Concentration And The Hydraulic Loading Of Constructed Wetland, And The Effects Of Nitrogen And Phosphorus

With the rapid economic development, agricultural and industrial sewage especially rural life of non-point source pollution without treatment direct emissions to rivers then into lakes. Lake eutrophication is severe day by day. Treatment of lake’s pollution is imminent in Yunnan plateau.The experience of lake eutrophication solution both from domestic and oversea should combine ecological restoration and pollution sources control.The constructed wetland is a new green ecological sewage treatment and new technology. Compared with traditional sewage treatment. Constructed wetland can save more energy, less investment, lower cost, and higher efficiency. It partly solve plateau lake wetland eutrophication in China.This paper based on the National Natural Technology Fund " the plateau lake wetland plants-water-sand pollutants interaction mechanism research project"(No:50769001). The experiment simulate plateau constructed lake wetland by build outdoor experimental district, combined with the unique eastern of yunnan-guizhou plateau climate and natural condition. Compare and analysis about TP and TN removal effect when change water hydraulic loading and water concentration in different plants in surface flow wetland (SFW) and subsurface flow wetland (SSFW).The results of experiment as follow:(1)SFW and SSFW constructed wetlands can remove TP and TN.With the increase of water concentration and hydraulic loading, removal rate reduced. SSFW TP average removal rate is7.26%higher than SFW, the average TN removal rate is4.03%higher. SSFW constructed wetland treatment effect is better than SFW, but SSF require larger investment and higher technical.(2)With water concentration and hydraulic loading increase, different plants in SFW and SSFW have different TP and TN reduced removal rate. Purple leaf canna in SFW and SSFW with increased water concentration TP are largest reduce removal rate, reed in SFW and SSFW is the largest TN reduce removal rate. With hydraulic load increasing, the maximum TP removal rate decline in SFW constructed wetlands is water onion, the maximum TN removal rate decline is purple leaf canna. Purple leaf canna has the maximum TP treatment rate reduce,the maximum TN removal rate is reed.(3)Different plants in SFW and SSFW have difference TP and TN removal rate reduce. With the increasing of the concentration of water, reed in SSFW TP removal rate reduce value difference is the largest between SFW. TN removal rate reduce of water onion in SFW the value difference is the largest. With the water hydraulic load increasing, water onion TP and TN removal rate educe the value difference is the largest between SFW and SSFW.(4)Water concentration and hydraulic loading increase, TP and TN removal rate of different plants in SFW and SSFW constructed wetland is different. With the water concentration increasing, calamus is the largest average TP removal rate reduce value between SFW and SSFW. Reed is the largest reduce value for total nitrogen removal. With the hydraulic load increasing, calamus has the largest difference reduce of TP average removal rate in SFW and SSFW, reed the average difference of TN removal is the largest.(5)Water concentration increase, water hyacinth in SFW and SSFW wetland daily cleansing load of TP and TN are largest. Hydraulic loading increase, water hyacinth in SFW daily cleansing load of TP is the largest, the maximum daily cleansing load of TP is water onion in SFW. And the maximum daily cleansing load of TP and TN in SSFW is water hyacinth. So water hyacinth and water onion in SFW are better for TP and TN reduce. Water hyacinth, water onion and reed in SSFW is better for TP reduce and water hyacinth, water onion and calamus is better for TN (6)When change water concentration, TP average maximum daily cleansing load is60.16g/(d·m2) in SFW,81.50g/(d·m2) in SSFW. TN maximum daily cleansing load is547.2g/(d·m2) in SFW and557.60g/(d·m2) in SSFW. When change hydraulic loading, TP average maximum daily cleansing load is81.92g/(d·m2) in SFW,140.22g/(d·m2) in SSFW. TN average maximum daily cleansing load is634.31g/(d·m2) in SFW,704.93g/(d·m2) in SSFW.