Research On FGD By Thiobacillus Cultured In Optimal Conditions

The technics of biological flue gas desulphurization and plasma had been the point in recent years. In the research, the growth characteristics of Thiobacillus ferrooxidans was investigated. The low-temperature plasma technology had been used to change the Thiobacillus. The effects of sulfate cumulative on the oxidation activity of Thiobacillus ferrooxidans had been detectived. In addition, we had also accomplished the experiment of desulfurization by biological trickling filter.It takes about 60 hours for ferrooxidans belonged to gram-negative bacteria to finish a growth cycle. The optimum temperature is 30? and the best p H keeps 2.01.The oxidation rate of Fe²⁺increases when the amount of inoculum rises. We achieve the kinetic model by nonlinear fitting under different parametric conditions. The correlation coefficients are all greater than 0.9236. Plasma mutation experiments show that the survival rate are fluctuant when discharge spacing keeps in the same value. The survival rate increase gradually when the discharge spacing increase. We can not get an ideal mutation rate, when the discharge spacing and mutagenesis time are too high or too low. The mutation rate gets maximum 24.2% when irradiate for 5minutes at the distance of 4mm. The growth cycle of mutant strains are 6 hours shorter than the original strains, and the volume of polymeric extracellular is increases to 1.49 times as compared with the original strains. When the medium containing both Fe²⁺ and S^2-, the iron oxide system works firstly, the sulfur oxidation system works after Fe²⁺ is oxidized completely. The most number of S^2- is oxidized to S, The remaining S^2- is oxidized to S₂O₃^2-, S is turned into SO₃^2- and SO₃^2- is turned into SO₄^2- with the increasing of bacteria concentration. The upper limit of conductivity for Thiobacillus ferrooxidans reaches 13320?s.cm^-1. The FGD experiments show that the desulfurization rate is inversely proportional to the initial concentration of SO₂,while is proportional to the residence time of the flue gas. The desulfurization rate gets the maximum 97.23% when the feasible residence time of flue as is 20.2min, the initial concentration of SO₂ is 3980mg/m³ and the spray density is 6.34m³.m^-2.h^-1.