Study On The Features Of Particulate Pollutants In Runoff And Stormwater Filtration Technology

Nonpoint source pollution that is triggered by stormwater runoff is the main source of pollution in urban cities and other areas; it has influenced people’s life, social and economic activities and environmental quality to a great extent. The source of pollution in different underlying surfaces and the relevant management and treatment measures have been the focus of the research on stormwater runoff for a long time. Many scholars at home and abroad have conducted extensive research on this issue and have obtained great achievement. With the increase of people’s understanding of pollution in stormwater runoff, people have realized that particles were the main carriers of all kinds of water pollution. Therefore, it’s of great importance to study the law of particle accumulation in different periods, the migration and transformation of particles when they are washed away by stormwater, the size distribution of particles in stormwater runoff and the occurrence and distribution of pollution for the removal of pollution in stormwater runoff and for sewage treatment in an effective way. On the basis of data analysis and summarization, the distribution and characteristics of particles in stormwater runoff were discussed in the paper in which the advantages and disadvantages of different ways of treating and controlling stormwater runoff were compared. It was analyzed from the perspective of stormwater filtering the equipment and techniques adopted in experiment by China and other countries; the properties and characteristics of all kinds of filter materials were also compared. The upflow filtering was chosen for designing the experiment on dynamic stormwater-runoff filter cartridges; and the data obtained from the experiment were used for analyzing the removal of particles and pollution. The research was carried out by combining the methods of document analysis, data statistics and physical experiment. The following achievement was obtained:(1) Analyzed the plans and measures for stormwater runoff management at home and abroad, compared biotechnology and other technology that were applied in China and other countries for retaining and filtering stormwater runoff, and drew the conclusion that, under the condition of the current construction management system in China’s urban cities, filtering is a practical, easy, convenient, low-investment and efficient method that is applicable to China’s urban cities, especially the build-up areas.(2) Summarized the characteristics of the distribution of particles in stormwater runoff that were mentioned in domestic and foreign research by adopting the method of document analysis and comparative statistics. It was found that the size and concentration of particles in stormwater runoff and the concentration of pollution in stormwater runoff demonstrated different laws and had different features in different underlying surfaces, during different dry spells and with different sources of pollution. On this basis, the equipment for filtering stormwater runoff, the filter materials and the technology for filtering stormwater runoff in different underlying surfaces were compared and analyzed; the effect of the experiment for filtering stormwater runoff on the size of particles and on the concentration of particulate pollutants were discussed, which laid the foundation for the mini filter experiment to be performed in the research.(3) Selected upflow filter experiment. By using the self-made filtration devices, four groups of filter materials, i.e. silica sand and zeolite, sponge iron, manganese sand and activated aluminium oxide, were added into the devices separately for carrying out the experiment on rainstorm water filtration. The effect of these materials on removing pollution such as SS, COD, TP, TN was analyzed. The result showed that all the materials managed to filter over95%of SS; the effect of the double-layer filter material that comprised silica sand and zeolite was better than that comprised silica sand itself when it comes to pollution filtration; at different speeds of filtration, the removal efficiency increased with the decrease of speed; when the speed of filtration was low, zeolite was able to absorb COD while silica sand was not. The efficiency of the four filter cartridges in removing TP showed that under the condition of low-speed filtration, activated aluminium oxide could absorb dissolved phosphorus to a certain extent; however, their efficiency in removing TN showed that the filter material containing zeolite had the ability to absorb dissolved ammonia nitrogen and to remove25%of the ammonia nitrogen. None of the filter materials were effective enough in removing other forms of dissolved nitrogen. The filter cartridges with sponge iron and manganese sand added was able to remove3%of nitrate nitrogen in water, but the data was not convincing.(4) According to the basic principle of stormwater filtration technology, based on the different goals (pollution control targets or stormwater reuse target) are suitable for China’s city of various types of stormwater harvesting facilities. Discusses the general structure design of a variety of stormwaterwater harvesting facilities based on the pollution control as the target, comprising a water outlet structure, pretreatment, filter media and filter the size of the facility design, and describes the various parts of the processing runoff and the role of construction requirements.