A commercial composting system is like a conversion plant for organic materials, converting various types of organic wastes into nutrient-rich compost through a rigorous process.
Waste Collection and Classification
The feedstock utilized for commercial composting is derived from a multitude of sources. Food waste from restaurants, canteens and food processing plants; crop residues and manure from farms (chicken manure, cow manure, sheep manure, pig manure); grass clippings and leaves from horticultural companies; and organic wastes from the municipal waste system, such as household food waste and garden waste, are all significant sources of feedstock for commercial composting. The initial stage in the process of collecting organic waste is the sorting of said waste. It is of the utmost importance to remove non-degradable materials such as plastics, glass, metals and other impurities at this stage, as they will otherwise impede the degradation process. The presence of impurities in the composting process not only affects the quality of the final product, but may also result in damage to the composting equipment. The sorted waste is then divided into two categories: green materials with a high nitrogen content, including raw food waste, grass and manure, and brown materials with a high carbon content, such as leaves, straw, wood chips and cardboard. A suitable carbon-to-nitrogen ratio (C/N ratio) of approximately 30:1 is essential for successful composting. Green materials provide nitrogen, which facilitates the rapid breakdown of organic matter by microorganisms, while brown materials offer carbon, which balances and supports microbial activity.
Pretreatment and Mixing
The preliminary stages of treatment and mixing serve as the primary assurances for the effective decomposition of compost. For larger organic materials, such as tree branches and crop residues, the necessary preliminary step is crushing and shredding. The conversion of larger items into smaller pieces increases the surface area, accelerates microbial decomposition, and facilitates pile management, thereby reducing the overall composting cycle. It is also important to regulate moisture levels, as the optimum humidity for composting is between 40% and 60%. In the event that the waste is too dry, water should be added. Conversely, if the carbonaceous materials, such as wood chips or hay, are too wet, they can be added if necessary. The mixing of brown materials with a high carbon content and green materials with a high nitrogen content is also done in proportion, which helps to maintain the optimal C/N ratio and create the optimal conditions for microbial decomposition. Otherwise, odour problems or a slowdown in decomposition may occur.
Composting process management
Following the preliminary phase of treatment, the compost is transferred to the main decomposition stage. There are a number of common commercial composting methods. In static composting, the waste is stacked into a static pile and oxygenated through a natural ventilation system or regular turning. This method is suitable for medium-scale operations. In windrow composting, long piles of waste are formed and regularly turned to ensure an adequate oxygen supply. This method is well-suited to large-scale operations and is relatively cost-effective. In contrast, closed composting systems regulate temperature, humidity and oxygen supply within a sealed reactor, thereby accelerating decomposition and reducing odour emissions. They are well suited to scenarios where space is limited or where efficient composting is required.
The management of several key parameters is of paramount importance throughout the composting process. With regard to temperature, microbial activity will result in an increase to a range of approximately 50 to 70 degrees Celsius. This high-temperature phase accelerates the decomposition of organic matter and kills pathogens and weed seeds. However, high temperatures can also kill beneficial microorganisms, so it is important to monitor and regulate the temperature. Furthermore, an adequate oxygen supply is essential. The aerobic decomposition of microorganisms necessitates adequate ventilation, which can be facilitated through regular turning of the heap or the implementation of a blower system. Otherwise, anaerobic fermentation will result in the production of odours and harmful gases. It is also crucial to manage humidity levels. Excessive dryness or moisture can impair microbial activity and compromise the quality of the compost. Regular monitoring and regulation are essential to maintain optimal conditions.
Compost maturation and screening
The composting process typically lasts between three and six months, with the duration dependent on a number of factors, including the size of the compost, the composition of the materials being composted, and the management practices employed. As the microorganisms decompose, the temperature of the compost heap gradually decreases, indicating that the compost has entered the maturity stage. A mature compost has a dark brown appearance, is loose and uniform in texture, exhibits no visible food residues or undecomposed organic matter, and has an odour reminiscent of fresh soil, devoid of any foul smell. Subsequently, the compost is screened in order to remove any incompletely decomposed materials and impurities. Following screening, the compost is transformed into a high-quality product that can be utilised in agricultural and horticultural practices, as well as other fields, to provide rich nutrients to the soil, enhance soil structure, and facilitate the recycling of organic waste.
The commercial composting system is a process that is interlinked in its entirety, from the collection and classification of waste at the source to the final screening of the compost maturity. Each step is carried out in accordance with the scientific principles and operational specifications that have been established, thereby ensuring the effective transformation of organic waste into compost.
