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As the final link of urban solid waste treatment, landfills have long faced environmental threats from leachate, landfill gas and odorous pollutants. These leachates not only have a pungent smell, but also contain high concentrations of heavy metals, organic matter and a variety of toxic substances.

As the final link of urban solid waste treatment, landfills have long faced environmental threats from leachate, landfill gas and odorous pollutants. These leachates not only have a pungent smell, but also contain high concentrations of heavy metals, organic matter and a variety of toxic substances. For example, the concentrations of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) can reach tens of thousands of milligrams per liter, and some pollutants even have the risk of carcinogenicity, teratogenicity or mutagenicity. With the improvement of environmental protection standards and the increasing scarcity of land resources, how to efficiently manage polluted sites, achieve ecological restoration and land reuse has become a difficult problem that needs to be broken through in the global environmental protection field.

Pollution control in landfills needs to deal with multiple complex problems. First, the water quality and water volume of leachate fluctuate greatly, which is significantly affected by the landfill age, climatic conditions and precipitation. Traditional single treatment processes are often difficult to stably meet the standards. In addition, contaminated soil is extremely difficult to repair due to the accumulation of heavy metals and the destruction of organic matter. Taking cadmium pollution as an example, the cadmium concentration in the soil must be reduced to below 0.3 mg per kilogram before it can be safely used, which places strict requirements on technical efficiency and cost control. Faced with these challenges, traditional landfill or simple covering can no longer meet the needs of sustainable development. The management of contaminated sites urgently needs to shift to the "active remediation" mode, that is, to achieve efficient removal of pollutants, resource utilization and rapid regeneration of sites through technological innovation.

Against this background, the modular soil Washing equipment developed by Desen Environment has become a powerful tool in the field of contaminated site management with its flexibility and efficiency. This technology breaks through the limitations of traditional remediation technology through modular design, intelligent control and multi-process collaboration, and provides a new idea for the management of complex contaminated sites.

Modular design improves engineering efficiency: The core innovation of Desen's modular Washing equipment is to disassemble the soil Washing process into ten functional modules such as feeding, crushing, grading, and concentration. Each module is quickly assembled through standardized interfaces and can be flexibly adapted to different site sizes and pollution types. For example, in a hexavalent chromium pollution remediation project in Hunan, the equipment only takes 24 hours from transportation to commissioning, with a processing capacity of up to 100 tons per hour, and the repair cycle is 60% shorter than traditional methods. This "plug and play" design greatly reduces the complexity of construction, especially for redevelopment projects with tight construction schedules in urban renewal.

Intelligent driving precise remediation: The integrated Washing equipment equipped with 5G communication and intelligent control system can monitor key parameters such as pollutant concentration and pH value of Washing solution in real time, and dynamically adjust the dosage of reagents and process flow through algorithms. In the treatment of an arsenic contaminated site in Qinghai, the system automatically optimized the Washing agent ratio to stabilize the arsenic removal rate at more than 95%, while avoiding secondary pollution caused by excessive use of reagents. This precise control capability not only improves the remediation efficiency, but also significantly reduces operating costs.

Multi-pollutant synergistic removal and resource recycling: For the combined pollution of heavy metals and organic matter, Desen Washing equipment achieves layered treatment through the synergy of hydraulic classification and chemical Washing. For example, in a lead-contaminated industrial plot in Beijing, the lead concentration of the contaminated soil was reduced from 850 mg/kg to less than 35 mg/kg after Washing, the recycling rate of the Washing solution reached 90%, and the repaired soil was directly reused for road construction. For organic pollutants such as petroleum hydrocarbons, the equipment can integrate a bio-enhancement module to increase the decomposition rate of polycyclic aromatic hydrocarbons (PAHs) to more than 94% using efficient degradation bacteria. This "graded treatment + resource recycling" model not only reduces the amount of waste generated, but also lays the foundation for land appreciation.

The success of Desen's modular Washing equipment has been verified in many typical projects across the country. In a chemical legacy plot in Jiangsu, the removal rates of hexavalent chromium and benzene organic matter reached 98% and 99.5% respectively through the "Washing + thermal desorption" combined process, giving this piece of land that had been abandoned for more than ten years a new lease of life. In a mining area in the northwest, this technology was used to repair arsenic and cadmium compound contaminated soil. The repaired area has been successfully transformed into an ecological park, becoming a benchmark for green regeneration of industrial sites.

In the future, with the advancement of the "dual carbon" goals and the tightening of environmental protection regulations, soil remediation technology will iterate in a more efficient and low-carbon direction. Desen Environment is exploring the combination of Washing technology with microbial remediation and ecological reconstruction to build a full-chain solution of "pollution stripping-biodegradation-vegetation restoration". At the same time, by promoting the internationalization of the "Standard for Modular Equipment for Ex Situ Soil Washing and Remediation", Chinese technology is expected to provide a new paradigm for global contaminated site governance.