rate decreased significantly as the culture temperature decreased to 10°C. These results confirm the negative impact of quaternary ammonium compounds on the nitrification process, which is further exacerbated by prolonged, low temperature conditions.
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA.
authors.forename: Jeongwoo
authors.initials: J
authors.lastname: Yang
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA.
authors.forename: Ulas
authors.initials: U
authors.lastname: Tezel
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA.
authors.forename: Kexun
authors.initials: K
authors.lastname: Li
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA. Electronic address: spyros.pavlostathis@ce.gatech.edu.
authors.forename: Spyros G
authors.initials: SG
authors.lastname: Pavlostathis
mesh_terms: D000332:Aerobiosis / Q000187:drug effects; D000641:Ammonia / Q000302:isolation & purification; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism; D061249:Batch Cell Culture Techniques; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D018533:Biomass; D003080:Cold Temperature; D052836:Heterotrophic Processes / Q000187:drug effects; D009566:Nitrates / Q000032:analysis; D058465:Nitrification / Q000187:drug effects*; D009573:Nitrites / Q000032:analysis; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D013997:Time Factors
chemical_list: D001548:Benzalkonium Compounds; D009566:Nitrates; D009573:Nitrites; D000641:Ammonia; D009584:Nitrogen
keywords: Biodegradation; Inhibition; Nitrification; Quaternary ammonium compounds; Temperature effect