Search Results (42)

The oily wastewater produced by transformer oil leakage contains pollutants such as mineral oil, metal particles, aged oil and additives, which can disrupt the dissolved oxygen balance in water bodies, pollute soil and endanger human health through the food chain, causing serious environmental pollution. Effective oil–water separation technology is the key to ecological protection and resource recovery. This paper reviews the principles, influencing factors and research progress of traditional (gravity sedimentation, air flotation, adsorption, demulsification) and new (nanocomposite adsorption, metal–organic skeleton materials, superhydrophobic/superlipophilic modified films) transformer oil–water separation technologies. Traditional technologies are mostly applicable to large-particle-free oil and are difficult to adapt to complex matrix wastewater. However, the new technology has significant advantages in separation efficiency (up to over 99.5%), selectivity and cycling stability (with a performance retention rate of over 85% after 20–60 cycles), breaking through the bottlenecks of traditional methods. In the future, it is necessary to develop low-cost and efficient separation technologies, promote the research and development of intelligent responsive materials, upgrade low-carbon preparation processes and their engineering applications, support environmental protection treatment in the power industry and encourage the coupling of material innovation and processes. Full article

This study valorizes onion peel, an agro-industrial by-product rich in phenolic compounds and structural carbohydrates, for the development of cassava starch-based biodegradable films. The films were prepared using the solution casting method; a cassava starch matrix was mixed with a 2.5% glycerol solution and heated to 85 °C for 30 min. A separate solution of onion peel powder (OPP) in distilled water was prepared at 25 °C. The two solutions were then combined and stirred for an additional 2 min before 25 mL of the final mixture was cast to form the films. Onion peel powder (OPP) incorporation produced darker and more opaque films, suitable for packaging light-sensitive foods. Film thickness increased with OPP content (0.138–0.218 mm), while moisture content (19.2–32.6%) and solubility (24.0–25.2%) decreased. Conversely, water vapor permeability (WVP) significantly increased (1.69 × 10⁻⁹–2.77 × 10⁻⁹ g·m⁻¹·s⁻¹·Pa⁻¹; p < 0.0001), reflecting the hydrophilic nature of OPP. Thermal analysis (TGA/DSC) indicated stability up to 245 °C, supporting applications as food coatings. Morphological analysis (SEM) revealed OPP microparticles embedded in the starch matrix, with FTIR and XRD suggesting electrostatic and hydrogen–bond interactions. Mechanically, tensile strength improved (up to 2.71 MPa) while elongation decreased (14.1%), indicating stronger but less flexible films. Biodegradability assays showed slightly reduced degradation (29.0–31.8%) compared with the control (38.4%), likely due to antimicrobial phenolics inhibiting soil microbiota. Overall, OPP and cassava starch represent low-cost, abundant raw materials for the formulation of functional biopolymer films with potential in sustainable food packaging. Full article

Due to the complexity of impurity removal from the residual film, there is currently no better impurity removal equipment. To improve the screening performance of the residual film mixture, the vibrating screen was designed. In this paper, the key factors A, B, C, and D were identified through mechanical analysis of the mixture (where they represented the screen aperture diameter, vibration amplitude, vibration frequency, and screen mesh inclination angle, respectively). The soil screen rate (Y₁) and screening loss rate (Y₂) were evaluated. And the optimal ranges for these factors were determined by single-factor experiments. Based on the EDEM, the discrete element model was established to simulate the interaction between residual film and soil. And the motion characteristics of the residual film mixture were analyzed within the screen body through a combination of simulation and bench tests. The vibrating screen’s structural parameters were optimized using Box-Behnken experiments. The most suitable combination of settings was as shown below: A = 6.5 mm, B = 25 mm, C = 3.8 Hz, and D = 4°. Following the optimization of these parameters, the screening performance was optimized. Results of bench tests showed that the soil screening rate was 80.33% and the screening loss rate was 19.31%. This study was expected to offer theoretical and simulation-based methods for optimizing the parameters of residual film-soil vibrating screening devices. Full article

