Characteristics Analysis Of Inhibition Of Nitrification Inhibitor Thiourea On Nitrification

Nitrogen is the highest dosage of fertilizer and ammonium nitrogen fertilizer is mainly used.Ammonium nitrogen fertilizer applied into soil easily turns into nitrate nitrogen and nitrate nitrogen under the action of nitrifying bacteria. The nitrate nitrogen and nitrate nitrogen is not easy to be absorbed by crops but suspected to leaching loss easily.,causing nitrogen pollution of the environment.In order to improve the utilization rate of nitrogen fertilizer and reduce environmental pollution,nitrification inhibitors is widely applied into the soil.Thiourea is a common nitrification inhibitor both at home and abroad.It has a stable physical properties,water soluble,and difficult biodegradation characteristics. When thiourea and urea applied together,it is in up to 30% of the amout in rice and corn, and nearly 20% in potato and wheat.As an agricultural country in our country, the fertilizer rate is high.The use of thiourea is easy to cause cumulative. Plenty of thiourea easily go into receiving waters by the action of rainfall or snowmelt As a result,the process of the nitrogen cycle of ammonia to nitrate nitrogen transformation process is blocked.It does harm to the area of agricultural production, water resource utilization and aquatic habitats and watershed hydrological features. At the same time, a part of thiourea drains into the sewage treatment plant,because of the existence of rural villages and towns rain pollution confluence pipe and the water ammonia nitrogen content is difficult to meet emissions requirements.Therefore, this article chooses thiourea as the inhibitor to design experiments.in order to improve the natural water cycle of nitrogen and provide support to village and town sewage treatment plant.1.The effect of thiourea on nitrification inhibition was obvious.When the concentration of thiourea was 0、0.05、0.1、0.15、0.2、0.3mg/L,pH increased with the increase of concentration of thiourea, ammonia nitrogen degradation rate as well as ammonia nitrogen degradation rate constant and dissolved oxygen consumption rate,decreased with the increase of concentration of thiourea,2. Thiourea was a competitive inhibition of nitrifying bacteria.The inhibition constant EC50 was equal to KI,and both were 0.14 mg/L.3. Thiourea mainly did harm to the first step of nitration and inhibit the activity of nitrifying bacteria.4. In the process of continuous adding thiourea to the sludge, the physicochemical properties, for instance,sludge concentration, SVI value and sludge form are changed.5.After domestication, nitrifying bacteria produce the adaptability of thiourea. After more than 120 d domestication, inhibition rate of the experimental group are less than the control group in each concentration of thiourea, That showed the nitrifying bacteria produced the adaptability of thiourea.6. The survival state and the population structure of nitrifying bacteria had changed. Weeksella、Luteibacter、Truepera was dominant fungi genera in the sludge without adding thiourea and Luteibacter、Marinobacter、Ignavibacterium was after the domestication of thiourea. Ignavibacterium appeared after adding thiourea.7.The bacteria in two kinds of sludge has a big difference. The diversity of microorganisms had a direct relationship to activated sludge’s environment.