Pollution Characteristics And Source Control Technology Of Urban Road Runoff

With the development of the city,urban non-point source pollution is becoming increasingly serious,and turning to be an important source of urban water pollution.Road runoff is an important part of non-point source pollution.In this paper,according to the different traffic conditions,six different monitoring points were selected around the school,the characteristic of road runoff pollution in these points was monitored.And this paper also study the control effect of grass swale,earth ditch,boulder ditch and hanging basket on runoff pollution.Road rainwater runoff pollution monitoring results show that the road runoff pollution in these monitoring points was serious,the concentrations of COD and SS were the much higher than others,so they must be controlled strictly.When the rainfalll was low,the pollutant concentrations of the road runoff fluctuated within a certain range,and they have a positive correlation to rainfall intensity.When the rainfalll was high,the pollutant concentrations of the runoff were very high at the beginning of the rainfall,then reduced and stabilized within a certain range,now it has a negative correlation to rainfall intensity.Road runoff concentration of TP did not change significantly with the seasons,and COD,TN,SS concentrations were higher in winter than in summer;The order of runoff quality of different road types is: square road surface > parking lot road > residential area road> bridge > municipal road.Road runoff pollutants have a good correlation between the pollutants COD,TN,TP and SS,so that the SS should be paid much attention.The grass swale,earth ditch and boulder ditch all had a certain effect on the removal of COD,TN,TP,SS.The removal of SS was highest.With the increase of rainfall return period,the removal rate of COD,TP,TN decreased,the removal rate of SS changed little.With the increase of pollution load,the removal rate of COD and TN decreased and the removal rate of TP and SS increased.With the deepening of the soil depth,the removal rate of COD,TP and SS increased and the removal rate of TN was fluctuated.COD,TN,SS removal mainly concentrated in the surface,TP removal mainly concentrated in the bottom.In the road runoff pollution control,grass swale has more advantages than the earth ditch,boulder ditch.With the increase in the number of nylon mesh,the thickness of the geotextile and the load of the influent particulate matter,the permeability of geotextile and nylon mesh decreased.The larger the number of nylon mesh,the greater the thickness of the geotextile,the higher the intercept rate of runoff solid contaminants.200-mesh nylon net to intercept solid contaminants in runoff was 86.17%,200 g/m2 of geotextile to intercept solid contaminants in runoff was 96.04%.Nylon mesh than geotextiles more suitable as a material for hanging basket.This study designed a hanging basket which can collect all rainwater runoff and have anti-clogging function.