Solid waste

Global waste generation is increasing rapidly and is projected to continue rising strongly without major changes in consumption and management.

Municipal solid waste is household and commercial waste such as food, paper, plastics, glass, and metals collected by local authorities.

Global MSW generation is increasing rapidly and is projected to rise substantially by 2050; per-capita waste generally increases with income and urbanisation.

HICs generally produce much more waste per person and more packaging/electronics, while LICs produce less waste per person and a higher proportion of organic waste.

Examples include chemicals, batteries, medical waste, solvents, or materials that are toxic, flammable, corrosive, or reactive (any three correct examples).

HICs have higher per-capita waste and more packaging/electronics; LICs have lower per-capita waste and more organic composition with weaker collection systems.

Municipal solid waste, industrial waste, agricultural waste, and construction and demolition waste are key categories by source (mining waste also common).

Urban living increases consumption of packaged goods and concentrates waste generation; higher incomes and access to consumer products also increase waste.

E-waste is discarded electronic equipment. It is a problem because it contains both valuable metals and toxic substances (e.g., lead, mercury), and is often poorly recycled, causing pollution and health risks.

Waste composition typically shifts from mostly organic materials toward more packaging, plastics, and electronic waste as consumption rises.

Non-hazardous waste is typical municipal waste that is not toxic or reactive, while hazardous waste has properties (toxic, flammable, corrosive, reactive) that require special handling and disposal.

Because it links to rapid consumption growth, valuable resource recovery, hazardous pollution and health risks, and global inequality through waste export.

Informal recycling often involves burning or acid leaching without protection, releasing toxic fumes and contaminating soil and water, causing serious health impacts.

Describe both the quantity (total or per capita) and composition (types of waste), and link differences to development level or policy.

Link patterns to income/development level, consumption, urbanisation, and waste management infrastructure/policy differences.

Major methods include landfill, incineration, recycling, composting (and anaerobic digestion as an organic waste treatment).

Recycling aluminium saves very large amounts of energy compared with producing aluminium from ore and reduces the need for mining and landfill.

Leachate is liquid that drains through landfill waste, carrying dissolved contaminants. It is a concern because it can pollute groundwater and surface water if containment fails.

Landfill and incineration are end-of-pipe disposal methods, while recycling, composting, and waste-to-energy are recovery approaches that extract value.

Downcycling is recycling into lower-quality products (e.g., plastic bottles turned into fleece), meaning the material is less likely to be recycled again into the same product.

Advantage: relatively cheap and can handle mixed waste (and methane can be captured). Disadvantage: methane emissions and leachate risk, plus large land use.

Recycling is limited by contamination of materials, market demand/price volatility for recyclates, and the fact that some materials are difficult or uneconomic to recycle.

Because costs, infrastructure, waste composition, policy, and public acceptance vary, so the most suitable method differs by region and waste type.

Organic waste decomposes anaerobically in landfills and produces methane, a potent greenhouse gas, so uncontrolled emissions increase warming.

Advantage: reduces waste volume greatly and can recover energy (waste-to-energy). Disadvantage: air pollution (e.g., dioxins, particulates, heavy metals) and ash still needs disposal.

Incineration reduces waste volume but produces ash that must be disposed of safely and can contain toxic substances.

Composting is aerobic and avoids large methane production, whereas landfilled organic waste decomposes anaerobically and releases methane.

Common criteria include environmental impact, cost, feasibility, public acceptance, and suitability for different waste types.

Anaerobic digestion breaks down organic waste without oxygen and produces biogas (methane-rich gas) that can be used for energy, plus digestate.

Even with filters and scrubbers, emissions are reduced but not eliminated; incinerators are expensive, face public opposition, and may reduce incentives to recycle.

Prevent/Reduce, Reuse, Recycle, Recover (energy recovery), Dispose (landfill/incineration without energy recovery).

A circular economy is an economic model that eliminates waste by keeping materials in use through reuse, repair, remanufacturing, and recycling, so waste becomes an input for another process.

The waste hierarchy ranks waste options from prevention to disposal and prioritises preventing waste creation over managing waste after it is produced.

The circular economy aims to eliminate waste by keeping materials in use as long as possible through reuse, repair, and recycling.

Linear economy follows take-make-dispose, while a circular economy designs products and systems to reduce, reuse, recycle, and regenerate materials to minimise waste.

Because avoiding waste creation has the lowest environmental impact, reducing resource extraction and pollution across the entire product lifecycle.

Reduce: choose products with less packaging or buy less. Reuse: repair items, refill containers, or buy second-hand.

Examples include EPR, landfill taxes, deposit-return schemes, plastic bans, pay-as-you-throw, and education campaigns (any three).

EPR is a policy where manufacturers are responsible for the end-of-life management of their products, incentivising better design and higher recycling.

Recovery means extracting value from waste, commonly energy recovery through incineration with electricity/heat generation.

Evaluate strategies using effectiveness, cost, feasibility, environmental impact, and equity, then reach a justified conclusion.

Examples include plastic bag bans/taxes and deposit-return schemes; landfill taxes and pay-as-you-throw also incentivise reduction.

It means avoiding waste creation reduces impacts most because it prevents resource extraction, manufacturing emissions, and disposal pollution before they occur.

Design for durability, design for repair, design for disassembly, design for recyclability, and eliminating toxic materials are key strategies (any three).

Because higher-mark answers explain why options are ranked (resource use, energy demand, pollution) and discuss effectiveness and limitations, not just name the levels.