| Control of non-source pollution is one of the most significant issues in the construction of sponge cities.Road gully is an important part of non-point source pollution control in urban area,but there are few researched about the optimal design and function expansion of road gully.In this paper,a sponge-type intelligent rainwater diversion module for road runoff pollution control was developed,and experiments were conducted to analyze the hydrological and water quality effect of the modules.A model of hydrological and water quality effect for engineering application was established and verified by practical cases.The diversion module consists of four parts: shell,rainwater grate,hanging basket,and filter element.It has the characteristics of overflow,reducing runoff pollution,anti-mosquito and deodorization,good load-bearing performance,and convenient installation.According to different application scenarios,two types of modules(A and B)were developed.The inner diameter of the shell of A-type module is 800 × 500 × 1000 mm,and which of the B-type module is 640 × 440 × 810 mm.The intelligent unit of the diversion module is equipped with a set of intelligent monitoring system based on Internet of Things technology,which has functions such as rain grate shift alarm,water level over-limit alarm and maintenance prompt.The test results of the mechanical properties of the shell and the fouling interception performance of the filter unit showed that when the mass ratio of epoxy resin(E-44)and filler(standard sand)was 1:10,the compressive strength of the shell could reach 60 MPa,and the flexural strength was higher than 16 MPa,and it meets the compressive and flexural strength requirements of the gully shell in "Grain Standard Atlas 16S518".Filtration method,filter material gradation and filter brick thickness had a certain influence on the filter unit’s interception performance.After comprehensive comparison and selection,brick-type filter material was used.The ratio of main material(zeolite): filler(activated carbon)= 3:1,the thickness was 3 cm.The hydrological effect test results of the diversion module showed that the runoff time and runoff reduction rate of A-type diversion module were better than those of B-type under all test conditions.When the rainfall return period increased or the rainfall duration decreased,the runoff time and runoff reduction rate of the two modules decreased correspondingly.When the rainfall duration was 120 minutes,the rainfall interval was 1 day,and the rainfall return period was 2 years,the runoff time of the two diversion modules A and B was the longest,330 s and210 s,respectively;the runoff reduction rate was the highest,32.21% and 19.55% respectively.The results of the water quality effect test of the diversion module showed that: under various test conditions,the pollutant removal rate of the A-type diversion module was relatively higher;when the rainfall intensity increased or the concentration of pollutant in the influent decreased,the pollutant removal rate decreased;When concentration was high(SS 2000 mg/L,COD 1200mg/L,TN 8 mg/L,TP 2 mg/L),rainfall interval was 1 day,rainfall duration was 60 minutes and rainfall recurrence period was 5 years,the pollutant reduction effect of the two diversion modules was the best,and the removal rates of SS,COD,TN and TP of A-type module were80.3%±0.95%,65.5%±0.95%,60.1%± 0.84% and 49.5% ± 0.81%,which of B-type modules were 78.8% ± 0.96%,62.2% ± 0.97%,58.9% ± 0.91% and 47.8% ± 0.78%,respectively.According to the hydrology and water quality effect test data of the diversion module,the SWMM software was used to simulate and analyze the overall hydrology and water quality effect of Danqiao Road,Huaqiao Economic Development Zone,Kunshan City.The runoff reduction effect of the diversion module was not significant under the conditions of large catchment area and long-duration rainfall.The emission concentration and peak value of SS,COD,TN and TP all decreased significantly,and the pollutant removal rate decreased with the increase of rainfall intensity.When the rainfall return period was 1 year,and the rainfall duration was 2 years,the pollutant removal rates reached 76%,59%,58%,and 43%,respectively.In the new drainage project of Danqiao Road,Huaqiao Economic Development Zone,Kunshan City,the engineering application of the diversion module was carried out.The result of the practical test of runoff pollutant reduction showed that the average removal rates of SS,COD,TN and TP were 68.2%,56.1%,54.5%,and 38.7%,respectively,which were basically consistent with the pilot test results.The verification results of the SWMM model show that in the actual rainfall on March 17,2022,the Nash efficiency coefficients of road discharge flow and COD concentration were both greater than 0.5,indicating a good degree of fitting and high reliability of the simulation results.The application results of the intelligent system show that it can realize long-term stable operation,and can accurately monitor the information such as the displacement of the rain grate,the water level exceeding and the amount of garbage.This development and the research results provide an alternative technical path for road flow pollution control. |
