Waste Management: Types, Disposal, and the 4Rs of Sustainability
Waste
Waste Products
Waste products generated in all our production and consumption activities are called waste. Waste can be solids, liquids, or gases, and when released into the environment, can cause contamination, i.e., damage or deterioration to the environment, including harm to people.
Biodegradability
Waste production is a phase within natural systems. A balance exists between the natural production of waste and its absorption by nature, through microorganisms that break down matter and reuse it as nutrients. However, this balance is disrupted when there is excessive waste production that nature cannot absorb, especially if the waste is not biodegradable (i.e., cannot be broken down by microorganisms). The ability of some materials to return to the earth through natural processes is called biodegradation. During biodegradation, some chemicals (organic waste, paper, etc.) are used as food by microorganisms, which utilize them to produce energy and create other substances like amino acids, new tissues, and new organisms. Organic material can be degraded aerobically (with oxygen) or anaerobically (without oxygen). The biodegradability of materials depends on their physical and chemical structure; for example, glass cannot be biodegraded. A material is considered non-biodegradable when the time required for organisms to decompose it is extremely long or exceeds the capacity of organisms to process it, as is the case with plastic or aluminum cans. Today, many products are made with biodegradable agents, such as detergents, but many plastics, insecticides, and other substances are not.
Types of Waste
Residues are diverse and are usually classified according to their source:
- Agricultural, livestock, and forestry: Animal manure, crop residues, leaves, fertilizers, insecticides.
- Industrial: Ash from burning fuel, demolition debris, mining acids, heavy metal discharges from chemical industries. This also includes radioactive waste from nuclear power plants and toxic/hazardous wastes like pharmaceuticals, pesticides, and asbestos.
- Municipal Solid Waste (MSW): Solid waste generated in population centers or areas of influence. This can include:
- Organic materials such as paper, plastics, food, etc.
- Inorganic materials such as metals, glass, or ceramics.
Batteries are a significant source of pollution in our homes. Radios, flashlights, watches, Walkmans, cameras, calculators, toys, laptops, consoles, and many other products use batteries. Their commercial success is due to their portability and independence from the power grid. To understand the extent of contamination from batteries, it’s important to know that they contribute to:
- 93% of mercury in garbage
- 47% of zinc
- 48% of cadmium
- 22% of nickel, etc.
In short, batteries, especially button cells, are composed of highly polluting substances. Batteries are often disposed of with regular trash, ending up in domestic garbage dumps, vacant lots, ditches, roads, waterways, etc., leading to environmental destruction and the release of heavy metals. These metals seep into the soil, polluting all life forms, especially water.
Waste Disposal
Waste treatment should depend on the type of waste involved, but often the method is chosen based on economic criteria. The cheapest and most widely used method is controlled landfilling, although efforts are being made to recycle at least 50% of household waste. Landfilling involves storing waste on a suitable medium that is stable, airy, waterproof, and does not affect aquifers. The waste is stored in layers, pressed, leveled, and covered with a soil layer, as is done in municipal landfills. Incineration is the burning of combustible waste, sometimes used to generate heat or electricity. A drawback is that burning materials like PVC produces highly toxic gases. Composting involves obtaining compost (manure) from organic waste by burying it to accelerate decomposition. Hazardous waste treatment involves decomposing these wastes at high temperatures, oxidizing them with chemicals, or storing them in secure deposits. Currently, the most dangerous radioactive waste cannot be treated, removed, or recycled. While most are stored within the plant itself, some are stored in containers under the sea or in deep burial sites, such as the nuclear graveyard in Cabril, Cordoba.
Reuse and Recycle
Waste management should strive to follow the four Rs: Reduce, Reuse, Recycle, Recover. When we use a glass jar for preserves or incinerate waste for energy, we are using the waste for a different purpose than originally intended. However, when we make new paper from used paper or new glass from used glass, we are recycling, i.e., returning the waste to the same purpose for which it was created. Recycling involves sorting waste into special containers.