| Pyridine is one of the most widespread classes of heterocyclic contaminants. It will oroduce a large amount of industrial wastewater that containing pyridine in the process of the oroduction and use of it. Due to the toxicity and less-biodegradable of pyridine wastewater, it s difficult to work in routine biochemical treatment system (such as activated sludge process), n this paper, we study in order to the target of biodegradation of the wastewaters containing oyridine in an economic and harmless way, to discuss the construction and application method of the pyridine wastewater in a bioaugmentation system.In this study, a novel pyridine-degrading bacterium, strain NJUST18, was isolated from he soil contaminated by pyridine and identified as a member of genus Rhizobium. The oiodegradation assays suggested that strain NJUST18could utilize pyridine as the sole sources of carbon and nitrogen, at initial concentration as high as2600mg/L. The pyridine iepletion, biomass increase, TOC reduction, pH increase and NH4+release during biodegradation of pyridine indicated that pyridine could be mineralized by strain NJUST18. A neutral to slightly alkaline pH was crucial to achieve high concentration of pyridine degradation by NJUST18strain. The degradation of pyridine at high initial concentrations or high initial pH values demonstrated that the biodegradation process was both pH and NH4+dependent. Release of NH4+into the alkaline environment led to the delay of pyridine degradation by NJUST18, accompanied by the formation of free ammonia (NH3).Pyridine inhibited both growth of NJUST18and biodegradation of pyridine. Haldane model could be fitted to the growth kinetics data well with the kinetic constants μ*=0.1473h"1, Ks=793.97mg/L, K1＝268.60mg/L and Sm=461.80mg/L. The true μmax, calculated from.μ*was found to be0.0332h-1. The yield coefficient (Yx/s) depended on S1and reached a maximum of0.51g g-1at S1of589.9mg/L. The degradation kinetics could use Haldane equation to fit, yielding qSmax=0.1212g g-1h-1and q*=0.3874g g-1h-1at Sm’=507.83mg/L, Ks=558.03mg/L, and K1’=462.15mg/L. Compared with other pyridine degrader, μmax. and Sm obtained for NJUST18were relatively high. High Ki and Ki values, extremely high Ks and Ks’values indicated that, NJUST18was able to grow on pyridine within a wide range of concentrations, especially at relatively high concentrations.Inoculated with pure NJUST18strain, aerobic granular sludge capable of degrading pyridine was successfully cultivated, with the partical size around0.5-1mm. MLSS increased from0.88g/L to5.2g/L, MLVSS increased from0.847g/L to4.61g/L; SVI decreased to 25.6mL/g.4000mg/L of pyridine can be degraded completely by aerobic granular sludge within7.5hours. Compared with the pure strain system, the aerobic granular sludge reactor system was significantly improved in terms of degradation rate and tolerance towards pyridine. The results of PCR-DGGE indicated the microbial diversity. The initially inoculated Rhizobium sp.NJUST18did loss their dominance after six-month operation. However, the inoculation of Rhizobium sp. played a key role in the start-up of this bioaugmentation system.It is our view that Rhizobium sp.NJUST18and bioaugmentation based aerobic granules offer bright prospects for the bioremediation of wastewater containing high strength pyridine. |
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