ප්‍රතිචක්‍රණය

විකිපීඩියා, නිදහස් විශ්වකෝෂය වෙතින්
වෙත පනින්න: සංචලනය, සොයන්න
Recycling symbol.svg
3R සංකල්පය

ප්‍රතිචක්‍රණය ('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.[1][2] Recycling is a key component of modern waste management and is the third component of the "Reduce, Reuse, Recycle" waste hierarchy.

Recyclable materials include many kinds of glass, paper, metal, plastic, 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.[2] 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., cardboard) 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 recycling 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.

ඉතිහාසය[සංස්කරණය]

Early recycling[සංස්කරණය]

Recycling has been a common practice for most of human history, with recorded advocates as far back as Plato in 400 BC. During periods when resources were scarce, archaeological studies of ancient waste dumps show less household waste (such as ash, broken tools and pottery)—implying more waste was being recycled in the absence of new material.[3]

In pre-industrial times, there is evidence of scrap bronze and other metals being collected in Europe and melted down for perpetual reuse.[4] In Britain dust and ash from wood and coal fires was collected by 'dustmen' and downcycled as a base material used in brick making. The main driver for these types of recycling was the economic advantage of obtaining recycled feedstock instead of acquiring virgin material, as well as a lack of public waste removal in ever more densely populated areas.[3] In 1813, Benjamin Law developed the process of turning rags into 'shoddy' and 'mungo' wool in Batley, Yorkshire. This material combined recycled fibres with virgin wool. The West Yorkshire shoddy industry in towns such as Batley and Dewsbury, lasted from the early 19c to at least the First World War.

Publicity photo for US aluminium salvage campaign, 1942

Wartime recycling[සංස්කරණය]

Resource shortages caused by the world wars, and other such world-changing occurrences greatly encouraged recycling.[5] Massive government promotion campaigns were carried out in World War II in every country involved in the war, urging citizens to donate metals and conserve fibre, as a matter of significant patriotic importance. Resource conservation programs established during the war were continued in some countries without an abundance of natural resources, such as Japan, after the war ended.

Post-war recycling[සංස්කරණය]

The next big investment in recycling occurred in the 1970s, due to rising energy costs. Recycling aluminium uses only 5% of the energy required by virgin production; glass, paper and metals have less dramatic but very significant energy savings when recycled feedstock is used.[6]

Woodbury, New Jersey was the first city in the entire United States to mandate recycling.[7] Led by Rose Rowan[8] in the early 1970s, the idea of towing a "recycling" trailer behind a waste management vehicle to enable the collection of trash and recyclable material at the same time emerged. Other towns and cities soon followed suit, and today many cities in the U.S. make recycling a requirement.

In 1987, the Mobro 4000 barge hauled garbage from New York to North Carolina; where it was denied. It was then sent to Belize; where it was denied as well. Finally, the barge returned to New York and the garbage was incinerated. The incident led to heated discussions in the media about waste disposal and recycling. The incident is often referred to as igniting the recycling "hysteria" of the 1990s.[4]

නෛතික ප්‍රතිපාදන[සංස්කරණය]

Supply[සංස්කරණය]

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.[2]

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% 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.[2]

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.[2]

Government-mandated demand[සංස්කරණය]

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.[2]

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 tradeable 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.[2][9]

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.[2]

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.[2]

ප්‍රතිචක්‍රන ක්‍රියාවලිය[සංස්කරණය]

රැස්කිරීම (Collection)[සංස්කරණය]

ගොනුව:DeutscheBahnRecycling20050814 CopyrightKaihsuTai Rotated.jpg
Recycling and rubbish bin in a German railway station.

A number of different systems have been implemented to collect recyclates from the general waste stream. These systems tend to 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".[2]

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 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 Nation Solid Wastes Management Association it costs on average US$50 to process a ton of material, which can only be resold for US$30.[2]

Curbside collection[සංස්කරණය]

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.[2] A waste collection vehicle generally picks up the waste.

A recycling truck collecting the contents of a recycling bin in Canberra, Australia

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.[2]

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.[2][4]

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.[2]

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.[4]

ගබඩා කිරීම (Sorting)[සංස්කරණය]

Early sorting of recyclable materials: glass and plastic bottles (Poland)

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.[4] Some plants can now sort the materials automatically, known as Single Stream. A 30% increase in recycling rates has been seen in the areas where these plants exist.[10]

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 cardboard and plastic bags are removed by hand at this stage, as they can cause later machinery to jam.[4]

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.[4]

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 field induces 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.[4]

Finally, glass must be sorted by hand based on its color: brown, amber, green or clear.[4]

Cost-benefit analysis[සංස්කරණය]

+ Environmental effects of recycling[11]
Material Energy Savings Air Pollution Savings
Aluminium 95%[2][6] 95%[2][12]
Cardboard 24%
Glass 5-30% 20%
Paper 40%[6] 73%
Plastics 70%[6]
Steel 60%[4]

