| Aiming at insufficient report that denitrifying sulfide removal process?DSR?is effected by high-concentration NaCl and tetracycline,effects of different-concentration NaCl and tetracycline on the performance of the DSR reactor are investigatedand the change of microbial metabolism in experimental process is analyzed with modified UASB reactor.On this basis,structural composition and succession pattern of microbial community of all factors in different stages is analyzed from molecular level by taking the high-throughput sequencing method.Finally,the mechanism about effects of high-concentration NaCl and tetracycline on DSR is revealed preliminaryly,which providethe theoretical and technical reference for promoting the DSR industrialzation.In the study of effect of high-concentration NaCl on DSR,effects of different-concentration NaCl on the performance of the DSR reactor are investigated respectively by batch test and continuous-flow test.Experimental results show that NaCl has an inhibited effect on DSR performance under short-term exposure when concentrations of NaCl are 35 g·L-1?50 g·L-1 and 75 g·L-1.Under the long-term exposure,however,compared with no NaCl addition,removal efficiency of DSR is slightly down with high-concentration NaCl and removal efficiency maintains 90%on the whole.At the same time,the productive rate of elemental sulfur is gradually raised as increasing of NaCl concentration,which indicates that the high-concentration NaCl play a stimulative role at reduction of sulfate production and increment of elemental sulfur convertion.The dynamic structure of the microbial community results by high-throughput sequencing method show that the presence of NaCl will reduce the microbial community diversity in denitrifying desulfurization sludge.Moreover,when the concentration of NaCl range from 35 g·L-1 to 75 g·L-1,the proportion of heterotrophic denitrifying microorganisms are greater than the proportion of autotrophic denitrification,as well as the proportion of Halomonas sp.mushroom and become the dominant bacteria when concentration of NaCl is more than 50 g·L-1.The incorporation of Halomonas sp.make the optimal C/N/S ratio of 1:1:1 in denitrifying sulfide removal process.In the study of effect of tetracycline on DSR,effects of different-concentration tetracycline and oxytetracycline on the performance of the DSR reactor are investigated respectively by continuous-flow test.Experimental results document that low concentration of tetracycline(<50 mg·L-1)has a less effect on sulfur removal.The sulfur removal rate is over 97%and elemental sulfur yield is over 70%.However,medium-concentration and high-concentration(50 mg·L-1250 mg·L-1L)have greater effects on sulfur removal.The sulfur removal rate can decrease to 62%and elemental sulfur yield can decreased to 70%.Homoplastically,when oxytetracycline concentration is equal or lesser than 250 mg·L-1,the influence of sulfide removal efficiency decreased first then increased due to the change of microbial sensitivity and resistance to oxytetracycline.The sulfide removal rate reduces from 92.1%to 75.3%and then increases to 89.1%,as well as the production rate of elemental sulfur is increasing.When oxytetracycline concentration is up to 500 mg·L-1,sulfide removal rate and production rate of elemental sulfur are reduced.On the contrary,the tetracycline and oxytetracycline less effect on removal rate of acetate and nitrate.The high-throughput sequencing result shows that the similar phenomenon arises,which the proportion of heterotrophic denitrifying bacteria increases but the proportion of autotrophic denitrification bacteria reduces in reaction system when existence of tetracycline or oxytetracycline.Namely,the two kinds of antibiotics are stronger inhibition to autotrophic denitrifying microorganism than heterotrophic denitrifying microorganism. |
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