Landfill Waste in Waste Sorting

In the context of waste management, aged waste (also referred to as legacy waste or old landfills) represents a significant challenge. This type of waste has been buried in landfills for an extended period, typically ranging from several years to decades. During this time, it undergoes various biological, chemical, and physical changes that distinguish it from fresh waste. The decomposition process can lead to the production of landfill gases such as methane and carbon dioxide, leachate that can contaminate groundwater, and a complex mix of residual materials that are difficult to sort.

The sorting of aged waste is crucial for environmental protection and resource recovery. Advanced technologies and specialized equipment have been developed to address the unique characteristics of this waste stream. These technologies aim to separate recyclable materials, recover energy from organic components, and safely manage hazardous substances present in the aged waste.

Equipment used for processing aged waste often includes:

1. Excavators and Screening Systems: Heavy machinery like excavators is used to dig up the aged waste from old landfills. Once excavated, screening systems sort the waste into different fractions based on size, which helps in separating larger items from fines.

2. Air Classification Units: These units use air currents to separate light materials like paper and plastic from heavier materials such as glass and metals.

3. Magnetic and Eddy Current Separators: For removing ferrous and non-ferrous metals, these separators are critical in recovering valuable metals from the waste stream.

4. Optical Sorters: Utilizing near-infrared (NIR) technology, optical sorters can identify and separate plastics and other materials by their composition, improving recycling efficiency.

5. Biological Treatment Facilities: Facilities equipped for composting or anaerobic digestion can handle the biodegradable fraction of aged waste, converting organic matter into compost or biogas.

6. Specialized Handling and Safety Equipment: Given the potential presence of hazardous substances, proper handling and safety protocols must be observed, including the use of personal protective equipment (PPE) and containment measures.

7. Monitoring Systems: Continuous monitoring of emissions and effluents is essential to ensure compliance with environmental regulations and to mitigate any negative impacts on the surrounding environment.

In summary, the sorting of aged waste requires a combination of excavation, mechanical separation, and biological treatment processes, all supported by advanced equipment designed specifically for this purpose. Trials of new equipment and methodologies are ongoing, aimed at optimizing the recovery of resources and minimizing environmental impact. As we continue to refine our approaches, the goal remains to achieve sustainable waste management practices that protect our planet's natural resources for future generations.