What Happens to Non-Recyclable Materials?

Non recyclable materials processing
Non recyclable materials processing

Every year the world produces billions of tonnes of stuff we don’t need anymore. Some of it gets recycled and keeps cycling through new products. A lot of it doesn’t. So what actually happens to materials that can’t be recycled, and why does it matter? Below I’ll walk through the common fates of “non-recyclable” waste, explain why some items are non-recyclable in the first place, and point you to technical, high-authority sources if you want to dig deeper. UNEP – UN Environment Programme+1

Recyclable vs. non-recyclable — what’s the difference?

Recyclable materials are those that can be collected, sorted, and processed into feedstock for new products with technologies that are currently viable at scale. Think: clean paper, many metals, certain glass, and single-resin plastics (when accepted by local systems). Non-recyclable materials are items that — because of contamination, mixed materials, economics, or lack of local infrastructure — are not turned back into new products. Examples:

  • Composite packaging (chips bags laminated with different plastics/metal layers)
  • Soiled food-contaminated paper and cardboard
  • Thin, contaminated films and multi-layer plastics
  • Some small, mixed-material electronics components and textiles with mixed fibers

Whether something is recyclable is context dependent — a material that’s recyclable in one city (because it has a sorting line and market demand) may be non-recyclable somewhere else. That’s why design and market infrastructure matter as much as the chemistry. Ellen MacArthur Foundation+1

The main fates of non-recyclable materials

1. Landfill — the “store it and forget it” option

Most truly non-recyclable municipal solid waste ends up in sanitary landfills. Modern engineered landfills are lined, have leachate collection systems, and capture methane (to varying degrees), but they still store the waste for decades to centuries. Organic fractions in landfills decompose anaerobically and produce methane — a potent greenhouse gas — unless captured. Long-lived items (e.g., many plastics, treated textiles) can persist for centuries. Global and regional reports highlight how much residual waste still goes to landfill and the emissions and pollution risks this creates. Data Topics+1

Takeaway: landfill is stable short-term containment but not a climate-neutral solution — decomposition and leachate remain problems unless tightly managed. UNEP – UN Environment Programme

2. Incineration / Waste-to-Energy (WtE) — burn to reduce volume and recover energy

Where incineration is used, non-recyclable waste is combusted to reduce volume, produce heat, and often generate electricity. Modern WtE plants use pollution controls and, in some regions, capture energy efficiently. However, incineration produces residues (bottom ash, fly ash) that often still need landfilling or specialized treatment, and emissions must be tightly controlled to limit hazardous pollutants and CO₂. For many countries, WtE is a way to avoid landfill while recovering energy — but it also competes with recycling and requires careful regulation. US EPA+1

Takeaway: WtE reduces volume and provides energy but creates ash and emissions; it’s most defensible when it treats genuinely non-recoverable waste and uses best-practice pollution controls. US EPA

3. Mechanical-Biological Treatment (MBT) and advanced sorting

MBT facilities mix mechanical sorting (to recover what still can be reused/recycled) and biological processes (to stabilize organics) before landfilling or further treatment. MBT reduces the environmental impact of residual waste and can increase the fraction diverted to recycling or energy recovery. Countries developing waste systems often use MBT to manage heterogeneous residual streams. www-cycle.nies.go.jp

Takeaway: MBT is useful for mixed, contaminated residuals — it improves recovery rates and lowers risks before final disposal. www-cycle.nies.go.jp

4. Export / Informal recycling / Illegal disposal

When domestic infrastructure is lacking, residual waste is sometimes shipped abroad (with legal and ethical concerns) or ends up in informal recycling streams where waste pickers recover useful fractions. Illegal dumping and open burning are also realities in places without formal systems — with serious local health and environmental impacts. International reports warn that growing waste volumes plus uneven infrastructure raise these risks worldwide. Data Topics+1

Takeaway: Without investment in systems, non-recyclable waste can accentuate inequity and environmental harm, especially in low-income regions. UNEP – UN Environment Programme

Environmental and technical issues caused by non-recyclable materials

  • Greenhouse gas emissions: decomposing organics in landfills produce methane; incineration emits CO₂ (and other pollutants if not controlled). Global analyses show waste’s contribution to emissions, and projections warn of rising waste generation without action. UNEP – UN Environment Programme+1
  • Persistent pollution: many plastics fragment into microplastics that contaminate soils and water and can persist for centuries. Ellen MacArthur Foundation
  • Toxic residues: incinerator fly ash and some landfill leachates can concentrate hazardous substances that require specialized handling. US EPA, Slideshare

Why so much waste remains non-recyclable? (The technical bottlenecks)

  1. Material complexity: multilayer or composite materials are chemically and physically hard to separate and reprocess. Ellen MacArthur Foundation
  2. Contamination: food, oils, adhesives, and mixed residues degrade the quality of recyclate and can spoil entire batches. US EPA
  3. Economics & markets: recycling works only when there is a market for recovered material; low commodity prices or lack of local processors make some recycling unviable. Data Topics
  4. Infrastructure mismatch: even technically recyclable items may be non-recyclable if collection, sorting and processing capacity does not exist locally. www-cycle.nies.go.jp

What’s being done (policy & design responses)

  • Circular economy and redesign: organisations and governments push to redesign products so plastics and packaging are reusable or truly recyclable. The Ellen MacArthur Foundation frames this approach as eliminate–innovate–circulate for plastics. Ellen MacArthur Foundation+1
  • Regulatory shifts: many regions are tightening landfill rules, incentivising recycling, and regulating incineration emissions; the EU and member states have seen decreasing landfill rates and more incineration with energy recovery where appropriate. European Environment Agency+1
  • Investment in technology: better sorting (optical, AI), chemical recycling research, and MBT systems help recover more from previously “non-recyclable” streams — though scale and economics remain challenges. www-cycle.nies.go.jp+1

Practical tips for citizens (how to reduce your “non-recyclable” footprint)

  • Buy less single-use and packaging with mixed materials. Prioritise items labelled recyclable in your local system.
  • Clean and sort materials where possible — contamination is a major reason items get rejected.
  • Support policies and brands that design for recyclability and reuse (deposit return systems, reusable packaging).
  • When in doubt, check your local waste authority — “recyclable” on a product isn’t universal.

Quick, evidence-backed takeaways

  1. A lot of waste still ends up as residuals (landfill, incineration, or MBT) because of material complexity, contamination and infrastructure limits. Data Topics+1
  2. Landfills and incinerators are necessary in many systems to deal with genuine residuals, but both have climate and pollution tradeoffs that must be managed. US EPA+1
  3. Systemic change — product redesign, better collection/sorting, and market development for recyclates — is what can turn “non-recyclable” into recyclable at scale. The circular economy framework explains how. Ellen MacArthur Foundation

Further technical reading (authoritative sources)