Study On Aniline Removal By Aerobic Graules And High-Efficiency Aniline-Degrading Bacteria

Aerobic granular sludge was successfully developed with flocculent activated sludge as the seeding sludge and aniline as a sole carbon source via controlling the operation parameters.The seeding sludge had an average diameter of 67.7μm,and an average biomass concentration of 2562mL/g,while the diameter and biomass concentration for the matures aerobic granular sludge are 360.6μm and 4400mg/L,respectively.SEM observation indicates that the mature granules consisted of a wide variety of bacteria,mainly including cocci-like bacterium and brevibacterium. The aerobic granules could efficiently degraded aniline up to 6000mg/L. The Michaelis-Menten equation could be fitted to the experimental data of aniline degradation by aerobic granules.The highest aniline biodegradation rate was up to 0.07642g-aniline/(g-VSS·h).PCR-DGGE analysis indicated that microbial population differed obviously during the aerobic degradation.Some bands representing the microbial strainsdistributing in the seed sludge disappeared and some new bands appeared with the aerobic granulation,which related to the changes of microbial species,especially correlated with the development of aniline-degrading microbes during the granualtion.The PCR-DGGE fingerprints indicated that aerobic granules contained a wide diversity of microorganisms and had a stable community structure,implying little variation about the composition and diversity of microorganisms during the stable operation period.The microorganism members involved in the granules most closely related to Pseudomonas,Comamonas, Flavobacteria,Achromobacter,and Thermophilic.Several microbial strains capable of degrading aniline were screened from the aerobic granules,adx1 possessed the strongest autoaggregation ability with the autoaggregation indices of about 73.7%.Three coaggregation pairs(adx1/adx3,adx1/adx4,adx2/adx3) had coaggregation indices greater than 40%,indicating the good aggregation interactions might exert an important role in the granulation of aerobic activated sludge Basing on theanalysis of the Strains' morphological characteristics, physiological and biochemical characteristics,16S rDNA sequences and the Biolog identification,strains adx1 and adx3 belonged to Pseudomonas and Achromobacter,respectively.These two strains could grow well at neutral and trending alkaline condition.Aniline could be degraded efficiently by strain adx1 when the concentration is lower than 2500mg/L, while strain adx3 could degrade up to 4000mg/L,but strains adx1 has a higher degradation rate than adx3 under the same condition.The aniline degradation by these two strains had a good fit to the Haldane's kinetics model.The highest specific aniline degradation rate of adx1 and adx3 was up to 0.924g/(g·h) and 0.645g/(g·h),respectively.The hightest growth rate of adx1 and adx3 was up to 0.487g/(g·h) and 0.440g/(g·h),respectively.