Study On Design Optimization Of Innovative Multistage Lateral Flow Biological Aerated Filter And Its Treatment Efficiency

In recent years,with the rapid development of the country's new rural construction and continual improvement of rural residents living standard,the amount of sewage discharge has been increasing annually in the rural area of our country,and the pollutant is also increased,the research of rural sewage treatment technology and equipment has become a hot point at present.Based on fully considering the characteristic of sewage discharge of the rural areas in China,this paper develops innovative multistage lateral flow biological aerated filter combined with traditional biological aerated filter,gravel filter technology and biological contact oxidation technology,which provides some new ideas and choices involving sewage treatment of family,village and town.1.A innovative multistage lateral flow biological filter reactor is designed.The design flow of filter is 6m³/d,and the size is L×B×H=2.5m×0.6m×1.1m,the filter is divided into five sections,including intake area,level 1 packing area,level 2 packing area and discharge area,level 3 packing area,the five sections is filled with biochemical ball,zeolite and ceramsite as carrier,respectively.2.The equipment adopts the way to hang biofilm,and the way is adding sludge——aeration——sequencing water.After a period of about 17 days training,it can be seen a layer of gray and brown biofilm in the surface of packing and lining of experimental equipment.After the system started 11 days,the COD_Cr of influent has a large fluctuation,but the COD_Cr of effluent is below 10mg/L all the time,the removal rate has reached above 84.2% stably;After the system started 12 days,the NH₃-N of influent has a large fluctuation,but the NH₃-N of effluent is below 5mg/L all the time,the removal rate have reached above 81.2% stably,then the equipment finished hanging biofilm,and it started to enter stable operation period.3.Processing efficiency test: When the system finished hanging biofilm,dissloved oxygen,hydraulic loading of filter and filter treatment efficiency were studied and analyzed at all levels.?1?Dissloved oxygen test results showed that: when the design flow is 0.25 m³/h,the removal rate of COD_Cr and NH₃-N increased gradually with the increase of dissolved oxygen under the condition of aeration of level 1 filter.the optimal dissolved oxygen of the equipment is 3.0±0.1mg/L,the system removal rates of COD_Cr,NH₃-N,TN and TP were 89.43%,85.13%,44.52% and 56.62% under thecondition,respectively.dissolved oxygen of influent,level 1 packing area,level 2packing area and level 3 packing area were 0.48mg/L,2.98mg/L,2.05mg/L,1.54mg/L,respectively.?2?Hydraulic loading test results showed that: the removal rate of COD_Cr,NH₃-N TN and TP increased gradually with the increase of hydraulic loading.The removal rate of SS changed a litter,the effluent concentration was below 10mg/L,and removal rate was above 92%.when the dissolved oxygen of level 1 is 3.0±0.1mg/L,and the optimal hydraulic loading of the equipment is 1.39m³/?m2·h?,average effluent concentration of COD_Cr,NH₃-N,TN,TP and SS were 10.98mg/L,4.15mg/L,17.11mg/L,0.92mg/L,8.09,respectively.?3?The filter efficiency of various filter processing performance test results showed that : during the test period,the average concentration of COD_Cr,NH₃-N,TN,TP and SS of the equipment were 102.10mg/L,37.85mg/L,46.57mg/L,2.45mg/L and188.83mg/L,respectively.?1?for level1 filter,the average removal amount of COD_Cr,NH₃-N,TN,TP and SS and were 58.36mg/L,13.40mg/L,17.62mg/L,0.36mg/L and21.56mg/L,respectively.The level 1 filter of the systerm has good removal effect on all quality indexes,it mainly removes COD_Cr,NH₃-N and TN;?2?for level 2 filter,the average removal amount of COD_Cr,NH₃-N,TN,TP and SS were 18.74mg/L,12.86mg/L,8.43mg/L,1.01mg/L and 95.07mg/L,respectively.The level 2 filter of the system is mainly composed of and phosphorus and SS removal,and the average effluent SS concentration of two stage is 72.20mg/L,which meets the requirements of water suspension of the third stage filter;?3?for level 3 filter,the average removal amount of CODcr,NH₃-N,TN,TP and SS were 13.26mg/L,5.41mg/L,4.45mg/L and0.18mg/L and 65.13mg/L,respectively.The level3 filter of the systerm has good effect on removing SS,which can meet the discharge standard.The treated discharge of COD_Cr,NH₃-N,TN,TP and SS can meet the leve 1 B standards of “pollutant discharge standard of urban sewage treatment plant”?GB18918-2002?.