Study On Denitrifying And Phosphorus Removal Performance Of Improved Inverted A~2/O-MBR And Treatment Of Low C/N Domestic Sewage

The content of nitrogen and phosphorus in water exceeds the standard,causing water pollution and eutrophication of water bodies to become more serious and destroying the water ecological environment.Therefore,finding a method for efficiently removing nitrogen and phosphorus from sewage has become the research direction of many scholars.This study improved the inverted A2/O reflux system and the influent mode and studied the effect of low C/N wastewater treatment.The expperiment used improved inverted A2/0-MBR to treat domestic sewage,studied the influence of influent water distribution ratio,pH value,dissolved oxygen concentration and nitrifying liquid reflux ratio on the operation effect of the device,determined the operating parameters,and studied the treatment of low C/N domestic sewage.Processing effect.AbstractAfter 15 days of start-up culture,the improved combination system was stable in removing various pollutants.The average concentrations of COD,NH41-N,TN and TP were 21.01 mg· L-1,1.35 mg·L-1,9.70 mg ·L-1,and 0.66 respectively,the average removal rates were 94.76%,97.00%,78.38%,and 84.47%,respectively.When the water inoculation ratio of anoxic tank to anaerobic tank is 6:4,5:5 and 4:6,the remo val effect of COD and NH4’-N is better and the change is smaller,but when the influent distribution ratio is high,TN and The TP removal effect is good.In order to balance the effects of nitrogen removal and phosphorus removal,the influent water distribution ratio is selected to be 6:4.When the pH is 7.0-8.0,COD,NH4+-N，TN and TP can achieve better removal effects.The effluent concentrations are 25.53 mg·L-1,0.82 mg·L-1 and 7.77 mg ·L-1,1 and 0.42 mg·L-1,respectively.When the pH is increased to 9.0,the removal effect of TN and TP is deteriorated.The DO concentration in the aerobic pool was in the range of 1.6-2.4 mg·L-1,the COD removal effect was stable,and the nitrogen and phosphorus removal effects fluctuated slightly.When the concentration of DO in the aerobic pool was 2.0 mg·L-1,the average concentrations of COD,NH4+-N,TN and TP were 28.87 mg· L-1,1.34 mg· L-1,8.43 mg·L-1,0.50 mg·L-1,respectively.The average removal rates of were 92.90%,96.79%,79.77%,and 87.69%,respectively.The reflux ratio of nitrifying solution is in the range of 150%-250%,which has little effect on the removal of COD and NH4+-N,and has a great influence on the removal effect of TN,and rises and then decreases with the increase of reflux ratio.When the reflux ratio of nitrifying solution is 200%,the removal effect is optimal.The effluent concentrations of COD,NH41-N,TN and TP are 31.24 mg·L-1,1.10 mg·L-1,9.49 mg·L-1,and 0.43 mg·L-1,respectively,the removal rates were 92.22%,97.30%,76.60%and 89.26%,respectively.The improved inverted A2/O-MBR system for the treatment of low C/N domestic sewage shows that when the influent distribution ratio is adjusted to 5 5,the removal effect of TP is better,and the effluent concentration is 0.51 mg·L-1.The concentration of COD,NH4+-N and TN effluent was decreased by 21.55 mg-L-1,1.14 mg·L-1 and 12.85 mg·L-1,respectively.By increasing sludge recirculation and adopting segmented water inflow,the effect of nitrogen and phosphorus removal in inverted A2/O-MBR system is improved.The treated effluent concentration can reach Grade A standard,which has broad application prospects for upgrading and upgrading of water plants.