Study On Simultaneous Phosphorus And Nitrogen Removal Technology Treating Low Carbon To Nitrogen Ratio And High Strength Nitrogen And Phosphorus Wastewater

The by-product nitrate nitrogen produced in the single-stage autotrophic nitrogen removal process becomes the bottleneck of the system’s nitrogen removal efficiency,and the system does not have the ability to remove phosphorus.The research focused on low carbon to nitrogen ratio and high strength nitrogen and phosphorus wastewater,and proposed single-stage autotrophic nitrogen removal and simultaneous phosphorus removal technology.The effects of aeration mode,temperature,C/N ratio and the seed source on system construction were investigated.The construction method of single-stage autotrophic nitrogen removal and simultaneous phosphorus removal system was obtained.On this basis,the effects of DO,load and temperature on the processing efficiency of the system are investigated,and the key operating parameters are obtained.The main conclusions of the study are as follows:The aeration mode,temperature and C/N ratio have significant effects on the construction of single-stage autotrophic nitrogen removal and simultaneous phosphorus removal system,and the seed source has no significant effect on system construction.When the influent C/N ratio is 0.5,1.0,and 1.5,the reactor was constructed by the operation of 42d,47d,and 52d respectively.The average removal rate of NH₄⁺-N is over 99.5%,the average removal rate of TN was 97.5%,99.1%,99.3%,and the average removal rate of PO₄^3--P was 49.0%,71.4%and 88.2%,respectively.The C/N ratio had a significant effect on the simultaneous phosphorus removal capacity of the system.SMT test results showed that the reactors C/P ratio was 5,10 and 15,the proportion of inorganic phosphorus（IP/TP）in residual sludge was 84.39%,84.19%,86.40%,the proportion of non-apatite inorganic phosphorus（NAIP）in total phosphorus（TP）was19.79%,31.16%and 37.35%,respectively.The results showed that with the increase of C/P ratio,the content of inorganic phosphorus easily used in sludge increased.The effects of DO,load and temperature on the efficiency of single-stage autotrophic nitrogen removal and simultaneous phosphorus removal system are significant.Under the conditions of temperature 30°C,C/N ratio of 1.5 and a load of0.20 kg N·m^-3·d^-1,When the reactor DO was 4.0±0.2 mg·L^-1,4.5±0.1 mg·L^-1,5.0±0.2mg·L^-1,the average removal rate of NH₄⁺-N was more than 99.1%;the average removal rate of TN was 98.8%,99.4%,97.0%;the average removal rate of PO₄^3--P was69.2%and 81.5%,80.8%respectively.DO has significant effects on An AOB,NOB bacteria activity and phosphorus uptake process.Under the conditions of optimal working temperature 30°C,influent C/N was 1.5,nitrogen load was 0.20 kg N·m^-3·d^-1,DO was 4.5±0.1 mg·L^-1,The average removal rates of NH₄⁺-N,TN,COD and PO₄^3--P were 99.7%,99.4%,92.7%,and 84.2%,respectively.