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Drainage water can be recycled from subsurface pipe networks in farmland, in order to alleviate the shortage of irrigation water resources in the arid and semi-arid regions of Northwest China. The outsourcing filter material and structure of subsurface pipes play a key role in the effluent water quality. In this study, a self-developed seepage tank device was used to simulate and investigate the effects of different outsourcing filter material structures on soil water and salt transport, drainage water quality and flow rate, as well as saturated zone water quality and water level, under winter irrigation and leaching salt conditions. Adsorption materials were used instead of traditional sand filter materials. Two types of outer filter materials were tested, namely geotextile only and geotextile wrapped with 10 cm mixed filter materials. The soil water and salt dynamics were monitored from the start of irrigation to the end of drainage. The results showed that in the early stage of the leaching test, the water gradually infiltrated the soil, where the salt migrated vertically downward with the water flow, and then accumulated around the subsurface pipes in the soil layer at a depth of 60-90 cm. In the mid-stage of leaching, the water level of the saturation zone gradually rose from the bottom to the top. The subsurface pipe with geotextile only started draining, when the water level exceeded the axis of the pipe, whereas, the subsurface pipe wrapped with geotextile and 10 cm mixed filter materials started draining only, after the water level reached the top of the pipe. In terms of the desalination performance, the soil desalination rate of both outer filter materials decreased gradually with the increase of depth. The average desalination rate of the soil with geotextile only was 11.45% lower than that with mixed filter materials. The average mineralization level of the water samples from the subsurface pipe with the mixed filter materials was reduced by 1.89 and 1.21 g/L, respectively, after subsurface pipe drainage in Test 2-1 (the first round of leaching test of subsurface pipe wrapped with geotextile+10 cm mixed filter material) and Test 2-2 (the second round of leaching test of subsurface pipe wrapped with geotextile+10 cm mixed filter material), compared with the geotextile only. The drainage flow rate also increased significantly, with the maximum drainage flow rate of 6.27 mL/s for Test 2-1 and 2.46 mL/s for Test 2-2. In the late stage of leaching, the drainage stopped under the delayed effect of gravity drainage, when the water level of the saturation zone approached the bottom of the subsurface pipe. The salt in the soil was distributed mainly in a concave curve that centered around the subsurface pipe. The findings can provide a strong reference for the subsurface pipe drainage reuse in the Yinbei irrigation district of Ningxia. Nevertheless, the experimental process cannot consider evaporation, which is one of the main factors of soil salt accumulation. At the same time, the test environment of the seepage tank was greatly varied in the actual farmland drainage from the subsurface pipe project. Therefore, better performance can be expected for the adsorption filter material on the farmland soil. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the temporal and spatial migration of sediment in the sand filter column. Three kinds of sand filter columns (0.90-1.25, >1.25-1.60, and>1.60-2.0mm) were selected as the research object, and the sand filter layer was used as the fractal resistance model. The maximum pore diameters of the sand filter layers were 0.99, 1.14, and 1.41, and the average pore diameters were 0.41, 0.68, and 0.83. The Yellow River sediment of the People's Victory Canal was used as the raw water sediment impurity particles, where 0.4‰ muddy water was configured. The filtration rate was 2m³/h. After that, the filter column was removed to separate from the sediment during filtration. The quality of the sediment was calculated by the trapped filter layer of the three sand filter columns at different depths. The particle size distribution of sediment and sediment trapped by the filter column was measured by laser diffraction instrument. The results showed that the ratio of sediment intercepted by three filter columns was 97.08%, 94.53%, and 90.5%, respectively. The sediment intercepted by the surface filter layer accounted for 97.88%, 96.36%, and 81.48% of the total sediment intercepted by the filter column. Therefore, the smaller the particle size range of the filter column was, the larger the sediment retention ratio was, and the better the filtration effect was, but the more serious the surface filtration phenomenon was. An analysis was also made on the particle size distribution of the three filter layers at different depths. The D3 of the 0.90-1.25 sand filter column from the upper layer