Study On The Effect Of Different Carbon Sources On The Coupling Of Anammox And Denitrification

With the continuous development of economy and society,human activities greatly affect the circulation of nitrogen in nature,a large number of urban sewage and industrial waste water discharged into the water body,resulting in serious water nitrogen exceeded.Excessive nitrogen is discharged into water body,which is easy to be used as nutrients to cause eutrophication of water body,destroyed the ecological system of water body and affected the living environment of human beings.In the actual production,the carbon and nitrogen in some waste water are relatively low,so it is necessary to consume oxygen in the process of treating the waste water by the traditional nitrification-denitrification process.Therefore,it is a hot research topic in the field of wastewater treatment engineering to seek economic and efficient low C/N wastewater treatment process.Anaerobic ammonium oxidation(anammox)is a new nitrogen removal process,which has a wide application prospect because of its high efficiency and low cost.In this paper,through different reactors start-up of anammox process,then adding different types of inhibition of carbon source by control C/N,studied anammox-denitrification coupling mechanism,including the performance of different reactors,extracellular polymer characteristics and nitrogen functional genes and changes in the microbial community structure,the main conclusions are as follows:(1)In the start-up of anammox process in UASB reactor start-up time for 64 days,but the activity was increased and the autolysis stage of shorter duration,EGSB faster startup time for 58 days.With water load increases,the UASB reactor for 94 days when nitrite nitrogen effluent concentration is higher than 10mg/L,and which the EGSB reaction for 119 days.The EGSB reactor is more resistant to shock load.During the start-up process,with the enrichment of anammox bacteria,the protein/polysaccharide in the UASB reactor increased from 0.24 to 2.85,while the protein/polysaccharide in the EGSB reactor increased from 0.24 to 3.12.In the EGSB reactor,the change of protein/polysaccharide was greater,and the microbial floc had less negative charge and stronger hydrophobicity.(2)Two reactors microbial diversity microbial diversity is increased during early startup.When the late load increases,the EGSB reactor of microbial diversity changed little,and the UASB microbial diversity was decreased because the low anti impact ability.High throughput sequencing results showed that the abundance of Proteobacteria and Bacteroidetes decreased with the increase of Chloroflexi abundance at the phylum level,and the Planctomycetes abundance in the UASB and EGSB reactors could reach 2%and 7.25%,respectively.At the genus level,the abundance of Arenimonas,Thiobacillus and Thauera decreased,and the abundance of Candidatus Brocadia increased.The Candidatus Brocadia abundance in the UASB and EGSB reactors could reach 1.90%and 7.10%,respectively.In the process of anaerobic ammonia oxidation,the ability of the EGSB reactor to enrich the anaerobic ammonia oxidizing bacteria group is much better than that of the UASB reactor.(3)The addition of sodium acetate to anammox reactor that start-up success,in part?,? and ? stage C/N were 0.2,0.4 and 0.8,the reactor can effectively remove ammonia nitrogen in wastewater and nitrite nitrogen,while reducing nitrate in the effluent,the successful implementation of anammox and denitrification coupling.in ? and ? stage C/N were 1.2,1.6,ammonia nitrogen and nitrite nitrogen removal rate decreased rapidly,the Anammox process was inhibited,the coupling efficiency is reduced.The EPS of reactor showed decreased protein content and polysaccharide content increasing and the total EPS decreased,decreased protein content of anammox bacteria secreted by EPS,showed that its activity by inhibition of sodium acetate.(4)The gene abundance of denitrifying gene increased gradually,indicating that denitrification was gradually increasing.During the operation of the reactor,the number of anaerobic ammonium oxidation decreased gradually,especially in the stage IV and V,and its abundance decreased sharply,and the anammox was severely inhibited.High throughput sequencing results showed that the Planctomycetes abundance of anammox bacteria was reduced at the gate level,while the abundance of Proteobacteria containing denitrifying bacteria increased.In the genus level Candidatus Brocadia abundance decreased,indicates that the lower the efficiency of anaerobic ammonia oxidation;increased denitrifying bacteria and heterotrophic bacteria Denitratisoma Limnobacter,Ignavibacterium abundance,showed enhanced denitrification and heterotrophic bacteria in the reactor increased in the reactor.(5)The addition of glucose to the anaerobic ammonia oxidation reactor started successfully,in ? and ?,? and ? stage C/N were 0.2,0.4,0.8,1.2,total nitrogen removal efficiency can be achieved basically unchanged,coupled in phase V when C/N is 1.6,the reactor efficiency decrease,reduce the coupling efficiency of the process.The EPS of the reactor showed the decrease of protein content and the increase of polysaccharide content.The total amount of EPS decreased correspondingly,indicating that glucose also affected the secretion of protein in anaerobic ammonium oxidizing EPS of bacteria.(6)The gene abundance of anaerobic ammonium oxidation decreased gradually,indicating that anaerobic ammonium oxidation was severely inhibited.The growth of nirS gene was significantly increased at V stage.The growth of nosZ gene fragment at IV and V stage was more obvious,indicating that the late denitrifying bacteria increased and denitrification enhanced,which inhibited anaerobic ammonium oxidizing bacteria.High throughput sequencing results show that contains abundance of anammox bacteria decreased,containing denitrifying bacteria Proteobacteria and Bacteroidetes abundance increased;the decreased of Candidatus Brocadia abundance at genus level,showed that the reduction effect of anaerobic ammonia oxidation,Denitratisoma and Thauera increased abundance indicates that rapid growth of denitrifying bacteria in the reactor period heterotrophic bacteria,began to occupy the dominant position.(7)the carbon nitrogen coupling process of sodium acetate dosage ratio should be less than 0.8,and the limited concentration of anammox bacteria on acetate was 120 mg/L;carbon nitrogen coupling process of adding glucose ratio should be less than 1.2,and the limited concentration of anammox bacteria on glucose was 180 mg/L.When adding different carbon sources,the best C/N was 0.4.The reactor compared to adding sodium acetate,reactor operation process of adding glucose in the denitrifying functional genes abundance increased rapidly.High throughput sequencing is also showed higher abundance of anammox bacteria in the reactor with glucose.These results indicate that the glucose has higher tolerance and wider range of application than sodium acetate.