Recycling
Definition:
Recycling is the third R of the three R’s: Reduce, Reuse, Recycle. Recycling means taking a product or material at the end of its useful life and turning it into a usable raw material to make another product.
Recycling is the reprocessing of old materials into new products, with the aims of preventing the waste of potentially useful materials, reducing the consumption of fresh raw materials and reducing energy usage, and thereby lowering greenhouse gas emissions compared to virgin production. Recycling is a key concept of modern waste management and is the third component of the “Reduce, Reuse, Recycle” waste hierarchy, though colloquial usage of “recycling” can also include “reuse”.
“Recyclable materials” or “recyclables”, may originate from home, business or industry. They include glass, paper, metal, textiles and plastics. Though analogus, the composting of biodegradable waste—such as food or garden waste—is not typically considered recycling.[2] These materials are either brought to a collection centre or picked-up from the curbside, sorted , cleaned and reprocessed into new products bound for manufacturing.
To judge the environmental benefits of recycling, the cost of this entire process must be compared to the cost of virgin extraction. In order for recycling to be economically viable, there must be a steady supply of recyclates and constant demand for the reprocessed goods, both of which can be stimulated through government legislation.
Common recyclables:-
Many different materials can be recycled but each type requires a different technique.
Curbside Recycling
Curbside recycling now serves half of the U.S. population, providing the most convenient means for households to recycle a variety of materials.
While all curbside programs differ, the most commonly included materials are The Big Five: aluminum cans, glass bottles, paper, plastic and steel/tin cans.
Electronics
Technology has revolutionized our lifestyle through telephones, radios, TVs, computers and cell phones. However, the brisk pace of technology means these devices become obsolete quickly.
The direct disposal of electrical equipment—such as old computers and mobile phones—is banned in many areas due to the toxic contents of certain components. The recycling process works by mechanically separating the metals, plastics and circuit boards contained in the appliance. When this is done on a large scale at an electronic waste recycling plant, component recovery can be achieved in a cost-effective manner.
A more recent issue is how our old electronics should be disposed of, because they often contain dangerous elements such as lead and mercury that can contaminate our soil and water supply.
Composting
Managing organic material at your home can not only decrease the amount of material you send to the landfill; it can also help turn your organic waste into a landscape asset.
Composting will reduce the amount of food waste in your garbage can, while creating nutrient-rich fertilizer for your garden.
Garage Garbage
Did you know that used motor oil can be recycled? How about paint? It turns out many of the items in your garage are recyclable.
Claim your garage back, learn what to do with the mess and help the planet while you’re at it.
Aggregates and concrete
Concrete aggregate collected from demolition sites is put through a crushing machine, often along with asphalt, bricks, dirt, and rocks. Smaller pieces of concrete are used as gravel for new construction projects. Crushed recycled concrete can also be used as the dry aggregate for brand new concrete if it is free of contaminants. This reduces the need for other rocks to be dug up, which in turn saves trees and habitats.
Batteries
The large variation in size and type of batteries makes their recycling extremely difficult: they must first be sorted into similar kinds and each kind requires an individual recycling process. Additionally, older batteries contain mercury and cadmium, harmful materials which must be handled with care. Because of their potential environmental damage, proper disposal of used batteries is required by law in many areas. Unfortunately, this mandate has been difficult to enforce.
Lead-acid batteries, like those used in automobiles, are relatively easy to recycle and many regions have legislation requiring vendors to accept used products. In the US, the recycling rate is 90%, with new batteries containing up to 80% recycled material.
Biodegradable waste
Kitchen, garden and other green waste can be recycled into useful material by composting. This process allows natural aerobic bacteria to break down the waste into fertile topsoil. Much composting is done on a household scale, but municipal green-waste collection programs also exist. These programs can supplement their funding by selling the topsoil produced.
Ferrous metals
Iron and steel are the world’s most recycled materials, and among the easiest materials to reprocess, as they can be separated magnetically from the waste stream. Recycling is via a steelworks: scrap is either remelted in an Electric Arc Furnace (90-100% scrap), or used as part of the charge in a Basic Oxygen Furnace (around 25% scrap). Any grade of steel can be recycled to top quality new metal, with no ‘downgrading’ from prime to lower quality materials as steel is recycled repeatedly. 42% of crude steel produced is recycled material.
Non-ferrous metals
Aluminium is shredded and ground into small pieces or crushed into bales. These pieces or bales are melted in an aluminium smelter to produce molten aluminium. By this stage the recycled aluminium is indistinguishable from virgin aluminium and further processing is identical for both. This process does not produce any change in the metal, so aluminium can be recycled indefinitely.
Recycling aluminium saves 95% of the energy cost of processing new aluminium. This is because the temperature necessary for melting recycled, nearly pure, aluminium is 600 °C, while to extract mined aluminium from its ore requires 900 °C. To reach this higher temperature, much more energy is needed, leading to the high environmental benefits of aluminium recycling.
