Study On Nitrogen And Phosphorus Removal By Enhanced Ecological Filter

Based on the characteristics of high nitrogen and phosphorus content in the tailwater of sewage treatment plant,six plants such as reed,cyperus alternifolius and calamus were used to construct an ecological filter to purify sewage,and the strengthening effect of tubificidaes on phosphorus and nitrogen removal in ecological filter was studied.Combined with the operation of the tubificidae ecological filter,the influencing factors of nitrogen and phosphorus removal were studied.The following conclusions were obtained:The removal of nitrogen and phosphorus in the ecological filter showed obvious seasonal characteristics,and the six plant ecological filters showed the best performance in summer in terms of total nitrogen,ammonia nitrogen and total phosphorus,followed by spring and autumn,and worst in winter.Among the five pollution indexes of total nitrogen,ammonia nitrogen,nitrate nitrogen,total phosphorus and phosphate,the highest annual average removal rates were calamus(78.6%),paralysa(69.1%),calamus(79.4%),reed(89%)and calamus(87%).Calamus had the best effect on the comprehensive removal of nitrogen and phosphorus,and the comprehensive pollution index of nitrogen and phosphorus in the effluent of six plant ecological filters was calamus(26.9),reed(27.7),umbrella grass(30.0),cannabis(30.1),green onion(32.2)and cattail(33.1).After the addition of tubificidaes,the removal of nitrogen and phosphorus from the plant ecological filter was strengthened.Among the five pollution indexes of total nitrogen,ammonia nitrogen,nitrate nitrogen,total phosphorus and phosphate,the most obvious strengthening effects were Umbrella grass(4.8%),calamus(6.7%),green onion(7.7%),calamus(4.0%)and cattail(6.0%).The reduction values of the comprehensive nitrogen and phosphorus pollution index were calamus(8.8),umbrella grass(7.0),cattail(6.4),green onion(6.3),cannabis(4.5)and reed(3.9)in descending order.Different operating parameters affect the removal of nitrogen and phosphorus from the tubificidae-ecological filter.As the water intake increases,the filter deteriorates the removal of nitrogen and phosphorus.The comprehensive nitrogen and phosphorus pollution index of the effluent between different influents increased significantly(p<0.05),and in terms of the amount of applied carbon sources,the removal rate of total nitrogen and total phosphorus increased significantly,and the removal rate of ammonia nitrogen did not change significantly,and the total nitrogen removal rate increased by 11.6%when the amount of additional carbon source was 600mg/L.The stocking density of tubificidaes increased,the removal effect of nitrogen and phosphorus became better,and the comprehensive pollution index decreased significantly after 0.5kg/m~2,which decreased by 5.8;the removal effect of nitrogen and phosphorus became better after increasing the planting density,and the pollution index did not change significantly after 36 plants/m~2,and the removal rates of total nitrogen,ammonia nitrogen and total phosphorus were 81.2%,74.1%and 97.2%,respectively,and increased by 17.8%,14.1%and 5.9%,respectively.Compared with traditional ecological filtration,the enhanced ecological filter has low cost,easy construction and good management,and has a higher efficiency in removing nitrogen and phosphorus from sewage,which can effectively remove nitrogen and phosphorus in the tailwater of sewage treatment plants,and provide technical support for reducing nitrogen and phosphorus in the tailwater of sewage plants.