| Because of the prominent environmental problems in China,water quality has been greatly improved in recent years.However,the over standard situation of nitrogen and phosphorus in main drainage basins in China still occurs.In order to improve the quality of water environment,it is necessary to improve the effluent quality of urban sewage treatment plants around the watershed.Because the water quality of the tail water has the characteristics of low C/N ratio and low phosphorus concentration,how to effectively reduce the concentration of nitrogen and phosphorus in the tail water has become the core problem of the renovation project of sewage extraction.On the basis of bioactive carbon technology,this research was based on the construction of biological carbon filter with different proportions of fillers,and a more mature biofilm was formed on the surface of the packing surface by natural membrane method.The influence of carbon source dosage,anaerobic/aerobic height ratio and surface hydraulic load on pollutant removal by reactor was investigated by control variable method.Under the conditions of better operating parameters,the stability of the reactor and the effect of the reactor on the removal of pollutants under different nitrogen load conditions were studied.Scanning electron microscope scanning of the fillers before and after the film was carried out.The protozoan species and bacterial species on the fillers were preliminarily analyzed.The main conclusions were as follows:?1?The reactor has probably experienced 3 stages during the startup of the membrane,which were the early stage of the biofilm culturing?06d?,the middle stage of the biofilm culturing?820d?and the later stage of the biofilm culturing?2238d?.With the increase of biofilm culturing time,the removal rate of pollutants was increased.In the later stage,the average removal rate of pollutants reached the maximum,and the average removal rates of COD,TN and TP were 75%,20% and 63?,respectively.?2?Under different C/N ratios,the removal rates of COD and NH4+-N were almost the same in 1#,2#and 3#reactors.But for NO3--N and TN,the removal rate of 2#and 3#reactor was higher than that of 1#reactor,which indicated that adding biological carbon in the river sand reactor was helpful to denitrification.?3?The removal rate of NO3--N,TN and TP in the 3#reactor was all higher than that of 2#and 1#reactor under different anaerobic/aerobic height ratio condition,which indicated that the addition of a proper amount of iron chips in the reactor was helpful to nitrogen and phosphorus removal.?4?When the surface hydraulic load was increased from 0.13cm3/?cm2·min?to0.26cm3/?cm2·min?,1#,2#and 3#reactors were basically reduced with the increase of the surface hydraulic load.However,the effect of 2#and 3#reactor on the overall removal of pollutants was better than that of the 1#reactor,which showed that the reactor containing biological carbon had more impact on the impact of the surface hydraulic load than the ordinary river sand reactor.?5?Under the conditions of better technological parameters,C/N was 6.30:1,the anaerobic/aerobic height ratio was 5:5 and the surface hydraulic load was0.13cm3/?cm2·min?,respectively.Although 1#,2#,3#and 4#reactors almost all could better simulate the first class B standard water quality to the first class A standard water quality to achieve the purpose of the water quality standard.However,the effect of nitrogen and phosphorus removal in 3#and 4#reactors were obviously better than that of 1#and 2#reactors.The removal rate of TN and TP in 3#reactor were 69.78%and 92.11%respectively,while 4#reactor's removal rate of TN and TP were 67.20%and 84.53%respectively.The concentration of TN and TP effluent met the urban sewage treatment of the Minjiang River and Tuojiang River Basins in Sichuan province.The standard of pollutant discharge of the factory?DB51?.?6?The results of SEM scanning of river sand and biofilm before and after hanging film showed that the surface of the river sand before biofilm culturing was smooth,and the biological carbon showed a good pore structure.After biofilm culturing,the river sand and biological carbon formed the structure of the biofilm polymer.The results of microscopic examination showed that the protozoa distributed on the surface of fillers were mainly composed of Sarcodina,Rotifer and Nematode.?7?By microbiological analysis of the fillers at different heights in the reactor with high throughput sequencing,which showed the denitrifying bacteria were mainly Betaproteobacteria in the reactors.The analysis of the richnes and diversity of denitrifying bacteria communities with nirS functional genes showed that both of them were the smallest in the lower part of the pure sand reactor.Therefore,it was explained that the removal rate of TN in the bio carbon filter reactor was greater than that of the pure sand reactor. |
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