to the lower layer was 4.47, 1.00, 0.90, and 0.91μm. D98 was 476.30, 111.40, 98.31, and 97.79 μm. Span was 1.82, 5.13, 5.47, and 5.56; From the upper layer to the lower layer, D3 of ＞1.25-1.60 sand filter column was 3.77, 1.54, 0.97, and 0.99μm. D98 was 460.20, 344.20, 107.60, and 298.20μm. The Span was 1.95, 3.13, 4.50, and 4.47, and the D3 of ＞1.60-2.0 mm sand filter column from the upper layer to lower layer was 4.33, 3.50, 2.43, and 1.45 μm. D98 was 463.90, 456.00, 415.40, and 215.20 μm. The Span was 1.82, 1.86, 2.38, and 2.59. Consequently, the larger the filter column toward the lower layer was, the smaller the sediment particle size was, where the particle size tended to be concentrated. Each filter column was in the same depth of the filter layer, the larger the filter particle size was, the larger the particle size was, and the larger the particle size span was. Finally, the loss of sediment mass and particle size distribution were calculated using the sediment mass and particle size distribution intercepted by the sand filter column. Specifically, about 50% of the clay and silt particles of the original soil flew away in the process of the three sand filter columns, whereas, only 3% of the fine, medium and coarse sand of the original soil was lost. According to the hydraulic test, the smaller the particle size of the sand filter material composing the filter column was, the larger the reduction of the filter speed was, the larger the particle size of the filter material was, the gentler the flow rate was, the lighter the degree of blockage inside the filter column was, and the more stable the flow field of the water flow in the filter layer was. The larger the particle size of the sand filter layer was, the larger the pore diameter was, the slower the pressure rise was, and the stronger the anti-clogging ability of the filter layer was. This finding can provide a strong reference to optimize the layer thickness and particle size of the sand filter. [ABSTRACT FROM AUTHOR]

Sand media filters are often among the common filter modes in micro-irrigation system due to its excellent fouling capacity. The sand filter intercepts impurity particles mainly through the filter layer pores. The pore structure of filter layers directly affects the effect of particle deposition and transport during filtration .The objective of this work was to to master the internal pore structure characteristics of sand filter layers composed of different granular filter media. Taking ordinary Quartz Sand(QS1), Sea Sand(SS2), ASM Modified Glass(MG3) and Glass Beads(GB4) with selected grain size1.0~1.18 mm as research objective, this study employs the advanced CT scanning technique to construct the three-dimensional(3D) structure of four filter layers. In combination with image analysis software VGStudio MAX, Image J, et al, the pore structure parameters such as porosity, pore size distribution, pore roundness value and flatness ratio of four filter layers were obtained by processing different filter layer CT slices. In order to investigate the complexity of different layer pore structure, the box-counting fractal dimensions of pore structures were calculated with fractal theory. The research results showed that the apparent porosity range of the four filter layers were 39.7%-44.6% (QS1), 38.5%-42.3%(SS2), 40.7%-45.6%(MG3), 34.8%-38.7%(GB4) and the volume porosities were 42.2%, 41.2%, 44.1%, 36.6% respectively. The pore size intervals were 75-960, 80-760, 70-1 050, 85-930 μm and the difference was not significant. The calculated pore roundness value ranges were 1.59-1.78, 1.35-1.54, 1.65-2.03, 1.20-1.36, the pore flatness ranges were 2.62-2.75, 2.05-2.20, 3.04-3.21, 1.94-2.04, the fractal dimensions Db of the four filter layers were 1.621, 1.566, 1.661 and 1.446, respectively. This study quantitatively characterized the pore structure characteristics of the filter layer, and obtained the differences of meso-pore structure of different granular filter media. The apparent porosities of the top filter layers were more higher than that of the bottom layers along the depth of the filter. The pore size distribution law was that small pores (<75 μm) accounted for the majority for all the four granular media and the pore shapes were mainly narrow and long type. With the media particle angularity increase, the distribution of the apparent porosity was more dispersed and the volume porosity was higher, the proportion of macro-pores increased accordingly and the maximum value reached 17.24% for MG3. The tendency of pore shape parameters deviation from sphericity was more obvious. The fractal box-counting dimension, which represented the complexity of pore structure, increased with the media angularity accordingly, and fractal dimension was negatively correlated with apparent porosity. The quantitative analysis of filter layers pore structure can overcome the shortage of traditional model experiment and provide a foundation for the subsequent study of particle deposition and migration in the filter layers. [ABSTRACT FROM AUTHOR]

