Test Study On Enhancing Capability Of Simultaneous Desulfurization And Denitrification From Flue Gas By Biological Purification Method

Nitrogen oxides (NO_x) and sulfur dioxide (SO₂) are most important classes of air pollutants, causing acid rain, being harmful to human health, resulting in the photochemistry smoke and environment and climate change. Biological purification technology became one of hot topics of the world's industrial waste gas purification for its good purifying effect, operation stability, small energy consumption, low investment and low operating costs, no secondary pollution, etc. But as a new type of flue gas treatment, the technology of purifies SO₂ and NO_x from flue gas by biological method is still in the stage of laboratory research. Optimization of purification methods and devices, as well as the study of biological characteristics of microbial degradation of the biochemical reactions and the nutritional needs of microbe, enhancing capability of desulfurization and denitrification, will lay the foundation for the application; it has an important engineering value and academic significance.The methods of enhancing capability of purifying SO₂ and NO_x from flue gas by biological method are studies in this paper. Test studies on the relationship between SO₂ and NO_x in the process of simultaneous desulfurization and denitrification by biological methods and the effect of addition of nutrient solution for purification efficiency of purifying SO₂ and NO_x. And the test using series-wound desulfurizing and denitrifying system which assembled by a biotrickling filter which used to desulfurization link with a biotrickling filter which used to denitrification to purifying SO₂ and NO_x from flue gas to solve the low purification efficiency of denitrification when purifying SO₂ and NO_x from flue gas by biological method. The test also studies on the capability of purifying SO₂ and NO_x from flue gas by using series-wound desulfurizing and denitrifying system, recycle the outgrowth, isolated and identificated special microorganisms. The major results are:In the process of desulfurization and denitrification by using biotrickling filter, the purification efficiency of NO_x will decrease when the concentration of SO₂ enhances; the purification efficiency of SO₂ was increased from 86.4% to 100% when the concentration of NO_x enhances; NO_x are propitious to microbial reproduction and increased microbial activity. The addition of autotroph nutrient solution significantly increased the purification efficiency of denitrification, was increased 45%.In the same experimental conditions dealing with the same concentration of SO₂ and NO_x gases, the capability of purifying SO₂ and NO_x from flue gas by using series-wound desulfurizing and denitrifying system was better than the purification efficiency of simultaneous desulfurization and denitrification by using only one biotrickling filter, the purification efficiency of SO₂ was 100% and the purification efficiency of NO_x could up to 90%.In series-wound desulfurizing and denitrifying system, there is basicly balance between the reactants and the products in the biotrickling filter which used to desulfurization; there is a large gap between the measured and calculated results of the NO3- concentration in the biotrickling filter which used to denitrification, the reactants and the products do not balance. The circulating fluid from the biotrickling filter which used to desulfurization cans effectively leaching copper from copper oxide.Sphingomonas paucimobilis, Acidithiobacillus thiooxidans, Trichosporon pullulans, Nitrobacter, Delftia acidovorans and Bispora sp. have been isolated from the biotrickling filter which used to desulfurization. And Nitrobacter vulgaris, Thermomonas brevis, Acinetobacter venetianus and Chloroflexi bacterium have been isolated from the biotrickling filter which used to denitrification.