Wastewater treatment has been one of the restricting factors in the development of livestock and poultry industry, due to the difficulty and high cost. Furthermore, there is serious pollution to soil, air and groundwater, if the farming wastewater is discharged without any treatment. Current biogas engineering can cause a heavy load and high blocking of wastewater. Fortunately, crop straw can serve as filter material for the filtration pre-treatment of livestock and poultry farming wastewater. The suspended solids can also be removed to effectively improve wastewater treatment. However, it is very necessary to promote the filtering speed and utilization rate of straw at present. In this study, the filtering project was proposed to solve these challenges using negative pressure. A series of tests were also carried out on the livestock and poultry farming wastewater. Firstly, the test platform was constructed to filter the farming wastewater using negative pressure, which was mainly composed of a filtration device, control box, sewage pump, vacuum pump, and pressure sensor. Specifically, the filter device was used to form the filter layer built by crop straw and the enclosed space required for filtration; The sewage pump was to pump the wastewater into the filter device; The vacuum pump was to form a vacuum degree in the filter device; The pressure sensor was to detect the air pressure in the filter device, and then control the vacuum pump on (or off) together with the PLC controller in the control box, in order to ensure the pressure stable within the set range. Secondly, the test factors were selected as the thickness and compaction density of the filtration layer, as well as the filtration pressure. The test range of each factor was then determined by the single-factor experiments. Moreover, the quadratic regression experiment was implemented to determine the filtration parameters of the optimal performance on filtering by negative pressure. The thickness and compaction density of the filtration layer and the filtration pressure were 10 cm, 130 kg/m³, and 30 kPa, respectively. Design-Expert 12 software was used to analyze the influence of the interaction among factors on the removal performance of wastewater. It was found that the removal rates of total solid (TS), volatile solid (VS), chemical oxygen demand (COD), and NH4+-N were 40.47%, 45.07, 13.56%, and 11.75%, respectively, indicating effective removal of solid pollutants in wastewater. Then, comparative tests were conducted on filtration between negative pressure and gravity under the same conditions. It was found that the amount of treated wastewater filtering by negative pressure was four times that of gravity, and the duration was only 1/5, indicating the higher filtration speed and utilization rate of straw. Finally, a comparative test was carried out on the anaerobic fermentation of wastewater. The wastewater filtering by negative pressure and gravity shortened the fermentation period by 30%, compared with the untreated wastewater. Gas production was stable without any fluctuation, indicating the reduction of the load during anaerobic fermentation. In summary, it is feasible for the crop straw as filter material to filter the livestock and poultry farming wastewater by negative pressure. The finding can provide technical support to the filtration equipment for the livestock and poultry wastewater.

Resource utilization of animal manure can be used to reduce environmental pollution in the recycling of nutrients from the manure. Solid-liquid separation can serve as one of the pretreatment to improve the utilization efficiency for cost saving. However, existing treatments cannot fully meet the large-scale production in recent years, such as the high energy consumption, and low separation efficiency for sewage with a high viscosity and small solid particles, such as waterfowl feces and biogas slurry. Single-factor experiments were carried out to determine the effects of the centrifugal separation time, mesh number, and centrifugal separation speed on the separation effect of waterfowl feces. The quadratic general rotary unitized design was used to implement an optimization test. The optimal combination of parameters was obtained after the analysis of the data and consideration of the actual operating conditions. The data were analyzed by Excel 2016, Origin 2021, and Design Expert 12. The results showed that the treatment was achieved in better solid removal with the shorter hydraulic retention time of subsequent biochemical treatment. The content of pollutants in the waterfowl feces showed a trend of gradual decrease with the increase of screen mesh. The reason was that the aperture size decreased, as the number of sieve meshes increased. The larger solid particles were passed through to be trapped in the filter bag. The better performance of solid-liquid separation of waterfowl feces was achieved with the increase in centrifugal separation speed, due to the retention effect of the screen and stronger centrifugal action. The solids removal effect cannot be significantly enhanced under the action of low-speed centrifugation when the centrifugal separation speed continued to increase. The separation effect of free water was mainly achieved, where the adsorbed water was not strong enough to detach from the inter-particle adsorption. The thickness of the filter cake in the filter bag gradually increased, as the separation time increased. The solid particles were retained, whereas, the liquid also had sufficient time to separate through the filter cake. But the excessive separation time led to the clogging of the screen pores, where the liquid was difficult to pass through the filter cake. After the centrifuge separation optimization test and verification, the optimal separation effect was obtained, when the centrifuge separation time, mesh number, and centrifugal separation speed were set as 3 min, 120 mesh (aperture size 0.13 mm), and 700 r/min, respectively. At the same time, the removal rates of total solid (TS), volatile solids (VS), chemical oxygen demand (COD), NH₄⁺-N, and total phosphorus (TP) were 50.20%, 57.59%, 5.39%, 4.39%, and 5.76%, respectively. The separation effects (removal rates of TS and VS were 53.21% and 58.61%) were comparable to the separation effect of a high-speed centrifuge after the field operation of the prototype. The treatment cost was reduced by nearly 22% for one ton of sewage, indicating the feasible low-speed differential centrifugal separation. This finding can provide a promising scheme for the removal of suspended solids from the waterfowl feces in engineering popularization.

