Study On The Operating Efficiency Of Flue Gas Synchronous Desulfurization And Denitrification And Elemental Sulfur Recovery Technology Based On CABR

Compared with traditional methods,the complex absorption coupled biological reduction method（CABR）for desulfurization and denitrification has the characteristics of low cost and high efficiency,which has been widely studied at home and abroad.The presence of S^2-in the integrated simultaneous desulfurization and denitration system will affect the overall nitrogen oxide removal efficiency.Due to oxygen,microbial action and other reasons,the complexing agent Fe（II）EDTA is easily oxidized to Fe（Ⅲ）EDTA,resulting a serious loss.After above,based on the the separate treatment of SO₂ and NO_Xand the regeneration complexing agent and S element through mixing the tail liquid in two towers,this paper studies the following aspects:（1）The domestication efficiency of the sulfate reduction unit system and the iron reduction and denitrification system.（2）The operating efficiency of the sulfate reduction unit system and the iron reduction and denitrification system.The theoretical SO₂ removal efficiency of the desulfurization biological spray tower was calculated theoretically and verified through experiments.The conversion of sulfur and nitrogen under different gas-liquid ratios was analyzed.The removal and conversion of NO during operation were explored.（3）The optimal operating parameters（p H and stoichiometric ratio）of mixing the Fe（Ⅲ）EDTA effluent tail liquid and the S^2-effluent tail liquid together with the regeneration efficiency of the complex absorbent and the recovery efficiency of elemental sulfur.（4）Analysis of the microbial community structure in each operation stage and different packing layers.In the process of domestication experiment:the domesticated result of sulfate reduction unit unit is:the efficiency of SO₄^2-being reduced to S^2-is up to 92.5%,and the average reduction efficiency is 89%.The efficiency of Fe（Ⅲ）EDTA being reduced to Fe（Ⅱ）EDTA is 93.6%.The removal efficiency of NO₂^-reached 92.8%in 27 days,and the total efficiency of NO₂^-converted to N₂ by denitrification was 88%.In the process of the operating experiment:The theoretical SO₂ removal efficiency is calculated to be 100%at a gas volume of 1000 m L/min and was verified by experiments.Under the spray density of 6L/h,the conversion of SO₂ in the flue gas at different liquid-gas ratios at 100m L/min,500m L/min,and 1000 m L/min gas volume is obtained:the sulfate reduction efficiency is 92%,88%,and 88%,respectively.The proportions of sulfide formation are 61.2%,58%,and 55.78%,respectively.The total efficiency of elemental sulfur generation is 85.35%,81.36%,76.33%,respectively.The total NO removal efficiency under 100m L/min,500m L/min,1L/min gas volume in system are100%,100%,and 99.6%respectively.The final product of NO purification was N₂.N₂O accumulation was not detected in the system.Fe（Ⅱ）EDTA decreased by 34.7%,40.3%,and 57.6%within 54 hours respectively.The removal rate of Fe（Ⅱ）EDTA-NO reached99.5%,100%,and 97%,respectively.During the operation stage,The oxidation of Fe（Ⅱ）EDTA is easily affected by air tightness and microorganisms.In the experiment of sulfur element recovery and complexing agent regeneration:the optimal stoichiometric ratio and p H of chemical mixing are 1:2 and 8,respectively.The Fe（Ⅱ）EDTA generation efficiency and precipitation efficiency under the two optimization experiments are 78.6%,76.3%and 91.6%,92.8%respectively.And through environmental scanning electron microscopy,it was confirmed that the precipitate was elemental sulfur.In the microbial community structure analysis experiment:according to Alpha diversity analysis and Beta diversity analysis,five samples were divided into three categories,namely（1）S0（original sludge）and S2（iron reduction denitrification domesticated sludge）;（2）S1（sulphate reduction domesticated sludge）;（3）SU（the upper sludge in the reaction zone after the sulfate reduction tower runs）and SD（the lower reaction zone sludge after the sulfate reduction tower runs）.The structural analysis revealed the dominant phyla and the dominant genus of microorganisms in each sample.It was found that after flue gas impact,the proportions of Campylobacterota phylum and Pseudarcobacter genus in the SU and SD samples increased significantly.They have Potential for co-metabolism of sulfur and nitrogen.In the samples after domestication and operation,the phyla and genus that is strongly related to nitrogen and sulfur metabolism occupies a dominant position.