Landfill leachate treatment is a crucial aspect of municipal waste management, directly impacting environmental protection and public health safety. In China, sanitary landfilling is one of the primary methods for managing urban waste, resulting in leachate that is a highly concentrated organic wastewater characterized by significant variations in quality and quantity, complex compositions, and changes over time as the landfill ages. The treatment of this leachate has been a persistent challenge in the environmental protection field due to its high toxicity, complex components, elevated chemical oxygen demand (COD), high ammonia nitrogen content, imbalanced nutrient ratios, and poor biodegradability.
Characteristics of Landfill Leachate
The main sources of landfill leachate include water that percolates through the waste due to gravitational and other physical forces during landfill operations, natural precipitation, free water from waste, water generated by the decomposition of organic matter, and infiltrating groundwater. Leachate contains a variety of toxic and harmful substances, including dissolved organic matter, inorganic salts, heavy metals, and other pollutants that can cause carcinogenic, teratogenic, and mutagenic effects. This leachate is characterized by high pollution intensity, prolonged duration, significant fluctuations in water quality and quantity, high ammonia nitrogen content, imbalanced nutrient ratios, and excessive metal ion concentrations.
Application of Ruthenium-Iridium-Titanium Anode Plates in Leachate Treatment
Electrochemical water treatment technology demonstrates immense potential in landfill leachate management due to its highly selective nature. This technology can convert difficult-to-degrade organic compounds or toxic and inhibitory pollutants into biodegradable substances, thereby enhancing the biodegradability of wastewater. Ruthenium-iridium-titanium anode plates are effective electrochemical treatment materials known for their strong corrosion resistance, the ability to prevent short-circuiting issues caused by deformed lead anodes, lightweight, ease of shape fabrication, and the reusability of the substrate, making them widely applicable in electrochemical water treatment.
The working principle of ruthenium-iridium-titanium anode plates involves the direct electrochemical oxidation and degradation of organic pollutants. Under the influence of electric current, H₂O or OH⁻ in the wastewater discharges at the anode to produce adsorbed ·OH radicals, which react with organic compounds to facilitate degradation. For active electrodes, the generated ·OH combines with the metal oxide electrode material, subsequently binding to active sites to form higher oxidation state species (MOx+1). These species react with organic compounds for degradation, accompanied by the occurrence of oxygen evolution side reactions.
Research Progress in Leachate Treatment Technologies
Electrochemical oxidation technologies can be categorized into direct oxidation and indirect oxidation methods. Direct oxidation technology involves the direct electrochemical oxidation and degradation of organic pollutants at the anode. In contrast, indirect oxidation utilizes reversible redox pairs to indirectly oxidize organic materials or employs electro-Fenton processes to degrade organic compounds. The electro-Fenton method is particularly effective for treating difficult-to-degrade organic wastewater, such as landfill leachate.
In practical applications, permeable electrode reactors have demonstrated significant effectiveness in the electro-oxidative degradation of organic pollutants due to their high mass transfer efficiency and pollutant removal rates. Compared to traditional submerged reactors, permeable reactors improve mass transfer efficiency by more than three times and increase pollutant removal rates by two to three times.
Conclusion
In summary, ruthenium-iridium-titanium anode plates represent a highly efficient electrochemical treatment material with considerable potential for landfill leachate processing. Through electrochemical oxidation technology, it is possible to effectively reduce the COD and ammonia nitrogen content in leachate while improving its biodegradability, providing an economically viable solution for the sanitary landfill management of urban waste. With ongoing technological advancements, the application of ruthenium-iridium-titanium anode plates in landfill leachate treatment is expected to broaden significantly, playing a vital role in environmental protection and promoting sustainable development.