Compostable tableware refers to the substances in discarded tableware that are suitable for microbial fermentation and fertilizer. Compostable tableware is collected and transported to a composting plant. After composting processes such as fermentation and microbial decomposition, it can be turned into a hygienic and odorless organic fertilizer, which can be used as fertilizer for plants and soil improvement. Tableware composting is a method of processing and utilizing garbage. It uses microorganisms such as bacteria, yeast, fungi and actinomycetes in the soil to degrade (digest) the organic matter in the tableware through a biochemical reaction, forming a similar The substance of humus soil, used as fertilizer and to improve soil. Aerobic composting process consists of pre-treatment, main fermentation (also called primary fermentation), post-fermentation (also called secondary fermentation), post-treatment, deodorization and storage and other processes.
1. Compostable tableware process: pre-treatment
The main task of pretreatment is crushing and sorting, removing non-compostable substances, and crushing compostable dishware waste into a suitable particle size range of 12-60mm.
2. Compostable tableware process: main fermentation
The main fermentation can be carried out in the open air or in the fermentation tank, and the oxygen is supplied by stirring or forced ventilation. The method of supplying air varies with the type of fermentation tank. The decomposition of substances in the early stage of fermentation is carried out by mesophilic bacteria. With the increase of the heap temperature, the thermophilic bacteria with the optimum temperature of 45~65℃ replaced the mesophilic bacteria, which can carry out high-efficiency decomposition. The supply of oxygen and the goodness of the holding bed have a great influence on the temperature rise of the heap material. big impact. Then it will enter the cooling stage, usually the stage where the temperature is raised until it starts to decrease is called the main fermentation stage. The main fermentation period of aerobic composting of compostable tableware waste such as plant based tableware waste is about 4-12 days.
3. Compostable tableware process: post-fermentation
Immature compost with a high carbon-to-nitrogen ratio applied to the soil can cause the soil to be nitrogen-starved. Immature compost with too low carbon-nitrogen ratio is applied to the soil, which will decompose and produce ammonia gas, which will harm the growth of crops. Therefore, semi-finished products that have undergone main fermentation must be post-fermented. Post-fermentation can be carried out in a special warehouse, but usually the materials are stacked to a height of 1-2m for open post-fermentation. In order to improve the efficiency of post-fermentation, sometimes it is still necessary to turn over or ventilate. The organic matter that has not been decomposed in the main fermentation process and that is difficult to decompose may be completely decomposed at this stage and become relatively stable organic matter such as humic acid and amino acid, and a fully mature compost product is obtained. The post-fermentation time is usually more than 20 to 30 days.
4. Compostable tableware process: post-processing
In the material after secondary fermentation, almost all organic matter is stabilized and reduced. However, the plastic and other sundries that have not been completely removed in the pre-treatment process have to be removed by a sorting process. The above impurities can be separated and removed by pretreatment equipment such as rotary vibrating screen, magnetic separator, and air separator, and re-crushed as needed. It is also possible to produce compound fertilizers by adding N, P and K additives to bulk compost according to soil conditions.
5. Compostable tableware process: deodorization
During the composting process, there will be ammonia, hydrogen sulfide, methyl mercaptan, amines and other substances produced in each process, which must be deodorized. The methods of removing odor mainly include chemical deodorization and adsorbent adsorption. An economical and practical method is the biological deodorization method of oxidative adsorption of cooked compost. Put the decomposed compost from the compost products, for instance, pla tablewares into the deodorizer, the height of the heap is about 0.8-1.2m, and the odor is introduced into the system to make it act on biological decomposition and adsorption in time, and the removal efficiency of ammonia and hydrogen sulfide can reach more than 98%.
6. Compostable tableware process: storage
Compostable tableware is generally used in spring and autumn, and needs to be stored in summer and winter. Therefore, it is necessary for general composting plants to set up storage facilities that can accommodate at least 6 months of production to ensure continuous production.