Study On Dynamics For The Removal Of Heavy Metal With Constructed Wetland

Wetland system has continuous and effective ability of removing heavy mental. At the same time, treatment of heavy mental wastewater by wetland system is a new research subject. Exploitation and study on relevant dynamics model of removing heavy mental by wetland system is not deep and enough, so wetland engineering lacks relevant guidance and optimization in practical construction and operation process.On the basis of existing dynamics model about constructed wetland, this thesis aims at dynamics model about constructed wetland removing heavy mental through experiments. It provides further theoretical support and reference for optimized design and efficient operation of constructed wetland, helpful to reasonable, effective operation and continuous development of constructed wetland in treating heavy mental wastewater.HRT of system is an important factor affecting removal of pollutants. The HRT experiment for the two wetland reed beds are made, the tanks-in-series and axial dispersion models are adopted to simulate the results of experiment, and non-ideality of the system is also analyzed. Fitting results show that fitting effects are much better with the flow rate at 65L/h and 60L/h for gravel system and at 40L/h and 50L/h for coke system. Langmuir and Freundlich equations are adopted to simulate the results of heavy metal wastewater experiment. Fitting results show that fitting effects are much better for coke system, but the gravel system can not be simulated. Fitting results of first order dynamic model show that fitting effects of Zn and Cu are good, and the constants of volume removal rate for Zn, Cu are 0.2326, 0.2017 for coke system and 0.1222, 0.3739 for gravel system, but the first order dynamic model cannot be used to describe the removal condition of Pb. Monod model, which accords with the reaction rules of microorganism much better, is quoted in the thesis. And the Monod model is used to describe two important hydraulic parameters of subsurface constructed wetland, namely, hydraulic loading and hydraulic retention time; the formula from fitting result is of realistic guiding significance for the normal operation of wetland system. Wetland plants have the effect of direct absorption and indirect enhancement in process of the removing of heavy metal with constructed wetland. The result of contrast experiment shows that there is a big increase in the removal of heavy metal by constructed wetland with reed comparing with constructed wetland without reed, and the removal rates of Cu, Zn, Pb each increase by 24.49%, 17.27%, 2.58% for coke system and 26.36%, 10.51%, 0.98% for gravel system.At last, on the basis of summarizing work already done, it discusses work need to be done in the future briefly.