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Current solid waste treatment scheme

Current solid waste treatment scheme

Current solid waste treatment scheme

At present, the main collection methods of urban domestic waste in China: at present, the methods used by countries around the world to treat urban waste and feces include landfill, incineration, composting, and biogas production.

Landfill

Landfill is divided into general landfill and sanitary landfill. The former destroys the environment, pollutes air and water sources, and most of them have been restricted; The current landfill method is mainly the latter.

Advantages and disadvantages:compared with incineration treatment, sanitary landfill has low investment and operation costs, but the landfill leachate impermeability, collection and treatment system load and technical difficulties, high investment, complex landfill operation and difficult management. The waste gases such as methane and hydrogen sulfide in the landfill must also be treated well to ensure explosion-proof and environmental protection requirements.

High temperature composting

Relying on bacteria, actinomycetes, fungi and other microorganisms widely distributed in nature, it is a microbiological process that artificially promotes the transformation of biodegradable organic matter into stable humus. Composting method can be divided into aerobic composting and anaerobic composting according to the aerobic degree of composting microorganisms. At present, the former is mostly used. According to the complexity of the process, it is specifically divided into intermittent stacking method and continuous stacking method. There are three composting methods: pure waste composting, waste manure mixed (7:3) composting, waste sludge mixed (7:3) composting.

Advantages and disadvantages:high temperature composting plays a certain role in promoting the decomposition of crop stems, human and animal manure, weeds, garbage sludge and other deposits, as well as killing bacteria, insect eggs and weed seeds. Although the treatment cost is low, it covers a large area, the decomposition of organic matter is slow, the cycle is long, it is difficult to control the process, and it is easy to produce pollution.

Biogas production

The strictly sealed biogas digester is used to ferment organic waste, plant straw, human and animal feces, sludge, etc. in an anaerobic environment. The carbides, proteins, fats, etc. in organic waste are (fermented) by a variety of microorganisms in an anaerobic environment with a certain temperature, humidity and pH to produce combustible gas (mainly methane).

Advantages and disadvantages:the process is simple, and the by-product (fertilizer) is of high quality and low price (the fertilizer efficiency of raw materials is improved, and parasitic eggs can be killed), but the efficiency and sustainability are poor.

Incineration and pyrolysis technology

Incineration is a comprehensive treatment process of high-temperature decomposition and deep oxidation of solid waste. As the proportion of combustibles in solid waste is gradually increasing, the use of incineration to treat solid waste, a large number of harmful waste decomposition into harmless substances, the use of its heat energy has become a necessary development trend.

Advantages and disadvantages:small land occupation and large treatment capacity, but toxic and harmful substances are discharged into the atmosphere during the incineration process, increasing the content of urban dust. Pyrolysis is heating organic matter at high temperature (500 ℃ - 1000 ℃) under anaerobic or anoxic conditions to decompose it into gas, liquid and solid products. Compared with incineration method, pyrolysis method is a more promising treatment method, and its most significant advantage is less capital investment.

Solid waste recycling and treatment plan

Treatment and utilization of household solid waste:domestic waste treatment is cumbersome and low utilization rate, mainly due to inadequate classification. Classification and recycling of solid waste is a key step, which can not only reduce the difficulty of waste sorting, but also minimize the waste of resources. Compared with previous treatment, a classification process is added first, It is divided into: ① combustible: leftovers and some combustible household garbage, but excluding plastic and rubber film; ② Resources: newspapers, books, plastic drink bottles, glass drink bottles; ③ Non combustible: Waste small household appliances (electric kettle, radio recorder), clothing, toys, ceramic products, iron containers; ④ Major categories: large furniture, electrical appliances (television, air conditioning), bicycles. After classified collection, the municipal environmental sanitation department will carry out unified clearance and transportation, and then carry out sanitary landfill or other disposal schemes.

Treatment and utilization of industrial and mining solid waste:fill and mine pits after mining, flatten them and cover them with a certain thickness of good soil, and plant plants on them, so that the land can be reused. Utilization of blast furnace slag and coal ash: blast furnace slag can be water quenched to form granular glass, or form pumice like substances, or hot cast into blocks, which can be used as raw materials for cement industry; Coal ash slag is the main waste of power plants, which can be used as wall materials or the production of fly ash Portland cement, as well as fly ash to build roads, etc.

Solid waste collection:solid waste is collected by enterprises and institutions in the urban area and transported to the municipal solid waste landfill by special vehicles for treatment. In the transportation of solid waste, first, the selection of transportation vehicles should meet the following points: ① the car body is easy to clean; ② Good sealing; ③ The number of transportation vehicles is compatible with the transportation volume of solid waste. Second, pay attention to the following points during transportation: ① fully consider the clearing time and collection method; ② Solid waste shall be sealed during transportation and shall not be spilled. Third, weak solid wastes that have been listed in the national directory of hazardous wastes or identified as hazardous wastes in accordance with the technical specifications for the identification of hazardous wastes should be disposed of in accordance with the hazardous waste disposal plan and should not be disposed of together with general solid wastes. Now it has caused irreparable disastrous results when it causes pollution. In a sense, the harm caused by solid waste, especially hazardous waste, to the environment may be much more serious than that caused by water and gas.

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