Impact of Ni~(2+) on denitrification of mining waters in fluidized-bed reactors

摘要

In mining processes, nitrate is released into the environment due to the use of N-based explosives and leaching agents such as cyanide. The present study assessed the effect of Ni on denitrification in fluidized-bed reactors (FBRs) at 7-8 and 22°C. In absence of nickel, the feed acidic pH was neutralized due to the pH buffering produced by denitrification and the FBR internal recycling. At feed pH of 2.5 and 5.5 mg/L of Ni, nitrate and nitrite removals were not inhibited. However, effluent pH decreased to 5.0. At feed pH of 5.5, denitrification was efficiently maintained even at 100 mg/L Ni, resulting in complete nitrate removal and stable effluent pH of 7.1. In summary, denitrification tolerated high nickel concentrations demonstrating to be suitable for mining water treatment.