The Optimal Design Of The Hydraulics Parameters In Constructed Wetlands

Constructed wetlands is a new technology which is widely used in domestic wastewater and industry wastewater purifying treatment. It can purify wastewater by the multiple effects of substrates, wetland plants and microbe in constructed wetland and shows well effective. The factor about hydraulics has a great influence on the system's treatment effect. However, nowadays in our country, there are few researches on the interior mechanism of the constructed wetland system, especially the ones relevant to the hydraulics. Compare with these countries with mature constructed wetland technology, we usually design constructed wetland base on tradition experience formula and project practice. Few of these works focus on hydraulics problem in wetland designing and operation and no rules or conclusion obtained. The author work comprehensively on the important problems on hydraulics and parameter optimal design of constructed wetland, then develop the optimal design modelThis paper also analyze the effects on wastewater treatment, which cause by the factor of hydraulics including hydraulic loading rate, hydraulic retention time and system depth etc. Further more , introduces three important constructed wetland system calculating model. One is first reaction kinetics model under Darcy flow impact. The second is Monod reaction kinetic model, which is few been studied and the other is Convection-dispersion Equations Model. Then, these researches get the value of the important parameter rate such as constant "k_v" of first reaction kinetics model, coefficient of permeability "K" of Darcy's Law and Hydrodynamic Diffusion Coefficient "D" of Convection-dispersion Equations. Finally, this paper investigates these three calculating models in optimal design Constructed Wetland system and focus on the application of Convection-dispersion model in the design of Constructed Wetland system. At the same time, it put forwards a late-model Artificial Neural Networks model. Then, the author validates these kinds of model by experiment data of small scale test.After summarizes domestic and foreign researches of wetland, the researches indicate that compare with other styles of constructed wetland, vertical-flow constructed wetland (VFCW) system has superiorities on sewage management, sanitation condition and occupied land area as well. So, this thesis constructed a vertical-flow wetland system and validate the simulation effect. By analyzing and comparing the advantage and disadvantage of different model, the author finds out that Convection-dispersion Equations Model is the optimal hydraulics parameter design model. The researches indicate we can get well predictiveness and feasibility by using Convection Dispersion Equations Model in VCW system. It should provide some information to those who depend on experience and lack of scientific basis in designing of constructed wetland.Through studies above, the author expects to provide useful information for the optimal design and effective operation of constructed wetland and promote the applicant and development of the constructed wetland wastewater treatment technology.