Characteristic Of The Emitters Clogging In Drip Irrigation With Biogas Slurry And Its Prevention Methods

In recent years,with the continuous expansion of the scale of the aquaculture industry,the domestic biogas project has developed rapidly,but the treatment of a large amount of by-product biogas residue and biogas slurry has become an urgent problem to be solved in biogas production.The organic fertilizer-rich biogas slurry is used as the water and fertilizer integration project for irrigation and fertilizer construction.Irrigation of crops through drip irrigation and micro-irrigation is effective way in solving biogas discharge,avoiding environmental pollution,turning waste into treasure,and realizing the reuse of biogas slurry.However,the biogas slurry contains a large amount of suspended particulate matter,colloid and other impurities,which easily cause the emitters to block,which seriously restricts the application of the drip irrigation technology with biogas slurry.In order to solve the problem of clogging of the emitters of the drip irrigation with biogas slurry,this paper studies the basic regular pattern and characteristics of the clogging of the emitters under the conditions of the drip irrigation with biogas slurry.By visually analyzing the emitters’ channel after the anti-blocking experiment,it is clear that the clogging material’s distribution regular pattern in the emitters;Based on the response surface method,a mathematical prediction model of the degree of blockage and clogging time of the emitter of the drip irrigation system with biogas slurry was established,and the clogging parameters of the emitter were optimized;The composition characteristics and phenotypic characteristics of the clogging substances in the emitters were qualitatively analyzed by modern analytical techniques such as Fourier transform infrared spectroscopy,and the clogging type of the emitters was determined;Finally,based on the physicochemical properties of clogging materials,the type of emitters clogging,the advanced treatment technology of organic wastewater and the advanced treatment of biogas slurry and the anti-blocking verification experiment of emitters,the method of controlling the emitters clogging for the drip irrigation system with biogas slurry was proposed from the perspective of reducing the source of clogging materials.The main conclusions are as follows:(1)The clogging characteristics of the emitters of the drip irrigation system with biogas slurry were studied by a fixed-cycle intermittent irrigation anti-blocking experiment.The results show that the smaller the ratio of water to biogas slurry,the greater the concentration of biogas slurry,the more likely the emitter is clogged;the larger the flow rate of the dripper,the larger the average relative flow rate,and the larger flow rate of emitter is relatively less likely to clogged;The average relative flow rate increases first and then decreases with the increase of irrigation pressure.If the irrigation pressure is too large,the dripper will be clogged.The moderate irrigation pressure should be selected during the agricultural irrigation process.The overall clogging characteristics of the emitter show smooth fluctuations first and then a linear decline with the system’s working.(2)Using the response surface method,a mathematical prediction model for quantitatively evaluating the degree of emitters clogging and clogging time in the drip irrigation system with biogas slurry was established.Based on the model optimization of response surface,a regression prediction model based on average relative flow and clogging time was established.The combination of emitters clogging parameters in the optimal irrigation mode was determined: the ratio of water to biogas slurry is 3:1,and the irrigation pressure is 0.14 MPa,the dripper flow rate is 12 L/h,the corresponding average relative flow rate is 0.8087,and the clogging time is 53.6 h.The experimental results show that the average relative error between the actual values and the theoretical predictions of the model is only 2.29% and 3.77%,and the prediction model is reliable.The research results can be used as an effective reference for quickly assessing the risk of emitters clogging and controlling the cleaning time of the drip irrigation system with biogas slurry,and provide a scientific basis for the rational management of the emitters clogging.(3)Using modern analytical techniques such as Fourier transform infrared spectroscopy,the composition of the clogging material of the drip irrigation system with biogas slurry was explored,and the type of clogging of the emitter was clarified.According to the composition characteristics of the biogas slurry,the phenotypic characteristics of the clogging material and the results of Fourier transform infrared spectroscopy,it is known that the main components of the clogging material in the drip irrigation system with biogas slurry are proteins,lipids,aromatic compounds and other organic substances and ammonium.Inorganic compounds such as salts,carbonates,phosphates,and microorganisms are mostly soluble substances,and there are few solid particles with large particle diameters.It is difficult to form a large amount of insoluble chemical precipitation due to low content under certain conditions.Therefore,on the whole,the emitters clogging of the drip irrigation system with biogas slurry is characterized by complex clogging caused by the synergy of physics,chemistry and biology,and mainly consists of physical blockage and biological blockage.(4)Based on the composition characteristics of the clogging material of the emitters and the advanced treatment technology of the organic waste water,a method for controlling the emitters clogging of the drip irrigation system with biogas slurry was established.From the perspective of effectively controlling the source of clogging materials,the biogas pretreatment technology using ozone/vacuum ultraviolet light coupling deep treatment process can significantly reduce macromolecular organic matter,colloids,microorganisms and other substances in the biogas slurry that may cause emitters clogging,thereby controlling the source of the clogging materials and effectively prevent the clogging of the emitters.The optimum treatment effect is to use ozone/vacuum ultraviolet light coupling deep treatment process,the total reaction time is 5 h,wherein the ozone ventilation time is 40 min(0-40 min),and the vacuum ultraviolet photo degradation time is 5 h.