Study On Deep Purification Of Low C/N River By New Type Of Leaching Compound Wetland

In order to study the deep purification process of low-polluted city rivers,the HexiTangxi River water was used as the object to be treated,and the pond water treatment project of Tangxi River was constructed,including leaching and wetland and floodplain wetland.From the end of August to the end of August 2015,the effluent from the leaching type wetland and the flood plain wetland was continuously monitored.The removal efficiency of the pollutants such as nitrogen,phosphorus and COD_Cr was analyzed.The results showed that the four kinds of materials,such as fruit shell,PCL,PLA and peat,were used to analyze the carbon release properties and the types of dissolved organic matter.The denitrification effect of these four materials was further tested by simulated column experiment.The main results as follows:?1?Under the condition of average temperature of not less than 10?,the removal efficiency of TN,NH4+-N,TP,COD_Cr and chlorophyll a was better than that of TN,NH4+-N,TP,COD_Cr and chlorophyll a The recoveries were 61.09%,90.58%,58.81%,33.23% and 70.26%,respectively.The average effluent concentration of COD_Cr is below 30mg/L,which is better than Environment Quality Standard for Surface Water?GB3838-2002?IV.?2?The removal of pollutants from the two purification units of the leach-type and wetland and the wetland of the floodplain is different.In addition to the low temperature of 12,1,and 2 months,the removal of TN,NH4+-N and TP is mainly in the flood plain The purification rate of TN,NH4+-N and TP is 89.9%,57.1% and 81.5% of the total purification rate respectively.The reduction of COD_Cr and chlorophyll a in the wetland system is mainly in the superimposed wetland unit,The purification rate accounted for 69.7% and 59.50% of the total purification rate,respectively.?3?The order of carbon release capacity of four kinds of denitrifying carbon source of shell,PCL,PLA and peat was: shell> PCL> peat > PLA,and the concentration of COD_Cr after stabilization was 94.93 mg/L,66.13 mg/L,16.33 mg/L,33.73 mg/L.Compared with the three-dimensional fluorescence spectra of four carbon source materials,it can be seen that the peaks of the peaks in the spectra of the shell and peat are significantly higher than those of PCL and PLA.The contents of four kinds of humus,protein-like substances,fulvic acid and microbial metabolites were as follows: peat > PLA> shell> PCL;PLA> shell> PLA> peat;PLA> peat > PCL> shell;shell> PCL> PLA> peat.?4?The average influent concentration was 0.09 mg/L,0.13 mg/L,3.95 mg/L,3.36 mg/L,the average temperature was 25.3?,the influent NO3-concentration was 4.60±1.08 mg/L,the average removal rate was 97.84%,97.02%,12.82% and 30.08% respectively.By scanning electron microscopy,the biomass of the shell material decreased from 100 mm to 700 mm,To 700 mm after the material surface and the surface of the material before the experiment is not very different,PCL from the water inlet 100 mm to 700 mm can be observed at the surface of the material cracks and holes,indicating that the packing layer is relatively complete.