| Drip irrigation is currently one of the most effective irrigation methods in arid and waterdeficient areas,but the clogging of the irrigator will directly affect the uniformity of irrigation,and even make the entire drip irrigation system ineffective.According to the water quality,the clogging type of the irrigator can be divided into three types: physical clogging,chemical clogging and biological clogging.Among them,physical clogging is the most obvious,and particle flocculation and sedimentation are the direct causes of physical clogging of the irrigator.For many years,the Ningxia,Inner Mongolia and other regions of the Yellow River Basin and Xinjiang have been affected by high sediment flow,which seriously restricted the application of drip irrigation technology.This section has a high sediment content and a large proportion of fine particles.The extremely small particle size of fine-grained sediment makes it have strong electrochemical properties.Under certain conditions,it will collide and bond to form sediment flocs,which will aggravate the blockage of the dripper.After magnetization,the intermolecular hydrogen bonds of water are broken,and the water molecules change from clusters to single polar water molecules.The dissolved oxygen in the water increases by 4～6 mg/L,the solubility increases by 20%～70%,and the conductivity of water increases by at least 2%,the clarification speed is increased by 20%～90%,and the properties of water are changed.After magnetization,the internal energy of free ions in water increases,and the collision probability increases,which will affect the flocculation and sedimentation process of viscous particles.Magnetized water irrigation can promote plant growth,improve plant root vitality,change the distribution of water and salt in salinized soil,reduce soil salinity,and enhance soil water retention capacity.Magnetic water treatment technology has a wide range of effects in promoting soil desalination,improving plant salt tolerance and soil nutrient availability,and promoting plant growth.The application of magnetized water has attracted extensive attention,but the current research on the effect of magnetization on agricultural production is mostly concentrated in crops and soil,and there are few studies on the effect of magnetization on the flocculation and settlement of finegrained sediment in drip irrigation systems.It is urgent to explore the effect of magnetization treatment on the flocculation and sedimentation process of fine-grained sediment in drip irrigation system,so as to provide a theoretical basis for the prevention and control of dripper clogging.In this study,4 kinds of magnetization(0,0.2,0.4 and 0.6 T)were set,and 4000 mesh kaolin and different particle size gradations(0～0.038,0.038～0.075,0.075～0.1 and 0～0.1 mm)Weihe fine Using granular sediment as the research object,the effect of magnetization on the flocculation and sedimentation of different concentrations of kaolin(0.5,1,1.5,3 and 5 g/L)was explored through hydrostatic flocculation sedimentation test,dynamic water flocculation sedimentation test and short-period intermittent irrigation test.The effect of magnetization on the flocculation and sedimentation of kaolin(1.5 g/L)under the application of potassium sulfate fertilizer,urea and compound fertilizer of 0.25,0.5 and 0.75 g/L respectively,the effect of magnetization on Weihe fine grains with different particle size gradations The effect of particle sediment flocculation and settling and the clogging of the dripper,under the water flow turbulence intensity of different inner cylinder speed(0,15,30 and 60 r/min),the effect of magnetization on different salinity(0,2,4 and 6 g/L)The effect of flocculation and settlement of fine-grained sediment in Weihe River in the mixed water of Yellow River and brackish water.The research results can provide a theoretical basis for the prevention and control of drip irrigation dripper clogging with magnetized water.And draw the following main conclusions.(1)The magnetization treatment significantly promoted the flocculation and sedimentation process of fine-grained sediment(P<0.05),and the promoting effect increased first and then decreased with the increase of the magnetization.In this experiment,when the magnetization was 0.4 T,the magnetization The treatment has the greatest promotion effect on the flocculation and sedimentation of fine-grained sediment.Compared with the unmagnetized treatment,the median settling velocity of the fine-grained sediment after magnetization increased by 5.85%-67.58%.The magnetization treatment can change some water quality indicators of the muddy water in the test.Compared with the unmagnetized treatment,the p H value of the muddy water after magnetization is increased by 0.22%～11.24%,the electrical conductivity is increased by 0.03%～25.56%,and the viscosity coefficient is increased by 0.09 %～17.45%,the zeta potential decreased by 20.35%～68.70%.(2)Different fertilizer types and concentrations have different degrees of aggravation of the flocculation and sedimentation of fine-grained sediment by magnetization treatment.When potassium sulfate fertilizer is applied,the aggravation degree of magnetization treatment is the largest,followed by compound fertilizer,and urea is the smallest.The treatments have the highest increases of 67.6%,52.5% and 40.1%.And the intensity of magnetization treatment increased with the increase of potassium sulfate concentration,decreased with the increase of compound fertilizer concentration,and was basically not affected by urea concentration.(3)The degree of aggravation of the flocculation and sedimentation effect of different magnetization treatments of sediment particle size gradation is different.After magnetization treatment,the relative concentration of sediment in muddy water D1(65.3% of sediment particles with a particle size smaller than 0.03 mm)decreased by 29.44% compared with the unmagnetized treatment,while in muddy water D4(no sediment smaller than 0.03 mm)particles)fell by only 8.85%.(4)The magnetization treatment slowed down the downward trend of the average relative flow rate of the dripper and the uniform irrigation.At the end of the irrigation,the magnetized dripper Dra and Cu increased by 4.80%～17.42% respectively compared with the nonmagnetized dripper,and the magnetization treatment increased the front section of the capillary tube.The blockage rate of dripper,under the treatment of muddy water D1,D2,D3 and D4,the blockage rate of dripper in the front section of the capillary increased by 11.77%,20.37%,15.56% and 23.15% respectively.(5)Water flow turbulence hinders the flocculation and sedimentation process of finegrained sediment in water.When the salinity of the mixed water is less than 4 g/L,the promotion effect of magnetization treatment on the flocculation and settlement of fine-grained sediment increases with the increase of the salinity of the water.The promoting effect of flocculation sedimentation has no obvious increasing trend with the increase of mineralization. |
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