Study On Constructed Wetlands For Landscape Water Treatment

With the continuous development of urban construction in recent years and continuous improvement of people’s living conditions, a lot of man-made landscape waters are appearing in cities, especially in sites such as high-end residential, tourist attractions, parks and other places. But most of them are enclosed waters with small areas and low self-purification, which are apt to be polluted. If the surface water on the landscape or the corresponding river are left under poor management, or pollutants around the waters are emitted without control, they tend to be receivers of sewage, storm water and waste emissions, resulting in different degrees of pollution, even serious physical landscape blooms of algae. This will affect the surrounding natural environment and people’s quality of life.Constructed wetland, as an eco-friendly waste water treatment technology with low disposal cost and construction expenses, utilizing the combined physical and bio-chemical effect of plant-soil-microorganism to treat sewage water, is drawing more and more attention.This issue mainly studied the removal of eutrophication matter of the landscape waters. The subjects investigated contain the Youth Lake of Tianjin University and the moat of Tianjin Airport Economic Area. According to the water quality of the subjects investigated, a small test wetland with three step series where reeds, typha and canna are planted orderly is constructed by the Youth Lake. And it becomes a wetland wastewater treatment system by installing inlet and outlet controlling equipments; the pilot-plant of a constructed wetland of the management’s is borrowed to experiment by the moat of Tianjin Airport Economic Area. By sampling and detecting the in and out water of the two systems, the effect of the nitrogen and phosphorous removal is analyzed.In the experiment of the bench scale equipment which runs under the continuous and intermittent conditions, contrasted to the water quality standard, the ability of the wetland’s improving the landscape water quality is inspected; a conclusion is drawed that Wetland system has a better removal of pollutants in landscape water and removal rate was less affected by temperature, but by the impact on raw water quality. Simultaneously in the pilot-plant which runs under the operation mode, the ability of the constructed wetland to remove the contaminants of the landscape water was analyzed. It is concluded that Airport wetlands of COD、TP、NH3-N、TN average effluent concentrations were 51mg/L、0.7 mg/L、1.3 mg/L、1.49mg/L. Average removal rates were 32.45%, 40.37%, 41.07% and 41.34%. Based on the previous experiment, conclusions were summarized, including that it has a good operational effect under continuous flow conditions; the better HRT is 4h; pilot-plant wetland has many factors to improve in practice. At last, the main conclusions were reached, and further investigation in the aftertime was brought up.