New technology for comprehensive utilization of municipal waste
Release Time：2022-11-22 Source：Lithium battery recycling equipment Share：
With the rapid development of socialist economic construction and various undertakings, the scale of the city is expanding and the tourism business is becoming more and more prosperous, which has put forward higher requirements for urban environmental sanitation and cityscape. The serious harm caused by urban waste to the ecological environment has become a serious social problem, hindering the sustainable development of the national economy. Among various waste treatment methods, composting can firstly transform the perishable organic matter in the waste into organic nutrient soil that is easily accepted by the soil; secondly, the high temperature fermentation in the composting process makes the pathogenic bacteria and parasitic eggs in the waste basically be killed, eliminating the spread of harmful germs, while turning the waste into organic fertilizer, realizing resource recovery, promoting the virtuous cycle of materials and conforming to the law of ecological balance. It not only effectively solves the problem of urban household waste reduction, but also solves the problem of urban household waste pollution. Therefore, the use of composting technology to treat municipal waste is highly valued by governments at all levels.
Second, the existing composting system
There are many kinds of composting systems used for the treatment of MSW. According to the way of biological fermentation can be divided into aerobic composting and anaerobic composting.
1. Aerobic composting. Aerobic decomposition process is generally produced in the presence of oxygen and water, and its formation is shown as follows
Organic material + aerobic bacteria + oxygen + water → carbon dioxide + water (vapor state) + nitrate + sulfate + oxide
This reaction process produces no harmful substances, and although no biodegradation is odorless, properly treated aerobic fermentation produces very little odor. It shortens the anaerobic digestion process from several years to less than 20 days compared with traditional sanitary landfill. Aerobic composting treatment is characterized by controllable process, easy operation, fast degradation, good resourceization effect, ability to handle mixed waste, and low operating cost. According to the composting oxygen supply method and material flow form, the domestic waste composting system commonly used abroad can be divided into the following categories.
① Natural ventilation static composting. This is a kind of composting method, that is, the preparation of materials on a piece of ground, the height of the pile in about 2 meters, the shape of the pile is generally long, can also be combined with the site conditions pile into other shapes. This composting method is very similar to the open natural pile, the interior of the pile is often under pressure, the outside air often can not diffuse to the interior of the pile and make it anaerobic, odor, fermentation is not sufficient, fermentation cycle is long.
② forced ventilation static composting. To overcome the shortcomings of insufficient oxygen supply that often occurs in naturally ventilated static composting piles, generally set up ventilation pipes or ventilation slots along the length of the bottom of the pile, forced ventilation by high pressure according to the fermentation condition of the pile. Since the oxygen demand and water content of the pile can be controlled to a certain extent by controlling the amount of air blowing, the fermentation cycle is significantly shorter than that of naturally ventilated static composting.
③ mechanical turning pile strip composting, strip composting is the use of mechanical means of composting materials into long strips. The cross-section of the pile is trapezoidal, with a height of about 2 meters and a width of about 4 meters; the length of the pile is determined according to the site. Through mechanical turning pile to promote the contact between the pile and air is called mechanical turning pile strip composting.
④ Confined mechanized turning compost pile. The main process is: mixed waste treatment of compostable material into a special fermentation workshop, the use of special turning equipment - turning machine, turning the waste to facilitate aerobic fermentation of waste, fully aerobic fermentation of waste and then sieving treatment according to need.
2. Anaerobic composting. Anaerobic composting of organic waste is an anaerobic digestion technology that uses microorganisms to rapidly convert organic matter in waste into methane and ammonia under anaerobic conditions. The anaerobic process is generally produced under anoxic conditions, and its formation is shown as follows.
Organic matter + + CO2 + water → gaseous methane (biogas) + ammonia + final product
The products of anaerobic decomposition contain many thermophilic bacteria and can cause serious environmental pollution. It obviously contains organic fatty acids, acetaldehyde, mercaptans (wine smell), gas with some compounds and some harmful mixtures. For example, it is a very active and deadly high concentration of gas, which can quickly combine with part of the waste organic matter to form a black odorous mixture.
