Effect of mixed liquor suspended solids (MLSS) on simultaneous nitrification and denitrification in a sequencing batch reactor

Abstract

This study investigated the effect of MLSS on simultaneous nitrification and denitrification in a sequencing batch reactor treating domestic wastewater. The average removal efficiencies of COD and TN increased from 93 and 68.21% to 97 and 74.20% with the increase in MLSS from 3.5-4.0 to 7.5-8.0 g/L, respectively. However, the average removal efficiency of TN decreased to 39.45% when MLSS increased to 9.5-10.0 g/L. Simultaneous nitrification and denitrification (SND) was carried out in high MLSS (7.5-8.0 and 9.5-10.0 g/L), and SND efficiencies were 43.4-52.0% and 72.1-80.7%, respectively. Batch tests suggested that there was a strong potential to apply high MLSS for treating wastewater containing high-strength ammonia nitrogen.