| Phenol is widely used in petroleum refining,leather manufacturing,resin synthesis,fragrance production and other industries.As a result,a large amount of industrial wastewater containing phenol is produced,which seriously pollutes the ecological environment.Because of its high toxicity at low concentrations,it has been identified as a priority environmental pollutant by the national environmental protection department.Biological methods,especially microbial removal methods,which are clean and efficient and have outstanding environmental benefits,have been paid more and more attention.Therefore,how to efficiently deal with phenol polluted soil and water by biological methods has become a hot topic for many researchers.In this study,Pseudomonas ZH-1,which was isolated and screened from the sludge of Fenhe River in Linfen,Shanxi Province,was taken as the research object.Based on the previous laboratory research,the degradation characteristics of phenol by strain ZH-1 were explored and analyzed.The effects of copolymerization and degradation of phenol by vitamin-phenolic pollutants from additional carbon and nitrogen sources were investigated.The degradation effects of bamboo charcoal as carrier fixed bacteria and free bacteria on phenol were compared,and the metabolic pathway of phenol degradation was speculated by using LC-MS technology.The specific contents and results were display as following:1.In order to explore the maximum tolerance of strain ZH-1 to phenol concentration,the tolerance of strain ZH-1 was qualitatively and quantitatively analyzed by plate test and phenol concentration tolerance test.The results showed that P.stutzeri ZH-1 grew well on the plate containing phenol 100～800 mg/L,and the maximum tolerance of strain ZH-1 to phenol concentration was 1000 mg/L.2.In order to explore the adhesion of strain ZH-1 to organic compounds,the adhesion of strain ZH-1 to xylene was determined by the adhesion method.The results showed that the maximum hydrophobic rate of strain ZH-1 on the cell surface was 64.2 ± 0.33 %,and the adhesion of strain ZH-1 to xylene was good,and the strain could effectively degrade organic pollutants.3.Provide the best degradation conditions for the phenol degradation characteristics of strain ZH-1.The effect of strain ZH-1 on the degradation of phenol is studied by adding co-metabolites.The results showed that when the co-metabolites are glucose,ammonium bicarbonate,vitamin C,and catechol,the degradation effect of phenol is the best and the degradation rate is the best.They are 84.7 ± 2.78 %,81.5± 2.89 %,83.1 ± 2.78 %,and 79.4 ± 1.05 %.The experiment is based on single factor analysis to select four factors of glucose concentration,temperature,p H,and inoculum to carry out Box-Benhnken experimental design and response surface analysis for strain ZH-1.The results show that the optimal combination is temperature37?C,p H = 7,glucose concentration 0.6 g/L,and inoculum amount 5 %.Under these conditions,the degradation rate of strain ZH-1 to phenol can reach as high as 89.6 ±0.65.%.4.In order to provide a theoretical reference for immobilization technology in the treatment of phenol-containing wastewater,the experiment used orthogonal design to optimize the optimal preparation conditions of bamboo charcoal immobilized strain ZH-1,and its structure was characterized by scanning electron microscopy,and the immobilization was compared.The degrading efficiency of phenol-degrading strain ZH-1 and free bacteria,and the recyclability of bamboo charcoal-immobilized strain ZH-1,the results show that the best preparation combination of bamboo charcoal-immobilized strain ZH-1 is bamboo charcoal 1 g and inoculation amount 5 %,the adsorption time is 24 h.Under these conditions,the degradation rate of strain ZH-1 to phenol can reach up to 92.88 ± 1.43 %;SEM shows that the irregular porous structure of bamboo carbon can effectively immobilize strain ZH-1;bamboo charcoal immobilization Compared with the free bacteria with the same amount of inoculation,the immobilized bacteria showed obvious advantages in degradation,and the degradation rate reached 92.37 ± 0.69 % at 48 h,which was an increase of 15 ± 0.86 % compared with the free bacteria(p < 0.05);after 10 cycles of the bamboo charcoal-fixed bacteria,the degradation rate of phenol by the bamboo charcoal-fixed bacteria can still reach 64.6 ± 0.69 %,which is an increase of 173 ±2.94 % compared with the free bacteria(p < 0.05).5.In order to explore the degradation pathway of phenol by strain ZH-1,the experiment uses LC-MS technology to detect the degradation products of 36 h and72 h in the phenol degradation system.The results show that there are 18 significant difference metabolites in the negative ion mode.Among them,there are 3 kinds of up-regulated expression and 15 kinds of down-regulated expression.In the positive ion mode,there are 86 kinds of significantly different metabolites,of which 9 are up-regulated and 77 are down-regulated.KEGG was used to analyze the metabolic pathways of strain ZH-1 to degrade phenol.The results showed that the metabolism of glycine,serine,and threonine was the most significant metabolism of strain ZH-1 to degrade phenol(p < 0.05);through the ratio of known phenol degradation products The LC-MS total compound table was measured for the sample,and it was determined that the strain ZH-1 degraded phenol products as adipic acid,lactone,β-ketoadipate,etc.Therefore,it is speculated that the degradation pathway is through the first pathway: phthalate Phenol 1,2 oxygenase pathway(C120 pathway).In conclusion,the strain ZH-1 has a certain tolerance to phenol and good adhesion,and the bamboo charcoal immobilized strain showed a significant advantage in phenol degradation,and the degradation of phenol by LC-MS was concluded that the degradation of phenol by C120 pathway.Therefore,this paper provides technical and theoretical reference for biological treatment of phenol-containing wastewater. |
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