| River is a vital component of urban ecological environment and landscape whichcontribute a lot to the urban construction and development. However, quantities ofurban river in our country have been severely contaminated and lead to the appearanceof black and odorous rivers in the last decades. Herein, we proposed a kind ofecological restoration method as well as some concrete implement issues to solve thisproblem. First of all, lab scale plot of static experiment for choosing the ideal plant andpacking was studied. Then the pilot plant test of surface flow constructed wetland(SFW)and the enhanced ecological pond were both investigated for the river water purifying.In the lab scale static experiment along some river in Nanning, Guangxi provincein China, five kinds of plants and two kinds of packing were studied to remove CODMn、NH4+-N、TN、TP in the polluted river water. These plants are canna, Myriophyllumaquaticum,Cyperus alterniflius, reed, calamus and packing are river stone and lava stoneindividually. The experimental results showed different kinds of plant and packing leadto diverse purifying performance as following: Myriophyllum aquaticum> Cyperusalterniflius≈canna>reed> calamus, lava stone> river stone. The removal efficiencyincreased with HRT, especially, in the first three days obviously, while furtheringprolong HRT did not cause higher removal efficiency.Canna and reed for the urban river water purifying and the resistance of the SFWfor impact load were studied through the pilot-scale surface flow wetland whenhydraulic loading was0.15m3/(m2·d). The purifying efficiency of the SFW when HLwere0.10,0.15,0.25,0.40m3/(m2·d) and t were examined individually;.Theexperimental results showed (1) the constructed wetland with canna has a betterpurification efficiency than the wetland with reed for urban river wastewater;(2)CODMn, TP in the polluted river water were removed in the first1/4section of wetlandsystem, this phenomenon was caused by the different removal way of CODMnand TPpurification, NH4+-N、TN have the same removal trend along water flow, SFW didn’thave significant increase for removal rate of NH4+-N、TN from1/4to half section ofthe system, the reasons can be ascribe to the small nitration rate caused by the removeof organic pollutants needs a lot of DO compete consumption;(3)SFW had the strongresistance to impact load, SFW has no significant furthering purifying ability because ofthe characteristics of difficulty degradation in low concentration inflow;(4) The removalrate of CODMn、NH4+-N、TN、TP in the inflow decreased with the increase of HL.This study compared the performance of a pilot scale enhanced ecological pond technology and traditional floating bed in treating river water. Results showed thatenhanced ecological pond was superior to traditional floating bed in CODMn, NH4+-N,TN and TP removal. While the two technologies exhibited higher removal efficiencythan the blank system. The reasons can be ascribe to the effect of the plants and thebiological film attached to the plants. At the initial period of the reactor operation, theenhanced pond system showed poor capacity in purifying river water due to lowtemperature and relative less quantity of microorganism. With the operating time gettinglonger, the plants turned into growth period from adaptive period, the root system ofthem gradually stretched to deeper water and they absorbed more energy, thus theremoval efficiency of two technologies improved. |
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