Characteristics Of Simultaneous Removal Of Phenol And Ammonia By Diaphorobacter Strain

Phenolic wastewater is from the refinery, coal conversion, coking plants and other industry. Phenolic wastewater contains large amounts of ammonia. Ammonia is one of the most important oxide consumable pollutions in water and causes the eutrophication. The study about simultaneous phenol degradation and nitrogen removal of the wastewater is rare. Microbical methods of simultaneous phenol degradation and nitrogen removal are preferable due to low costs and low secondary pollution. The key of this method is isolating microorganism that has the capacity of simultaneous phenol degradation and nitrogen removal. The heterotrophic nitrification and aerobic denitrification strain can remove phenol and ammonia simultaneously. And nitrification and aerobic denitrification were carried out simultaneously. This provides the theoretical basis for simultaneous phenol degradation and nitrogen removal. In addition, the simultaneous heterotrophic nitrification and aerobic denitrification mechanism of nitrogen removal must be further studied, which is beneficial for understanding the metabolic process of the strain.Under aerobic condition, with phenol as the sole carbon and energy source, a novel stable aerobic denitrification strain was isolated from the domesticatactive sludge using the traditional microbial technology. Based on its colony morphology, physiology and biochemical characteristics 16 S rDNA gene sequence, the isolated strain named PDB3 was identified as the genus of Diaphorobacter. Furthermore, the characteristic of heterotrophic nitrification was verified. The optimum simultaneous removal of phenol and ammonia condition were further investigated(temperature 30 ℃, initial pH 7.2, carbon-nitrogen ratio 7 and shaking speed 160 r/min).Under the optimum condition, ammonia nitrogen was removed within 21 h and the removal rate of ammonia was 3.2 mg /(L ? h) in the heterotrophic nitrification medium with initial 365 mg/L phenol. During the whole cultivation, the accumulated NO3--N reached the maximum at 1.92 mg/L after 9 h, and the accumulated NO2--N reached the maximum at 1.07 mg/L after 12 h. The detection of hydroxylamine oxidase, nitrate reductase and nitrite reductase activities demonstrated a coupled heterotrophic nitrifying-aerobic denitrifying pathway of strain PDB3. Under the optimum condition, the nitrate was removed completely after 24 h in the aerobic denitrification medium with the initial 365 mg/L phenol and the accumulated NO2--N reached the maximum at 1.27 mg/L after 9 h.The effect of 365 mg/L, 522 mg/L and 679 mg/L phenol on ammonia removal was investigated with the increase of phenol concentration, the inhibitory effect increased and the ammonium removal rate reduced, leading to lower efficiency of ammonium removal. With phenol as sole carbon and energy source and ammonia the sole nitrogen source, the growth process was simulated using Haldane kinetic model at phenol concentration ranging from 0 to 700 mg/L. The fitting results had a good correlation with the experimental data. The fitting parameters were: max(maximum specific growth rate) =0.313 h-1, Ks(half-saturation constant) =8.17 mg/L, Ki(inhibition constant) =155.87 mg/L, R2=0.992.