Animal waste can serve as a raw material source for feed preparation, and can also be used, after appropriate processing, as fuel, fertilizer, biogas, and other useful products. In addition, the practical use of these wastes eliminates their mandatory disposal. Recycling animal waste is a feature of the circular economy, leading to environmental sustainability. In this regard, we conducted a search and review of contemporary scientific publications from open sources, including publications and data from Internet portals, Web of Science, Scopus scientometric databases, websites of patent offices, libraries, and reading rooms. It has been found that animal by-products are desirable for use in combination with vegetable protein sources. The 15 most relevant types of animal waste and their use are indicated based on current scientific publications. Moreover, 13 types of feed of animal origin, along with their purposes and descriptions, are also identified. Current scientific publications and research on the processing of insects into feed; the use of bird droppings, meat, and bone and bone meal; and the processing of seafood waste, bird waste, and eggshells are reviewed. As a result, firstly, the most important types of technological equipment involved in animal waste processing technologies, particularly devices for drying, grinding, and mixing, are analyzed and discussed. Secondly, technologies for processing waste into useful products of animal origin are analyzed and discussed.

The application method of granular fertilizers and wheat seeds depends on the colter design and parameters. In this research, a new double disc colter is studied to apply the wheat seeds to the horizontal band 12 cm in width and apply granular fertilizers deeper 2 cm than the wheat seed level precisely to the middle of the band. Applying granular fertilizers and wheat seeds at different levels increases the granular fertilizer dose without harm to the wheat seeds. Furthermore, applying high doses of wheat seeds to the horizontal band decreases the competition between the seeds and suppresses the weeds. Therefore, preparing a plain seedbed after applying the fertilizers and distributing wheat seeds to the horizontal band was the research objective. The comparison experiments of the base and designed double disc colters were provided in the soil bin determining the horizontal and vertical forces and the placement of the fertilizers and seeds. The discrete element method (DEM) was used to track the soil particle behavior interacting with the double-disc colter. The simulation results and actual experiment results were satisfactory when the AB length of the wing orifice was 60 mm.

The aim of this article was to study degreasing of raw materials raw fish bone waste and animal waste. A new method was developed, aimed at intensive extraction of fat with an additional absorber- de-limonene, placed in water during high-temperature cooking of raw materials of animal origin. De-limonene is a widespread terpene hydrocarbon, and a primary component of orange peel oil (constitutes up to 80–90%). Degreasing with the inclusion of de-limonene increases the degree of hydrolysis of collagen from animal raw materials, which intensifies the extraction of fat from the processed raw materials. High-temperature cooking promotes the breakdown of triglycerides into free fatty acids, which further break down into low molecular weight products. At the end of the heat the temperature of the heating plates is 70-90 ° C, the pressure inside the boiler is 1.6,-2.4 kPa, the duration is 60-100 minutes treatment of the raw material, a two-phase system was obtained: dry fat greaves and fat. Fat was sucked off by pumps connected to digesters, and greasy greaves were sent for degreasing by pressing. The method produced broth, fat, and feed.

The interaction properties of the seeds have to be calibrated to simulate the realistic behavior of the seed bulk. Here, a simple and accurate calibration method of DEM interaction properties of seeds with adequate equipment to simulate each seed’s behavior remains a challenge. In this research, the rotary drum is chosen as simple equipment to calibrate particle–particle and particle–material interaction properties, as there is a lack of research on whether the rotary drum is adequate equipment to calibrate particle–material interaction properties. Therefore, this article calibrates particle–particle and particle–material static and rolling interaction coefficients using a rotary drum. The calibration of particle–material static and rolling friction coefficients are described using the rotating drum with a 45 degrees inclination. The particle–particle static and rolling friction coefficients were calibrated according to the angle of repose when the rotary drum is vertical.

In the conditions of farms, it becomes necessary to grind feed that has a different degree of moisture. Therefore, the choice of universal working bodies is the object of research, and the theoretical determination of the average size of pre-crushed feed particles is of great scientific and practical importance and is a problem that needs to be solved. Proceeding from this, a constructive-technological scheme of a grinder with a universal grinding working body is proposed. The grinding apparatus is equipped with a hammer working body which has cutting edges. In this case, hammers with cutting edges crush the wet mass, and also create an air flow and work as flow accelerators at high speed. As a result of theoretical studies, the steps for arranging these working bodies were determined. Analytical expressions are obtained for determining the average length of pre-crushed feed particles depending on the distance between the faces of replaceable knife working bodies, i.e. from the step of arranging them in rows. At the same time, the calculation results showed that with a distance between the faces of replaceable hammers of 20 mm, the value of the average length of the grinded particles was 38.38 mm. The average size of pre-crushed particles from feed raw materials intended for farm animals was 37.64 mm, i. e. the difference between theoretical and actual value is only 2.0 %. This proves the reliability of the obtained analytical expression, which provides the determination of the main parameter of the grinding working body, i. e. spacing of radial knives in rows. The proposed method of determining the average length of crushed particles allows theoretically finding and planning the required particle size

The design of hammers for crushers is considered on the basis of a mathematical model of cracking in the production of bone meal. The proposed hammer desig