反硝化细菌抑制石油集输系统中硫酸盐还原菌试验研究

建立了两个UASB反应器(UASB-1和UASB-2)。其中UASB-1模拟石油集输系统中硫酸盐还原菌的生存环境,强化系统中硫酸盐还原菌的滋生,使其不断产生硫化氢气体。该系统的液体进入后续UASB-2厌氧反应器,其主要作用是在其中形成反硝化作用的环境条件,以控制石油输集系统中不断滋生的硫酸盐还原菌,从而达到控制硫化氢气体的目的。结果表明,硫酸盐还原菌的最佳氧化还原电位(ORP)为-370～-300mV,而反硝化细菌的最佳ORP为-150～-50mV。向系统中投加亚硝酸钠可迅速增加反应器中的ORP,并为反硝化细菌提供充足的氮源。当系统中的w(SO24-)∶w(NO2-)=8∶1.2时,抑制效果最佳,可以将硫化氢的产生降低至10%。运用16S rDNA基因克隆-变性梯度凝胶电泳分析方法研究了系统中微生物种属的变化情况。结果表明,反硝化细菌能够有效抑制系统中硫酸盐还原菌繁殖,系统中3种典型硫酸盐还原菌(脱硫弧菌属、脱硫肠状菌属、脱硫单胞菌属)逐渐消失,同时反硝化细菌的种属和数量都显著增加。

Inhibiting function of denitrification in reducing the activities of sulfate bacteria in the crude oil refilling and transportation process

The present paper intends to report our research on the inhibiting function of denitrification in reducing the activities of sulfate bacteria in the crude oil refilling and transportation process.In our research,we have prepared two sets of UASB(up-flow anaerobic sludge blanket) reactors(UASB-1 and UASB-2).The first reactor is to simulate the current environment of sulfate-reducing bacteria in the crude oil refilling and transportation process in order to promote the breeding of such bacteria for producing hydrogen sulfide,whereas the second reactor,the subsequent reactor,is mainly used to form the denitrification condition to let the oil liquid in so as to control the sulfate-reducing bacteria in producing hydrogen sulfide.Through adjusting the ratio of w(SO2-4):w(NO-2),DNB could be made to be the superior population in UASB-2,which helps to control the hydrogen sulfide.The results of our experiments indicate that the optimal ORP(Oxidation-Reduction Potential) value with sulfate-reducing bacteria can be made to increase from-370 mV to-300 mV when-150 mV to-50 mV are just needed for denitrifying bacteria.Adding sodium nitrite to UASB-2 is not only helpful to improve ORP value but also able to provide sufficient nitrogen sources.In our experiments,we have succeeded in achieving the best inhibitory effect on the decrease of hydrogen sulfide by 10% in the ratio of w(SO2-4):w(NO-2) is 8:1.2. We have also studied the change taking place in the microbial communities by using 16S rDNA gene based method and denaturing gradient gel electrophoresis(DGGE) analysis.The results prove that the sulfate-reducing bacteria could be successfully inhibited by the denitrifying bacteria,with the three typical SRB(Desulfovibrio,Desulfotomaculum,Desulfomonas) gradually vanishing.At the same time, both the genera and the amount of the denitrifying bacteria were found increased remarkably.The analysis of the microorganism growth reveals that the different microenvironments are likely to sift microorganisms in which different species may strive for their survival through competition.In other words,the species vary with the changing environment.The process of our experiments helps to find that there may exists three mechanisms,i.e.the substrate competition between DNB and SRB,the inhibition of the middle product of denitrification and the oxidation of the autotrophic nitrate-reducing bacteria.