The Research On The Water Quality Evaluation And Protection Technology Of Outdoor Building Landscape Water

Outdoor building landscape water is an important part of urban water environment, and is an important participant of urban environmental ecological system and sponge city urban ecosystem, a good building outdoor landscape water is in reaction to the urban life, and is the inevitable requirement of ecological civilization construction. Outdoor building landscape water has the characteristics of poor mobility, small size, poor self-purification capacity, a wide source of pollution, etc, and is prone to water eutrophication. At present there are no unified standards of outdoor building landscape water quality requirements, no unified and effective solutions of the water quality security.This paper selected four building outdoor landscapes in Beijing as the research objects,and obtained the change rule of outdoor landscape water quality through the long-term monitoring of water quality. The paper evaluated the water quality building outdoor landscape water by grey clustering model. The paper made a research on the removing algae and floating algae of landscape water eutrophication.The paper explored the removal effects on algae, ammonia nitrogen and total phosphorus,under the conditions of different concentrations, settling time, pH and different composite kaolin.The paper researched water quality and protection of technology demonstration projects based on Ming Lake.The results of the paper are as follows:(1)Building outdoor landscape water quality changes greatly depending on the season. The number of algae, turbidity, pH, COD index is on the rise during April to September, showed a trend of gradual decline during September to November. Dissolved oxygen, ammonia nitrogen index declined in the April to September period, with gradual increase from September to November; Total phosphorus content from April to November showed a trend of cumulative increase; Water temperature change rule is in accordance with the temperature change rule.(2) Establish the gray clustering evaluation model of water quality of water in landscape, to evaluate the water quality in Ming Lake, Jia Park, He Park, Lai Park around the typical architectural landscape outdoor water.(3) Polymeric ferric sulfate coagulation and remove algae test results show that the concentration of Polymeric ferric sulfate is30mg/l; the setting time is 30min;the best pH of the algae remove effect is 7-8, the highest removal rate reached 95%.(4) The research about algae floating again after coagulation shows that:when the temperature is 25℃ and the light intensity is 5001x, the floating phenomenon is the most obvious. Polymeric ferric sulfate compounding different kaolin can partly inhibit algal body to float, when composite kaolin particle size is 180 mesh, the concentration of 30 mg/1 of algae floating inhibition effect is best.(5) Relying on the Ming Lake building outdoor landscape water quality security technology demonstration project. Multi medium filter combined with coagulation sedimentation filtration unit running process on Ming Lake water governance. Engineering run long-term effects:The removal rate of Ming Lake water turbidity is 75%; The removal rate of Nitrogen and phosphorus is approximately 80%;The algae removal rate is approximately 85%;Total phosphorus removal rate is about 70%. Th benefit value of this demonstration project is greater than the cost, it is worth popularizing widely.