Waste is any material which is no longer useful as it has served its purpose and it is generally discarded. It is the unwanted materials and objects that people have thrown away. It is often also called trash, garbage, rubbish, or junk. It can be solid, liquid, or gas, or it can be waste heat. There are many different kinds of waste. Garbage is the waste we produce daily in our homes.
When waste is a liquid or gas, it can be called an emission. This is usually pollution.
Waste can also be something abstract (something that you cannot touch), for example "a waste of time" or "wasted opportunities". When people use the words Waste or Wasted in this way, they are saying (directly or indirectly) that something has been used badly (using too much of it or using it incorrectly).
Today waste is a big menace as most of our land is dumped with waste. Thus we need to reuse or recycle waste.
Recycling of waste products
Recycling is the process of converting waste materials into new materials and objects. Recycling can prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials, thereby reducing: energy usage, air pollution (from incineration), and water pollution (from land filling).
When you throw stuff away, you might be very glad to get rid of it: into the trash it goes, never to be seen again! Unfortunately, that's not the end of the story. The things we throw away have to go somewhere—usually they go off to be bulldozed underground in a landfill or burnt in an incinerator. Landfills can be horribly polluting. They look awful, they stink, they take up space that could be used for better things, and they sometimes create toxic soil and water that can kill fish in our rivers and seas.
Most things that you throw away can be recycled and turned into new products although some are easier to recycle than others.
Kitchen and garden waste
You can recycle up to half your kitchen and garden waste by making your own compost a rich, crumbly, earthlike material that forms when organic (carbon-based) materials biodegrade (are broken down by worms and bacteria). Compost is great for using in your garden: it returns nutrients to the soil that help your plants to grow.
Most of the metal we throw away at home comes from food and drink cans . Typically food cans are made from steel, which can be melted down and turned into new food cans
Plastic drinks bottles are usually made from a type of clear plastic called PET (polyethylene terephthalate) and can be turned into such things as textile insulation (for thermal jackets and sleeping bags). Milk bottles tend to be made from a thicker, opaque plastic called HDPE (high-density polyethylene) and can be recycled into more durable products like flower pots and plastic pipes.
When food is exposed to air, microorganisms can land on the food and begin their work of breaking down the food for their own uses. The presence of oxygen enhances the growth of microorganisms, such as molds and yeasts, and contributes directly to deterioration of fats, vitamins, flavors, and colors within foods through the work of enzymes.
All food is made up of a certain percentage of water. Over time, microorganisms use the water within food to fuel the chemical reactions they need to dissolve the food for energy and growth. Moisture on the outside of food also allows molds and other microorganisms to grow on the outside of food, as well as within any cracks or holes in the surface of the food, further contributing to increased decay.
When food is exposed to light, its outer layers can begin to spoil in a process. It can result in discoloration, as well as loss of flavor, vitamins, and proteins.
Temperature also plays a role in food spoilage. As temperature increases, the chemical reactions that drive the spoiling process accelerate. That's why putting foods in the refrigerator or freezer helps to slow down the rotting process.
Almost anything organic (plant or animal based) will rot -- that includes paper, actually. Nothing inorganic (metals, stone, etc) will rot. They do fall apart and decay -- metal rusts, stones are eroded -- but rotting means that bacteria and fungi start attacking something and eating it.