Pilot study on treatment of rare earth mine wastewater by partial denitrification

Abstract

In this study,a pilot scale experiment was conducted to verify the possibility of part denitrification(PD) to provide substrate NO2- for anaerobic ammonium oxidation(Anammox) in the treatment of ion-type rare earth mine wastewater. The results showed that the start-up and long-term stable operation of the PD reactor could be ensured by inoculating the residual sludge of the municipal sewage treatment plant, taking the actual mine wastewater as influent,regulating the carbon to nitrogen ratio(COD/N) to 2.1 and adopting the real-time COD/N control strategy. Nitrite accumulation ratio(NAR) was remained at (58±7.32)%. The evolution of microbial community showed that the relative abundance of Thauera, the main contributor to PD, increased from 4.39% at the beginning to 17.58% at the end. SEM-EDS showed that Ca2+ combined with Extracellular polymeric substances(EPS) provided sludge good retention ability. This study provides an important reference for the application of partial denitrification coupled anammox(PD/A) technology in large-scale ion-type rare earth mine tailwater treatment engineering.

Keywords

• partial denitrification
• anammox
• real earth mine wastewater