Effect of nitrate concentration on performance of pre-denitrification moving bed biofilm reactor system in treating coal gasification wastewater

Abstract

An anoxic moving bed biofilm reactor (ANMBBR) followed by an aerobic moving bed biofilm reactor (AEMBBR) operated as pre-denitrification system was used to investigate the effect of different influent NO₃ ⁻-N concentrations on performance of the pre-denitrification system in treating real coal gasification wastewater. Influent NO₃ ⁻-N concentration was controlled at 50, 100, 200, and 400 mg/L during the experiments. Evolution of COD and phenols in the effluent of the ANMBBR and AEMBBR, and performance of nitrification in the AEMBBR with different influent NO₃ ⁻-N concentrations were studied. Almost complete denitrification was achieved when influent NO₃ ⁻-N concentration was 100 mg/L. NO₃ ⁻-N and NO₂ ⁻-N accumulated in the effluent of the ANMBBR with influent NO₃ ⁻-N concentrations of 200 and 400 mg/L. NO₃ ⁻-N concentration of 400 mg/L facilitated high NH₄ ⁺-N removal efficiency in the AEMBBR when influent NH₄ ⁺-N concentration was around 165 mg/L. The ratio of COD_consumed/NO₃ ⁻-N_consumed along with phenols removal of the ANMBBR under different influent NO₃ ⁻-N concentrations was discussed.

Keywords:

• Moving bed biofilm reactor
• Coal gasification wastewater
• Nitrate concentration
• COD
• Phenols

Acknowledgments

This work was supported by National High Technology Research Development Plan (863) of China (No. 2007AA06A411).