Optimization Of Conditions For Phenol Degradation By Halomonas Sp. H17 And Effects Of Sugars On Phenol Degradation Characteristics

Phenol,a kind of hazardous pollutant with high toxicity,is widespread in the industrial wastewater of petroleum,coking and chemical engineering et al.There are numerous treatment methods for phenol-containing wastewater,among of which biodegradation methods were widely applied for its cost-benefit,high efficiency and no secondary pollution.Whereas,the high concentration of salt in the phenolic wastewater increases the difficulty of phenol degradation.Thus,it's of great significance to study how phenol-degrading halophilic bacterial works in the hypersaline environment.In this study,the phenol-degrading halophilic bacteria Halomonas sp.H17 was investigated.Phenol-degradation conditions of the bacterial strain H17 were optimized by response surface method,moreover,the growth and phenol-degradation ability of the strain H17 were studied by adding different carbohydrate s?glucose,arabinose,xylose,lactose?,and conclusions were shown as follows:?1?To enhance the phenol degradation of strain H17,the Box-Benhnken design and response surface method were utilized in this study,and the optimal phenol-degradation conditions?pH8.0,glucose of 0.82 g/L,30??were confirmed,where the phenol-degradation rate of strain H17 achieved up to 73.92%.?2?Strain H17 proved to be high tolerant for phenol by analyzing kinetics of phenol-degradation,which could be characterized by the Halane model,and the corresponding parameters were:?_max=0.35 h^-1,K_s=165.92 mg/L,K_i=460.13 mg/L.?3?Presence of either of glucose,xylose,arabinose and lactose helped increase the biomass and phenol degradation rate of strain H17.The biomass of strain H17increased gradually with the increasing sugar concentrations,while the phenol-degradation rate increased first and then decreased.When 2.0 g/L glucose,xylose,arabinose and lactose were added respectively,the biomass of strain H17reached the maximum,2.31,1.66,1.72 and 1.29,respectively;when 0.8 g/L glucose,arabinose and lactose and 0.4 g/L xylose were added respectively,the phenol-degradation rate of strain H17 reached the maximum of 73.18%,58.37%,49.04%and 60.35%,respectively.?4?The instantaneous growth and phenol-degradation rate of strain H17 were affected by the types and concentrations of sugars.At certain sugars,instantaneous growth and phenol-degradation rate presented a trend of increasing first and then decreasing with the increasing concentration.When 1.2 g/L glucose was added,the instantaneous phenol degradation rate by H17 at 18²4 h could reach a maximum of6.89 mg-DCW/h and 5.88 mg-DCW/h could be reached when 1.6 g/L of xylose was added.When 0.8 g/L arabinose and lactose were added respectively,the instantaneous phenol degradation rate by strain H17 could reach the maximum of4.58 mg-DCW/h and 5.19 mg-DCW/h at 24³0 h,respectively.?5?The average growth and phenol-degradation rate of strain H17 were affected by the types and concentrations of sugars.The average growth rate of H17 increased gradually with the increasing sugar concentrations while phenol-degradation rate increased first and then decreased.When 2.0 g/L glucose,xylose,arabinose and lactose were added respectively,the average growth rate of strain H17 reached the maximum of 11.57 mg-DCW/h,8.23 mg-DCW/h,8.21 mg-DCW/h and 6.46mg-DCW/h within 60 h,respectively;When adding 0.8 g/L glucose,arabinose,lactose and 0.4 g/L xylose,the maximum phenol degradation rate of 2.39mg/?L?h?,2.01 mg/?L?h?,1.65 mg/?L?h?and 2.03 mg/?L?h?were obtained,respectively.