A disc filter has been rapidly and widely applied in the irrigation field in recent years owing to its composite three-dimensional filtering and the filtering characteristics of both screen filter and sand filter. Therefore, it has presented a promising application prospect in the very broad filtration system worldwide. However, the head loss of the disc filter can increase sharply within the critical range in a short time, due to the complex channel structure and uneven channel clogging during operation. Therefore, frequent backwashing can increase the water volume and energy consumption, and leading to the low operating efficiency of the whole micro-irrigation system. Thus, it is a high demand to elucidate reasons for the head loss increasing sharply of the disc filter. This study aims to avoid the steep increase in head loss for the higher operation efficiency of the filtering system, the hydraulic and filtration performance of the disc filter was tested on five flow velocities (0.37, 0.40, 0.43, 0.46, and 0.49 m/s), five sand concentrations (0.10, 0.15, 0.20, 0.25, and 0.30 g/L), and five compositions of median particle sizes in sand (49, 66, 82, 100, and 127 μm). Some indexes were determined, including the head loss, the sand interception, the particle size of intercepted sand, and the position distribution of intercepted sand in the laminated channel of the filter under different working conditions. The methods for calculating the head loss were established under the clean and sand water conditions using regression analysis, respectively. A Malvern particle size analyzer was utilized to determine the sensitive particle size, which was caused by the fluctuation of the head loss under the different flow velocities and the particle size of laminated intercepted sand. In addition, the position distribution of intercepted sand was also characterized by an optical microscope. The results showed that the average local head loss coefficient was achieved at 290.60 under the clean water condition. It illustrated that the head loss was only related to the effective water-crossing area. The correlation between the head loss and flow velocity, and sand concentration was high (R ²>0.90) under the sand water with different gradations. Moreover, the sensitive flow velocity of head loss outstandingly increased by 0.37, 0.40, 0.43, 0.46, and 0.49 m/s, respectively, when the sand size in sand water was in the range of 0-50, 50-75, 75-100, 100-125, and 125-150 μm. There was a strong correlation between the head loss and sand interception, and sand size was greater in the sand water, where both were less affected by the flow velocity. Furthermore, the fine sand with 0-65 μm easily passed through the channel without any interception, whereas, the sand with 65-100 μm was intercepted by the laminated channel. There was a ratio of 1:1.8 between the actual filtration accuracy of the lamination and the diameter of the inscribed circle in the minimum section of the channel. Specifically, the sand with the size range of 100-125 μm was possible to enter the laminated channel. Correspondingly, the sand was easily accumulated at the inlet of the channel, indicating the relatively low sand intercepted capacity of the filter. By contrast, the sand with 125-150 μm cannot enter the laminations. In conclusion, the finding can provide a strong reference for the rational configuration and use of disc filters under different irrigation parameters and water quality conditions, such as the flow velocity, sand concentration, and size composition. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the filtration performance of sand filters using fractal dimensions. Three kinds of sand filters were also selected with particle size in the range of 1.0-1.18, >1.18-1.4, and >1.4-1.7 mm. The Yellow River sediment in the people's Victory Canal was collected as impurity particles in the raw water. The distribution of particle size in the Yellow River sediment was measured using a laser diffraction particle size analyzer (Mastersizer 3000, Dandong Baite Instrument Co., Ltd). It was found that the calculated mean values of skewness and kurtosis were 0.12 and -0.01, respectively, for the samples from the Yellow River sediment, indicating an outstanding normal distribution. Additionally, the samples were also collected from the Yellow River sediment in Lankao County, thereby verifying the distribution of particle size. It was found that the skewness and kurtosis values of the sediment sample in Lankao County were -0.11 and -0.23, respectively, where the frequency distribution of particle size also conformed to the normal distribution. An industrial CT scanner (C16M3201, Luoyang Tengda Testing Service Co., Ltd) was used to map the filter layer. The image processing and pixel coverage