Synergistic Enrichment,Influencing Factors And Nitrogen Degradation Regulation Of Anaerobic Methane Oxidizing Microorganism And Anaerobic Ammonia Oxidizing Bacteria

The inter symbiosis of anammox bacteria and denitrifying anaerobic methane archaea（n-DAMO）can achieve simultaneous removal of ammonia nitrogen,nitrate nitrogen,nitrite carbon-nitrogen,and methane.It provides a technical route for the efficient removal of nitrogen in the anaerobic treatment of wastewater with a high N/C ratio and solves the problem of anaerobic methane efflux.Existing Anammox-DAMO coupling technologies with the two as core functional bacteria generally have problems such as too long start-up time,poor stability,and low nitrogen removal rate.The core reason for these problems lies in the long generation time and narrow ecological niche of the two core functional bacteria.And substrate competition for bacterial communities such as denitrifying anaerobic methane-oxidizing bacteria（n-DAMO bacteria）.It is an important method to enhance the enrichment,growth,and metabolism of Anammox bacteria and DAMO archaea by improving the reactor structure to improve the retention rate and residence time of sludge,by adding carbon and other conductive materials to improve the direct electron transfer between species and the effect of microbial community sensing aggregation,and by promoting the growth and metabolism of core functional bacteria through trace elements.However,current studies on the synergistic enrichment of the two compounds mainly focus on reactor optimization,microbial structure analysis,and nitrogen removal efficiency,while insufficient attention has been paid to the enhancement of exogenous substances’synergistic nitrogen and methane removal.Based on further optimization of the reactor,in-depth exploration of the enhanced pathway and effect of exogenous substances addition on the collaborative nitrogen and methane removal of Anammox bacteria and DAMO archaea is of great significance for the development of nitrogen and methane removal technology based on the interaction function of Anammox bacteria and DAMO archaea.The purpose of this study was to explore an enhanced anaerobic methane oxidation model for simultaneous nitrogen and methane removal based on the interaction function of DAMO and Anammox bacteria.This study adopted continuous flow and batch test mode,combined with chromatography,microbial high-throughput sequencing,electron microscope analysis,stoichiometric analysis,and other test and analysis methods.From the continuous flow enrichment of DAMO and Anammox strains,modified activated carbon to enhance the denitrification and methane removal of strains,The operation and optimization of Anammox-DAMO continuous flow enhancement system analyzed the microbial process of collaborative enrichment and metabolism of nitrogen and methane by DAMO and Anammox bacteria,explored the possible strengthening mechanism of collaborative enrichment and inter-metabolism by conductive materials,and verified the realization of the enrichment of DAMO and Anammox bacteria by conductive materials Feasibility of efficient nitrogen and methane removal technology route.The main contents and conclusions are as follows:Firstly,a continuous flow enrichment system was constructed using a Membrane Aerated Membrane Bioreactor（MAMBR）and an Anaerobic Baffle Reactor（ABR）.After 348 days of operation,the Anammox-DAMO process was successfully started.High-throughput sequencing suggests that after a long period of domestication,The microbial community in the system changed from Methanobacterium,Pseudomonas,and Denitratisoma to Candidatus Brocadia（up to 35.38%）,aerobic methane-oxidizing bacteria Methylomonas（up to 5.60%）,anaerobic methane-oxidizing bacteria Candidatus Methylomirabilis（up to4.57%）,anaerobic methane-oxidizing archaea Candidatus Methanoperedens（up to 5.12%）and other major microbial flora.Using the system to treat simulated sludge anaerobic digestion solution(NH₄⁺-N,NO₂^--N,and NO₃^--N concentrations are 800,1000,and 200 mg N·L^-1,respectively),the TN treatment rate is 439.94±22.31 mg N·L^-1·d^-1.The removal efficiency of NH₄⁺-N,NO₂^--N and NO₃^--N were 37.18%,56.48%and 26.44%,respectively.The results indicated that the Anammox and anaerobic methane oxidation bacteria were preliminarily enriched in the MAMBR-ABR coupling reactor,but the nitrogen removal efficiency needed to be further improved.Secondly,to further improve the nitrogen removal performance of the system,modified activated carbon was added for biological enhancement.Modified carbon（powder-activated carbon:PAC,Fe loaded powder activated carbon:Fe PAC,and Fe/Cu loaded powder activated carbon:Fe Cu PAC）Short-term experimental results show that the most suitable dosage of PAC,Fe PAC,and Fe Cu PAC is 0.25 g·L^-1,0.25 g·L^-1and 0.025 g·L^-1,respectively.The long-term experiment of the above three optimal dosages of modified activated carbon showed that 0.25 g·L^-1Fe PAC had the best effect on improving the activity of coupling bacteria,followed by 0.25 g·L^-1PAC.In addition,the Chao and Shannon indexes of the Fe PAC group indicate that the Fe PAC group has the largest microbial species and the most uniform distribution.Therefore,the dosage of 0.25 g·L^-1Fe PAC is selected as the strengthening material in the subsequent strengthening experiment.Finally,according to the optimal dosage determined by the batch test,0.25 g·L^-1Fe PAC was added to the reactor and continued to run for 120 days.The results showed that the removal rate of TN increased by 434.65 mg N·L^-1·d^-1during the treatment of sludge anaerobic digestion liquid.The removal efficiency of NH₄⁺-N and NO₂^--N reached 97.15%and 93.14%,respectively.The methane oxidation rate increased from 2.57 to 4.43μmol·L^-1·d^-1.In addition,Candidatus Brocadia,Pseudomonas,Denitratisoma,Methylomonas,and Candidatus Methanoperedens were added to the reactor microorganisms after Fe PAC.The relative abundance was increased by 3.16,12.06,0.74,5.27,and 1.12 percentage points,respectively.The increase of Pseudomonas abundance（0.03%up to 12.06%）promoted the growth of Anammox bacteria,denitrifying bacteria,and methane-oxidizing bacteria.Meanwhile,Methylomonas produces organic matter that feeds denitrifying bacteria.Fe PAC may promote Direct Interspecific Electron Transfer（DIET）,thereby increasing the bioactivity of Anammox-DAMO colonies.