The Experimental Study On Nitrogen And Phosphorus Removal By Optimized Biofilter Technology

As a typical biological membrane wastewater treatment technology,biofilter has its own unique advantages,such as simple equipment,less sludge and low energy consumption.However,appropriate pretreatment facilities are needed,and as an aerobic biofilm treatment system,the lack of necessary anoxic or anaerobic conditions leads to poor removal of nitrogen and phosphorus and the inhibition of nitrification in decarburization and denitrification,which restricts the application of biofilter.In order to promote the research and development of biofilter and its application in wastewater treatment,a series of optimization studies such as structure optimization,operation parameters optimization and process optimization have been carried out.The followings are the main conclusions in this study:Firstly,the adsorption characteristics comparison tests of four kinds of filter media,volcanic rock,ceramsite,anthracite and zeolite were carried out,and then the film hanging test was carried out.It is concluded that the adsorption capacity of volcanic rock and zeolite filter material has better adsorption effect on COD and ammonia nitrogen,reached 37mgCOD_Cr/g and 1.3mgNH₃-N/g respectively.Two sets of devices are used to cultivate the biofilm,the results show that the two stage biofilter with the anoxic filter column filling the volcanic rock and the aerobic filter column filling the zeolite filter has more advantages for the treatment of ammonia nitrogen.Secondly,the effects of biological filter operating parameters such as the height of submerged effluent,feeding frequency and reflux ratio on the pollutant removal efficiency of biological filter were studied.The test results show that the removal rate of COD,TN and TP increased first and then decrease with the increase of feeding frequency and reflux ratio,which could take feeding frequency 5min/15mi,reflux ratio100%,the increase of the height of submerged effluent would inhibit the removal of ammonia nitrogen and TP,and the optimum submergence ratio is 1/3.The hydraulic load of the biofilter is 0.05m³/?m²·d?,the feeding frequency is 5min/15min,the height of submerged effluent is 1/3,the reflux ratio is 100%,the removal rate of COD,ammonia nitrogen,TN and TP are 84.5%,68.7%,66.7%,26.7%respectively.Finally,a pilot plant of hydrolytic acidification-denitrogenation and phosphorus removal biological filter was established in Xiedao Resort.The hydraulic load is 1m³/?m²·d?,the feeding frequency is 5min/15min,the height of submerged effluent is 1/3,the reflux ratio is 100%,the average effluent concentration of COD,ammonia nitrogen,TN and TP are 23mg/L,6.9 mg/L,13.0 mg/L,1.40 mg/L,the average removal rates of COD,NH₃-N,TN and TP are 81.5%,78.8%,64.5%,49.1%respectively.Nitrogen removal is mainly achieved by hydrolytic acidification and denitrogenation and dephosphorization pool.The removal of TP is mainly removed by chemical precipitation of dephosphorization filter material in denitrogenation and dephosphorization pool.The process of hydrolytic acidification-denitrogenation and phosphorus removal biological filter could improve the shortcoming of nitrogen and phosphorus removal in biological filter.