I. Understanding Practice Purpose Through the understanding practice of the garbage disposal plant, we can understand the technological process and corresponding facilities of the garbage disposal machine, and understand the nature and characteristics of the environmental science major, which is conducive to students' subsequent professional courses. Two. Brief introduction of Zhengzhou waste treatment plant Zhengzhou comprehensive waste treatment plant is located in Houzhai Township, Erqi District, 800 meters away from the southwest ring road, with a total area of about 1.280 mu. The whole factory is divided into three parts: garbage disposal, sewage purification and excrement disposal. The first phase of the project includes sanitary landfill, sewage treatment station, fecal harmless treatment plant and management office area, and the second phase will build a high temperature reactor. Garbage disposal technology is mainly sanitary landfill, supplemented by high temperature composting. The designed service life is 22 years, and the treatment scale of biochemical waste is 2300 tons/day. The total volume of sanitary landfill is130,000 cubic meters, and the volume from A to D to your brother is 60,000 cubic meters. According to the current daily output of 2500 tons of sand monk or garbage, it will take about seven or eight years to fill the A-D area. Three. Composition and characteristics of solid waste in China In the process of developing resources and manufacturing products, human beings will inevitably produce waste, which will become waste after consumption and use. The useless solid and semi-solid substances produced by all human activities are called solid wastes. The garbage in China mainly includes industrial garbage, agricultural garbage, mining garbage and urban garbage. Urban garbage mainly comes from residents' consumption, municipal construction and maintenance, and commercial activities. Urban garbage accounts for the vast majority of the total amount of garbage generated. The composition of municipal waste is mainly related to the economic level of the city. In the composition of municipal waste in China, the proportion of organic waste is generally low, with low calorific value and high water content. It is not conducive to the utilization of resources, so at present, most of the urban garbage disposal in China adopts sanitary landfill. Advantages and disadvantages of landfill sanitary landfill is the main way of centralized disposal of municipal solid waste in China at present because of its mature technology and low treatment cost. The sanitary landfill of garbage has less investment, simple process, large treatment capacity and harmless surface. At the same time, the landfill garbage has not been treated harmlessly, leaving a lot of bacteria and viruses; Biogas also has hidden dangers such as heavy metal pollution; Garbage leakage will pollute groundwater resources for a long time, so this method is potentially harmful and will bring endless troubles to future generations. This method not only fails to realize the resource treatment of garbage, but also occupies a lot of land, which is a dangerous way to reserve pollution sources for future generations. At present, many developed countries explicitly prohibit landfill. The competent departments at all levels of our government have gradually realized the problems existing in this treatment technology, and this kind of behavior will inevitably be banned and eliminated. V. Possible pollution and prevention measures during landfill 1. Landfill leachate Contaminated garbage will produce leachate after anaerobic fermentation in the long-term landfill process. Landfill leachate is a kind of high-concentration wastewater containing many pollutants, containing refractory organic matter and metal ions, which has a long time, a wide range and great harm, and cannot be directly discharged, so leachate treatment is particularly important. There are many anti-seepage measures for landfill, which can be generally divided into natural anti-seepage and artificial anti-seepage. However, no matter which anti-seepage method is adopted, it must meet the requirements of anti-seepage rate and compressive strength, that is, the horizontal and vertical anti-seepage rate of your brother is not greater than 1.0* 10-7cm/s, and the compressive strength must be greater than 0.6MPa. Natural anti-seepage refers to the anti-seepage work by using the soil hydrogeological conditions of natural sites. Artificial seepage control can be divided into vertical seepage control, horizontal seepage control and top seepage control. According to the design, the comprehensive garbage treatment plant has three systems to prevent pollution: first, the sanitary landfill seepage control system, with strict seepage control measures at the bottom and side walls, will not pollute groundwater; It is a sewage treatment system, and the landfill leachate can reach the national second-class water quality standard for farmland irrigation after being treated by the sewage treatment station; The biogas inversion system discharges biogas from the bottom of the sanitary landfill to the trachea. The leachate of Zhengzhou Municipal Garbage Comprehensive Treatment Plant adopts advanced treatment project, namely anaerobic (UBF)+FEO reactor+oxidation ditch+membrane biological treatment A/O/MBR+ ultrafiltration+nanofiltration/reverse osmosis process. The discharge standard of sewage treatment project is Grade I discharge standard in Integrated Wastewater Discharge Standard (GB8978- 1996), which can be directly discharged into the reservoir. 2. Pollution of the landfill to the atmosphere Due to the fermentation during the landfill, the air quality near the landfill is not good, and the landfill emits a lot of irritating gases, including methane gas, carbon dioxide, ammonia gas, etc. Most of its gases contain greenhouse gases, and direct discharge into the atmosphere will increase the content of greenhouse gases in the atmosphere and produce greenhouse effect. A large number of bacteria, mosquitoes and flies are produced in the landfill process, which pollutes the local and nearby air. The waste treatment plant is introducing advanced technology and cooperating with companies that use biogas to recover biogas and other waste gases during landfill. 3. The garbage dump covers an area of a populous country like China with a high population density. In the process of sanitary landfill, there is no doubt that large-scale land occupation will be carried out, that is, garbage is competing with people for scarce land resources. Only by properly solving the way of garbage disposal can we reduce the waste of land resources and alleviate the sharp contradiction between garbage disposal and people's demand for land. At present, the feasible method is to classify the garbage from the source, reduce the amount of garbage and reduce the occupied area. Alleviate such a sharp contradiction between garbage and people at present. The concept of garbage disposal method 1. Implementing the garbage classification system is the first step to reduce the amount of domestic garbage. Different types of garbage have different treatment methods. We should learn from the garbage treatment methods of advanced cities at home and abroad and implement the principle of taking proper measures to treat garbage chemically, quantitatively and dangerously. Form a garbage industrial chain, make a garbage economy and build an environment-friendly harmonious society. For example, we can learn from Nagoya's experience. According to the composition of domestic waste, it can be roughly divided into four categories: ① recyclable non-biological waste, such as paper products, plastic products, metal products, glass products and so on. (2) kitchen waste, such as leftovers, eggshell skins, cabbage leaves, etc.; ③ Other rubbish, such as brick and tile ceramics, sanitary waste paper, lime soil, fabrics, etc. (4) Toxic and harmful wastes, such as waste batteries, fluorescent tubes, bottles containing toxic substances, etc. 2. Actively develop composting technology. Composting is a treatment technology for organic components in garbage. Domestic garbage can be used as compound fertilizer for crops after composting. At present, the organic components in domestic waste are relatively high, and the domestic waste compost after classified collection has broad development prospects. 3. Proper Incineration Due to the expensive incineration equipment, it is difficult to adopt the incineration method in Shiyan City, but the simple incineration method can be considered. The equipment is simple, the investment is relatively small, the operation is easy, and the requirements for disposal sites are low, which is more suitable. After the simple incineration method is introduced, the recovered heat energy is heated, which reduces the pollution of smoke and dust to the environment. Understanding the practical experience of intransitive verbs Through this understanding and practice in Zhengzhou Comprehensive Waste Treatment Plant, we have learned the present situation of waste treatment in most parts of China and the development direction of waste treatment methods in the future. Today, I learned the composition of garbage dump and the technological process of garbage disposal in garbage dump, especially the treatment process of leachate, and got a very full perceptual understanding. Will have a clearer goal and motivation for the next step of learning.