Isolation And Identification Of Methane Oxidizing Bacteria And Adsorption Characteristics On Coal Surface

Coal mine gas is an important factor restricting coal mine safety production.Biological control of gas was a new method to digest coal mine gas by methane oxidizing bacteria.In this dissertation,the community of methane oxidizing bacteria were enriched and screened from the mine water of Zhangji Coal Mine in Huainan.The community composition of bacteria was obtained and methane-oxidizing bacteria were separated from the community composition.The effects of different culture conditions on the adsorption of methane-oxidizing bacteria on coal surface,the adsorption characteristics of bacteria on coal surface and the changes of coal surface properties after adsorption were studied.The main conclusions were as follows:?1?At the phylum level,the mixed bacteria of methane-oxidizing bacteria were mainly Proteus?93.44%?and methane-oxidizing bacteria?75.85%?at the genus level.A methane-oxidizing strain HNM1 was isolated from mixed microflora by plate separation method.The 16S rDNA sequencing comparison showed that the strain was Methylophilus.The strain was rod-shaped,with a diameter of 0.5-1?m and a length of about 2?m.The methane oxidation rate reached 85.26%in 6 days when methane was used as energy substrate.?2?Plackett-Burman design was used to screen out the main factors affecting the contact angle between methane oxidizing bacteria HNM1 and coal.The results showed that MgSO₄,NH₄Cl and CaCl₂ were the main factors.Then the Box-Behnken test was used to optimize the three factors and regression analysis was carried out.It was found that the significant degree of the three factors affecting the contact angle was NH₄Cl>MgSO₄>CaCl₂.The optimal medium composition was 0.15 g/L of MgSO₄,0.31 g/L of NH₄Cl,0.15 g/L of CaCl₂ and 89.166°of contact angle under the theoretical optimum conditions.The validation test is 89.326°.?3?The methane oxidizing bacteria HNM1 can be adsorbed on the surface of coal,and the adsorption equilibrium was reached in 6 minutes.The adsorption rate was 44.65%.When the pH value is 5.5-7.0,the adsorption rate decreases gradually,but the trend is not obvious.When the pH value exceeds 7.0,the adsorption rate decreases rapidly.The temperature change has little effect on the adsorption rate of methane oxidizing bacteria between 24-36?.?4?Adsorption of methane oxidizing bacteria on coal surface can significantly change the contact angle of coal.The contact angle of coal increases from 64.60°to87.72°.The adsorption of bacteria on coal surface will not change the composition and structure of coal.After adsorption,the saturated adsorption capacity of coal decreases from 24.588 mL/g to 21.824 mL/g,and the adsorption constant increases from 1.02 MPa^-1 to 1.15 MPa^-1.This change was beneficial to the desorption of methane in coal.It also shows that the surface modification of coal by methane oxidizing bacteria was an effective way to promote the biodegradation of coal seam gas..