Study On Simulaneous Degradation Of Phenoland KCN By Alcaligenes Faecalis JF101

Phenol and cyanide are highly toxic substances,which can inhibit the activity of microorganisms.The industrial wastewater discharged from coke-oven plant often contains these two substances,which makes the biological treatment of this kind of wastewater very difficult.In this study,a strainof Alcaligenes Faecalis JF101 was screened,and its characteristics and mechanism of simultaneous degradation of phenol and KCN were studied.It was found that the strain not only could degrade phenol and KCN,but also have good salt-tolerance,which laid a foundation for the biological treatment of the conventional phenol-cyanide wastewater or the salt-containing phenol-cyanide wastewater.In this thesis,the characteristics of degradation of phenol and cyanide by strain JF101 were investigated.?1?The strains degraded phenol and KCN,respectively;?2?the strains degraded phenol and cyanide simultaneously;?3?the effect of osmotic pressure on the degradation of strains.The results showed that the degradation time of200,400,600 mg/L phenol was 30 h,96 h,and 176 h,respectively,in the phenol mono-substrate system.When 100mg/L cyanide was added,the degradation time of phenol was reduced to 22 h,40 h and 50 h respectively.The presence of cyanide promoted the degradation of phenol.HPLC was used to track phenol degradation products.During the degradation of phenol,the degradation products of phenol were catechol and cis-cis muconate.It was concluded that the degradation pathway was ortho path.The degradation products of cyanide are formic acid,formamide and ammonia nitrogen.The growth of strain and the degradation of phenol were measured under the condition of 0?6%salt concentration,It was found that the strain could tolerate the high salt concentration of 6%Na Cl,and the highest degradation activity of phenol was 5.52 mg(L·h·OD₆₀₀)^-1at 3%salt concentration.When the salt concentration increase to 6%,the degradation activity of phenol was decreased,but the degradation activity was still maintained by 23%.It is considered that the enzyme activity of microbe will be inhibited under high salinity,and there may be product inhibition phenomenon,which will lead to the decrease of activity.The reason of accelerating degradation of phenol by JF101 under the presence of cyanide was discussed.the aspects were studied from enzyme degradation,p H change of the system and degradation products.The results showed that the cyanidase and phenolase were easily inactivated by ultrasonic disruption,and the degradation ability of the enzyme solution to the substrate could not reach the effect of complete cell degradation.When cyanide was added,the activity of phenol degrading enzyme was inhibited,leading to the degradation rate of phenol was reduced,and the"promoting effect"only appeared in the cell,which did not exist in the degradation of enzyme solution.After the complete degradation of cyanide,the p H value of the system decreased from 8.0 to6.9,but the p H change did not affect the degradation of phenol by the strain.It was found that the strain JF101 could grow by using formamide and formic acid,the degradation products of cyanide.Adding cyanide in different periods of time,it was found that the promotion of cyanide on phenol occurred in the stagnation period of phenol degradation.Adding cyanide before the stagnation period can shorten the stagnation period of phenol degradation,while the addition of cyanide after the stagflation period has no promoting effect on the degradation of phenol.It was believed that JF101 obtained C and N sources by degrading cyanide and then promoted the degradation of phenol,indicating that the strain accelerated the degradation of phenol through co-metabolism of cyanide,and it was speculated that co-metabolism was one of the reasons for accelerating the degradation of phenol by the strain.