Third, the new technology proposed
The current level of domestic waste treatment and the current situation of waste shows that: the waste collection method is basically mixed collection; the characteristics of waste composition are high moisture, high ash and low calorific value; most cities are financially constrained and spend very little on waste treatment; the waste treatment method adopts piles and simple landfills in most cities, and the phenomenon of indiscriminate piling is common. Thus, for a developing country like China, it is necessary to find a treatment technology with low investment, low operation cost and no secondary pollution in order to achieve the unity of economic, social and environmental benefits. Analyzing the above waste treatment level and waste status, it can be seen that aerobic fermentation is more suitable for mixed waste and its advantage of low operating cost than anaerobic fermentation.
In the aerobic fermentation method, we took the lead in the early 1990s to propose the use of full hydraulic drive pile turner for the comprehensive treatment of municipal waste technology, full hydraulic drive pile turner is a set of mechanical, electrical, hydraulic integration of efficient equipment. It can aerate, crush, loosen, mix and turn the waste while spraying strains, and keep the waste in ideal strip pile shape. The equipment has the advantages of fuel consumption, high power, compact structure, flexible operation and convenient maintenance, etc. It also has good mixing and stirring functions, which not only effectively controls the fermentation parameters presenting the state, but also can shorten one fermentation cycle to 48-72h, greatly improving the efficiency and reducing the floor space and pollution to the environment. The equipment has been identified and confirmed that its technology fills the domestic gap and is at the leading level in China.
Fourth, the use of fully hydraulic drive pile turner on municipal waste for comprehensive treatment technology process and features
After years of research and development, the technology has thoroughly realized the "harmless, reduction and resourcefulness" policy of waste treatment, and the organic material of fertilizer - soil conditioner has been tested to meet the GB8172-87 standard. National control standard. The organic compound granular fertilizer has been tested to meet the NY481-2002 standard of the Ministry of Agriculture. The detailed process flow is shown in the figure above. The technology consists of aerobic fermentation of waste, waste sorting, soil conditioner to make granular fertilizer and other parts, of which the harmless landfill part can be used as needed.
① The part that cannot make fertilizer is incinerated, and the incinerated ash is used to make road bricks
② The plastic granulation or oil refining of the part that cannot be made into fertilizer, and the rest of the part made into road bricks, these two combinations. Use these two combinations to make all the waste resource utilization.
The technology makes full use of the fully hydraulic driven pile turner, using the ecological engineering principle of aerobic bacterial fermentation to mechanically turn the waste, strip composting, open aerobic fermentation. It has the following main features.
① Low investment in equipment.
②Low operating costs for harmless and reduced waste treatment.
③Higher return of products from resource-based treatment.
④No secondary pollution in the process of treatment and utilization.
⑤Bag breaking, strain spraying, ventilation and mixing are done at the same time during the fermentation process.
⑥Selecting process combinations according to customers' needs with high flexibility.
⑦basically solves the problem of classification in waste treatment.
⑧Short harmless time, large volume of waste treatment, and the occupied land can be used repeatedly.
⑨ High degree of mechanization and good labor protection measures for workers.
Composting of domestic waste is one of the main methods of waste treatment at home and abroad. After composting the organic matter in municipal domestic waste at high temperature, the resulting mature compost is actually humus, i.e. organic components in the soil, containing a certain amount of nitrogen, phosphorus, potassium and a small amount of trace elements needed for the growth of crops. The analysis results show that the application of fertilizer made from municipal waste on agricultural land has a significant impact on the physical and chemical properties of the soil, which can improve the water content of the soil, increase the void ratio, increase organic matter and soil fertility, etc. It is a valuable "soil conditioner". Garbage compost can also be corrected due to improper application of chemical fertilizers caused by the ground power disorders. Therefore, the State Council 1988 State Development (83) notice on strengthening the work of organic fertilizer, urban sanitation departments are required to urban garbage, manure factory treatment, so as to supplement the rural need for organic fertilizer.
The technology has been appraised and confirmed to be in line with the national industrial policy and the policy of "harmless, resourceful, and reduction" of waste treatment. It adopts a fully hydraulic driven pile turner to mechanically crush the garbage, spray the strain at the same time, and aerate, crush, loosen and turn the garbage, using the biotechnological principle of open aerobic fermentation, through crushing and sieving, the garbage is harmless and quantified, and the granular fertilizer is made from the sieved material in the garbage, which is in line with the Technical Regulations for Operation, Maintenance and Safety of Municipal Domestic Waste Composting Plant (CJJ/T86-2000), low comprehensive treatment cost, less land occupation, good environmental benefits, social benefits and certain economic benefits, has a high use and promotion value. It is an advanced process of urban waste treatment and is at the leading level in China.
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