| Compared with the traditional biological denitrification technology,anaerobic ammonia oxidation?ANAMMOX?technology holds the advantages of high NH4+-N removal efficiency and low operation cost,which has become a research hotspot in the field of biological nitrogen removal.The actual nitrogen-containing wastewater often contains organic matter and low nitrite nitrogen concentration,which led to barriers to the pratical application of ANAMMOX technology.Facing with this problem,three-stage reactor by combination of carbon removal pretreatment,partial nitrification and ANAMMOX has been adopted by many researchers to reduce the influence of organic matter on the nitrogen removal efficiency of ANAMMOX technology and provide the necessary substrate for ANAMMOX process.According to the characteristics of anaerobic baffled reactor?ABR?with separator and biological phase separation,an effective combination of anaerobic digestion,partial nitrification and ANAMMOX process was used to achieve the effective treatment of organic wastewater containing nitrogen.In the ABR reactor,the average COD and TN removal efficiencies of organic wastewater containing nitrogen are 98.7%and 89.1%respectively.The research mainly contents the following three parts.?1?The start-up characteristics of ABR reactor were investigated,and the operation status of each compartment was analyzed through various parameters,to provide data support for subaequent treatment of organic wastewater containing nitrogen by ABR reactor.The results showed that the removal efficiencies of COD and NH4+-N by ABR reactor are about90.0%and 15.0%respectively in the stable stage.1#and 2#compartments mainly play the role of COD removal.When VLR is 2.0 kg COD/?m3·d?,the removal efficiencies of COD in compartments 1#and 2#accounted for 46.28%and 43.53%of the total COD,respectively.The variation of NH4+-N in five compartments was tiny when VLR increased from 0.5kgCOD/?m3·d?to 1.5 kgCOD/?m3·d?.However,NH4+-N in five compartments changed significantly when VLR increased to 2.0 kgCOD/?m3·d?.At such COD load,NH4+-N concentration increased along the length of the reactor.With the increase of VLR,NH4+-N in compartments 1#,2#,3#showed down trend and then up trend.Along the length of the reactor,VFAs in each compartment showed down trend,while pH showed up trend.Effluent in 4#compartment of anaerobic digestion could meet the requirement of influent about COD in the partial nitrification-ANAMMOX process.?2?The enrichment and cultivation of anaerobic ammonia oxidation bacteria.In the enrichment and cultivation process,temperature and pH were maintained at 32?and 7.6-7.8,respectively.The effects of volumetric loading rate?VLR?on the nitrogen removal of anaerobic ammonia-oxidizing bacteria and the change of microbial community were investigated.In addition,the effect of granular activated carbon on the nitrogen removal of ANAMMOX process was also investigated.The results show that with the increase of NLR,the concentration of NH4+-N in effluent shows down trend,while the concentration of NO2--N increases firstly and then decreases.The removal efficiencies of NH4+-N and NO2--N reached62.5%and 70.0%respectively in the stable stage of exponential growth phase,and the consumption ratios of NO2--N and NH4+-N also gradually stabilized between 1.27 and 1.38.At the same time,the sludge morphology gradually changed from black to reddish brown.High-throughput sequencing showed that the microbial community also changed greatly,there were two anaerobic ammonia oxidizing bacteria named Candidatus Brocadia?4.46%?and Candidates Kuenenia?0.60%?in the sludge sample.therefore,it could be concluded that anaerobic ammonia oxidation occured in the reaction system.In the early stage of operation,NH4+-N and NO2--N could be adsorbed partly by the added activated carbon,which can reduce the impact of NLR increase.The long-term existence of activated carbon plays a role of immobilizing anaerobic ammonia oxidizing bacteria and enhancing nitrogen removal.?3?The effective combination of anaerobic digestion,partial nitrification and ANAMMOX process in ABR reactor was achieved,which could dispose the nitrogen-containing organic wastewater efficiently.The designed ABR reactor included seven compartments.Anaerobic digestion process was mainly acted in the 1#-4#compartments,which was used to remove carbon.Partial nitrification process was mainly acted in the 5#-6#compartments by controlling dissolved oxygen and free ammonia concentration,during which,the ammonia nitrogen oxidation rate and nitrite accumulation rate were stable at 51.4-64.1%and 90%,respectively,by optimizing DO and FA.ANAMMOX process mainly acted in the7#compartment by introducing the pH-regulationg effluent of partial nitrification compartment.The removal of organic matter and nitrogen by anaerobic digestion-partial nitrification-ANAMMOX system under steady state was realized in the disigend ABR reactor,and the average removal efficiencies of COD and TN were 98.7%and 89.1%.The results showed that the contribution to COD removal in order was anaerobic digestion compartment>partial nitritation compartment>ANAMMOX compartment.In terms of TN removal,the contribution in order was ANAMMOX compartment>anaerobic digestion compartment>partial nitritation compartment. |
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