Research On Embankment Flowing System For Control Of Urban Non-point Source Pollution

At present, along with the accelerating urbanization process, urban non-point sourcepollution is more and more serious. Rainfall runoff will carry solid particulate matter,nitrogen and phosphorus nutrients, heavy metals, organic pollutants and bacteria andother pollutants to rivers, however, the characteristics of non-point source pollution aremore sources, strong randomness, more influence factors, more kinds of pollutants andthe concentration changes more, so the governance is very difficult. Riparian zone, whichaction can not be ignored, is the last barrier before urban rainfall runoff into the rivers,how to carry on the reasonable utilization across the side band, choose the appropriatetechnology for ecological reconstruction, restore and strengthen the control of urbannon-point source pollution ecological resistance ability become one of hot topics in thestudy of the current global urban environment.In view of the situation of urban non-point source pollution, the technology ofsewage land treatment technology in surface flowing and the urban river Banks of theriver system are used to propose a river embankment flowing technology, and thenthrough the laboratory simulation probes into the practical engineering design of thetechnology, and studied the technology of rainfall runoff suspended particulate matter(SS), chemical oxygen demand (COD), ammonia (NH3-N), total phosphorus (TP), andother major pollutants purification effect, and discusses the technology of main pollutantsremoval performance. Main conclusions are as follows:(1)Two kinds of plants(the tall fescue and perennial ryegrass) and three kinds ofmatrix(brown loam, loess, mixed matrix (loess, sand and coal cinder proportion mixture))are selected to seek the best equipping way of plants and substrate in the system, theresults showed that: the overall removal efficiency of three kinds of matrix are: mixedmatrix> loess>brown loam; the overall removal efficiency of two kinds of plants are: tallfescue> perennial ryegrass. Embankment flowing system has good removal effect of SS,NH3-N and TP, the removal rate is over60%, the COD removal rate is only about30%. (2)The main operation parameters optimization research of embankment flowingsystem shows: the influence of hydraulic load on the system running is effected, whenthe COD is the main controlling parameters design, hydraulic load can selected5cm/d,batching time can be selected12h/d; when the NH3-N is the main controlling parametersdesign, hydraulic load can selected5cm/d, batching time can be selected24h/d. For thebest removal effect of system, the best pollution load is: SS is700~1000mg/L, COD is270~350mg/L, NH3-N is5~20mg/L, TP is1~1.5mg/L. The degradation of pollutantsalong the slope length has a certain regularity, under the condition of urban riparian zoneallows, embankment flowing system optimal slope length is2~4m.(3)Through the actual runoff simulation studies of embankment flowing system,found that the removal rate of SS, COD and NH3-N and TP in embankment flowingsystem is about70%,40%,45%,60%respectively. The result of the removal effect is thesame as the removal effect of simulated rain, the embankment flowing system cancompletely in the practical engineering applications, can be used as a kind of urbannon-point source pollution purification measures.