VMBO Year 3 · Sustainable living · Section 7.7

Soil and waste

Why protect soil?

Soil supports food production, ecosystems and the supply of some raw materials. Harmful substances in soil can affect organisms, and some can enter food chains through plant uptake or soil-feeding animals. Preventing pollution is preferable to removing it afterwards. Where contamination has occurred, soil remediation can reduce or remove the problem.

Types of household waste

Separating waste allows different materials to be treated appropriately.

• Recyclable materials: materials suitable for processing into new raw materials, such as some paper, glass, metals and plastics.
• Biodegradable kitchen and garden waste: suitable organic material that can be broken down biologically.
• Household hazardous waste: materials containing harmful substances, such as batteries and some paint residues, requiring separate collection.
• Residual waste: waste remaining after separately collected streams have been removed. It can still contain biodegradable material, but is not being collected for that treatment.

Recycling and composting

During recycling, recovered materials are processed into materials for new products. This can save virgin resources and reduce particular environmental impacts.

During composting, microorganisms break down suitable organic waste under controlled, oxygen-rich conditions. The resulting compost improves soil and supplies some nutrients. It is not identical to concentrated fertiliser.

Incineration and landfill

Residual waste may be incinerated. Heat can be recovered for electricity generation or heating, although emissions and ash still require management. Some waste is placed in landfill. Poorly managed landfill can cause odours, pests, methane emissions and contamination of soil or water. Engineered sites use measures to reduce these risks.

Reducing waste

Good separation helps materials remain in use, but preventing unnecessary waste and reusing products can avoid the need for treatment in the first place. Recycling and composting help conserve resources and protect soil and the wider environment.