Laboratorial Optimization Study Of Nitrification And Partial Nitrification With Nitrifying Flora Under Low Temperature

In this study, the activated sludge from Three Wa Yao sewage treatment plant, use the method of cultivation at mesotherm and domestication at low temperature to domesticate the activated sludge, the result comes out that the sludge which cultivate 6 days at mesotherm then domesticate at low temperature has the best nitrification effect, and the experiment shows a tendency that the longer cultivate at mesotherm, the better the nitrification effect is. After 21 days’ period, the sludge is domesticated to be nitrifying flora under low temperature successfully.By comparing the nitrification ability in the experiment, the nitrification ability of the flora under 10℃ is almost the same of fresh activated sludge under 20℃, and even be better latterly. At the same time, it has very obvious advantages compare to the nitrification ability of activated sludge. Calculate by ammonia nitrogen degradation, they have 2.77 times’ largest difference. Add the flora to domestic wastewater and pharmaceutical wastewater, it also can maintain a higher rate of ammonia nitrogen degradation.Throuth the experiment of nitrification optimization of different wastewater treatment, the result shows that, after a long time domestication at low temperature, the flora has wide scope of low temperature to adapt to in treatment of domestic wastewater and pharmaceutical wastewater, but nitrifying effect is different under different temperature, ranging from 5℃ to 15℃, the higher the temperature, the better the nitrification effect is. The experiment of shaking speed has the same result, the faster the shaking speed, the better the nitrification effect is. Treating the two kinds of wastewater, the optimal p H of nitrifying flora is alkalescence, the domestic wastewater is 7~7.5, and pharmaceutical wastewater is 7.5~8. Treating domestic wastewater, the optimal MLSS is 0.5~1g/L, pharmaceutical wastewater is 1.5~2g/L. High concentration of ammonia nitrogen could suppress the nitrification rate when treating domestic wastewater, but it’s advantageous to the nitrification effect when treating pharmaceutical wastewater. The optimal concentration of ammonia nitrogen is 30~40mg/L and 55~60mg/L, respectively. Combine all the optimal conditions, the flora has the optimization effect when treating domestic wastewater, the rate of nitrification is higher than before, but it hasn’t the optimization effect which expected when treating pharmaceutical wastewater.Throuth the experiment of partial nitrification optimization of domestic wastewater treatment, the result shows that, high concentration of ammonia nitrogen could promoted partial nitrification, when the concentration of ammonia nitrogen about 75mg/L, the accumulation rate of nitrate nitrogen is the highest. At the same time, when p H is about 9 can promoted partial nitrification, too. When the temperature ranging from 10℃ to 15℃, accumulation rate of nitrate nitrogen has a narrow margin under 10℃. It’s not big difference when shaking speed is different. Combine all the optimal conditions, has large amount of accumulation of nitrate nitrogen, the rate of accumulation of nitrate nitrogen is higher than before, too. It’s advantageous to the partial nitrification.The flora has commendable effect of nitrification and partial nitrification when treating domestic wastewater, so it has wide development prospects in the nitrification system under low temperature.