Aiming at key issues in harvesting film-covered potatoes in hilly and mountainous areas—incomplete residual film collection, poor potato–soil separation, and high damage from potato-collecting devices—this study developed a crawler self-propelled potato harvester suitable for these regions. This study first expounds the overall structure and working principle of the potato harvester and then conducts principal analysis and structural design for key components (film-collecting device, digging device, primary conveying and separating device, secondary conveying and separating device, and intelligent potato-collecting device) from the perspectives of material force and movement. Finally, field performance tests were carried out in Huangzhong County, Xining City, Qinghai Province. The test results show that the machine can achieve an operation effect with a potato harvest loss rate of 2.4%, a potato damage rate of 1.4%, an impurity content rate of 2.8%, a skin-breaking rate of 2.7%, and a residual film cleaning rate of 89.6%, meeting the potato harvesting needs of this region. The lightweight self-propelled crawler potato harvester designed in this paper can realize functions such as residual film collection, potato–soil vibration separation, manual auxiliary sorting, and intelligent potato boxing, providing technical and equipment references for the harvesting of film-covered potatoes in complex terrain areas. Full article

To address the issue of poor film–soil separation in traditional subsoil residual film recovery machines, which leads to recovered film containing excessive soil, a film–soil conveying and separation device was designed. By establishing a mechanical model for the balanced conveyance of the film–soil composite, the range of conveyor chain inclination angles enabling stable transport was determined. Using RecurDyn 2023 simulation software, a sensitivity analysis was conducted on the effects of vibrating wheel speed, vibrating wheel mounting distance, and conveyor chain inclination angle on vibration characteristics. This analysis revealed that vibrating wheel speed and mounting distance have a significant impact on the vibrating mechanism. Based on the DEM–MBD (Discrete Element Method—Multi-Body Dynamics) coupling approach, a discrete element simulation model was built for the film–soil vibrating conveyor device, residual film, and soil. Using the primary conveyor chain speed, vibrating wheel speed, and mounting distance as experimental factors, and soil content rate and film leakage rate as experimental indicators, single-factor tests and a three-factor, five-level orthogonal rotational composite design test were performed. The results showed that, at a primary conveyor chain speed of 1.61 m/s, a vibrating wheel speed of 186.2 r/min, and a mounting distance of 688.2 mm, the soil content rate was 18.11% and the film leakage rate was 7.61%. The film–soil conveying and separation process was also analyzed via simulation. Field validation tests using the optimal parameter combination yielded relative errors of 3.43% and 5.51%, respectively, demonstrating effective film–soil separation. This research provides a theoretical foundation and equipment support for addressing residual film pollution in the cultivated layer of Xinjiang region. Full article

To address poor film pickup, incomplete soil–film separation, and high soil content in conventional residual film recovery machines, this study designed a belt-tooth type residual film recovery machine. Its core component integrates flexible belts with nail-teeth, providing both overload protection and efficient conveying. EDEM simulations compared film pickup performance across tooth profiles, identifying an optimal structure. Based on the kinematics and mechanical properties of residual film, a film removal mechanism and packing device were designed, incorporating partitioned packing belts to reduce soil content rate in the collected film. Using Box–Behnken experimental design, response surface methodology analyzed the effects of machine forward speed, film-lifting tooth penetration depth, and pickup belt inclination angle. Key findings show: forward speed, belt angle, and tooth depth (descending order) primarily influence recovery rate; while tooth depth, belt angle, and forward speed primarily affect soil content rate. Multi-objective optimization in Design-Expert determined optimal parameters: 5.2 km/h speed, 44 mm tooth depth, and 75° belt angle. Field validation achieved a 90.15% recovery rate and 5.86% soil content rate. Relative errors below 2.73% confirmed the regression model’s reliability. Compared with common models, the recovery rate has increased slightly, while the soil content rate has decreased by more than 4%, meeting the technical requirements for resource recovery of residual plastic film. Full article

The disposal of orchard garbage (including pruning branches, fallen leaves, and non-biodegradable materials such as pesticide containers and plastic film) poses major difficulties for horticultural production and soil sustainability. Unlike general agricultural garbage, orchard garbage often contains both biodegradable organic matter and hazardous pollutants, which complicates efficient recycling. Traditional manual sorting methods are labour-intensive and inefficient in large-scale operations. To this end, we propose a lightweight YOLOv7-based detection model tailored for the orchard environment. By replacing the CSPDarknet53 backbone with MobileNetV3 and GhostNet, an average accuracy (mAP) of 84.4% is achieved, while the computational load of the original model is only 16%. Meanwhile, a supervised comparative learning strategy further strengthens feature discrimination between horticulturally relevant categories and can distinguish compost pruning residues from toxic materials. Experiments on a dataset containing 16 orchard-specific garbage types (e.g., pineapple shells, plastic mulch, and fertiliser bags) show that the model has high classification accuracy, especially for materials commonly found in tropical orchards. The lightweight nature of the algorithm allows for real-time deployment on edge devices such as drones or robotic platforms, and future integration with robotic arms for automated collection and sorting. By converting garbage into a compostable resource and separating contaminants, the technology is aligned with the country’s garbage segregation initiatives and global sustainability goals, providing a scalable pathway to reconcile ecological preservation and horticultural efficiency. Full article

