| It has proposed higher requirements for the effect of nitrogen and phosphorus removal treatment of rural domestic sewage based on high techniques along with the issuing and implementation of emission standards in various provinces of China.The treatment techniques with high efficiency,easy maintenance,low operational cost,stable and standardized nitrogen and phosphorus which are suitable for the features of sewage in rural areas are urgently demanded.The paper researches and develops the assembled integrated synchronous nitrogen and phosphorus removal bio-filter which is able to resist the fluctuations of water quantity and quality,easy for installation and maintenance by relying on establishing the nitrogen and phosphorus removal composite filler with high efficiency.Furthermore,it is adopted for the standardized treatment of scattered sewage in rural areas.The main results are presented in the following content of the paper:（1）It is to determine the intensified phosphorus removal filler for bio-filter.It is found out by the static adsorption experiment that the dephosphorization for the sponge iron and aerated concrete block are mainly chemical adsorption.Theoretically,the maximum adsorption capacities are respectively 2.139 mg/g and 1.849 mg/g,which demonstrated both two have good phosphorus removal performance.In this regard,the aerated concrete block waste is chosen as the phosphorus removal filler after cost saving and resource reuse are taken into consideration.（2）It is to optimize the best operational parameters for bio-filter.It is concluded by carrying out three single-factor experiments as hydraulic load,aeration rate and pollution load in the pilot-scale reactor that there is no obvious effect for disturbance of single factor on the removal rate of total phosphorus（TP）.When it comes to NH3-N,TN and COD,the effect is relatively more obvious.Additionally,it analyzes the variance and response results of regression model of removal rate in accordance with the response surface methodology used to quantify the effect of the three variables on the removal rate within the system.Finally,it is obtained that the optimum operational parameters for the system are:1.92 m3/m2/d for hydraulic load,without aeration,2.01 times as the secondary discharge standard for the concentration load.（3）It is to test and verify the operational effect and stability of the system.By operating with the optimum operational parameters,the NH3-N,TN,COD and TP of the effluent have reached A standard of level 1.Regarding the experiment of anti-hydraulic load impact,the average variation rate related to NH3-N,TN,COD and TP removal rate is respectively-5.32%,-6.31%,-6.52%and-0.53%;regarding the experiment of anti-pollution load fluctuation,the average variation rate related to NH3-N,TN,COD and TP removal rate is respectively-3.74%,-5.24%,-4.91%and-0.32%;it is proved by the above data that there are relatively better anti-hydraulic load and anti-concentration load fluctuation abilities in the system.（4）It is to analyze the microbial community’s relevant structure and function.It is obtained in accordance with the analysis of microbial Alpha diversity that the comparison of microbial diversity can be concluded as:aerobic unit<denitrification unit,zeolite<composite medium soil;among the top 30 dominant bacteria categories,the microorganism with the function to remove COD accounts for 30%,moreover,it is mainly distributed in aerobic zeolite（41.28%）and denitrifying layer zeolite（39.93%）;the microorganism with the function to remove NH3-N accounts for 26%,moreover,it is mainly distributed in aerobic zeolite（40.30%）and denitrifying layer zeolite（45.74%）;the microorganism with the function to remove nitrate nitrogen accounts for 28%,moreover,it is mainly distributed in composite medium soil（55.95%）;it is obtained in accordance with the analysis of Network that the crucial species of zeolite flora in the aerobic layer are respectively Nitrospira and Burkholderia-Cabal-leronia-Paraburkholderia.The crucial species of zeolite flora in the denitrifying layer are respectively Nitrococcus and Sinomonas.The crucial species of soil flora in denitrification layer is Zobellella.The above key species play a central role in the microbial population.（5）It is to analyze the relevant operational effect and cost for the demonstration project.The average increasing rate related to the removal rate of COD,NH3-N,TN and TP is respectively 27.08%,46.45%,48.08%and 55.17%after the integrated bio-filter technique is added in the practical engineering application.In this regard,the concentration of each pollutant in the terminal outlet reaches A standard of level 1;in light of the investment cost of engineering water,it is 5200 Yuan/T with the operational cost being 0.35 Yuan/T.It is concluded that the technique is low in investment and operational cost and it is feasible for upgrading and transforming the current sewage treatment projects in rural areas. |
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