With the acceleration of urbanization, the problem of garbage disposal is becoming more and more prominent. As one of the main ways of garbage disposal, landfills are of great significance for protecting the environment and human health. This paper will introduce the principle, process flow, technical difficulties and solutions of landfill leachate treatment engineering in detail, in order to provide reference for research and practice in related fields.
2. The engineering principle of landfill leachate treatment.
Landfill leachate is mainly produced by the water and organic matter in the garbage during the landfill process. These leachates contain a large amount of organic matter, heavy metal ions, ammonia nitrogen and other pollutants, which will cause serious pollution to the environment if not properly treated. The landfill leachate treatment project mainly uses physical, chemical and biological methods to remove or convert the pollutants in the leachate into harmless substances to meet the discharge standards or reuse requirements.
3. Landfill leachate treatment process.
1.Pretreatment: Mainly pretreatment of leachate, including adjusting pH value, removing large particle impurities, etc., to provide good conditions for subsequent treatment.
2.Physical treatment: Suspended solids and some dissolved substances in the leachate are removed by physical methods such as precipitation and filtration.
3.Chemical treatment: The use of chemical reactions to convert pollutants such as organic matter and heavy metal ions in leachate into harmless substances or substances that are easy to biologically treat.
4.Biological treatment: Through the metabolism of microorganisms, the organic matter in the leachate is decomposed into carbon dioxide and water, and at the same time, substances such as ammonia nitrogen are converted into harmless substances.
5.Advanced treatment: Further treatment of biologically treated leachate, such as membrane filtration, advanced oxidation, etc., to meet higher discharge standards or reuse requirements.
4. Technical difficulties and solutions for leachate treatment in landfills.
1.High concentrations of organics: The high concentration of organics in landfill leachate puts a lot of stress on the biological treatment system. Solution: Anaerobic-aerobic combined treatment process is used to improve the removal efficiency of organic matter. At the same time, adsorption, chemical oxidation and other methods can be used to pretreat organic matter to reduce the difficulty of subsequent treatment.
2.Heavy metal ions: Landfill leachate contains a variety of heavy metal ions, which pose a threat to the environment and human health. Solution: Heavy metal ions are treated by physical and chemical methods such as chemical precipitation and adsorption. At the same time, the enrichment of microorganisms can be used to convert heavy metal ions into biomass and realize the biological fixation of heavy metal ions.
3.Ammonia nitrogen: The high levels of ammonia nitrogen in landfill leachate negatively affect biological treatment systems. Solution: Ammonia nitrogen is treated by biological denitrification technologies such as anaerobic ammonia oxidation, nitrification and denitrification. At the same time, chemical precipitation method, ion exchange method and other methods can be used to pretreat ammonia nitrogen to improve the efficiency of subsequent treatment.
4.Nutrient imbalance: The proportion of nutrients in landfill leachate is unbalanced, affecting the efficiency of biological treatment. Solution: Regulate the nutrients by adding nutrients and adjusting the proportion of influent water to ensure the normal operation of biological treatment. At the same time, constructed wetlands and other technologies can be used to naturally regulate nutrients and realize the recycling of nutrients.
5.Large amount of sludge generated: A large amount of sludge will be produced during the leachate treatment process of landfills, which will cause secondary pollution to the environment. Solution: Adopt sludge reduction technology, sludge resource utilization technology and other means to reduce the amount of sludge generated. At the same time, the sludge produced can be properly disposed of, such as incineration for power generation, brick making, etc., to realize the resource utilization of sludge.
V. Conclusions. Landfill leachate treatment project is one of the important measures to protect the environment and human health. Through reasonable process flow and technical means, the pollutants in the leachate can be effectively removed and the best utilization of resources can be realized. In future research, we should continue to pay attention to the innovation and development of leachate treatment technology and the improvement and implementation of environmental protection policies, so as to make greater contributions to promoting green and low-carbon development.