Study On Performance Impact And Control Of Organic Carbon Source On The Complete Autotrophic Nitrogen Removal Granule Sludge

The complete autotrophic nitrogen removal process?CANON?is one of the most economical and effective denitrification processes at present.Compared with the traditional nitrification and denitrification process,it has the advantages of low energy consumption,low sludge yield and less investment cost.But the process still has some disadvantages,such as unstable starting process,long starting time,low sludge removal load and so on.Granular sludge has been widely used in total autotrophic nitrogen removal process because of its high compactness,good settling performance,bio-retention capacity ability and strong impact load capability.mainly based on the autotrophic nitrogen removal of granular sludge,we studied the proliferation of nitrosation granular sludge,and discussed the effect of organic matter on the performance of CANON granular sludge and the influence of the microorganism population and structure in this thesis.The specific research content and results are as follows:?1?Through the regulation of NLR,explore the changing rules of nitrosation granular sludge?NGS?performance and sludge proliferation ability.few inoculum sludge was inoculated for the start-up of a columNRE sequencing reactor?SBR?.During 130 days,the increase of mixed liquor suspended solids?MLSS?concentration in SBR from 0.1 g·L^-11 to 11.8 g·L^-11 was observed,corresponding to the nitrite nitrogen accumulation rate from 0.4 kg·?m³·d?^-11 to 4.9 kg·?m³·d?^-1,which was promoted by the higher ammonia nitrogen loading rate?NLR?from 0.74 kg·?m³·d?^-1to 6.66 kg·?m³·d?^-11 in the influent.Because of the obvious increase of small granules?size<200?m?,the mean average diameter of NGS decreased significantly at the NLR lower than 4.44 kg·?m³·d?^-1.With the higher NLR value,the growth of mean average diameter of NGS could be fitted well using modified Logistic model,and the specific growth rate of k value was around 0.0229 d^-1.In addition,the combined inhibition of nitrite oxidation bacteria?NOB?was expected by the relative high concentrations of both free ammonia?FA?and free nitrite acid?FNA?,thus the nitrite accumulation ratio?NAR?in the effluent was always higher than 80%.These results could provide a feasible approach to start up a high performance NGS reactor in industrial-scale.?2?Improve the OLR by reducing HRT,explore the effect of OLR on the performance of CANON granular sludge and microbial colony structure?sodium acetate was used as the organic carbon source to inoculate and cultivate mature CANON granules in the CSTR reactor to control the concentration of influent COD and NH₄⁺-N.The HRT was scaled down step by step,the OLR increased from 0.47kg·?m³·d?^-11 to 0.84 kg·?m³·d?^-1.The lower COD concentration did not seriously affect the denitrification performance of CANON granular sludge.When the OLR was 0.47and 0.57 kg·?m³·d?^-1,the system maintained high nitrogen removal performance with NRR of 81%and 82%,respectively,and increased OLR to 0.84 kg·?m³·d?^-1,NRR is72%.During the process of organic load enhancement,the f-value remained within the range of 0.11±0.02,and the apparent color of CANON granular sludge turned from reddish brown to light red.The results of Miseq High-Throughput Sequencing show that,with the increase of OLR,the richness and diversity of microorganisms in CANON granular sludge has increased,and some heterotrophic microorganisms and a small amount of AMX microorganisms that can oxidize organic carbon sources have emerged.AOB?Nitrosomonas genus?and AMX?Candidatus_Kuenenia genus?abundance decreased.The abundance of Nitrosomonas decreased from 4.5%to 0.01%,and the abundance of Candidatus_Kuenenia decreased from 35.39%to 18.38%.In addition,at the beginning of the study,when NLR was 3.2kg·?m³·d?^-1,the removal rate of OLR decreased from 72%to 64%and 27%to 24%when OLR was increased from 0 kg·?m³·d?^-11 to 1.6 kg·?m³·d?^-1,which reduced the activity of granular sludge to recover.?3?Through gradual increase of C/N,exploring changes in CANON particle performance and changes in microbial colony structure under different C/N conditions?The CANON granular sludge with good nitrogen removal performance in a CSTR reactor for a long time in C/N 0.25 water is seeded into the reactor,gradually increasing the C/N ratio by 0.5.0.75,1,and reduced to 0.It was found that as the C/N increases,MLSS and SVI show an upward trend.When C/N is 1,MLSS and SVI are15.9 g·L^-11 and 35.1 ml·g^-1,respectively,when C/N drops to 0.MLSS and SVI were15.1 g·L^-11 and 27.53 ml·g^-1.The NRR and NRE showed a downward trend with the increase of C/N.When the C/N ratio was increased to 1,the NRR and NRE decreased from 73%,86%to 18.2%,13.6%,and the C/N ratio decreased to 0.NRR and NRE recovery to 68%,88%.The results of Miseq high throughput sequencing showed that the improvement of C/N changed the microbial structure and composition of CAONO granular sludge,and increased the biodiversity of CANON granular sludge.The abundance of Candidatus_Brocadia and Nitrosomonas increased,and the abundance of Candidatus_Kuenenia decreased from 18.38%to 16.93%.The change of C/N can not change the status of Candidatus_Kuenenia dominant bacteria in the CANON granular sludge.