were utilized to calculate the porosity of cross section, the box-counting fractal dimension, and the ratio of the minimum to the maximum aperture (aperture ratio) in the three kinds of sand filter layers. The results showed that the porosities were 0.421, 0.431, and 0.439, respectively, while the box-counting fractal dimensions were 1.695, 1.709 and 1.726, respectively, and the aperture ratio was 1/17, 1/18, and 1/21, respectively, for the three types of layers. Then, the applicability of fractal theory was also evaluated for the quartz sand filters. Subsequently, a fractal model of filtration probability was established for the sand filters. The ranges of pore diameter in the three kinds of sand filters were 59.5-1 002, 66.9-1 220, and 72.9-1 503 μm, respectively. In the sediment of the Yellow River from the people's Victory Canal, the probabilities of impurity particles above 100 um passing through the sand filter were 0.67%, 0.81%, and 0.93%, respectively. In the Yellow River Sediment from Lankao County, the probabilities of impurity particles above 100 μm passing through the sand filter were 0.62%, 0.80%, and 0.91%, respectively. It inferred that the presence of surface filtration was proved theoretically. A systematic investigation was also made on the influence of surface filtration on Backwash frequency. Consequently, an optimal filter layer was achieved to reduce the surface filtration, particularly with the particle size in the range of >1.4-1.7 mm suitable for sand filters. The finding can provide strong support to explore the internal structure of sand filters and the selection of filter material. [ABSTRACT FROM AUTHOR]

Diversified irrigation water has become an increasingly urgent need, due mainly to the limited fresh water resources and water pollution in China. Consequently, Yellow-river water irrigation has attracted more attention in recent decades. Since the Yellow River is the most sediment-filled river on earth, emitter clogging by a high concentration of sand has confined to the application of drip irrigation. Naturally, anti-clogging performance has been a commonly-used indicator to select the appropriate emitters. However, resource waste, high costs, and carbon footprint have posed a great challenge on both the anti-clogging performance and service life, when selecting the emitter products. In this study, an experimental field test was conducted to select emitter and lateral products suitable for drip irrigation with Yellow-River water, concurrently considering the anti-clogging performance, service life, system cost, and carbon footprint. SPSS principal component analysis (PCA) was used to establish selection indexes, and then to screen the suitable emitter products for various crops in different years. 16 kinds of emitters were also analyzed using Cristiansen Uniformity (CU) coefficient, including inlaid plain channel emitters, inlaid cylindrical emitters, single-wing labyrinth, and inlaid strip emitters. 3 crops were selected to evaluate the drip irrigation laterals. The experimental water was taken from the Wushen Canal in Hetao Irrigation District, and then filtered with sedimentation basin before entering into the drip irrigation system. Irrigation water was treated through the homogeneous filtration of a sand filter and a laminated filter. The work pressure was maintained at 0.1 MPa in operation. The Yellow-River water was operated for 9 hours/day with a flushing frequency of 60 h/time at a flow rate of 0.45 m/s and a flushing time of 6min, a total of 600 hours (flushing water) and 720 hours (non-flushing water). The results showed that there were significant differences in life cycle, cost and carbon footprint in different types of emitters. The longest life cycle was found in the inlaid plain channel emitters, followed by the inlaid cylindrical, inlaid strip, and single wing labyrinth emitters. The highest cost was found in the inlaid cylindrical emitters, followed by the inlaid plain channel, inlaid strip, and the single wing labyrinth emitters. CU of all emitters showed a slow and then rapid downward trend. The highest carbon footprint was the inlaid cylindrical emitters, followed by the inlaid plain channel, inlaid strip, and the single wing labyrinth emitters. Consequently, it was recommended to use the single wing labyrinth drip emitter with 2.94 L/h for a 1-year usage period (sunflower), plain channel emitter with 1.4 L/h for a 3-year usage period (lycium), and plain channel emitter with 2.8 L/h (with capillary flushing) for a 5-year usage period (alfalfa) in the crop irrigation in Inner Mongolia Hetao Irrigation Area. Capillary flushing demonstrated relatively low effects on the 1 and 3-year period (sunflower and lycium), however, the effects were more obvious on the 5-year use period (alfalfa). This finding can provide a new perspective for the selection of emitter products in large-scale drip irrigation with the high-sand Yellow-River water. [ABSTRACT FROM AUTHOR]