Meat goose can represent one of the most significant economic waterfowl in China. An excessively high stocking density can reduce the production performance and welfare of geese. Moreover, the light-emitting diode (LED) green light can play a pivotal role in regulating the growth and development of embryos and offspring in chickens. This study aims to determine the optimal regimen of LED green light in the high-density rearing mode of goslings. According to the actual production, a two-factor experiment was designed with the incubation light (dark and LED green) and growth light (LED white and LED green). A systematic analysis was made to explore the effects of LED green light on growth performance, intestinal development, blood hormones, feather quality, and pecking behaviors of geese in high-stocking density. The results show that the light intensities were 30–40 and 30–35 lx during the incubation and brooding period, respectively, with a light cycle of L:D = 24:0. The growth performance of geese was significantly improved by LED green light during the gosling brooding period. The LED green light during the growing period was found to significantly increase the body weight of geese at 14 days, as well as the daily gain and feed intake of geese for 1 to 14 days (P < 0.05). Furthermore, there was a significant decrease in the ratio of feed to gain of geese for 1 to 14 days (P < 0.05). A significant reduction was found in the concentration of serotonin and corticosterone in the blood, as well as the duodenal crypt depth of the geese at 14 days in the green light group during the growth period (P < 0.05), compared with the white light group. Furthermore, the LED green light irradiation during the growing period was observed to significantly increase the length of the chest and abdomen feathers of geese at 14 days post-hatching (P < 0.05), whereas, the back bare score of geese was reduced at 14 days post-hatching (P < 0.01), and the average pecking time and frequency of geese was reduced for 1 to 14 days post-hatching (P < 0.001). Thus, the green light environment during the growing period was significantly beneficial to the quality of the feathers and the development of geese plumage. The LED green light during the embryonic period was found to significantly reduce the average pecking time and frequency (P < 0.05) for better feather pecking behavior in geese. Moreover, the hatching procedure of green light outstandingly reduced the duodenal crypt depth (P < 0.01), where there was an increase in the jejunal villus height of geese at 14 days (P < 0.05), compared with the control group. The adverse effects of intensive farming were reduced on the intestinal development of geese. Moreover, there was no significant interaction to identify between the incubation and brood lights, in terms of the regulation of growth performance, intestinal development, blood hormones, feather quality (feather length, cleanliness, and damage degree), and feather pecking behavior of geese. Therefore, the LED green light shared the positive regulations on the negative effects of high-density rearing of goslings. Moreover, the LED green light during the growing period of goslings yielded superior outcomes. It is thus recommended that green light irradiation can be employed at the brood stage of goslings in actual production, in order to mitigate the adverse effects of modern intensive farming on goslings. The findings can provide a theoretical basis for the efficient production of geese.

Currently, friction characteristics obtained from empirical parameters or soil direct shear tests are widely applied in the resistance calculation and operational parameter optimization of soil tillage components. However, the operation of soil-touching components is a dynamic process, and there are few reports on the dynamic friction characteristics of soil-contacting components in agricultural tillage based on factors such as different moisture content, pressure, and relative velocity. Herein, a test device to measure the friction characteristics of compressible bulk materials was developed: the interface friction between the soil and 65Mn plate and the internal friction characteristics of soil were tested using this device, and the dynamic changes of interface friction coefficient and internal friction coefficient with moisture content, pressure, and relative velocity were obtained. Based on the dynamic friction parameters of soil, the ditching resistance model of a typical ploughshare opener was established, the ditching resistance value was predicted, and field experiments were performed under different operating speeds (0.5 m/s, 0.7 m/s, and 0.9 m/s) and ditching depths (60 mm, 100 mm, and 140 mm). The results indicated that the calculated values of the ditching resistance model based on the dynamic friction parameters of soil reduced the error by 15% compared with the calculated values based on the friction characteristics of the soil direct shear test, which verified the accuracy of the ditching resistance model and the validity of the parameters obtained from the test device for the friction characteristics of compressible bulk materials. In addition, the minimum ditching resistance can be obtained when the ditching speed is 0.7 m/s at the same ditching depths, which is consistent with the dynamic friction characteristics of soil. It can be found that the dynamic friction characteristics of bulk materials have basic theoretical support for the optimization of operational component structures and operational parameters.