| Based on autotrophs denitrification technology processing,livestock and poultry breeding wastewater,landfill leachate agricultural wastewater such as high ammonia nitrogen and low carbon special wastewater has a big advantage compared with the traditional biological denitrification process,however,the current related research results of the process of special waste water is mainly based on the biofilm and granular sludge reactor for processing,but in the current related study,found that biofilm flexibility is poor,the problem such as granular sludge is sensitive to water quality changes.In order to maximize the efficiency of biofilm and granular sludge treatment of special wastewater.Therefore,in this study,the self-constructed expanded granular sludge reactor-biofilm(EGSB-BR)composite reactor was used to treat artificially simulated special wastewater through the simultaneous domestication of granular sludge and biofilm to achieve autotrophic biological denitrification.The new type of EGSB-BR reactor is developed on the basis of the expanded granular sludge reactor(EGSB).Therefore,the EGSB-BR reactor not only has the advantages of EGSB reactor,such as good sedimentation and large capacity of biomass,but also has the advantages of membrane reactor,such as strong adaptability and good stability.Taking EGSB-BR as a reactor,this study mainly studied the water quality transformation characteristics during the operation of the reactor,parameter optimization during the start-up process,sludge property analysis,and comparative analysis of microbial community differences.On this basis,the application feasibility of autotrophic biological nitrogen removal process based on EGSB-BR reactor was analyzed.The results are as follows:The autotrophic biological denitrification process was initiated by an EGSB-BR reactor.The most important thing was to cultivate nitrifying bacteria and anammox bacteria to achieve nitrogen removal through the combined action of the two.This study run 137 d,first of all influence factors to adjust and control in a suitable range,influence factors had stopped time ratio and hydraulic retention time(HRT),dissolved oxygen(DO)concentration,temperature,respectively,in 2 h: 1 h,h,60 mg/L 0.7/0.4aeration period/stop(section),30 ?,denitrification performance of the system is good,total nitrogen removal rate can reach 74.43%,ammonia nitrogen removal rate can reach 99.47%,successfully started autotrophs denitrification.Secondly,the physical properties of the sludge in the reactor were analyzed.The results showed that the sludge after 137 d operation had changes in morphology and composition.The sludge in the biofilm area was mainly filamentous and spherical bacteria,while the EGSB area was mainly spherical and short rod shaped bacteria,and the average particle size of the sludge in the EGSB area was up to 2.12 mm.At the same time,the functional groups in sludge were analyzed,and it was found that with the successful initiation of autotrophic denitrification,the fluorescence intensity of aromatic proteins was enhanced.The absorption peaks around 1600cm-1 and 1400cm-1 in the infrared band were also enhanced,indicating that aromatic proteins and proteins corresponding to the absorption peaks around 1600cm-1 and 1400cm-1 were conducive to the start-up and operation of the EGSB-BR reactor for autotrophic nitrogen removal.In order to further illustrate that the EGSB-BR reactor has successfully started autotrophic denitrification from a microscopic perspective,high-throughput sequencing technology was used to study the changes of flora structure before and after the reactor was started from a molecular biological level.Run results show that after 137 d,in the system of floating mold gate(Planctomycetes),green door bending bacteria(Chloroflexi)proportion is very big,the relative abundance of the floating gate mold(Planctomycetes)by the end of sludge increased to 3.22% of the early reaction EGSB area by 33.36% and the 6.82% of biological membrane area,relative abundance of metarhizium curved door(Chloroflexi)by the end of sludge increased to 1.56% of the early reaction EGSB area 16.35% and biofilm area 6.32%.A total of 1Nitrosomonas was detected in the EGSB-BR complex reactor by comparing the EGSB region and biofilm region at the late stage of the reaction with that at the early stage of the reaction.The relative abundance of Candidatus Brocadia increased from1.83% in the early stage to 3.7% in the EGSB region and 4.31% in the biofilm region.Chloroflexi consists of norank?o?SBR1031 and OLB12.The EGSB region andbiofilm region were 11.19% and 2.07%,respectively.During the whole process,the structure of anammox community changed significantly,and the EGSB-BR reactor successfully started the autotrophic denitrification.To sum up,in this study,the self-constructed EGSB-BR reactor was used to treat the artificial simulated special wastewater,and the autotrophic biological nitrogen removal process was successfully started within 137 d by adjusting the exposure time ratio,hydraulic retention time,temperature,etc.,with a total nitrogen removal rate of74.43%.During the start-up process,the microbial community structure in the reactor changed obviously,and the nitrite bacteria and anammox bacteria were enriched to a certain extent.In order to promote the application of EGSB-BR complex reactor in practical engineering,this reactor is combined with the existing wastewater treatment unit,and different combinations of nitrogen containing wastewater of different concentrations are carried out,and theoretical analysis is carried out from the feasibility and economic aspects to provide theoretical support for the future engineering application of EGSB-BR reactor. |
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