Legislation
Supply
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, plastic, 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 percent 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.
Government-mandated demand
Legislation has also been used to increase and maintain a demand for
recycled materials. Four methods of such legislation exist: minimum
recycled content mandates, utilization rates, procurement policies, recycled product labeling.
Both minimum recycled content mandates and utilization rates
increase demand directly by forcing manufacturers to include recycling
in their operations. Content mandates specify that a certain percentage
of a new product must consist of recycled material. Utilization rates
are a more flexible option: industries are permitted to meet the
recycling targets at any point of their operation or even contract
recycling out in exchange for [trade]able credits. Opponents to both of
these methods point to the large increase in reporting requirements
they impose, and claim that they rob industry of necessary flexibility.
Governments have used their own purchasing power
to increase recycling demand through what are called "procurement
policies." These policies are either "set-asides," which earmark a
certain amount of spending solely towards recycled products, or "price
preference" programs which provide a larger budget when recycled items are purchased. Additional regulations can target specific cases: in the United States, for example, the Environmental Protection Agency mandates the purchase of oil, paper, tires and building insulation from recycled or re-refined sources whenever possible.
The final government regulation towards increased demand is recycled
product labeling. When producers are required to label their packaging
with amount of recycled material in the product (including the
packaging), consumers are better able to make educated choices.
Consumers with sufficient buying power
can then choose more environmentally conscious options, prompt
producers to increase the amount of recycled material in their
products, and indirectly increase demand. Standardized recycling
labeling can also have a positive effect on supply of recyclates if the
labeling includes information on how and where the product can be
recycled.
Recycling consumer waste
Collection
A number of different systems have been implemented to collect
recyclates from the general waste stream. These systems lie along the
spectrum of trade-off between public convenience and government ease
and expense. The three main categories of collection are "drop-off
centres", "buy-back centres" and "curbside collection".
Drop-off centres
Drop off centres require the waste producer to carry the recyclates
to a central location, either an installed or mobile collection station
or the reprocessing plant itself. They are the easiest type of
collection to establish, but suffer from low and unpredictable
throughput.
Buy-back centres
Buy-back centres differ in that the cleaned recyclates are
purchased, thus providing a clear incentive for use and creating a
stable supply. The post-processed material can then be sold on,
hopefully creating a profit. Unfortunately government subsidies are
necessary to make buy-back centres a viable enterprise, as according to
the United States National Solid Wastes Management Association it costs
on average US$50 to process a ton of material, which can only be resold
for US$30.
Curbside collection
Main article: Curbside collection
Curbside collection encompasses many subtly different systems, which
differ mostly on where in the process the recyclates are sorted and
cleaned. The main categories are mixed waste collection, commingled
recyclables and source separation. A waste collection vehicle generally picks up the waste.
At one end of the spectrum is mixed waste collection, in which all
recyclates are collected mixed in with the rest of the waste, and the
desired material is then sorted out and cleaned at a central sorting
facility. This results in a large amount of recyclable waste, paper
especially, being too soiled to reprocess, but has advantages as well:
the city need not pay for a separate collection of recyclates and no
public education is needed. Any changes to which materials are
recyclable is easy to accommodate as all sorting happens in a central
location.
In a Commingled or single-stream system,
all recyclables for collection are mixed but kept separate from other
waste. This greatly reduces the need for post-collection cleaning but
does require public education on what materials are recyclable.
Source separation is the other extreme, where each material is
cleaned and sorted prior to collection. This method requires the least
post-collection sorting and produces the purest recyclates, but incurs
additional operating costs
for collection of each separate material. An extensive public education
program is also required, which must be successful if recyclate
contamination is to be avoided.
Source separation used to be the preferred method due to the high
sorting costs incurred by commingled collection. Advances in sorting
technology (see sorting
below), however, have lowered this overhead substantially—many areas
which had developed source separation programs have since switched to
comingled collection.
Sorting
Once commingled recyclates are collected and delivered to a central collection facility,
the different types of materials must be sorted. This is done in a
series of stages, many of which involve automated processes such that a
truck-load of material can be fully sorted in less than an hour. Some plants can now sort the materials automatically, known as single-stream recycling. A 30 percent increase in recycling rates has been seen in the areas where these plants exist.
Initially, the commingled recyclates are removed from the collection
vehicle and placed on a conveyor belt spread out in a single layer.
Large pieces of corrugated fiberboard and plastic bags are removed by hand at this stage, as they can cause later machinery to jam.
Next, automated machinery separates the recyclates by weight,
splitting lighter paper and plastic from heavier glass and metal.
Cardboard is removed from the mixed paper, and the most common types of
plastic, PET (#1) and HDPE (#2), are collected. This separation is usually done by hand, but has become automated in some sorting centers: a spectroscopic
scanner is used to differentiate between different types of paper and
plastic based on the absorbed wavelengths, and subsequently divert each
material into the proper collection channel.
Strong magnets are used to separate out ferrous metals, such as iron, steel, and tin-plated steel cans ("tin cans"). Non-ferrous metals are ejected by magnetic eddy currents in which a rotating magnetic fieldinduces
an electric current around the aluminium cans, which in turn creates a
magnetic eddy current inside the cans. This magnetic eddy current is
repulsed by a large magnetic field, and the cans are ejected from the
rest of the recyclate stream.
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