Study On The Start-up And Efficiency Of The Process Of CANON Coupled With Denitrifying Phosphorus Removal For Municipal Sewage Treatment

In order to meet the demand for high-efficiency and low-consumption treatment of municipal sewage,completely autotrophic nitrogen removal over nitrite is coupled with denitrifying phosphorus removal process to achieve the goal of simultaneous nitrogen and phosphorus removal.Based on this,this study used a continuous flow ABR-MBR reactor to start the coupling process to treat municipal sewage,and explored the impact of different organic loads and the effectiveness of actual urban sewage.The main conclusions of the study are as follows:1.Taking artificially prepared simulated municipal sewage as the treatment object,the ABR-MBR reactor was operated by gradually reducing the concentration of the influent substrate(NH₄⁺-N=100 mg·L^-1～50 mg·L^-1)to make the coupling process adapt to low substrate,and to cultivate and enrich AOB,An AOB and DPAOs for becoming the dominant strains.Results showed that when the influent water was at a higher NH₄⁺-N concentration(100 mg·L^-1),by adjusting the stop-exposure ratio（60min:45min→45min:45min）the coupling process was started,and after 55 days,more than 85%of carbon,nitrogen and phosphorus were removed.Then the NH₄⁺-N concentration of the influent was further reduced to 50 mg·L^-1,the operation of the coupling system was seriously destabilized.By reducing the dissolved oxygen(0.6mg·L^-1→0.4 mg·L^-1)and increasing the nitrate reflux ratio（200%→250%）to inhibit NOB,and to recover and enhance the adaptability of AOB,An AOB and DPAOs in the low substrate environmentthe,the start-up of the coupling process for the treatment of simulated municipal sewage was completed.A total of 102 days,under the conditions of DO=0.4 mg·L^-1and reflux ratio of 250%,the removal efficiencies of TN,PO₄^3--P and COD in the reactor effluent respectively reached 92.7%,85.8%and 92.3%,finally achieving the goal of efficient nitrogen and phosphorus removal and demonstrating the feasibility of the coupling process to treat municipal sewage.2.Keep the influent NH₄⁺-N concentration at 50 mg·L^-1,increase the influent organics concentration,and explore the efficiency of the coupling process in the treatment of municipal sewage under different organic loads(0.15 kg·m^-3·d^-1,0.30kg·m^-3·d^-1,0.45 kg·m^-3·d^-1,0.60 kg·m^-3·d^-1).The results showed that nitrogen was the least affected,and the removal rate of phosphorus and carbon was slightly increased.When the organic load was 0.45 kg·m^-3·d^-1,the removal rate of PO₄^3--P in the coupling process was the highest,which was 91.3%.When the organic load was 0.60kg·m^-3·d^-1,the TN removal and COD removal of coupling process had the best effect,and the removal rate reached 92.5%and 94.6%,respectively.Using high-throughput sequencing technology analysis,with the increase of organic load,the diversity of the biological community in the MBR system gradually decreases,and the ABR system has the lowest performance in stage III microbial community diversity,and the dominant bacteria phyla are all Proteobacteria、Chloroflxi、Bacteroidetes and etc.3.The influent water was replaced with actual urban sewage.Because the raw water matrix was low,glucose was added in the first 12 days to slightly increase the COD concentration of the influent water as a transition.During this period,the DO was reduced to 0.3 mg·L^-1.In addition,the reflux ratio was controlled to 250%.Stop exposure ratio is 45min:45min.It took one month to run the coupled process to treat actual urban sewage,which can achieve 93%carbon removal,90%nitrogen removal,and 83%phosphorus removal,which proves that the coupled process can efficiently treat actual municipal sewage.Compared with the sufficient amount of organic matter provided in the simulated urban sewage,the actual amount of organic matter in the actual sewage is limited,so the phosphorus removal effect is slightly lower.