Study On Treatment Of Low C/N Domestic Sewage Of Inverted A~2/o-MBR Process

Sewage denitrification and phosphorus removal have always been the main problems to be solved in the field of sewage treatment in China and even the world.With the further improvement of China's sewage discharge standards,the removal of TN and TP has become the key to whether the effluent of the sewage treatment plant can meet the level A discharge standard of the Pollutant Discharge Standard for Urban Wastewater Treatment Plants.For low C/N ratio wastewater,it is more difficult to remove nitrogen and phosphorus,Therefore,it is very important to study the technology of denitrification and phosphorus removal of low C/N ratio wastewater,and it is of great significance to meet the discharge standards of wastewater treatment plants and upgrade existing sewage treatment plants.This study is mainly to study the effect and process parameters of the inverted A²/O-MBR combined process for treating low C/N ratio wastewater,and to provide technical basis for the popularization and application of the A²/O-MBR combined process.The test is based on simulated low C/N ratio wastewater.Combined static and dynamic methods are used to study the treatment effect and influencing factors of the inverted A²/O-MBR combined process on low C/N ratio wastewater.The main contents include:the start-up study of the inverted A²/O-MBR combined process;the effect of the inlet water distribution ratio,dissolved oxygen,and the mixed liquid reflux ratio on the combined process;the addition of a carbon source to the inverted A²/O-MBR combined process to handle low C/N wastewater research.The acclimation method of stepwise reducing the concentration of organic matter in the feed water is beneficial to the start of the inverted A²/O-MBR combination process.After 44days of startup,the amount of microorganisms in the reactor was relatively rich,and the removal of pollutants became stable.In the stable operation phase,the average effluent concentrations of COD,NH₄⁺-N,NO₃^--N,and TP were 17.04 mg/L,0.89 mg/L,17.73 mg/L,and 1.59 mg/L,respectively.No sludge swelling occurred during the entire startup process.Influent water distribution ratio,mixed liquid reflux ratio and dissolved oxygen have a greater impact on the removal of TN and TP.At the same time,dissolved oxygen also has an effect on the removal of NH₄⁺-N.The test was conducted under the condition that no carbon source was added,the feed water distribution ratio was 6:4,the dissolved oxygen was 2 mg/L,and the mixed liquid reflux ratio was 200%.The effluent mass concentration was 14.07 mg/L,0.87 mg/L,20.43 mg/L,and 1.22 mg/L.Due to the limitation of inadequate carbon source in the water,it is still difficult for TN and TP to meet the emission standard of Level A.Adding carbon source sodium acetate can improve the treatment effect.Compared with the treatment effect without adding a carbon source,the nitrogen removal rate and phosphorus removal rate increased by 27.1%and 16.32%,respectively,after adding sodium acetate.The lifting effect is significant.Sodium acetate dosing ratio has an influence on the treatment effect.The best effect is when the carbon source dosing ratio is 6:4.The concentration of nitrogen and phosphorus in the effluent can stably reach the emission standard of Grade A.The inverted A²/O-MBR combination process solves the contradiction of SRT between different strains,and through the optimization of operating parameters and the addition of a carbon source,the treatment effect of low C/N ratio wastewater can be stabilized to reach level A Emission Standards.The popularization and application of this process is of great significance for meeting the standards for the discharge of effluent from sewage plants and protecting the water environment.