Abstract:In order to clarify the impact of acidity on biological oxidation and the impact of the threshold. In this paper, the bacterial culture conditions of bacterial culture, biological oxidation acidity condition test, BIOX biological oxidation test and fluorescence PCR flora structure analysis. The results showed that the acidity had a significant effect on the activity of bacteria, and the initial acidity was controlled at 5 ~ 10 g / L. The high acid environment had adverse effects on pure bacterial culture and mineral oxidation. BIOX biooxidation process, The pH value of the acidity should be controlled at 1.0 ~ 1.3. With the oxidation process, the resistance of the bacteria to the acid in the second stage reactor will increase and the acidity will increase from 10 g / L to 35 g / L. The results of fluorescence PCR showed that the bacterial structure of Sulfobacillus and Ferroplasma decreased by 1 ~ 3, compared with the control acid system. Therefore, the study of the effect of acidity on the activity of bacteria has important guiding significance for the future production and control of the pre-oxidation industry.