Effects Of Three Typical Filler On Nitrogen And Phosphorus Removal From Domestic Wastewater By Bio-trickling Filter

Biotrickling filter is a kind of purification process relying on biofilm.It has the characteristics of low energy consumption and low sludge yield.It is widely used in the treatment of nitrogen and phosphorus removal under the condition of low energy consumption of rural domestic wastewater.As the main body of biological trickling filter,the effect of filler on the removal efficiency of nitrogen and phosphorus in trickling filter is studied,which is of great significance to improve the removal efficiency of nitrogen and phosphorus in trickling filter.In this study,red brick,ceramsite and activated carbon were selected as fillers to study the adsorption characteristics of nitrogen and phosphorus by isothermal adsorption and adsorption kinetics model.On this basis,a biotrickling filter with red brick,ceramsite and activated carbon as fillers was built to study its role in the process of nitrogen and phosphorus removal from domestic sewage by Biotrickling filter,and to analyze its effect on the nitrogen and phosphorus removal rate and operation efficiency of the reactor.It is hoped that a better filler for nitrogen and phosphorus removal in domestic sewage treatment by biotrickling filter can be found through this experiment.（1）Kinetics of nitrogen and phosphorus adsorption by three fillers were fitted by pseudo-first order,pseudo-second order,Elovich and two-constant equation.The results show that:The pseudo-first-order model is more suitable for describing the adsorption kinetics of nitrogen and phosphorus on three kinds of fillers,and the pseudo-second-order model is more suitable for describing the adsorption kinetics of phosphorus on red bricks and ceramsite.Elovich and double constant equation can well describe the adsorption kinetics of nitrogen and phosphorus by fillers,reaching a very significant level（R²>0.85）.（2）Bangham equation and intraparticle diffusion model were used to analyze the adsorption kinetics of nitrogen and phosphorus by three kinds of fillers.The results showed that the adsorption rate of nitrogen and phosphorus by fillers was affected by both intraparticle diffusion and extraparticle diffusion.（3）Langmuir and Freundlich isothermal models were used to fit the static adsorption test results.The results showed that Langmuir isothermal model was more suitable for describing the phosphorus adsorption process of red brick;Freundlich isothermal model was more suitable for describing the nitrogen adsorption process of three fillers and the phosphorus adsorption process of ceramsite and activated carbon;the theoretical saturated adsorption capacity of three fillers for nitrogen and phosphorus was activated carbon>red brick>ceramics.（4）It takes about 12 days for the system to be successful in film-hanging,and the rate of film-hanging is red brick>activated carbon>ceramsite;the removal efficiency of COD by Biotrickling Filter with different fillers is activated carbon>red brick>ceramsite;and the removal efficiency of NH₄⁺-N is red brick>activated carbon>ceramsite.（5）Hydraulic load has little effect on COD and TP removal efficiency of biotrickling filter with different fillers.The removal efficiency of NH₄⁺-N and TN increases first and then decreases with the increase of hydraulic load.The optimal hydraulic load is 0.6m³/（m²·d）.The removal effect of filler on COD,NH₄⁺-N and TP in wastewater was activated carbon>red brick>ceramsite,and the removal effect on TN was red brick>ceramsite>activated carbon.（6）The removal rates of COD and NH₄⁺-N in wastewater by trickling biofilter with different fillers increased obviously after changing the water distribution period.The optimal water distribution period was 10:1,and the removal effect was activated carbon>red brick>ceramsite.After changing the water distribution cycle,the removal rate of TN in the filter decreased significantly,and the removal effect was red brick>ceramsite>activated carbon.After changing the water distribution cycle,the removal rate of TP in the filter changed little,and the removal effect was activated carbon>ceramsite red brick.brick>ceramsite>activated carbon.After changing the water distribution cycle,the removal rate of TP in the filter changed little,and the removal effect was activated carbon>ceramsite red brick.（7）The removal of organic matter in water was analyzed by three-dimensional fluorescence spectroscopy.The results showed that the removal of organic matter in water by trickling biofilter was not only biological,but also the adsorption of fillers.