Study On An Integrated SEGSB-SBR Process Capable Of Shortcut Nitrogen Removal And Methanogenesis

An EGSB reactor was run on sequencing batch mode（SEGSB）to enrichmethanogens, as well as a SBR reactor for the enrichment of AOB by controlling timeand intensity of aeration. By combining the SEGSB reactor and the SBR reactor, anovel integrated SEGSB-SBR process was developed for the simultaneous removal ofCOD and ammonium through the mechanisms of methanogenesis, Anammox andshortcut nitrification-denitrification. The performance of the lab-scale SEGSB-SBRprocess was investigated by experiments with different influence and under differentoperational conditions. In addition, the contribution of different mechanism for theremoval of carbon and nitrogen were evaluated and the benefits of the process wereanalyzed. The following main results were obtained:①The methanogens were successfully enriched in the SEGSB reactor byinvreasing the influent COD concentration gradually from500mg/L to5000mg/L. Theeffluent COD after eight-hour anaerobic treatment was about60.2mg/L.②The concentrations of ammonium, NO-2-N and NO-3-N were5mg/L,20mg/L and3.5mg/L respectively in the effluent of the SBR reactor with the influent ammonium of40mg/L and without COD, which show a satisfied shortcut nitrification. However, whenthe influent contains ammonium of100mg/L and COD, the effluent ammonium andNO2--N nitrogen were22.1mg/L and18.9mg/L respectively. Although the presence ofCOD did not affect the removal rate of ammonium in the SBR reactor, shortcutnitrification were affected to some degree.③The SEGSB reactor with methanogensand the SBR reactor with AOB wereintegrated to form a new technology of wastewater treatmen. The operatingperformance of the integrated system was studied at the inner volume exchange ratio of20%,40%,57%.1）When the influent COD and ammonium were4332.87mg/L and90.64mg/L andthe inner volume exchange ratio was20%, the effluent COD and ammonium were70.87mg/L,39.88mg/L, the removal efficiency of COD and ammonium were98.34and56%. The result shows good methanogenesis and anammox activity in the SEGSBreactor of the integrated process. The concentrations of NH4+-N, NO2--N, NO3--N in theinfluent of SBR reactor of the integrated process were25.74mg/L,7.34mg/L and2.01mg/L, respectively. The corresponding effluent concentrations were3.47mg/, 21.75mg/L and1.93mg/L, respectively. The removal efficiency of ammonium was86.5%, the accumulation efficiency of nitrite was80.81%, which illustrates good shortcut nitrification in the SBR reactor.2）The whole experimental process was divided into three stages: B1（19-40）, B2（43-66）and B3（68-82）when the inner volume exchange ratio was40%. The influentCOD was4443mg/L and ammonium of the three stages were87.39mg/L,118.17mg/L,173.32mg/L, respectively. The effluent COD was76.25mg/L, and the effluentammonium of the three stages were26.85mg/L,35.12mg/L and49.49mg/L,respectively. The removal efficiency of COD was98.28%, the removal efficiency ofammonum were69.28%,70.28%,71.44%.The influent ammonium of the SBR reactor during the three stages were47.22mg/L,62.07mg/L and78.38mg/L, respectively. The corresponding effluentconcentration of ammonia were2.03mg/L,4.62mg/L and6.70mg/L, nitrite of18.42mg/L,29.08mg/L and36.83mg/L, nitrate of3.7mg/L,1.49mg/L and1.49mg/L. Theaccumulation efficiency of nitrite were95.62%,92.40%,91.04%, respectively. Theresults indicated the methanogenesis activity maintained a high stable level and not onlythe quantity but also the activity of anaerobic ammonium oxidation bacteria increased inthe integrated system. In other words, the activity of shortcut nitrification improved.3）Synthetic wastewater containing COD of4288.5mg/L and ammonium of174.48mg/L was treated by the SEGSB-SBR integrated system when the inner volumeexchange ratio was57%at85~106d.The concentrations of COD and ammonium in theeffluent of the system were92.18mg/L and40.39mg/L and the removal efficiency ofCOD and ammonium were95.23and76.82%. The concentration of NH4+-N in theinfluent of the SBR reactor was44.87mg/L. The effluent ammonium, nitrite, nitrate ofthe SBR reactor were1.97mg/L,29.78mg/L and0.73mg/L, respectively. The removalefficiency of ammonium was95.23%and the accumulation efficiency of nitrite was91.69%.4)The AOB activity and the accumulation of nitrite in the SBR increased when theinner volume exchange ratio was increased from20%to57%. The anaerobicammonium oxidation activity in the SEGSB reactor increased when the nitrite quantitywas increased. The removal efficiency of ammonia was improved, while the removalefficiency of COD was not affected obviously. Comparing with B1, B2and B3, theconcentration of ammonia in the influent did not affect the removal efficiency of CODand ammonia. 5） In order to study the operation characteristics, the synthetic wastewatercontaining COD of4722.76mg/L and ammonia of95.87mg/L was treated by theSEGSB-SBR with the inner volume exchange ratio of57%. The effluent concentrationsof COD and ammonia were55.59mg/L and17.38mg/L in the SEGSB-SBR. Theremoval efficiency of COD and ammonia were98.91%and55.8%.The concentration ofammonia, nitrite and nitrate were20.29mg/L,0.18mg/L,0.35mg/L in the influent ofSBR. While the corresponding effluent concentrations were3.30mg/,14.54mg/L、0.94mg/L respectively. The loss of total nitrogen was9.8%, and the rate of nitriteaccumulation was98.54%.③The mass balance of SEGSB-SBR was calculated at108-138d.35.3%ammoniawas removed by anaerobic ammonium oxidation,22.7%was removed by shortcutnitrification and0.5%was removed by complete nitrification，the total loss of TN was22.8%, while there was also18.69%in the effluent.83%COD was removed bymethanogenesis,2.3%COD was removed by denitrification, there was only1%was inthe effluent and the total loss of COD was14%. The methane production rate is287LCH4/kg COD of SEGSB-SBR.9703KJ energy and0.95kWh electrical energywere generated. Compared to complete nitrification dennitrification,27.72kgCOD and1.78kg O2were saved.