Study On Removal Mechanism Of Light Pollution Water In Ecological Pond/Wetland System

The qianwei village which is famous as one of the five hundred bestecological village is Shanghai's ecological base in chongming. It'sradicalization on ecologic has been more and more obvious. But based ofthe more peple visiting , the biggest landscape-lake-The Center lake,has shown the characteristic of bad loading capability, easy to be polluted,The water quality is worse and worse.Based on this case, we put forward the technics of ecologicalpond/wetland treatment system to control the pollution of lake. since thistechnics was applied very little in domestic or abroad, As a kind of try,the operation lasted about one year round and the research detailsincluded:(1) the performance and characteristic of ecological system for contaminative surface water under the special climate in chongming; (2) The influences of temperature ,influent concentration ,hydraulic loadingand organic loading on pollution removal. In the process of the wholeexperimentation ,the maintenance and management of eco-system had beensummarized to some extent.It is important for it to control water level and hydraulic loading at thebeginning of the mixture constructed wetland systems start-up. We put theplant on the constructed wetland system at Mar. But it has been rainingduring the time, and the water level submerges the constructed wetland. Itmakes the plant's growth influenced. It shows that it is influencing to someextent for hydraulic loading to control the growth of plant. Under the samehydraulic loading, the wetland with relatively better growing plantsdemonstrated higher pollutants removal efficiency than that with relativelyworse growing plants, that is the pollutants removal efficiency waspositively correlated to the growth status of plants. In addition, because ofthe small capability in the system ,we have to make essential measures tocontrol the in or out water level so that we can keep the eligible waterquality.The results showed the results as follow: when the HRT was between3 days to 5 days, the system had a higher removal efficiencies for thepolluted water. The removal efficiencies for COD_cr,TSS, NH₄⁺-N, TN,TP were 10%～40%, 35%～90%, 10%～50%, 35%～65% and 10%～ 55%, respectively.Because of the small capability, it's easy to be influenced by theoutside environment factors, The system showed the instability duringsome time. By the long-time experimentation, the final dates indicated: thesystem had most removal effect for TSS. This is because the results ofalgae's absorbing in organic grain in oxidation pond and aggregate'sadsorption effect in wetland system. In addition, the temperature and DO inthe water was a strong affect factors for the removal efficiency of pollution.The drop of temperature would bring on directly the drop of microbialactive. The removal rates of COD_cr and NH₄⁺-N lowered with theincrease of hydraulic loading rate, But the removal rates of total phosphorhad a negative correlation instead.