Purification law of surface rainwater runoff by gradient filtration process
Based on the time mass concentrations(EMCs)values of SS,COD,TN,NH3-N,and TP in rainwater runoff of a higher education district,the permeability,blockage resistance,and pollution interception performance of different filtration media were comprehensively compared and analyzed.The permeability,anti-blockage performance,and pollutant interception performance of different types of filter media were comprehensively compared.The improvement of anti-blockage and pollution intercep-tion capacity of filtration system when gradient filtration process was applied to rainwater runoff treat-ment was explored.The results show that rainwater runoff pollution in this higher education area is se-vere.There is a linear relationship between the filtration speed and filtration pressure of various types of filtration media.The larger the mass per unit area or the higher the filtration accuracy,the worse the permeability and anti-blocking performance,and the stronger the intercepting capacity.When using geotextile with a unit area mass of 300 g/m2geotextile is used as a filter medium,the effluent meets the requirements of"Urban Sewage Recycling Landscape Environmental Water Quality"(GB/T 18921-2019).Compared with the single-stage gradient filtration process,the gradient filtration process can effectively improve the anti-blocking performance and pollution interception performance of the gradient filtration system.When the 150-mesh nylon mesh is used as the first-stage gradient filtra-tion medium and 300 g/m2 geotextile is used as the second-stage filtration medium,the anti-blocking performance and pollutant interception performance of the gradient filtration system are the best.
rainwater runoffgradient filtrationgeotextilenylon meshphysical filtration process
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