Posted by
kaitianbag on Thursday, April 15, 2010 4:56:08 AM
Recycling involves processing used materials into new products to
prevent waste of potentially useful materials, reduce the consumption
of fresh raw materials, reduce energy usage, reduce air pollution (from
incineration) and water pollution (from landfilling) by reducing the
need for "conventional" waste disposal, and lower greenhouse gas
emissions as compared to virgin production. Recycling is a key
component of modern waste reduction and is the third component of the
"Reduce, Reuse, Recycle" waste hierarchy.
Recyclable materials include many kinds of glass, paper, metal,
Waste plastic recycling
, textiles, and electronics. Although similar in effect, the composting
or other reuse of biodegradable waste – such as food or garden waste –
is not typically considered recycling. Materials to be recycled are
either brought to a collection center or picked up from the curbside,
then sorted, cleaned, and reprocessed into new materials bound for
manufacturing.
In a strict sense, recycling of a material would
produce a fresh supply of the same material, for example used office
paper to more office paper, or used foamed polystyrene to more
polystyrene. However, this is often difficult or too expensive
(compared with producing the same product from raw materials or other
sources), so "recycling" of many products or materials involves their
reuse in producing different materials (e.g., paperboard) instead.
Another form of recycling is the salvage of certain materials from
complex products, either due to their intrinsic value (e.g., lead from
car batteries, or gold from computer components), or due to their
hazardous nature (e.g., removal and reuse of mercury from various
items).
Critics dispute the net economic and environmental benefits of
plastic recycling machinery
over its costs, and suggest that proponents of recycling often make
matters worse and suffer from confirmation bias. Specifically, critics
argue that the costs and energy used in collection and transportation
detract from (and outweigh) the costs and energy saved in the
production process; also that the jobs produced by the recycling
industry can be a poor trade for the jobs lost in logging, mining, and
other industries associated with virgin production; and that materials
such as paper pulp can only be recycled a few times before material
degradation prevents further recycling. Proponents of recycling dispute
each of these claims, and the validity of arguments from both sides has
led to enduring controversy.
Plastic recycling line
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.
To
help in identifying the materials in various plastic items, resin
identification code numbers 1-6 have been assigned to six common kinds
of recyclable plastic resins, with the number 7 indicating any other
kind of plastic, whether recyclable or not. Standardized symbols are
available incorporating each of these resin codes.For a recycling
program to work, having a large, stable supply of recyclable material
is crucial. Three legislative options have been used to create such a
supply: mandatory recycling collection, container deposit legislation,
and refuse bans. Mandatory collection laws set recycling targets for
cities to aim for, usually in the form that a certain percentage of a
material must be diverted from the city's waste stream by a target
date. The city is then responsible for working to meet this target.
Container deposit legislation involves offering a refund for the return of certain containers, typically glass,
Waste plastic recycling
, and metal. When a product in such a container is purchased, a small
surcharge is added to the price. This surcharge can be reclaimed by the
consumer if the container is returned to a collection point. These
programs have been very successful, often resulting in an 80% recycling
rate. Despite such good results, the shift in collection costs from
local government to industry and consumers has created strong
opposition to the creation of such programs in some areas.
A
third method of increase supply of recyclates is to ban the disposal of
certain materials as waste, often including used oil, old batteries,
tires and garden waste. One aim of this method is to create a viable
economy for proper disposal of banned products. Care must be taken that
enough of these recycling services exist, or such bans simply lead to
increased illegal dumping.