Promotive Effect of Pyridine on the Biodegradation of Isoquinoline by Activated Sludge under Denitrifying Conditions

Lab-scale batch experiments were conducted to investigate the promotive effect of pyridine on the biodegradability of isoquinoline under denitrifying conditions. The effect of pH and temperature on the biodegradation of isoquinoline in the presence of pyridine were also investigated. The biodegradation of isoquinoline was significantly influenced by pH and temperature. At pH of 7.5, both isoquinoline and pyridine were completely removed, whereas at pH of 6.5 and 8.0, isoquinoline was only removed by 84% and 86%, respectively. The high pH even inhibited the degradation of pyridine. While pyridine was completely degraded in the temperature range of 20-35degC , isoquinoline was removed by 90% only in the temperature range of 28-30degC. When the concentration ratio of isoquinoline to pyridine was in the range of 10:1 and 2:1, pyridine accelerated the degradation of isoquinoline; however, pyridine exhibited inhibition effect on the biodegradation of isoquinoline when the ratio reached 1:1.