Research on removing NO3− in in-situ leaching uranium mine by DNB

It was the first time that the Influences of main factors, such as pH of solution, the value of C/N, the different kinds of carbon sources and temperature on removing NO3⁻ in polluted groundwater from in-situ leaching uranium mine by denitrifying bacteria (DNB), have been studied domestically. The tests results showed that the optimum pH was between 6 to 8. When pH≦5, the removing rate of NO3⁻ decreased. The end pH value of solution was about 7. When C/N≥1, the removing rate of NO3⁻ was more than 90%. The optimum value of C/N was about 1∼1.5. The different kinds of carbon sources affected the removing rate of NO3⁻ and the removing effect of NO3⁻ was the best when sodium lactate was used as carbon source. When Oxidation-Reduction Potential (ORP) was −50 mV∼−200 mV, the lower the ORP was, the faster the removal rate of NO3⁻ was by DNB. Dissolved oxygen (DO) affected the removal rate of NO3⁻. When DO>1 mg·L⁻¹, the removing effect of NO3⁻ was restrained. The removing rate of NO3⁻ increased with the increasing of the temperature. When the experimental temperature was 17 °C, the removing Influences of NO3⁻ was also good. It was good for removing NO3⁻ in polluted groundwater in in-situ leaching uranium mine by DNB.