Dynamics Research On Degradation Of Pollutants In Subsurface Flow Wetlands

The degradation of pollutants in subsurface wetlands is a complex process of physical,chemical and biological reactions.In the system,the dynamics of each reaction is the main factor determining the efficiency of pollutant treatment.According to the characteristics of plants,substrate and microorganism in subsurface wetlands,the degradation mechanism and the biological and chemical kinetics of the major pollutants were studied,the effects of temperature,p H,dissolved oxygen on the degradation of pollutants were analyzed,the removal effects of COD,NH3-N,TN and TP were simulated and the kinetic equation were established.The results are summarized as follows:Temperature,p H and dissolved oxygen have significant effect on the degradation of pollutants in subsurface wetlands.The optimum temperature for degradation of COD,NH3-N,TN and TP in subsurface wetland is 10~35?,the optimum p H is 6.5 ~8.5,the concentration of dissolved oxygen in anaerobic zone should be less than 0.2mg/L,in aerobic zone should ranged from 1.5mg/L to 2.5mg/L.The degradation effects of COD,NH3-N,TN and TP in the two types of subsurface wetlands all satisfy with the first-order kinetic reaction,the correlation coefficient of the first-order kinetics simulation of COD,NH3-N,TN and TP is 0.9732,0.9640,0.9600 and 0.9912,respectively,in horizontal-slag subsurface wetland,and in horizontal-volcanic subsurface wetland is 0.9641,0.9365,0.9709 and 0.9662,respectively,the correlation of each fitting curve is high.It showd that the first-order reaction kinetics model is a mathematical model with good reference value for the design and operation of subsurface wetlands.