高氨氮废水应用CANON工艺之N2O释放机理研究

Autotrophic nitrogen removal over nitrite (CANON) process, which can carry out the partial nitritation and Anammox process simultaneously within one reactor, is ideal process for ammonia-rich wastewater treatment;. However, CANON process produces more greenhouse gas nitrous oxide (N2O) than traditional nitrification/denitrification process. On the basis of start-up of CANON process, the N2O production was examined in details in the study. First, the amount of N2O production factors are examined to establish the optimal control parameters to minimize N2O emissions by changing the operation of the reactor operating conditions; Second, N2O production inside the reactor will be studied by using 15N nitrogen isotope tracer technology, and the N2O release pathways and mechanism inside the reactor will be revealed by using molecular biology methods such as fluorescence in situ determination (FISH) and PCR-DGGE analysis methods. Third, the main bacteria and the activity of key enzymes inside the reactor need to examined by using f molecular biology methods. Finally, problems that may exist will be studied when reject water was treated, and deviations with synthetic wastewater will be corrected, both the wastewater treatment cost and disadvantage of N2O emission will be considered to proposed optimal control strategy. Therefore, this study has academic innovation and technical feasibility.

全程自养脱氮（CANON）工艺是将短程硝化和厌氧氨氧化结合到一个反应器中处理高氨氮废水的理想工艺，本研究针对该工艺产生的温室气体N2O明显高于传统硝化反硝化工艺的问题，在成功启动CANON反应器的基础上，首先通过改变操作反应器的运行条件，对N2O产生量的各个因素进行考查，确立最佳控制参数以尽可能减少N2O的排放；其次， 采用15N示踪技术研究反应器内部N2O产生途径，同时采用PCR-DGGE分析方法以及荧光原位测定（FISH）等分子生物学手段，揭示N2O的释放途径、产生机理；第三，应用分子生物学手段确定出该反应器体系中的主要菌种及关键酶的活性；最后，以污泥消化液为处理对象，研究CANON工艺在实际应用时可能存在的问题，并校正此前采用人工配水进行N2O减量化研究所存在的偏差，综合CANON工艺处理高氨氮废水的处理成本与排放N2O的危害，提出最优化控制策略。本课题具有学术创新性和技术可行性。

以ANAMMOX技术为基础的CANON工艺具有不需有机碳源、节省曝气量和剩余污泥少等优点，目前主要适用于垃圾渗滤液、污泥消化液等高氨氮废水的处理。但是， CANON工艺在完成高效脱氮效果的同时，容易释放出强温室气体——N2O。首先，启动生物膜CANON工艺和ANAMMOX工艺，试验发现：（1）随着NH4+-N、NO2--N浓度的增加，N2O的释放率均逐渐增加，当NH4+-N=500mg•L-1、NO2--N=100mg•L-1时，分别达到7.15%、11.94%，其中NO2--N对N2O的影响更大。（2）而pH值越小，N2O的释放率越大，当pH=6.64时，达到8.75%。（3）曝气速率越大，N2O的释放率越大，其中曝气速率为8 m3.(m3.h)-1时，其高达9.73%，而间歇曝气时，适当缩短好氧的持续时间（0.5h），可使得N2O的释放量减少约21%。曝气反应初期N2O释放来源主要为NH2OH的氧化，而中期N2O的释放主要是由于NO2--N积累而导致AOB反硝化作用的结果。（4）好氧条件下，反硝化菌是N2O释放的主要承担者，其释放的N2O约占总释放量的65%，其次是AOB，它大约可释放23%的N2O，而ANAMMOX菌若不能及时氧化NO2--N，也会增加N2O的释放量。（5）缺氧条件下，AOB是N2O释放的重要承担者，而ANAMMOX菌和反硝化菌扮演的均是减少N2O释放的角色，前者通过争夺NH4+-N、NO2--N等电子而抑制AOB的反硝化作用，而后者则可以将AOB反硝化作用产生的N2O还原至N2，两者均可达到减少N2O释放的结果。