Sand filter is considered to be one of the best choice to prevent clogging in micro-irrigation system. Head losses in media filter are produced by the friction loss due to the internal auxiliary elements of the filter container and the resistance offered by the media layer. The underdrain element is a core component in sand filter. To deeply understand the hydraulic behavior of underdrain, the experimental and numerical investigations were conducted to explore the flow resistance characteristics and flow field distribution in the underdrain. Laboratory experiments of filtering and backwashing were conducted in Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang, China. A trapezoidal underdrain element applied commonly in domestic market was selected in the experiment. It was installed in a scaled sand filter based on a commercial filter with 600 mm internal diameter. The sand filter model were tested at eight filtering velocities ranging from 0.010 to 0.040 m/s, and eight backwashing velocities ranging from 0.005 to 0.040 m/s, which were consist with the actual commercial filter operation. The experimental variables were monitored in real time by a data acquisition system consisted of a flowmeter and pressure transmitter. The internal flow behavior through the filter was simulated using the Computational Fluid Dynamics (CFD) method. A CFD model of the underdrain was developed by ANSYS Fluent 15.0. The geometry of the underdrain and its unstructured mesh were designed by ICEM software. Due to the turbulent flow regime in the underdrain and layer, the realizable k-ε turbulence model and the porous medium model were selected for solution. The computing area and the boundary condition of inlet and outlet were proposed. To ensure the reliability of the numerical simulation, the experimental values were compared with the simulated results. The results showed that the simulated values of head loss were in good agreement with the experimental values with the relative errors between 3.54% and 6.53%. The tested results showed that as the filtering velocity increased (>0.024 m/s), the pressure drop produced by the underdrain improved more significantly than the media layer. When the velocity increased to 0.040 m/s, the 72.3% of the pressure drop were produced by the underdrain. At the same filtration velocity, the pressure drop of backwashing mode was higher than filtering mode. The results confirmed that it was important to select appropriate filter model and avoid overload operation for the irrigation system. The simulated pressure and velocity contours showed that the structure without slots at the top of underdrain increased the non-uniformity of the flow streamlines and affected the backwash efficiency. Due to the narrowing of the flow section gradually from the layer to the underdrain outlet, the flow velocity increased drastically. When filtration velocity was 0.030 m/s, the velocities at the narrow slots and the entrance of the collector reached 2.57 and 4.01 m/s, respectively, resulting in significant pressure drop in the two region subsequently. The pressure contours of the collector at different cross sections showed non-uniformity due to the violent disturbance of the flow. In view of these results, a spherical flat underdrain with smaller aspect ratio and more uniform slots distribution was designed. Compared to the trapezoidal underdrain, the distance of the flow through the underdrain decreased by 14% and the passing area increased by 27%. In addition, the diameter of the tube outlet increased to 30 mm. The modification favored vertical flow through the porous medium and the underdrain chamber with a more direct exit, thereby reducing pressure drop. The CFD simulations of the modified underdrain showed the smoother streamline around the underdrain for filtering mode and a smaller vortex scale for backwashing mode, indicating excellent passing capacity and backwash efficiency. The study could guide the design of filter for irrigation equipment manufacturer, irrigation project designer and field operator. [ABSTRACT FROM AUTHOR]

The guide vanes can make movement of water and sand in the filter more complicated and difficult to distinguish as it changes the water and sand movement. The characteristics of water movement, the change of flow rate distribution and pressure drop coefficient were analyzed for the filter with or without guide vanes filter. Simulation with CFD-DEM (Computational Fluid Dynamics-Discrete Element Method) and experimental method were used to study the movement and distribution law of sand in the filter cavity and on the screen surface. The results showed that under the condition of clean water, the pressure drop coefficient of the filter with the guide vanes was 17.92% higher than that without the guide vanes, and the head loss was larger than that without the guide vanes also. While filtering the muddy