Study On MBBR Denitrification Reactor For Domestic Wastewater Treatment Based On Precaptured Carbon

China’s sewage discharge has increased year by year,and the amount of sewage treatment has remained high.With the increasingly prominent problems of energy,resource shortages and global temperature changes,low-carbon treatment,energy development and resource recovery have also become current sewage treatment plants long-term goals and urgent needs for development and change.The denitrification process based on the anaerobic ammonia oxidation process can greatly reduce the aeration and allow the carbon source in the sewage to be used for methane production for energy recovery,which has high application value for reducing energy consumption in the sewage plants and achieving energy self-sufficiency.However,due to the slow growth and the stringent growth conditions of An AOB,the mainstream application of this technology in urban domestic sewage treatment is still very limited.MBBR technology is an existing mature sewage plant transformation plan.Based on it,the experiment builds a pre-carbon capture+MBBR process system.The SBR reactor（No.A0）was used for pre-carbon capture.And through the long-term commissioning and operation of the MBBR reactor（B section）which could introduce the An AOB nitrogen removal system to study its nitrogen removal effect on domestic sewage.The main results are as follows:（1）Compared with the MBR reactor,SBR is used as a pre-carbon capture reactor for pretreatment,which has better stability and economy.During the entire operation period,the A0 reactor has an important positive effect on the stability of the B-stage influent water quality.The hydraulic cycle of the A0 reactor is 45min,the drainage ratio is 0.25,the average removal rates of COD and NH₄⁺-N are 53.6%and 13.7%respectively.And the average C/N ratio of the effluent from the A0 reactor is 2.23 in 165d to 260d of the later experiment period,which is conducive to the cultivation of An AOB in B-stage reactor.（2）MBBR reactor（No.B1）directly uses the effluent from the A0 reactor to start the single-stage denitrification system.The anaerobic ammonia oxidation phenomenon appeared for the first time on the 132th day of the experiment.At this time,the TN removal rate was 50.37%,the removal load was 0.06 kg/（m³·d）,and the An AOB abundance in the system was 1.56×10⁸ copies/50ul.At the end of the experiment,the TN removal rate of the B1 reactor reached a maximum value of 74.86%.At the same time,it was calculated based on the stoichiometric relationship that the denitrification contribution of An AOB was greater than 20%,indicating that in the B1 reactor system,An AOB played a certain role in assisting denitrification effect.（3）MBBR reactor（No.B2）was successfully operated by 130d artificial water distribution culture,and the anaerobic ammonia oxidation was successfully started.Stable to the 150th day,the TN removal rate was 85.36%,the removal load was 0.57kg/（m³·d）,and the An AOB abundance reached a peak value of 5.71×10⁹ copies/50ul.After the B2reactor is connected to the B-stage to treat domestic sewage,after debugging,the maximum TN removal rate at the end of the experiment is 60.62%,and the maximum removal load is 0.06 kg/（m³·d）.Among them,the nitrogen removal effect contributed by An AOB can reach more than 60%at the highest,which shows that the B2 reactor system formed a DB and An AOB synergistic denitrification reaction system.By summarizing the whole experiment,it can be concluded that under the combined action of higher temperature,lower C/N,intermittent aeration,low DO content,precise aeration control and other factors,DB and An AOB can be effectively denitrified to maintain MBBR what a single-stage denitrification reactor.Therefore,in practical engineering applications,the addition of MBBR filler is an effective and commonly used strategy for the transformation of existing wastewater treatment plants.If the operating parameters are adjusted and optimized,a certain amount of An AOB can be in the reaction tank.Among them,the low C/N ratio of influent water can be achieved by pretreatment of the raw water in the pre-reaction tank and the homogenization of the adjustment tank,while low-DO uniform intermittent aeration can be considered to introduce an online monitoring system to achieve accurate aeration system control.