(Image of sea glass: Flickr user mckennaslivensky)
Waste is not an inherent property of a material. It is rather its use that dictates what it is. Something can be waste for a period of time but useful in some other time. In our universe, stars die and the same star dust gives birth to new stars. Another example is of that of a human body. It flushes out waste products because they are of no use to the body. Even though it is a waste to the human body, when it goes into the soil it can become a fertilizer for plants. To see how this happens, look at this interesting video:
Kinds of waste:
We know waste is a relative word. Waste also can be classified into different types. We will limit this discussion to solid waste. Solid waste can be classified as follows:
- Household waste
- Industrial waste
- Biomedical waste
Solid waste management:
Source: Opportunities to Reduce Greenhouse Gas Emissions through Materials and Land Management Practices (PDF) (98 pp, 1.6MB), U.S. EPA, 2009.
Based on the statistics shown in the above figure, EPA has created the Waste Reduction Model (WARM). A solid waste planner or an organization can use this model for tracking and for voluntarily reporting greenhouse gas (GHG) emissions reductions. The model is periodically updated with new information for efficient solid waste management. Countries across the globe have their own waste management protocols in place and undergo constant improvement.
Waste management is crucial to well-being of all species on this planet. It concerns health, environment and aesthetics. In a recent UN report, it was found that plastic accounts for $13B in Damage to Marine Habitat. In 2012, the United Nations reported that in five years, the world’s electronic waste would grow by 33% from 49.7 million tons to 65.4 million tons. That’s the weight of 200 Empire State Buildings or 11 Great Pyramids of Giza. – Tech Republic
Construction waste contains rubble, wood and toxic elements like lead. These are screened and recycled. Some of the waste can be reduced or reused. Depending on its kind, wastes are managed differently. Waste can be reduced, reused or recycled. It can be disposed/dumped, combusted, gasified, pyrolyzed, and anaerobically digested or incinerated. There are various technologies that do this and more.
The more time a material it takes to degrade, the more resilient it is to environmental conditions, the more stable it is. Stability is inversely proportional to degradability. Did you know that Tin, aluminium, and other metal items such as cans can take as much as centuries to degenerate? A glass can take as much as a million years! The Glass Beach in MacKerricher State Park near Fort Bragg, California is full of such sea glass. It’s going to stay that way for a million years until we do something about it. The type of litter we generate and the approximate time it takes to degenerate is given in tables here and here.
Waste to energy:
Since we don’t have enough land to dump all the waste and since some processes of managing waste are expensive, people look to using this waste to generate energy. This waste is processes in plants that are called ‘Waste to Energy Plants’ (WtE). The process is known as ‘Energy recovery’.
Example (1) Biogas plant:
Biogas plant is a classic example of such a plant. Household and agricultural waste are anerobically digested (treated in absence of oxgen) or fermented. This produces gases such as methane. These can then be combusted with oxygen. Lots of energy evolves when we do this to biomass. This energy can be used as a fuel. Garbage is not only capable of being transformed into fuel but it can also be converted to specific chemicals. A plant that converts biomass into not just fuel, heat or electricity but to also chemicals is called a bio refinery. The chemicals produced in such a plant are known as renewable chemicals.
Example (2) Plastic to fuel:
Waste plastic can be converted back into its basic hydrocarbons – oil (biofuel).
In our electronic world, a large amount of electronic waste (e-waste) is generated. Its disposal is tricky to manage since it contains toxic elements. This calls for resource recovery. It recovers valuable elements from the e-waste to be used back in the electronic manufacturing processes.
In India, dust washers sweep the streets that are home to an array of jewellery shops. What they find in the dust is gold. This is another example of resource recovery. Street cleaning is thus a part of environmental services. Companies think of this as a source of income. Veolia Environmental Services believes it can find at least £1 million worth of materials like platinum, palladium and rhodium from the muck swept up from Britain’s streets each year. – The Telegraph