The Research On Simulating Constructed Wetlands To Deal With The Cadmium In Inorganic Wastewater

This research selected four plants that can concentrate and tolerate cadmium toconstruct two kinds of Integrated Vertical Flow Constructed Wetlands Systems(ⅠVCW)and Improving Integrated Vertical Flow Constructed Wetlands Systems(ⅡVCW).The structures of constructed wetlands,the the growth condition of plants in the Wetland,the effect of removing the Cd,the regularity of distribution of Cd and organic matter in the Wetland were studied,which just in order to find out the better combinations, plants and structures to remove the cadmium from wastewater by the wetland and obtaining some mechanisms about the removal efficiency of Cd.These results will provide the theory basis and practical experience for cadmium wastewater treatment with integrated vertical flow constructed wetlands in the future.The main results as follows:1.Results of the hydroponic experiment indicated that Echinodorus osiris,Tonina Fluviatilis,Cannal L and Coleus blumei Benth had good the tolerance in Cd patients,absorption and accumulation.Under the Cd stress, The Canna L has the most tolerance and absorption to the Cd,Echinodorus osiris was second,Tonina Fluviatilis was third,Coleus blumei Benth was last.2,The cadmium wastewater purification effect were well for both kinds of constructed wetland from the result of experiment.In the same constructed wetland,the removal rate of cadmium was better with plants than without plants.The removal rate of cadmium in theⅡVCW was better than in theⅠVCW with the same plants.The removal rate of cadmium was better planting Canna L and Echinodorus osiris than planting Tonina Fluviatilis and Coleus blumei Benth.In a word,the purification efficiency of Cd inⅡVCW was always better than inⅠVCW,and the constructed wetland planting Canna L and Echinodorus osiris was better than planting Tonina Fluviatilis and Coleus blumei Benth obviously.3.The contents of the organic carbon and Cd in the constructed wetland were:the upper layer(0-5cm)＞the middle layer(5-15cm)＞lower layer (15-20cm).With the increase of the depth,the concentration of Cd and organic carbon will be also decreased.4.Through the correlation analysis,we found that there were remarkable correlations between the proline and the content of Cd,the content of Cd and organic carbon in the constructed Wetland,the content of effective Cd and total Cd in the constructed Wetland,the increase in height of the plants and the content of effective Cd in the constructed Wetland.5.Considering the result above,the group of the Canna and Echinodorus osiris in the structure ofⅡVCW had the best purification effect to the Cd.