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The optimization of film-unloading and film–soil separation components can effectively improve the residual film unloading rate and reduce impurity content. So, the DEM models of soil and residual film were established and the suspension and flow characteristics under fluid action were analyzed based on the CFD—DEM coupling simulation in this article. The matching parameters of the film-unloading and film-lifting device were optimized with the Box–Behnken test. When the wind velocity was between 1.65 and 10.54 m · s − 1 , the film–soil separation effect was the best, with a film–impurity separation rate of 96.6%. The optimized parameter combination of the film-unloading device and film-lifting device is A = 9°, B = 40 mm, and C = 40 mm (A, B, and C represent the angle between the teeth and the normal of the air inlet, the minimum distance between the teeth and the air inlet, and the width of the air inlet, respectively). With the optimized parameter, the best film unloading effect is achieved, the minimum wind velocity of film unloading is 2.6 m · s − 1 . This article provides theoretical and simulation methods for assessing the flow characteristics of flexible particles and parameter optimization of air suction devices, which is conducive to the high-purity recovery of residual film. [ABSTRACT FROM AUTHOR]

If the nutrient solution used in the hydroponic system is recycled and reused without disinfection, the plant diseases are likely to spread. The current disinfection system still cannot conduct online monitoring of microorganisms at the same time as disinfection. In this paper, a UVA ultraviolet disinfection system and an online microbial monitoring system are proposed, which can conduct online monitoring at the same time as disinfection. This system includes the design of the disinfection system, the microbial online detection system and the microfluidic chip. The practical performance of the disinfection system and the microfluidic chip was verified by means of simulation and experiment. The relationship between the working power (P) of the UVA ultraviolet sterilizer used and its irradiance (Ee) is P = 29.98 Ee. The direct influencing factor of the ultraviolet disinfection rate of the nutrient solution residual liquid was the ultraviolet light irradiation dose. When the power of the ultraviolet lamp (radiation flux) is 30 W, the optimum wavelength is close to 300 nm, and the absorbance value is approximately 0.07. The error between bioluminescence detection and laboratory culture detection error is 0.002. The disinfection method and microfluidic chip proposed in this paper can be used in a greenhouse hydroponic system to reduce the impact of harmful microorganisms in the nutrient solution return on plants, and improve the effect of the return solution. [ABSTRACT FROM AUTHOR]