water, the head loss of the guide vanes filter was smaller than that without a guide vanes, and the flow rate decreased more gently than that of clear water. The flow capacity of the filter with the guide vanes was significantly increased, and both the filtration effect and efficiency were improved. The flow field distribution on the screen filter without the guide vanes was extremely uneven, and the difference between the maximum flow rate and the minimum flow rate was 4.9 times. Compared with characteristics of water movement in the filter with and without guide vanes, the maximum flow rate of the guide vanes filter decreased by 4.78% while the minimum flow rate increased by 10.75%, and the area of the high-speed flow area decreased by 47.05% when it was greater than 13 L/h. That indicated that the guide vans had the characteristics of diversion and distribution, making the flow in and out of filter more stable. When the filter was without guide vanes, the sand was mainly distributed on the center line of the screen and on both sides, these positions correspond to areas with high flow rate. The sand was mainly distributed in the plug, which accounted for 90.07% when the filter was with guide vanes at the time of 4 s, and a small amount of sand was on the screen surface, while only 50.98% of the sand was in the plug of filter without guide vanes. It could be seen that the guide vanes let more particles flow to the plug with the water flow, and fewer particles are distributed in the filter chamber and attached to the filter screen, then the probability of blocking was reduced. Through the muddy water experiment, the filtration performance of the filter with and without the guide vanes was tested. The experiment results showed that the filtration volume of the guide vanes filter was larger than that without the guide vanes at the same time, which indicated that the filter with guide vanes had higher filtration efficiency. The distribution of particles of experiment on the filter screen was basically consistent with the distribution of simulation results. Therefore, reasonable design of guide vanes and plug can improve the anti-clogging performance of the screen filter. [ABSTRACT FROM AUTHOR]

In China, the freshwater pearl mussel aquaculture plays an important role in agricultural production. The freshwater pearl mussel’s growth process does not harm the environment, but the traditional aquaculture model has caused problems such as serious water pollution, eutrophication, and ecological environment destruction. Facing such a situation, it’s necessary to develop a new model for freshwater pearl aquaculture. This study showed a new industrialized circulating water aquaculture model (using multi-layer dimensional cages and feed pearl mussel with high-quality microalgae). Due to the high density of aquaculture, this model had very high requirements for water quality, so it was particularly important to monitor the circulating water quality. This study developed a distributed monitoring system for the water quality monitoring based on ZigBee wireless sensor network. The system used the three-layer architecture of the field sensing layer, transmission layer and application layer, and mainly included the following 4 parts: water quality monitoring subsystem, meteorological monitoring subsystem, equipment control subsystem, and monitoring data center. The system used the ZigBee module to set up the wireless transmission network, the advantage of this method was flexible networking and easy operation, and it simplified the installation and maintenance work. In the field scene, we set up multiple monitoring points in different places, multi-parameter water quality sensors were used to monitor key circulating water quality parameters (including temperature, pH value, dissolved oxygen, ammonia nitrogen, calcium concentration, and algae concentration), and meteorological parameters (such as temperature, humidity, barometric pressure, illumination, wind direction, and wind speed) were collected at meteorological station. All the sensors sent real-time detection data to their related ZigBee routers by RS485 protocol, and through the ZigBee wireless communication network, the data (including water quality and meteorological parameters) would be gathered in the ZigBee coordinator. The ZigBee coordinator was the center of the wireless communication network, it was also connected to the PLC controller by RS485 protocol, so the PLC controller could collect real-time detection data from basic monitoring points. At the same time, the PLC controller and MCGS touch screen communicated through the serial port, so the water quality and meteorological parameters monitoring information could be displayed on the MCGS touch screen. According to the designed procedure, the MCGS touch screen displayed the water quality data change curve, and users could also issue equipment control commands at the