7.3 Solid wasteIB Environmental Systems and Societies HL: Revision notes

The use of natural resources generates waste, which can be classified by source (domestic, industrial, agricultural, construction, commercial) or by type (organic, plastic, paper, metal, glass, hazardous, electronic).

Solid domestic waste (SDW) typically has diverse content: food and garden waste, paper and card, plastics, glass, metals, textiles and electrical goods.

The volume and composition of waste varies over time and between societies because of socioeconomic, political, environmental and technological factors.

• Higher-income societies produce more waste per person, with more packaging and electronic goods (paper, plastic).
• Lower-income societies often produce more organic waste, a higher share of food and garden waste.
• Laws (such as plastic bag bans), climate, and new technologies (electronic waste) change waste over time.

The production, treatment and management of waste has environmental and social impacts, which may be felt in a different location from where the waste was generated. Example: electronic waste from high-income countries processed informally at Agbogbloshie, Ghana, with toxic fumes from burning cables.

Ecosystems can absorb some waste, but pollution occurs when harmful substances are added to an environment at a rate faster than they are transformed into harmless substances.

Different options have different advantages and disadvantages for society and ecosystems.

• Landfill: cheap, simple; uses land, produces leachate and methane, fills up.
• Incineration: reduces volume, can generate energy; costly, air pollution, CO₂, toxic ash.
• Recycling: saves raw materials and energy, reduces landfill; needs collection and sorting, contamination, energy use.
• Composting: returns nutrients to soil, reduces landfill; needs separated organic waste, can smell.
• Reuse: extends life of products with little processing.

Preventative strategies avoid waste being produced (reducing consumption, reusing, redesigning products and packaging, bans on single-use items). Restorative strategies deal with waste after it has been created (recycling, incineration, landfill, clean-up).

Preventative strategies are more sustainable than restorative ones because they save resources and avoid disposal impacts.

Sustainable options for management of SDW can be promoted in societies through education, legislation, deposit-return schemes, charging by weight, and kerbside collection of recyclables and compost.

A linear economy extracts resources, makes products, uses them and discards them. The principles of a circular economy provide a holistic perspective on sustainable waste management:

• Design out waste and pollution.
• Keep products and materials in use (reuse, repair, remanufacture, recycle).
• Regenerate natural systems (return organic material to the soil).

Example: Kamikatsu, Japan, a zero-waste town where residents sort waste into around 45 categories and about 80% is recycled.