抄録
Immobilized Alcaligenes faecalis, a typical heterotrophic nitrifier, was added into activated sludge to make A. faecalis predominant genus in the activated sludge. Responses of the systems to variation of DO, pH and quantities of inoculated A. faecalis were tested and behaviors of the systems were evaluated. Experimental results showed that: the systems containing A. faecalis generally produced N2O 5 times less than those containing only activated sludge. In addition, the systems containing A. faecalis had a higher total nitrogen removal capability, average total nitrogen removal efficiencies of them were 10% higher than those of the activated sludge systems. Little influences appeared to TOC removal after the addition of immobilized A. faecalis. Among the experimental conditions, low DO concentration, high amount of A. faecalis and neutral pH led to low N2O emission and high total nitrogen removal. Therefore, increasing quantity of A. faecalis in activated sludge should be encouraged for controlling N2O emission and removing nitrogen in wastewater treatment. N2O producing ways were put forth to explain the influences of DO on N2O emission, and relative quantities of autotrophic nitrifying denitrifying organisms and heterotrophic nitrifiers were suggested to have significance in affecting behaviors of activated sludge toward N2O emission. On the other hand, serious accumulation of NO2-N and NO3-N resulted in high N2O emission, to reduce NO2-N and NO3-N quickly and thoroughly was thus suggested for both reducing N2O emission and improving nitrogen removal.
