| Taking Shenfu coal as participarts, strains were extracted from Shenfu coal-washing waste water. In order to obtain highly efficient strains for bioconversion Shenfu coal, weathered coal and photo-oxidazed coal were respectively used as sole carbon source to screen strains. The bioconversional characteristics of photo-oxidazed coal and the structure of bioconversion products were analyzed for clarifying the coupling between photo-oxidation and bioconversion.Firstly, Shenfu coal was pretreated by UV-photocatalytic oxidation. The humic acid content of the coal photo-oxidazed for 6h was maxmum, reached to 10.19%. Photo-oxidazed coal was characterized by FTIR and ultimate analysis. The results showed that the content of oxygen containing groups (ether, carboxyl, phenolic hydroxyl) were increased by UV-photocatalytic oxidation. Meanwhile, the ratio of O/C and H/C were increased.47 strains were isolated and purificated from Shenfu coal-washing water with differential mediums (fungi,actinomycete,bacteria).Weathered coal was used as sole carbon source to primarily screen strains with solid inorganic salt plate culture. And photo-oxidazed coal was used as sole carbon source to further screen strains with liquid culture medium, finally 3 strains with higher performance to shenfu coal bioconversion , which are b strain (fungi), g strain (actinomycete), and h strain (bacteria), were obtained. The effect of different cultivation systems on bioconversion were investigated in detail. The results incidented that inorganic medium was better than organic medium, dynamic culture was better than static culture for coal bioconversion. the best bioconversional cycle was 14 days for coal bioconversion with inorganic medium dynamic culture. The bioconverted solution products was weak acidic.The bioconverial yield of photo-oxidazed Shenfu coals with strains were higher than that of Shenfu raw coal. The bioconversion yield of photo-oxidazed Shenfu coal using g strain was up to 22.3% .The bioconversional solution products were yellow for 3 strains (b, g, h). Their water-soluble products were precipitated by NaOH. The bioconverted precipitate yield of photo-oxidazed coal for g was up to 17.5%. FTIR analysis showed that the precipitate contained hydroxyl, ether, aromatic ring groups. After bioconversion, the ratio of O/C and H/C in remains of Shenfu coal were greatly increased. The ether groups in the bioconverted residual for g strain were decreased. It meaned that g strain was easy to break ether group. The results showed that photo-oxidation can improve bioconversion of Shenfu coal.Graded extraction was used to characterize the effect of photo-oxidation and bioconversion on the structure of bioconversional residuals by Soxhlet extraction apparatus. The solvents were acetone and THF.The results showed that photo-oxidation made the yield of acetone extraction decreased. After acetone extraction, the residuals were further extracted by THF. The yield of THF extraction for photo-oxidized coal was increased by more than 2 times. After bioconversion of the coals with 3 screened strains, the acetone extraction yield were rapidly increased. The THF extraction yield of bioconverted coals was related with the type of strains. The acetone extraction yield of bioconverted Shenfu coal with g strain was highest ,and it was up to 14.96% as compared with Shenfu coal, the acetone extraction yield of bioconverted photo-oxidazed coal with g strain was increased in an small extent. The THF extraction yield of remain of acetone extraction of bioconverted photo-oxidazed coal by b and g strains were increased by 1 times as compared with Shenfu raw coal. Acetone extraction yield of bioconverted photo-oxidazed coal by b strain were increased in a large extent, the total extraction yield was highest. The total extraction yield of Shenfu raw coal was only 2.92%.The effect of photo-oxidation on h strain conversion of Shenfu coal was less than others. So there was some coupling relationship between the photo-oxidation and b or g strain for coal bioconversion. FTIR analysis indicated that after coal bioconversion with 3 strains, the carbonyl group and ether bond in the acetone solule extract were decreased. |
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