Study On Phosphorus And Nitrogen Removal Performance Of Modified Combined Filler In Tail Water Of Sewage Treatment Plant

With the release of"Water Ten",some key areas require that the concentration of nitrogen and phosphorus in the discharged surface water is close to or up to the surface water classⅳstandard,so it is of great significance to the depth of nitrogen and phosphorus removal in the tail water of sewage treatment plants.This study abandoned brick and maize straw charcoal as the research object,by acid,alkali,salt and composite modification methods of waste brick and corn straw charcoal were modified to improve its adsorption ability of nitrogen and phosphorus in water,by static experiments and dynamic experiments,optimal modifier types and concentrations,filler composition proportion,reaction time and reaction temperature and other process parameters,The adsorption mechanism was analyzed by adsorption kinetics model fitting,adsorption isotherm model fitting,electron microscope surface characteristics analysis,Thomas model and Yoon-Nelson model fitting.The final conclusion is as follows:（1）Waste bricks have a certain adsorption effect on ammonia nitrogen and phosphorus.The waste bricks were modified by 1.0 mol/L Na OH solution,and the removal rate and adsorption capacity were 98.18%,69.57%and 0.065 mg/g,0.371 mg/g,respectively.The straw charcoal was first modified by hydrochloric acid,sodium hydroxide and Zn Cl₂for 24 h,and then combined modified by adding 0.5 mol/L lanthanum chloride solution seven hydrate.The adsorption effect of phosphorus and ammonia nitrogen was the best,and the removal rate and adsorption capacity were 98.95%and 35.86%,0.990 mg/g and 2.869 mg/g,respectively.（2）Adsorption kinetics and adsorption isotherm fitting were carried out for modified waste bricks and modified straw charcoal.The results showed that R²was greater than 0.9,and the quasi-second-order kinetics model fitted well with Langmuir adsorption isotherm model.（3）Scanning electron microscopy showed that the surface of the waste bricks modified by sodium hydroxide was rough and the specific surface area increased.The surface holes of the straw carbon modified by Zn Cl₂-Lanthanum chloride se7hydrate were increased and arranged regularly,which increased the specific surface area.After modification,both of the two fillers provided more adsorption sites.（4）Response surface experiment shows that the best combination ratio of waste bricks modified by na OH and straw carbon modified by Zn Cl₂-lanthanum chloride se7hydrate is 9:1,the best reaction time is 24 h,and the best temperature is 25℃.At this time,the removal rates of phosphorus and ammonia nitrogen are 99.06%and 46.72%,respectively.（5）Dynamic experiments show that the penetration time of phosphorus removal by the combined packing column is 8 h and the saturation time is 16 h when the inlet flow rate is 5m L/min under different control.The penetration time of the combined packing for ammonia nitrogen removal is 11 h,and the saturation time is 16 h.The fitting of Thomas model and Yoon-Nelson model was carried out,and the fitting was in accordance with Thomas model and Yoon-Nelson model,indicating that influent velocity had a significant impact on penetration time and saturation time.Modified combination packing can be used in the artificial wetland for sewage plant of tail water depth processing,execute when the sewage treatment plant effluent index in the urban sewage treatment plant pollutant discharge standard"level 1 B standard,the phosphorus removal effect can reach the surface water environmental quality standards,Ⅳclass standard,in addition to the effect of ammonia nitrogen can reach the town sewage treatment plant pollutant discharge standard"in the level of A standard,At the same time,a new way to use waste is found to realize resource utilization.