screen, such as controlling the circulating water treatment equipment (including arc screen separator, microfiltration filter, protein separator, sand filter, and disinfection pool) and the algae feeding system device. By using the PLC controller, the study designed a program to control the start and stop status of aquaculture equipment and adopted a two-position control strategy for the algae feeding system. Besides, the PLC controller communicated with the host computer via the CP243-1 Ethernet communication module, so all the monitoring data was uploaded to the host computer in the monitoring center house. On the host computer, MCGS (network version) software and SQL Server database software were used to build a database to save the water quality data, and this database could provide a decision basis for scientific aquaculture. Through the practical test, the communication success rate of the whole system was more than 98%, and the average relative errors of dissolved oxygen, temperature, pH, and ammonia nitrogen were ±0.3 mg/L, ±0.4 ℃, ±0.3 and ±0.04 mg/L, respectively. It could be seen that this system met the monitoring needs of freshwater pearl mussel aquaculture. This system was conducive to solve the previous shortcomings and ensure the growth of production, it was very worthy of promotion and application, and it would open up a new situation for the establishment of a new environment-friendly and efficient aquaculture mode of freshwater pearl mussel. [ABSTRACT FROM AUTHOR]

Laminated filter has the characteristics of screen filter and sand filter, and can achieve three-dimensional filtration. The structure size of laminated filter is the most important parameter affecting the filter performance. In this study, we established a comprehensive evaluation method of laminated filter performance. Experiment was carried out at Tongzhou Test Station of China Agricultural University. A total of 5 kinds of laminated filters commonly used were selected. The hydraulic and filtration performance of laminated filters were tested under different sediment concentration (0.02%, 0.03% and 0.04%) and flow rate (25, 30, 35 m³/h). Dynamic change of head loss with time, clogging uniformity index, amount of intercepting sediment and median particle size of intercepted sediment were analyzed. Based on the performance test, the 3 single performance indices (amount of intercepting sediment, median particle size of intercepted sediment and clogging uniformity index) related to the size parameters of laminates were selected through correlation analysis. By means of stepwise regression analysis and principal component analysis, the multivariate linear regression equations between 3 single performance indices and 6 laminated structural parameters (single laminate thickness, the number of laminations, length of the flow channel, the number of flow channels, the apex angle of triangle outside flow channel, the height of triangle outer section of flow channel ) were established respectively. And the regression equation of 3 single performance indices was used to establish the comprehensive evaluation function of laminated filter performance by direct weighting method. The results showed that there were great differences among the 5 laminated filters in head loss, amount of intercepting sediment, median particle size of intercepted sediment and clogging uniformity index. The evaluation value of comprehensive evaluative function established in this paper for 5 kinds of laminated filters was ordered by filter V(3.11), smaller than filter II(7.08), filter I(7.22), filter III(7.88) and filter IV(8.63). The smaller evaluation value indicated better comprehensive performance of laminated filters. According to the analysis of the test data, the evaluation results were in line with the actual situation, and could comprehensively and reasonably evaluate and compare the performances of laminated filters. In addition, the numerical value of the index also reflected the difference of the structure and size of the 5 kinds of laminated filters, which showed difference in clogging uniformity index, amount of intercepting sediment and median particle size of intercepted sediment. According to the design requirements of laminated filters, there was a certain constraint relationship between the structural size parameters of laminated filters. It was difficult to improve the hydraulic performance and sediment disposal capacity of the filter at the same time only by changing the value of a certain parameter. Therefore, the geometric structure and size of laminated filter should be considered comprehensively in order to optimize some performance parameters of laminated filter. This evaluation method cannot only be used to assess performance of laminated filter, but also provide information for improving the size of laminated filter structure and further optimizing the performance of filter. [ABSTRACT FROM AUTHOR]