Solid waste can be classified by source, meaning where it was generated, or by type, meaning its composition, properties or level of hazard. These classifications overlap: one source normally produces several types of waste.
This is core content for SL and HL in IB ESS subtopic 7.3 Solid waste. Classification matters because the source and type determine suitable collection, treatment and disposal strategies.
| Classification basis | Main categories and examples | Management implications |
|---|---|---|
| Source | Domestic waste from households; commercial waste from shops and offices; industrial waste from manufacturing; agricultural waste; construction and demolition waste; healthcare waste | Identifies who produces the waste and who may be responsible for collecting, regulating or paying for its management |
| Type | Organic or biodegradable waste, such as food; recyclable materials, such as glass and metals; hazardous waste, such as toxic chemicals; electronic waste; inert waste, such as rubble | Determines whether waste can be composted, recycled, treated, incinerated or placed in a secure landfill |
Solid domestic waste (SDW) has diverse content rather than being one material type. For example, a household waste stream may contain biodegradable food waste, recyclable aluminium, hazardous batteries and electronic waste. The common misconception is that “domestic” describes a type of material; it actually describes the waste's source.
Classification also reveals social and environmental impacts. Electronic waste generated by households or businesses in high-income countries may contain valuable recyclable metals but also hazardous substances. Its international movement to informal processing sites, including Agbogbloshie in Accra, Ghana, has raised environmental justice concerns because health and pollution costs may be experienced far from where products were consumed.
In an IB exam, distinguish the two classification bases explicitly: source = origin; type = material or properties. Use one item to demonstrate overlap, such as a discarded household battery classified as domestic by source and hazardous by type, then link its classification to an appropriate management strategy.
