18.1 Basic principles and concepts of waste management
Waste is introduced into the environment due to the day-to-day activities of humans. Waste management refers to the many methods and processes of dealing with waste at every stage from generation and collection through to final disposal.
Waste needs to be managed in order to prevent contact with humans or their immediate environment. Therefore, the main purpose of waste management is to isolate waste from humans and the environment, and consequently, safeguard individual, family and community health. In addition, the aesthetic value of a better outlook and a clean physical environment is important for our emotional wellbeing.
The waste we produce can be categorised as liquid waste or solid waste depending on its physical state. It can also be categorised as hazardous or non-hazardous (see Box 18.1).
Box 18.1 Hazardous and non-hazardous waste
Hazardous wastes are not classified by their physical state (solid, liquid or gas) but by their properties and potential to cause harm. Hazardous wastes are defined as wastes that have one or more of the following properties. They may be:
- corrosive (substances that cause damage on contact, e.g. acids)
- ignitable (materials that can catch fire easily like benzene)
- toxic (materials that can be poisonous to humans when inhaled or ingested, or come in contact with skin or mucous membranes)
- reactive (substances that can yield a harmful chemical if they react with other substances)
- infectious (substances that are capable of causing or communicating infection).
Potential sources of hazardous waste in rural households include obsolete pesticides, herbicides or rodenticides.
Non-hazardous wastes include all other types of waste.
Learning Outcomes for Study Session 18
18.1.1 Liquid waste