Glass
Glass bottles and jars are gathered via curbside collection schemes and bottle banks, where the glass may be sorted into color categories. The collected glass cullet is taken to a glass recycling plant where it is monitored for purity and contaminants are removed. The cullet is crushed and added to a raw material mix in a melting furnace. It is then mechanically blown or molded into new jars or bottles. Glass cullet is also used in the construction industry for aggregate and glassphalt. Glassphalt is a road-laying material which comprises around 30% recycled glass. Glass can be recycled indefinitely as its structure does not deteriorate when reprocessed.
Paper
Paper can be recycled by reducing it to pulp and combing it with pulp from newly harvested wood. As the recycling process causes the paper fibres to breakdown, each time paper is recycled its quality decreases. This means that either a higher percentage of new fibres must be added, or the paper downcycled into lower quality products. Any writing or colouration of the paper must first be removed by deinking, which also removes fillers, clays, and fiber fragments.
Almost all paper can be recycled today, but some types are harder to recycle than others. Papers coated with plastic or aluminium foil, and papers that are waxed, pasted, or gummed are usually not recycled because the process is too expensive. Gift wrap paper also cannot be recycled due to the its already low quality.
Sometimes recyclers ask for the removal of the glossy inserts from newspapers because they are a different type of paper. Glossy inserts have a heavy clay coating that some paper mills cannot accept. Most of the clay is removed from the recycled pulp as sludge which must be disposed. If the coated paper is 20% by weight clay, then each ton of glossy paper produces more than 200 kg of sludge and less than 800 kg of fiber.
Plastic
Plastic recycling is the process of recovering scrap or waste plastics and reprocessing the material into useful products. Compared to glass or metallic materials, plastic poses unique challenges–because of the massive number of types of plastic, they each carry a resin identification code, and must be sorted before they can be recycled. This can be costly–while metals can be sorted using electromagnets, no such ‘easy sorting’ capability exists for plastics. In addition to this, while labels do not need to be removed from bottles for recycling, lids are often made from a different kind of non-recyclable plastic.
Plastics recycling rates lag far behind those of other items, such as newspaper and aluminium; consumers are typically unsure of how to recycle plastics, and compared to paper and metals fewer recycling facilities exist.
Textiles
When considering textile recycling one must understand what the material consists of. Most textiles are composites of cotton (biodegradable material) and synthetic plastics. The textile’s composition will affect its durability and method of recycling.
Workers sort and separate collected textiles into good quality clothing and shoes which can be reused or worn. There is a trend of moving these facilities from developed countries to developing countries. Damaged textiles are further sorted into grades to make industrial wiping cloths and for use in paper manufacture or material suitable for fibre reclamation and filling products. If textile reprocessors receive wet or soiled clothes however, these may still be disposed of in a landfill, as the washing and drying facilities are not present at sorting units.
Fibre reclamation mills sort textiles according to fibre type and colour. Colour sorting eliminates the need to re-dye the recycled textiles. The textiles are shredded into “shoddy” fibres and blended with other selected fibres, depending on the intended end use of the recycled yarn. The blended mixture is carded to clean and mix the fibres and spun ready for weaving or knitting. The fibres can also be compressed for mattress production. Textiles sent to the flocking industry are shredded to make filling material for car insulation, roofing felts, loudspeaker cones, panel linings and furniture padding.
Timber
Recycling timber has become popular due to its image as an environmentally friendly product, with consumers commonly believing that by purchasing recycled wood the demand for green timber will fall and ultimately benefit the environment. Greenpeace also view recycled timber as an environmentally friendly product, citing it as the most preferable timber source on their website. The arrival of recycled timber as a construction product has been important in both raising industry and consumer awareness towards deforestation and promoting timber mills to adopt more environmentally friendly practices.
Wood recycling is a subject which has in recent years taken an ever greater role in our lives. The problem, however, is that although many local authorities like the idea of recycling, they do not fully support it. One of the countless examples, which has been in the news is the concept of actually recycling wood which is growing in the cities. Namely, recycling timber, trees and other sources.
Other Techniques:
Several other materials are also commonly recycled, frequently at an industrial level.
Ship breaking is one example that has associated environmental, health, and safety risks for the area where the operation takes place; balancing all these considerations is an environmental justice problem.
Tires are also commonly recycled. Used tires can be added to asphalt, producing road surfaces that are more durable, create less traffic noise, and absorb precipitation better than traditional asphalt.[citation needed] Tires can also be used to make rubber mulch, which is used on playgrounds for safety.
Sustainable design:
Much of the difficulty inherent in recycling comes from the fact that most products are not designed with recycling in mind. The concept of sustainable design aims to solve this problem, and was first laid out in the book “Cradle to Cradle: Remaking the Way We Make Things” by architect William McDonough and chemist Michael Braungart. They suggest that every product (and all packaging they require) should have a complete “closed-loop” cycle mapped out for each component—a way in which every component will either return to the natural ecosystem through biodegradation or be recycled indefinitely.
Resources:
http://en.wikipedia.org/wiki/Recycling
http://earth911.org/recycling/