Application of Anti-clogging Ecological Soil Sewage Treatment Process in Rural Domestic Sewage Treatment and Prospects

[Objectives] By reasonable water distribution and air supply to soil, soil water permeability is maintained, and the nutrient conditions of degrading bacteria in soil are improved to effectively prevent soil clogging. [Methods] Through the innovation and improvement of traditional soil sewage treatment technology, the physical, chemical and biological characteristics of soil for sewage purification are utilized to enhance the pollutant decomposition ability of soil microorganisms and maintain soil water permeability.[Results] It has no secondary pollution, and can effectively remove pollutants such as COD_(Cr), TN, TP, NH_3-N, etc. in sewage. [Conclusions] The operation and maintenance cost is low, and the land can be reused, while water and nutrients can be restored to the land.

Structural Design of a Bionic Anti-Clogging Drip Irrigation Emitter Based on Shark Dorsal Fin

Due to the poor anti-clogging performance of the common drip irrigation emitters, this paper designed a new bionic flow channel in the emitter based on the shape of shark dorsal fin. After preliminary structural design, the computational fluid dynamics (CFD) simulation showed that the bionic emitter exhibited superior anti-clogging performance and reasonable hydraulic performance. The passage rate of particles of the bionic emitter in simulation reached 96.3% which was 37.6% higher than 70% of traditional emitter, and the discharge exponent reached 0.4995 which was close to traditional emitter. Physical experiments were consistent with the CFD results, which confirmed the correctness of simulation. After a short cycle anti-clogging performance experiment, the bionic emitter still maintained 96.09% of the initial flow rate.

Anti-clogging ability of the labyrinth emitter and its evaluation method

Emitter clogging is one of the most serious factors that restrict the drip irrigation system operation and water use efficiency.To scientifically characterize and evaluate emitter clogging risk,a literature review,short-period emitter anti-clogging tests,and CFD(Computational Fluid Dynamics)hydraulic performance tests were conducted.Results showed that the emitter anti-clogging ability is related to its structure,material,and processing technology,not external factors.This was evidenced in the irrigation tests,as with the different water qualities,the same emitters were repeatedly prone to clog or to avoid clogging.A predictive model of structural resistance coefficient(Cs),a quantitative indicator of the emitter anti-clogging ability,whose value ranges between 0 and 1,was utilized.Larger Cs values indicate a lower anti-clogging ability and thus a higher risk of clogging.A good linear relationship between Cs and the relative flow rate was detected,and the Cs relationship with the fluidity index(x)was determined to be a power function.The Cs should be controlled within the range of 0.146-0.461 when designing new emitters to ensure that they have good anti-clogging properties.This research will provide theoretical guidance for the anti-clogging management of drip irrigation systems and for the design of optimal emitter structures.

Flow Behaviour Analysis and Experimental Investigation for Emitter Micro-channels

The existing research of the flow behavior in emitter micro-channels mainly focuses on the single-phase flow behavior.And the recent micro-particle image velocimetry（PIV） experimental research on the flow characteristics in various micro-channels mainly focuses on the single-phase fluid flow.However,using an original-size emitter prototype to perform the experiments on the two-phase flow characteristics of the labyrinth channels is seldom reported.In this paper,the practical flow of water,mixed with sand escaped from filtering,in the labyrinth channel,is investigated.And some research work on the clogging mechanism of the labyrinth channel＇s structure is conducted.Computational fluid dynamics（CFD） analysis has been performed on liquid-solid two-phase flow in labyrinth-channel emitters.Based on flow visualization technology-micro-PIV,the flow in labyrinth channel has been photographed and recorded.The path line graph and velocity vector graph are obtained through the post-treatment of experimental results.The graphs agree well with CFD analysis results,so CFD analysis can be used in optimal design of labyrinth-channel emitters.And the optimized anti-clogging structures of the rectangular channel and zigzag channel have been designed here.The CFD numerical simulation and the micro-PIV experiments analysis on labyrinth-channel emitter,make the ＂black box＂ of the flow behavior in the emitter channel broken.Furthermore,the proposed research promotes an advanced method to evaluate the emitter＇s performance and can be used to conducting the optimal design of the labyrinth-channel emitters.

Bio-inspired Filter Design Based on Vortex Control Mechanism of Parallel Groove Structure

Solid–liquid separation is widely used in daily life and practical engineering.Traditional industrial filters are prone to clogging,but this rarely occurs in filter-feeding organisms.Inspired by the filter feeding mechanism of balaenid whales and considering the local grooves in the fringes layer,a new bionic filter is produced by 3D printing technology through the bionic design of the parallel channels inside the mouth of balaenid whales.At the same time,a test platform composed of the bionic filter,peristaltic pump,fluid pulse rectifier and water tank is built to carry out the fluid flow pattern dyeing and particle filtration experiments.It is found that fluid separation occurs near the groove structure and local vortices are generated.The vortex control filtration mechanism makes the particles in the front grooves tend to accumulate on the left side,which has a certain anti-clogging effect.Moreover,the increase of flow velocity leads to the enhancement of vortices,which makes the accumulation effect on the left more obvious.This study initially practices the bionic application from biological model to engineering design,and the vortex control anti-clogging filtration mechanism proposed in the study has a wide range of application prospects and values.

Design of an active seed throwing and cleaning unit for pneumatic rice seed metering device

To address the clogging of the rice seed metering device after a long period of operation without affecting the precision of normal seeding,an active seed throwing and cleaning unit was designed based on the fact that magnets of the same pole were mutually exclusive.The working principle of the two devices was analysed theoretically,and a mechanical model was created according to the relationship between the repulsion forces of magnets and the spring forces of springs.The super hybrid rice Y-2 You 900 with 22.5%moisture content(wet basis)was used as the test object.The whole factor experiments were carried out under different negative pressures,rotational speeds of the suction plates,and lengths of probes.The results indicated that under any test conditions,the active seed throwing and cleaning unit worked normally.The results of high-speed photography showed that the rate of seed cleaning was 100%.The results also showed that the optimal negative pressure was 0.8 kPa.The probability of 1-3 seeds per hill for the seed metering device was approximately 95%under the optimal negative pressure.The optimal length of the probe was found to be 2 mm.The average qualified rate of hill space was 96.04%under the optimal length of probe,the longer the length of the probe,the lower the qualified rate of hill space.It also showed that an active seed throwing and cleaning unit could effectively avoid the hole clogging caused by the long-term operation and had no influence on the normal operation of the pneumatic rice seed metering device.The active seed throwing and cleaning unit improved the stability of the seed metering device,and the research provided a reference for the optimal design of seed throwing and cleaning structures of the pneumatic rice seed metering device.