Microplastics (MP) are widespread pollutants that pose a risk to soil ecosystems globally, especially in agricultural soils. This study introduces a method to extract and identify MP in Brazilian tropical soils, targeting debris of low-density polyethylene (LDPE) and polyvinyl chloride (PVC) polymers, commonly present in agricultural settings. The method involves removing organic matter and extracting MP using density separation with three flotation solutions: distilled water, NaCl, and ZnCl₂. Extracted MP are then analyzed through optical microscopy and Fourier transform infrared spectroscopy. The organic matter removal efficiency ranged from 46% to 89%, depending on the initial organic matter content in the soil. Recovery rates for LDPE ranged from 81.0% to 98.8%, while PVC samples showed a range of 59.7% to 75.2%. Finally, this methodology was tested in four agricultural raw soil samples (i.e., without any polymer enrichment) The values found in the soil samples were 2517.5, 2245.0, 3867.5, and 1725.0 items kg⁻¹, for ferralsol, nitisol, gleysol, and cambisol samples, respectively, with MP having diverse shapes including fragments, granules, films, and fibers. This approach lays the groundwork for future studies on MP behavior in Brazilian tropical agricultural soils. Full article

Damage to buried gas pipelines caused by mining activities has been frequently reported. Based on a case study from the Central China coal mining area, this research employs a scaled model experiment to investigate the movement of overlying strata in a room-and-pillar mining goaf. Distributed optical fiber strain sensors and thin-film pressure sensors were used to simultaneously measure the stress variations in the pipeline and changes in the soil pressure surrounding it. As the mining recovery rate increased from 50% to 86%, the maximum displacement of the overburden sharply escalated from 33.55 mm to 79.19 mm. During surface subsidence, separation between the pipeline and surrounding soil was observed, leading to the formation of a soil-arching effect. The development of the soil-arching effect increased soil pressure on the top of the pipeline, while soil pressure at the bottom of the pipeline increased on the outer side of the subsidence area and decreased on the inner side. Three critical sections of the pipeline were identified, with the maximum stress reaching 1908.41 kPa. After the completion of mining activities, pipeline collapse occurred, leading to a weakening of the soil-arching effect. Consequently, both stress concentration in the pipeline and soil pressure decreased. The probability integral method was corrected by incorporating the fracture angle, which enabled the determination of the location of maximum surface subsidence curvature, found to be close to the three failure sections of the pipeline. Full article

The existing residual film-recycling machines struggle to efficiently recover and separate film stubble in a single operation. With roller-type film-rolling device unloading difficulties and other problems, in order to improve the recovery efficiency of film stubble and the separation effect while reducing human labor and to improve work efficiency, we designed an automatic hydraulic unloading film stubble-recycling integrated residual film-recycling machine. The angle of the membrane lifting device was determined by theoretical calculations using the method of coupled simulation of EDEM and ANSYS Workbench. We analyzed the amount of resistance as well as the maximum stress and deformation during the working process of the membrane-lifting device and focused on the design of the membrane–soil separating device and membrane-rolling device. The depth of the film shovel, the forward speed of the machine, and the rotational speed of the driving wheel of the jogging chain were selected as the test factors, and the residual film recovery rate was taken as the evaluation index. A three-factor, three-level test was designed by applying the principles of the Box–Behnken experimental design. The results show that when the forward speed is 1.36 m/s, the soil depth is 147.16 mm, and the rotational speed of the driving wheel of the shaking chain is 77.89 r/min, the recovery rate of the residual film is 87.56%, and the relative error between the experimental value and the optimized value is 2.73%. The experimental results can provide a theoretical basis for the design of the residual film-recycling machine. Full article

