Separation And Identification Of Bacterial Strain For The Degradation Of Biomass-Oil In Soil

In the present thesis, the research background was illustrated. Then, the relevant elementary knowledge of bio-oil and biodegradation was introduced. Biodegradation plays an important role in the degradation treatment of oil products. Based on understanding the elementary knowledge, two types experiments wascarried out. Firstly, a highly efficiency mode used for screening highly effective degradation strains for bio-oil was built, and then its degradation characters was investigated. In addition, the experiment conditions were optimized by using the single factor and orthogonal experimental design methods.A strain of degrading bio-oil aerobically was isolated from sludge collected from a paper mill. The bio-oil degradation ability with this bacterium was studied in soil. A method for the evaluation of biodegradability of bio-oil was established based on the measurement of carbon dioxide created by the tested bio-oil, and the kinetics of biodegradation was also studied. The results showed: (1) The strain isolated by enrichment culture were identified as Aspergill versicoir, according to their morphological character and physiological-biochemical character. (2) The strain was sensitive to five kinds of antibiotics. (3) Biodegradation reaction of bio-oil followed the first order kinetics equation. The degradation speed was related positively to the temperature. Regarding the application environment, the suitable temperature for the biodegradation of bio-oil in soil was selected to be 30℃. The degradation of the bio-oil could be enhanced at neutral pH value. The degradation rate of bio-oil decreased with the increase of substrate concentration. The present strain of bactera could degrade 40% of bio-oil with a concentration of 1200mg/kg in soil within 10 days. Without the strain, the biodegradation rate was only about 6% under the same conditions. When the inoculation amount of the strain was increased, the biodegradation rate was also increased as well. The biodegradation rate of bio-oil increased obviously when H₂O₂ was introduced into the bioreactor. The addition amount of H₂O₂ should be remained at 30% one time, which would not influence the growth of strain. (4) The present strain could also be utilized as carbon and energy sources for the aromatic compounds, such as benzene, p-chlorphenol, toluene and xylene.With an orthogonal design of 4 factors and 3 levels, it was found the factors effected the biodegradation was as follows: temperature, bio-oil concentration, pH value, inoculation amount of the strain. The optimal conditions were regarded as: temperature, 40℃, bio-oil concentration 400mg/kg, pH value 7, inoculation amount of the strain 20%.