A Study Of Reaction Kinetics On Denitrification And Decarbonization In Vertical Constructed Wetland

With the accelerating process of urbanization, the water environment situation was not optimistic in China. Under the grim circumstances of high energy consumption, construction and maintenance costs in municipal sewage urban centralized treatment, the constructed wetlands sewage treatment technology was increasingly favored by people. Compared with traditional process, the vertical flow constructed wetlands system which showed a great development prospects, was considered to be quality and economy in both construction and operating costs, with the high ability of decarbonization and denitrification.Based on the characteristics in vertical flow constructed wetlands, this study simulated to construct a system filled by small-medium-large particle size filler sequentially along the vertical depth direction. We selected the water bamboo to be planted in the wetlands, which was aimed at studying the ability of denitrification and decarbonization of this device.After the start-up phase of the test, the pollutants removal rate of the analog devices was relatively stable, in other words, the plant survived, grew, completed the formation and propagation of microorganisms as well, which indicated that the test has reached mature running conditions.During the trial operating stage, in order to find the most optimum environmental conditions for carbon-containing organic compounds, ammonia, nitrogen removal for domestic sewage, we studied the pollutant removal under different hydraulic loading and the thickness of the filler, at the same time, explored the correlations between the concentration and distribution regularity of dissolved oxygen in the system and the pollutants removal rate. The results indicated that the end of the vertical flow constructed wetlands system’s CODcr removal efficiency was the best when the water hydraulic of the system loading was0.12m3/(m2·d) and the concentration of CODCr in wastewater varied from290to330mg/L approximately; NH4+-N removal rate was the best when the water hydraulic of the system loading was0.18m3/(m2·d) and the thickness of the filler was about60cm;the TN reduction of this system increased with the thickness of filler slowly when the hydraulic loading was0.18m3/(m2-d). The test analyzed the concentration and distribution regularity of dissolved oxygen within the system, studied the influence upon the pollutant removal, which showed that the dissolved oxygen was negatively correlated with the thickness of filler in vertical direction in the system, the CODCr, NH4+-N removal rate continuously reduced with the reduction of DO, however, the TN removal capacity increased with a relatively slow growth of removal rate.Based on the first-order kinetics model, the experiment analyzed the pollutants degradation processes, simulated the reaction kinetics of decarbonization and denitrification in this vertical flow constructed wetlands system, which had a certain reference for the further study of the vertical flow constructed wetlands system.