Plastic film mulching technology can effectively enhance crop yield and quality, and the use of mulch has been increasing in recent years; however, the problem of mulch residue is worsening due to the large amount of recycling work and slow natural degradation. In this study, a potato seedling killing and residual film recycling machine is designed to provide good working conditions for potato harvesters before harvesting in response to the problems of difficult separation of film tangles, the low net rate of recycling due to the mixing of residual film with soil, and the high soil content in residual film recycling operations in northwest China. The machine is based on the potato monoculture and double row planting mode in Gansu area. This paper puts forward the overall design scheme and carries out the theoretical analysis and parameter determination of the key components, such as the seedling killing device, the film surface cleaning device, the film unloading device, and so on. Using EDEM software to carry out the virtual simulation test and Design-Expert13 to analyze the test results, we determined the optimal working scheme for the machine, with a forward speed of 0.8 m/s, a film gap of 125 mm, and a spiral stirrer speed of 600 r/min. Based on a field test for verification, the test results show that the machine’s residual film recovery rate was 83.3%, the impurity rate was 3.8%, and the rate of injury to the potatoes was 1.4%. The machine meets the requirements of national and industry standards, and it can simultaneously realize straw crushing, film surface cleaning, residual film recycling, and hydraulic film unloading operations, with better operating results and while reaching the expected results. It can also provide a reference for the design and testing of a seeding and residual film recycling machine. Full article

The mechanized harvesting level of potatoes in the arid areas of Northwest China is low and mainly relies on simple machinery to dig the soil surface, and then people manually pick up and bag the potatoes. This harvesting method has the problems of a high labor intensity, low operation efficiency, and high labor cost. Based on this, a wheeled-chassis potato combine harvester with integrated bagging and ton bag-lifting systems was developed, which could complete potato digging, potato–soil separation, potato–film separation, automatic bagging, and field ton bag lifting in one go. Firstly, based on the agronomic requirements and unique terrain characteristics of potato planting in this area, the structural design of the whole machine was completed with SOLIDORKS 2019 3D software. Secondly, the dynamic model was established for a numerical analysis, and the core parameters of key components were determined. The field experiments showed that the potato loss rate was 2.1%, the potato damage rate was 1.7%, the skin breaking rate was 2.5%, the impurity content was 1.9%, and the productivity was 0.15~0.23 hm²/h. The above field test indexes met the requirements of national and industrial standards. Full article

This study involves a material flow analysis (MFA) of single-use plastics (SUPs) and packaging materials in the Republic of Korea, focusing on their short lifespans and significant contributions to plastic waste. Based on the MFA results, recommended policies for managing packaging materials and SUPs were proposed. In 2021, 6.340 Mt of synthetic resin were produced, with 39.7% (2.518 Mt) utilized for packaging materials and SUPs. The per capita consumption of these materials was 48.7 kg/year, surpassing global averages. The separate collection rate was 54.6%, with films (26.2%) and manufacturing facilities (10.6%) exhibiting the lowest rates. The overall recycling rate was 52.7%, and 981 t of recycled waste was directly placed in soil. The reliability of the MFA results was estimated to be 83.1%, which is an improvement compared to previous studies. Recommendations include reducing plastic use, expanding recycling infrastructure, raising public awareness, and implementing stricter regulations to control soil contamination. Full article

The carbon source/sink nature and the water balance of a drip-irrigated and mulched watermelon cultivated under a semi-arid climate were investigated. Biodegradable films, plants and some fruits were left on the soil as green manure. The study spanned from watermelon planting to the subsequent crop (June–November 2023). The eddy covariance technique was employed to monitor water vapor (H₂O) and carbon dioxide (CO₂) fluxes, which were partitioned into transpiration, evaporation, photosynthesis and respiration, respectively, using the flux variance similarity method.This method utilizesthe Monin–Obukhov similarity theory to separate stomatal (photosynthesis and transpiration) from non-stomatal (respiration and evaporation) processes. The results indicate that mulching films contribute to carbon sequestration in the soil (+19.3 g C m⁻²). However, the mulched watermelon crop presented in this study functions as a net carbon source, with a net biome exchange, representing the net rate of C accumulation in or loss from ecosystems, equal to +230 g C m⁻². This is primarily due to the substantial amount of carbon exported through marketable fruits. Fixed water scheduling led to water waste through deep percolation (approximately 1/6 of the water supplied), which also contributed to the loss of organic carbon via leaching (−4.3 g C m⁻²). These findings recommend further research to enhance the sustainability of this crop in terms of both water and carbon balances. Full article

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 $\mathrm{m}·{\mathrm{s}}^{-1}$, 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 $\mathrm{m}·{\mathrm{s}}^{-1}$. 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. Full article