Mechanical Recycling: This involves sorting, washing, and shredding plastic waste into small pellets that can be melted and reformed into new products. This process is limited by the fact that each heating cycle can degrade the polymer chains, reducing the material's quality.
Feedstock (Chemical) Recycling: Polymers are chemically broken down into their original monomers or other small organic molecules. These 'feedstocks' can then be used as raw materials in refineries to create new polymers, effectively closing the loop.
Sorting Requirements: Effective recycling requires rigorous separation of different polymer types (e.g., HDPE vs. PET). Mixing different polymers often results in a low-grade material with poor mechanical properties that cannot be easily utilized.
| Feature | Landfill | Incineration | Recycling |
|---|---|---|---|
| Primary Benefit | Low immediate cost | Volume reduction & energy | Resource conservation |
| Main Drawback | Land usage & persistence | Toxic emissions (, ) | High sorting/processing cost |
| Sustainability | Low | Medium (Energy recovery) | High (Circular economy) |
| Chemical Change | None | Complete oxidation | Physical or chemical reversal |
Identify the Polymer Structure: When asked about incineration products, look at the repeat unit. If it contains chlorine (like PVC), always mention the production of acidic gas and the need for neutralization.
Evaluate Environmental Trade-offs: Be prepared to discuss why one method might be preferred over another. For instance, incineration is better than landfill for reducing volume, but worse for air quality unless strictly controlled.
Check for Specificity: Don't just say 'pollution.' Specify whether you mean greenhouse gas emissions (), toxic gas release (), or physical littering in oceans.
Common Mistake: Students often confuse 'recyclable' with 'biodegradable.' Ensure you distinguish between a material that can be reprocessed (recyclable) and one that can be broken down by biological organisms (biodegradable).
