Constructed Wetland To Deal With Pollution Of River And Wetland Plants Screening Studies

In recent years, China's surface water pollution was still very serious, The seven major river systems was moderately polluted water in general,Lake eutrophication is still a prominent problem. Erhai Lake is the second largest freshwater lake in Yunnan.it also is the seventh largest freshwater lake in China,is being in the transition from poor nutritional status to the eutrophication. Major pollutants are total suspended solids, ozone-depleting substances, nitrogen, phosphorus, volatile acid, sulfur and so on. Mi Ju River is the most important tributary of Erhai Lake, its drainage area accounts for 60% of Erhai Lake basin area, water accounts for the water inflow in Erhai 51% of the total. The water quality of Mi Ju River determines the water quality of Erhai Lake. Industrial development and critical rural non-point source pollution leaded to the water quality of Mi Ju River was once reduced to IV class, after remediation, water quality has improved.Constructed wetland for its good and stable effectiveness in dealing with sewage treatment, lower cost of operation and management features, has been widely applied to control non-point source pollution, purification and repair damaged rivers and so on.In this study,for Mi Ju river circumstances of runoff in different seasons, Chosen by the sedimentation tank-bio-oxidation pond-one sheet-flow constructed wetland-two sheet-flow constructed wetland composed of complex artificial wetland to deal with Mi Ju river water. The results showed that:When the wetland run for some time to stabilize, temperature effects has become an important factor in removal efficiency of artificial wetlands.The highest removal efficiency of composite artificial wetland happened in September and October, the lowest in May and June. The removal rate in November and December was relatively stable, Description of wetland operation has been basically stable, but the removal rate decreased, which may be attributed to the lower temperature.Through decontamination efficiency study in three kinds of high, medium and low simulation hydraulic load of the composite artificial wetlands,we found that, in different hydraulic load, there were obvious differences in the removal efficiency of pollutants, in general, when the hydraulic load was small, the removal rate was higher. The best hydraulic load should be 0.16 m·d-1 Through the the study of concentration of pollutants along the way in the composite wetlands, it found that sedimentation tanks and oxidation pond to play a small role in the decontamination, but it also played a certain role in reducing the high pollution load and the total removal rate.The removal efficiency of composite wetlands is better than any one single processing unit.Wetland plants was an important part of constructed wetlands.In this paper, I studied the screening of wetland plants Preliminary,the results showed that:from the study of plant oxygen secretion can be seen,during the day when the light was strong, the concentration of dissolved oxygen increased rapidly in water, indicating during this time the plant photosynthesis was main, respiration was less. When light was weak or there is no light, the dissolved oxygen concentration began to decline rapidly, indicating during this time the respiration of plant was main, the respiration consumed a great deal of oxygen. Radial oxygen loss of six kinds of wetland plants' difference is not particularly significant, in order to measure the radial oxygen loss.I used the concentration of accumulated dissolved oxygens:Zizania latifolia (Griseb) Stapf>Phragmites australis>Pontederia cordata> Thalia dealbata>Canna glauca>Scirpus validus Vahl.From the experimental results of decontamination effects of the six kinds of macrophytes, we have seen the six kinds of water plants'removal effect on TN, TP, CODcr, NH3 is obvious, and for TN, CODcr, NH3,the system have plants'remove results were significantly better than non-plant system, while the TP removal, there is no significant difference between the plants and non-plant systems, indicating plant has played a leading role in the removal of TN, CODcr, NH3, while the plant played a supporting role in the removal of TP. From the experimental results,we have seen that better-performing plants include Phragmites australis, Zizania latifolia (Griseb) Stapf, Pontederia cordata, while the decontamination efficiency of Thalia dealbata, Canna glauca, Scirpus validus Vahl is relatively poor.We studied the release strength of the nutrients in six kinds of macrophytes. the release of CODcr and TN in six plants reached the highest value in the fourth day, while the release of TP reached the highest value in the tenth day, indicating the release rates of phosphorus is relatively slow, and it is closely related with the phosphorus content in plants. Based on a comprehensive analysis of the release strength of nutrients, we can see the release intensity of Pontederia cordata, Canna glauca and Zizania latifolia (Griseb.) Stapf were stronger than Thalia dealbata and Phragmites australis, in the selection of wetland plants, you can give priority to Thalia dealbata, Phragmites australis with weak release intensity could avoid the impact of water quality by decomposition of plants.