| Artificial wetland,as one of the widely implemented ecological wastewater treatment techniques,has been applied for municipal stormwater,domestic and industrial wastewater treatment due to its cost-effective property.However,there are limitations in engineering application of this technique such as occupation of large land area and low efficiency regarding the removal of nitrogen and phosphorus from the nutritive wastewater,etc.Considering the current status of the development and application of artificial wetland,this research presents a new integrated technology system of vertical flow artificial wetland.On the one hand,the research work can enrich the theory of artificial wetland treatment technology.On the other hand,it has broad prospects for the application of domestic sewage treatment in the vast scattered rural areas.The main research work lies in:1.A new integrated technology system of vertical flow artificial wetland consisting of pretreatment system,water distribution system,wastewater treatment system,effluent collection system,flushing system and phyto system has been developed.2.In order to optimize the low capability for matrix pollutants removal of the integrated system,this research selected the ceramicite as the matrix of the wetland system.A study on the physical and chemical properties of the material,pore size distribution,specific surface area,adsorption capacity and mechanical strength of the ceramicite as medium material was conducted.The results of this study indicated that the ceramicite possessed the properties including large specific surface area and high porosity,which favors the accumulation and development of microorganisms needed for the system’s proper functioning.The results of efficiency testing on organic matters,nitrogen and phosphorus removal in wastewater indicated a noticeable enhancement,specifically for phosphorus removal rate,which can be up to 93% or above.3.The results of long term operation of the system indicated that,using ceramicite as matrix in the system coupled with cyperusalternifolius as the treatment plant,at the equilibrium of the system,the concentration of organic matter in the effluent was reduced to 50 mg/L,reaching a removal rate of 80%.In addition,the removal rates for total nitrogen and total phosphorus were up to 80% and 70 %,respectively,and the TP concentration was lower than 0.2 mg/L.At the same time,studies were also conducted for analyzing the treatment efficiency of the integrated system at different matrix filling methods and hydraulic loading.The results indicated that a layered filling method would yield a more efficient system than evenly filled system.On the other hand,lower hydraulic loading would result in a more efficient system in removing organic matter and total nitrogen but no impact on the removal of total phosphorus.Moreover,the study regarding the correlation of dissolved oxygen and removal of pollutants in wastewater indicated that a higher dissolved oxygen level in wastewater would result in a better treatment.4.Dissolved organic matter(DOM)was investigated using fluorescence spectroscopy combined with parallel factor(PARAFAC)analysis,and two-dimensional correlation spectroscopy(2D-COS).The results indicated that fluorescent organic matter was removed by the constructed wetland.Also the results of fluorescence regional integration by the combination of three-dimensional fluorescence spectra,relative to humic like components,protein components with relatively high removal efficiency,and artificial wetland microbial DOM increased with the degree of humification decreases gradually.5.Using the first order kinetics model of the artificial wetland system on the removal of COD,TN,TP and hydraulic load inverse are fitted.The results show that the degradation of simulated artificial wetland system kinetic model can be used for COD,TN,TP.The results of this research indicate that the integrated treatment system of vertical flow artificial wetland embodied the following advantages including simplicity,high efficiency in treatment,stability and installation with ease. |
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