Removal Of NO_x From Flue Gas By Fe(â…¡) Cit/Fe(â…¡) EDTA Chelate Absorption Combined With Biological Reduction

The combustion of fossil fuels generates NO_x pollutants which cause photochemical pollution and acid rain.It is reported that the NO_x pollutants in China is seriously.Current technologies for NOx removal from flue gas have associated with some problems,such as high cost on Investment and operation,produced secondary pollutant and/or low removal efficiency.So,developing new technologies for NOx removal from flue gas is becoming an extremely urgent issue,presently.The newly proposed and adopted method in our work for NO_x removal from flue gas,i.e.chemical absorption-biological reduction integrated process,is deemed as a promising method.As a part of this work,in this paper,we established a mixture absorption system of Fe(â…¡)Cit and Fe(â…¡)EDTA,and also investigated its absorption characteristics of NO.Microbacteria proliferation experiments was carried in the selected bioreactor.Base on these two parts,we researched the chemical absorption-biological reduction integrated process.The aim of this work was to provide a new method and some fundamental data for NO_x removal from flue gas. The main experimental results were as follows:The mixture absorption system of Fe(â…¡)Cit and Fe(â…¡)EDTA was established,and the ratio of Cit and EDTA was 6:1.Using this system could reach high NO removal efficiency,and also could reduce the amount of EDTA by three quarters,which will relieved the second pollution caused by EDTA,and have better economical efficiency. NO could accelerate the oxidation reaction of Fe(â…¡)L.O₂ in the simulated flue gas had adverse effect,which would inhibit the NO removal efficiency.The suitable pH of absorbing solution was about 7.0.The research of NO removal efficiency in spray tower showed that removal efficiency was closely associated with the concentration of Fe(â…¡)L.A Packed Column madding by the material of PPR was used as bioreactor.The cultivation of Enterococcus sp.FR-3 lasted two months and the cultivation of Pseudomonas sp.DN-2 lasted one month.The formation of the biofilm on the filler was observed by ESEM(Environmental Scan Electro-Microscope).O₂ had disadvantage effect on reduction of Fe(â…¢)L.It was the key factor which would inhibit the NO removal efficiency.The method of chemical absorption-biological reduction integrated process was feasible to remove NO from flue gas.Under steady-state operation,the concentration of NO,O₂ and SO₂ had no obvious inhibition on NO removal,and the removal efficiency was almost kept on above 90%.However,when the gas flow increased from 800 mL·min^-1 to 2000 mL·min^-1,the removal efficiency was decreased from 97%to 77%.Citrate would be consumed,needing supplement timely.The biological reduction load was obviously higher than our previous experiments.