Isolation Of An Acrylonitrile Degradation Strain And Its Biodegradation Characteristic

As a very important chemical raw material, Acrylonitrile is widely used in the field of organic synthesis and attracts the academic attention of environmental science field because of its high toxicity. The problem of acrylonitrile wastewater has been more and more serious along with the more amout of acrylonitrile used. As one kind of high concentration and difficult degradation organic wastewater, how to treat the acrylonitrile wastewater effectively is still puzzled the acrylonitrile manufacturers.The common methods of treatment are physic-chemical and biological approach. Compared with physic-chemical treatment, biodegradation has advantages of mild reaction conditions, low consumption and few second pollution. But there are also some problems because the wastewater containing various pollutants and many of them are poisonous to microorganism. So the system is not always stable and the effect is unsatisfactory. Therefore, obtaining strains which can degradate acrylonitrile is quite important for biological method to treat acrylonitrile wastewater.This paper obtained an acrylonitrile isolate named YH-5 through enrichment screening from the activated sludge of a chemical plant in Zhenhai District of Ningbo City. Strain YH-5 was identified as Arthrobacter sp by analyzing the colony morphology, physiological and biochemical characteristics, and 16 S r DNA sequence.The result of single factor and orthogonal experiment indicated that the best medium composition was as follows: glucose 20 g/L,yeast extract 4 g/L,caprolactam 5 g/L, K2HPO4 0.5 g/L, KH2PO4 0.5 g/L, Mg SO4 0.5 g/L and the optimum conditions as follows:initial p H value 7.0,medium volumetric ratio 20%. The enzyme activity of strain YH-5 after optimization was increased about fifty-two percent. The optimum culture time was about sixty hours.The biodegradation of different acrylonitrile concentration by Strain YH-5 was investigated.The result showed that when the initial acrylonitrile concentration was 341.4 mg/L、624.9 mg/L、1205.1 mg/L、1829.8 mg/L respectively,the degradation rate was 63.47%、60.33%、70.19%、73.12% within 120 h.Moreover, kinetic studies of enzymatic reaction show that the Michaelis parameters were as follows:Vm=89.3 mg/L·h, Km=788.4 mg/L.