H₂S Removal With An Immobilized Cell Bio-chemical Reactor

H2S gas is harmful to people and causes water and air pollution, so it is an important environmental technology to remove hydrogen sulfide, now the available methods of removing H2S can be largely divided into physical, chemical and bio-chemical.Recently, the biodesulfurization become to be a new hot technology of H2S removal. The biodesulfurization have many advantages that require mild reaction conditions, and less tendencty to produce secondary pollution, and others. But compare to the traditional physical and chemical methods, the technology of biodesulfurization have many disadvantages, for example low reaction rate and efficiency.According to the above reasons, a bio-chemical reactor that compares the advantages of biodesulfurization and chemical desulfurization was built by our laboratory. In the bioreactor, Acidithiobacillus ferrooxidans oxidize iron from Fe2+to Fe3+; in the chemical reactor, the Fe3+react to H2S generates sulfur and Fe2+, then Acidithiobacillus ferrooxidans turn the Fe2+into Fe3+during cycling. And H2S can be removed by this process.Our lab has made many researches on this project, and this paper will focus our focal point of research on reactor process optimization and pilot-scale study. Through these studies, the main results and conclusions obtained are as follows:1st、The effects of pH, ferrous and ferric ion concentrations on iron oxidation by BY-3were examined. A rate equation has been developed. The unified rate equation is showed bellow: Rate=K’[Fe2+]-0.7437[Fe3+]-1.299,where K’=Pseudo first order reaction constant. It shows that the growth kinetics equation of the Gerd follows μ=0.3362CFe2+/60679＋CFe2+＋4.002×CFe3+, when the initial ferrous concerntration was10g/L, without striking competitively inhibition of Fe3+.2nd、We study the effects of pH、tempertature on the oxidation rate and jarosite precipitationof At.f BY-3, it shows that the oxidation as high as0.22445～0.22781g/L·h, with low jarosite precipitation of0.01644～0.01725g/L-h at conditions of pH1.7and1.8with an operating temperature of30℃.3rd、Effect of air flow rate and liquid flow rate on Fe2+oxidation rate of the immobilizedBY-3were investigated. It shows that when air flow rate125(L/h),liquid flow rate0.43h-1the Fe2+oxidation rate is as high as3.20544g/L·h.4th、We studied the effects of flow rate and the concerntration of Fe3+on absorptionefficiency of chemical-reactor. It suggests that when the concerntion of Fe3+at8-12g/L with the flow rate at40-60mL/min the reactor will get the best desulfurization effect.5th、According the bio-chemical double stage reactor we designed, we studied the desulfurization effect when the biological-chemical reactor was run constantly, experiment indicated that H2S removal efficiency may reach99%with the concentration of inlet2-4g/m3of H2S.