Solid waste

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

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

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

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

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).

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

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.

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

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.

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

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

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

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

Microplastics are plastic particles smaller than 5 mm in size.

Pollution is the introduction of harmful substances or harmful energy into the environment.

Some are persistent (do not break down easily), so they remain in ecosystems for long periods and continue to cause harm.

Wildlife can be injured or entangled and can ingest plastic, reducing feeding and causing starvation.

Pollution can be matter pollution (substances) or energy pollution (noise, light, heat).

Toxins can bioaccumulate in organisms and biomagnify up food chains, increasing exposure for humans as top consumers.

Microplastics are plastic particles smaller than 5 mm.

Many plastics fragment into smaller pieces rather than fully biodegrading, increasing microplastic pollution.

They can enter through air, water, or soil, be taken up by organisms, and then be transferred to predators through feeding.

Matter pollution adds substances such as chemicals or plastics; energy pollution adds forms of energy such as noise, light, or heat.

A persistent pollutant is a substance that resists breakdown and remains in the environment for long periods.

Through food, drinking water, and air.

Pollution can kill organisms or reduce their growth and reproduction, so less biomass and usable energy are transferred to higher trophic levels.

Plastics can be transported by rivers and ocean currents and can travel long distances before settling.

They persist in ecosystems, continue causing harm, and can build up in organisms and food chains.

Pollutants can bioaccumulate in organisms and biomagnify up food chains, leading to highest concentrations in top predators.

Small plastic fragments can be ingested by plankton and invertebrates, transferring to higher trophic levels when predators feed.

Noise pollution and light pollution (heat can also act as energy pollution).

Biomagnification increases pollutant concentration at higher trophic levels.

Some chemicals act as endocrine disruptors, interfering with hormones, development, and reproduction.

Plastics typically persist and fragment into microplastics rather than decomposing fully through biological processes.

Plastic pollution, including macroplastics and microplastics, entering marine ecosystems.

Industry (factory discharge), agriculture (pesticides/fertilisers), fuel combustion, and poorly managed waste.

Ingested plastic can block digestion, reduce feeding, cause injury, and increase risk of starvation.

Pollutants can cause toxicity, reduce growth, damage organs, and lower fertility, leading to population decline over time.

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

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.

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

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

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

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

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

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

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

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.

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

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).

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

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.

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

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.

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

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

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

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

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.

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.

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.

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

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

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