| Water is the source of life,the foundation of human survival.Although total water resources in China is big,but only for a quarter of the world's per capita.The region of northwest China rural area is arid and semi-arid(annual rainfall below 250mm),where per capita water resources is only half the national average per capita,is the extreme scarcity.In order to solve the drinking water problem of northwest rural area,our country actively supporting the construction of rainwater collection project since 1995,which has the advantages of low cost and water security.But some practices show that accumulation of water quality does not meet the drinking water health standards of these rainwater collection projects.Therefore,this study put forward new way of ecological rainwater collection,storage and ultrafiltration process,to assure the drinking water safey in the northwest rural.At first,this paper studies the roofing runoff pollution of teaching area in Wuhan.Through the monitoring of runoff quality of three kinds roofs,to analysis the main pollutant characteristics and the output rules of pollutant in different roofs,and discuss the the influence of the rainfall runoff water quality with some facts,such as characteristics of rainfall,dry days,air quality.Then,a ecological rainwater collection and storage system is made for field experiments,to study the collecting ability and water quality characteristics in storage tank.After that,hollow fiber membrane is used for ultrafiltration treatment,pollutants removal of ultrafiltration membranes were studed,and discuss the influence of such factors as pressure,the membrane material,water way.Through the above experimental analysis,the following conclusions:(1)The linoleum roof of rainfall runoff on COD,TN,TP and SS were higher than the average concentration of asphalt roofing and green brick and tile roof.Pollutants output law conforms to the first-order erosion model,and the initial effect is obvious,abandon flow 1-3 mm can remove 40%–70%of the initial runoff pollutants;(2)Collection and storage of the ecological system can collect roof runoff effectively,built system effective runoff storage volume is 48.73 m~3.Rain can make turbidity in water tank,TN,TP,and the increase of oxygen consumption,and to some extent,reduce the total number of colonies.As the growth of the drought days,oxygen consumption and turbidity falling fast,but the total number of colonies slow growth;(3)Storage of water cannot fully reached the standard of drinking water,the water quality after ultrafiltration membrane can meet basic standard.Membrane flux increases with pressure increase linearly,but the yield per unit pressure slow decline after the pressure is greater than 0.10 MPa.Finally,the paper designed a kind of practical pneumatic ultrafiltration device,has the advantages of low cost,high efficiency and easy to maintain,and its use to protect farmers in northwest rural cellar production water security. |
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