توسعه یک سامانه تولید پیوسته کمپوست در مقیاس متوسط از پسماندهای کشاورزی

Nowadays, considering the environmental challenges, it seems inevitable to replace organic fertilizers with chemical fertilizers. From the point of view of nature lovers, biological methods for producing fertilizer and compost are very popular. The use of earthworms to digest masses of organic matter, including agricultural waste and food waste, is one of the methods used to produce organic fertilizers, especially vermicompost. The production of vermicompost in the traditional way usually leads to the production of relatively low quality and non-homogeneous compost. In this research, a reactor has been used for the continuous production of vermicompost. The device built in its harvester part includes an innovative mechanism. In this section, a reciprocating system for harvesting blades is used, which is started by an electric jack, and has eliminated the possibility of fatal corrosion and tearing of the blades. The performance of the device has been evaluated and calibrated by adjusting parameters such as the management of water sprinklers and the harvesting system, and it has been successful. The quality of vermicompost produced by the machine has been better in terms of food content compared to the product of the traditional method. The constructed digester has the ability to be used for composting wastes and organic waste on a medium scale.
Sustainable agriculture can be understood as an ecosystem approach to agriculture. There are many ways to increase agricultural sustainability. When developing agriculture in sustainable food systems, it is important to develop business processes and flexible agricultural practices. Fertilizer application targets the needs of plants to help them grow faster. If a plant is deficient in micronutrients and macronutrients such as calcium, magnesium, potassium or phosphorus, adding fertilizer provides a quick and easy solution to reduce deficiencies. Organic wastes and especially degradable food wastes are a significant part of agricultural and sometimes urban industrial wastes. In many countries, food waste constitutes a large part of municipal waste generated daily. There are two main ways to produce vermicompost, vermicomposting in buckets and small, medium or large tanks and producing vermicomposting on a large and industrial scale. In this research, in order to design a continuous production system of compost from organic masses, the mechanisms used in various research works in recent years were examined and a correction mechanism was used in the harvesting unit section of the machine along with other common sections.
During this research, a sample of a vermicompost digester was designed and built for the continuous production of vermicompost, and then it was evaluated. The various parts of the mentioned device are chassis and bases of the device, drive system chassis, drive system, misting system, electrical panel, harvester and walls. These parts are designed, made and assembled according to the workshop process. One of the problems in the vermicompost harvesting system, which is also common in medium sizes, is related to the corrosion and tearing of the harvester's wire box, which is caused by the chemical effects of the acidic environment of the pile, as well as the frequent movement of the harvester and frictional contact with the chassis body. In order to solve this problem, an electric jack was used for the first time in the driving system of this device with an innovative method. In order to semi-mechanized irrigation operation, fogging system equipment was applied in the system. After making and assembling the device, tests have been carried out to check the performance of the device. These tests were done after loading the device using rotted cattle up to a height of 45 cm with layer by layer and gradual feeding. ANSYS finite element software environment was used to check the mechanical strength of parts of the device that were mobile and the possibility of causing problems such as breakage and high deformation was seen in them.
In order to check the performance of the device, the working parameters of the set, such as the humidity in the upper and lower layers of the beds, the amount of worm density in the bed and the quality of the vermicompost produced by the device, have been investigated. After the initial design, the vermicompost continuous flow production machine was built and assembled, and before the initial loading of the machine, some evaluations were carried out, including verifying the mechanical strength of the machine and the performance of the driving set of the cutting blades by applying some modifications and solving minor problems. The flow rate of the pump in a period of 10 seconds during the tests that were performed was about 230 cc, and during the tests and errors, this amount was used to provide 80% humidity in the upper layer of the device tank with three repetitions of 10 seconds which has been extracted as one of the functional specifications of the device. Based on the experiments, the amount of mass that has been poured under the device with each round trip of the harvesting system has been observed to be 5.4 kg on average. In order to calibrate the device and harvest a layer with a thickness of 5 cm in each harvest, the number of 2 back-and-forth cycles was found suitable for the blades and was recorded as another parameter for the use of the device. Based on the statistics of the density of worms in different layers, it can be seen that the number of worms in the first layer is high in the first days, and it indicates the presence of a larger population of worms in this layer, which is mostly due to the presence of more food in this layer and oxygen is higher in the upper layers. Over time and with less food in the upper level, worms seem to migrate to these layers despite the porosity and less air in the lower layers. In all conditions, it can be seen that the lower layers are not liked by the worms, and this issue is suitable for preparing the harvest of the lower layers so that the worms are not damaged by the movement of the blades. The results of the evaluations have indicated that the digester built in this research has the ability to produce a continuous flow of vermicompost, and in addition, this device has the possibility of separating the ripe compost from the worm in a biological way, which can overcome the limitations of worm separation. The device has an innovative system in its harvester section, which has been able to overcome the problem of corrosion of the boxel wire of the blade, because in conventional models, it passes through the tank and through the acidic and corrosive environment of the material inside the tank and continuously. Therefore, there is a risk of rotting and tearing. The results of measuring the amount of moisture in the vermicompost mass in different layers of the digester tank and in different time intervals showed that the amount of moisture in the upper layer is the optimal moisture for worms and that worms tend to accumulate more. In this area, they have more moisture and food, and this issue has been successfully observed in the manufactured device. Based on the laboratory evaluation of the vermicompost product produced by this machine, compared to conventional and bed production methods, the produced vermicompost has a higher quality in terms of nutritional elements. The setting parameters of the device can be determined and suggested for a semi-automatic production of vermicompost, which includes instructions for mass irrigation and harvesting of ripe compost.