| Compared with the traditional microbial denitrification process,the one-stage anammox process has the advantages of no additional carbon source,low aeration energy consumption,less sludge discharge and small floor area.The advantages of high efficiency and energy saving make anammox technology a research hotspot in the field of wastewater treatment.However,one-stage anammox reactor,because the two reaction processes of nitrification and anammox need to be completed in one reaction system,improper control of oxygen supply can easily lead to excessive proliferation of NOB in the system,resulting in the decline of nitrogen removal rate and even system collapse.Therefore,aeration mode and control mode have always been the research hotspot in the field of one-stage anammox technology.The key to achieve long-term stable running in the engineering application of one-stage anammox process is to select the appropriate aeration mode and explore a set of aeration control strategy matching with the reactor.In view of the above problems,this paper carries out the following three parts of research:(1)After 176 days of acclimation and cultivation,the start-up and stable running of the one-stage anammox process were realized in two EGSB by precisely controlling the gas supply.The removal rates of NH4+-N and TN were above 95%and 85%,respectively;(2)The effects of different aeration modes on the stable running of one-stage anammox process were explored,and the aeration strategies conducive to the stable operation of one-stage anammox process were explored;(3)Based on the intermittent aeration strategy of small-scale test,the start-up and running of one-stage anammox were carried out in the pilot SBR,and the aeration strategy was improved and optimized according to the operation of the system.It provides basic data and technical guidance for the regulation of aeration strategy in the application of one-stage anammox.In this paper,through 270 days of research,the results are as follows:The effects of different gas sources on the start-up and stable running of one-stage anammox were as follows:(1)After 176 days of acclimation and cultivation,the start-up and stable running of the one-stage anammox process were realized in two EGSB by precisely controlling the gas supply.The removal rates of NH4+-N and TN were above 95%and 85%,respectively;(2)The response speed of El reactor is obviously better than that of E2 reactor in the start-up and load lifting stages:the response time of El reactor is 15 days less than that of E2 reactor;(3)The stability of El is better than that of E2 in the running stage:the nitrogen removal efficiency and stoichiometric ratio do not fluctuate greatly in the long-term operation process;(4)The activity of nob was inhibited in both reactors,The activity of AnAOB and AOB in El reactor was about lmg·(g·h)-1 higher than that in E2 reactor;(5)Through high-throughput sequencing,the growth of AOB flora in El system was higher than that in E2 system,which proved that oxygen as aeration source was more conducive to the proliferation of AOB.The effects of aeration mode on the load increase and stable operation of one-stage anammox were as follows:(1)Under the condition of high aeration rate,long-term continuous aeration can inhibit the activity of AnAOB,which makes the nitrogen removal effect fluctuate and is not conducive to the stable running of the system.However,under the condition of intermittent aeration,the NH4+-N removal rate of the reaction system was more than 95%and the TN removal rate was more than 85%.The response time was within 7 days.It has obvious advantages in nitrogen removal effect and stability.Compared with continuous aeration,intermittent aeration is more suitable for one-stage anammox process;(2)The AOB and AnAOB activities in E2 system are higher than those of El.It is proved that the anoxic section set by intermittent aeration restricts the more sensitive NOB of oxygen concentration fluctuation,while AnAOB activity of anaerobic system is improved,which makes AOB and AnAOB form a better synergistic symbiosis effect;(3)From the comparison of nitrogen removal efficiency and stoichiometric ratio between batch experiment and process experiment,it can be seen that longer anaerobic time is not conducive to the improvement of nitrogen removal effect in the system.Under the condition of precise control of gas volume,lower anaerobic time can also effectively inhibit the activity of NOB,which is more conducive to the proliferation of AOB,and can improve the nitrogen removal rate of the reaction system,so that the system can complete the load increase faster and achieve better removal efficiency.The aeration parameters were optimized in SBR reactor:(1)After 250 days of cultivation,the start-up of one-stage anammox was successfully realized.Under the condition of influent NH4+-N 80 mg·L-1,the NH4+-N removal rate reached 95%.During the running period,according to the change of nitrogen removal effect in the reaction process,the aerobic and anaerobic time of the reactor were adjusted to optimize the system operation parameters.Under the inhibition of NOB activity,AOB and AnAOB in SBR showed good activity and synergistic effect.(2)Based on the stoichiometric analysis of the pilot SBR process from single anammox to one-stage anammox,it is determined that one-stage anammox is dominant in the process,and there is basically no nitrification in the system,so as to realize the stable running of one-stage anammox process;(2)Based on the stoichiometric analysis of the pilot SBR process from single anammox to one-stage anammox,it is determined that one-stage anammox is dominant in the process,and there is basically no nitrification in the system,so as to realize the stable running of one-stage anammox process;(3)According to the experiment of characteristic stage and the change of nitrogen removal rate in each stage,increasing aeration time can help the system stimulate the activity of AOB and improve the effect of one-stage anammox;According to the experiment along the process,adjusting the anaerobic time according to the reaction condition of the system can improve the nitrogen removal rate of the reaction system. |
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