Isolation Of Nitrifying Bacteria Adapted To Different Concentration Of Nitrogen

In recent years, the development of industrialization and urbanization process lead to worse water pollution. People take more attention on the rehabilitation of the water environment and focus on how to use nitrifying bacteria to remove the nitrogenous compound which is harmful to human's health from water. However, comparing to industrial effluents and sanitary wastewater nitrifying bacteria which is used for industry is hard to play a role in the lake for some reasons, such as low nitrogen content, large area of water and influence factor of environment.This task hopes to enrichment and isolation of nitrifying bacteria which possess effective nitrification and play a role in any lake of nitrogen pollution. The enrichment of nitrifying bacteria by means of keep mud when change culture medium and the isolation of nitrifying bacteria by means of spread plate and most probable number. Then, choose the right strain by test the concentration of ammonia nitrogen, nitrite-nitrogen and nitrate nitrogen. The main results are as follows:1. None nitrifying bacteria was obtained by means of spread plate and eight samples which have effective rate of nitrification were obtained by means of most probable number.2. None nitrifying bacteria was obtained from the culture medium which initial concentration of ammonium nitrogen was 2mg/L. One sample with nitrification called 1XN-1 was obtained from the culture medium which initial concentration of nitrite-nitrogen was 2mg/L. This sample can completely transform nitrite-nitrogen into nitrate nitrogen in 5 days.3. One sample has the ability to reduce the concentration of ammonia nitrogen called 1XA-2 was obtained from the culture medium which initial concentration of ammonium nitrogen was 100mg/L. This sample uses ammonia nitrogen as the only nitrogen source, it can transform ammonia nitrogen into nitrate nitrogen in 17 days and the highest concentration of nitrite-nitrogen was 1mg/L. Three samples with nitrification were obtained from the culture medium which initial concentration of nitrite-nitrogen was 100mg/L. Using the decrement of nitrite-nitrogen to calculate the rate of nitrification that the results of three samples was that, the rate of nitrification of 1SN-2 is 6.63 mg/L·d, 1ZN-2 is 9.27 mg/L·d and 1XN-2 is 11.23 mg/L·d.4. Two samples which have the ability to reduce the concentration of ammonia nitrogen were obtained from the culture medium which initial concentration of ammonium nitrogen was 400mg/L. But taking more time to reduce the concentration of ammonia nitrogen make these two samples isn't worth to be developed. Three samples with nitrification were obtained from the culture medium which initial concentration of nitrite-nitrogen was 400mg/L. Using the decrement of nitrite-nitrogen to calculate the rate of nitrification that the results of 3 samples was that, the rate of nitrification of 1SN-3 is 16.41 mg/L·d,1ZN-3 is 27.7 mg/L·d and 1XN-3 is 48.33 mg/L·d. For the rate of nitrification of 1XN-3 is faster than the other two, choosing 1XN-3 to study.5. Comparing all the samples, then chose 1XA-2 to make analogue experiment. Comparing to the negative control which didn't have 1XA-2, the descent velocity of the concentration of ammonia nitrogen in sample which had 1XA-2 was faster, the maximum of the concentration of nitrite-nitrogen and the finally concentration of nitrate nitrogen was lower. Besides that, half of the total nitrogen was removed from water.1XA-2 has the ability to reduce the concentration of ammonia nitrogen in the water.