Preliminary Design And Experimental Verification Of A Late-model Rainwater Filtration System

Drought and soil erosion has been one of the major problems hampering the economicand social development in the loess plateau, and it also seriously affects the ecologicalenvironment construction in the loess plateau. In recent years, under the policy of returningfarmland to forest resources slopes farmland become less and less, the loess plateau slopeefficient agriculture has become the main development direction of agriculture in this area. Asthe terrace greenhouses and terraced field of large-scale construction, efficient agriculture hasbecome the main direction of the local economy development. But sloping efficientagricultural development needs clean water for irrigation. This paper, based on the concept ofrainfall runoff regulation and water and soil resources efficient utilization, designed anecological environmental protection and efficient water filter system and we have doneverification by the experiment. This paper obtained the following conclusions:1. Composition of vegetation filtration system. This system, based on the characteristics ofthe biological and physical purification, included collecting surface, switch grass vegetationfilter strip and filtration pool. Because the content of sediment, nitrogen and phosphorus inrunoff is high in the loess plateau，This system collect the rainfall runoff by the collectingsurface, and bring in the vegetation strips. The filter with interception by vegetationpurification effect, a large number of pollutant removal, then through filtration pool filterremove the vegetation in the flow zone and decay, finally introduces the runoff water cellarstorage, and this system can provide clean irrigation water for the development of efficientagriculture.2. Vegetation filtration system is obvious to purify water. By simulating the purifyingeffect of system to rainfall runoff pollutants under different rainfall intensity, The resultsshowed that: vegetation filtration system has significant effect to purify pollutants, when thelength of vegetation filtration is5m, the average interception rate to sediment reached97.49%on rainfall intensity139mm/h,125mm/h,115mm/h,73mm/h,54mm/h,48mm/h.the average interception rate to total phosphorus reached91.18%. Vegetative filter strip ofCOD interception effect is relatively poor, the maximum and minimum interception ratereached56.07%and25.14%; Purification effect of front3m filter is more significant forsediment, nitrogen, phosphorus and other pollutants. Laying gravel filtration pools of differentsize, just intercept firewood down from vegetative filter strip, layout can be greatly simplified,cost can be significantly reduced. The water purification system can be used to develophigh-efficient agricultural in the Loess Plateau. 3. The basic parameters of vegetation filtration system. The intercepting and purifyingeffect of front3m vegetation filter is remarkable, therefore suitable arrangement length ofvegetation filter is3-5m, less than7m. Switchgrass grows well in the Loess Plateau, theaverage height of switchgrass reaches25cm in initial test,an average height of102.7cm atthe end of the trial lasted three months, plants grow spacing is5mm-10mm; Under thecondition of vegetation filter, filtration pool mainly intercept the firewood and fine sandfrom the vegetation filter,layout can be greatly simplified: along the filter with linear layoutor point layout. The length, width and height of point layout point were2m,1m,1m underthe experimental conditions, laying gravel of four different size in filtration pool, graveldiameter is chosen over20mm,10-20mm,,5-10mm, below5mm,thickness of each20cm,of which the smallest diameter lay in the lowest level of filtration pool, followed by thelaying up, a total of4layers. The test verifies that the effect of the system for interceptingrainfall runoff pollutants is obvious, and also can simplify the layout.4. Switchgrass used for test were growing better. Therefore, switchgrass can grow wellin the Loess Plateau. Meanwhile, switchgrass as vegetative filter strip has good waterpurification effect, the use of vegetative filter strip-Filtration pool-cistern system to collectrainfall runoff during the dry season prepare for irrigation has good economic benefits;switchgrass hay yields of two different experimental plots were1.322kg/m2and1.475kg/m2,the hay can be used for livestock farming, has certain economic value; In addition,switchgrass planting can effectively increase the green area. It also can be used to control thesoil erosion.