There is some debate over whether recycling is economically efficient. Municipalities often see fiscal benefits from implementing recycling programs, largely due to the reduced landfill costs.[13] A study conducted by the Technical University of Denmark found that in 83% of cases, recycling is the most efficient method to dispose of household waste.[4][6] However, a 2004 assessment by the Danish Environmental Assessment Institute concluded that incineration was the most effective method for disposing of drink containers, even aluminium ones.[14]

Fiscal efficiency is separate from economic efficiency. Economic analysis of recycling includes what economists call externalities, which are unpriced costs and benefits that accrue to individuals outside of private transactions. Examples include: decreased air pollution and greenhouse gases from incineration, reduced hazardous waste leaching from landfills, reduced energy consumption, and reduced waste and resource consumption, which leads to a reduction in environmentally damaging mining and timber activity. Without mechanisms such as taxes or subsidies to internalize externalities, businesses will ignore them despite the costs imposed on society. To make such non-fiscal benefits economically relevant, advocates have pushed for legislative action to increase the demand for recycled materials.[2] The United States Environmental Protection Agency (EPA) has concluded in favor of recycling, saying that recycling efforts reduced the country's carbon emissions by a net 49 million metric tonnes in 2005.[4] In the United Kingdom, the Waste and Resources Action Programme stated that Great Britain's recycling efforts reduce CO2 emissions by 10-15 million tonnes a year.[4] Recycling is more efficient in densely populated areas, as there are economies of scale involved.[2]

Certain requirements must be met for recycling to be economically feasible and environmentally effective. These include an adequate source of recyclates, a system to extract those recyclates from the waste stream, a nearby factory capable of reprocessing the recyclates, and a potential demand for the recycled products. These last two requirements are often overlooked—without both an industrial market for production using the collected materials and a consumer market for the manufactured goods, recycling is incomplete and in fact only "collection".[2]

Many economists favor a moderate level of government intervention to provide recycling services. Economists of this mindset probably view product disposal as an externality of production and subsequently argue government is most capable of alleviating such a dilemma. However, those of the laissez faire approach to municipal recycling see product disposal as a service that consumers value. A free-market approach is more likely to suit the preferences of consumers since profit-seeking businesses have greater incentive to produce a quality product or service than does government. Moreover, economists most always advise against government intrusion in any market with little or no externalities.” [15]

Trade in recyclates[සංස්කරණය]

Computers being collected for recycling at a pickup event in Olympia, Washington, United States.

Certain countries trade in unprocessed recyclates. Some have complained that the ultimate fate of recyclates sold to another country is unknown and they may end up in landfills instead of reprocessed. According to one report, in America, 50-80% of computers destined for recycling are actually not recycled.[16][17] There are reports of illegal-waste imports to China being dismantled and recycled solely for monetary gain, without consideration for workers' health or environmental damage. Though the Chinese government has banned these practices, it has not been able to eradicate them.[18] In 2008, the prices of recyclable waste plummeted before rebounding in 2009. Cardboard averaged about £53/tonne from 2004-2008, dropped to £19/tonne, and then went up to £59/tonne in May 2009. PET plastic averaged about £156/tonne, dropped to £75/tonne and then moved up to £195/tonne in May 2009.[19] Certain regions have difficulty using or exporting as much of a material as they recycle. This problem is most prevalent with glass: both Britain and the U.S. import large quantities of wine bottled in green glass. Though much of this glass is sent to be recycled, outside the American Midwest there is not enough wine production to use all of the reprocessed material. The extra must be downcycled into building materials or re-inserted into the regular waste stream.[2][4]

Similarly, the northwestern United States has difficulty finding markets for recycled newspaper, given the large number of pulp mills in the region as well as the proximity to Asian markets. In other areas of the U.S., however, demand for used newsprint has seen wide fluctuation.[2]

In some U.S. states, a program called RecycleBank pays people with coupons to recycle, receiving money from local municipalities for the reduction in landfill space which must be purchased. It uses a single stream process in which all material is automatically sorted.[20]

විවේචන[සංස්කරණය]

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.[4]

As with environmental economics, care must be taken to ensure a complete view of the costs and benefits involved. For example, cardboard packaging for food products is more easily recycled than plastic, but is heavier to ship and may result in more waste from spoilage.[21]

The following are criticisms of many popular points used for recycling.

Saves energy[සංස්කරණය]

There is controversy on just how much energy is saved through recycling. The Energy Information Administration (EIA) states on its website that "a paper mill uses 40 percent less energy to make paper from recycled paper than it does to make paper from fresh lumber."[22] Critics often argue that in the overall processes, it can take more energy to produce recycled products than it does to dispose of them in traditional landfill methods. This argument is followed from the curbside collection of recyclables, which critics note is often done by a second waste truck. Recycling proponents point out that a second timber or logging truck is eliminated when paper is collected for recycling.

It is difficult to determine the exact amount of energy consumed or produced in waste disposal processes. How much energy is used in recycling depends largely on the type of material being recycled and the process used to do so. Aluminium is generally agreed to use far less energy when recycled rather than being produced from scratch. The EPA states that "recycling aluminum cans, for example, saves 95 percent of the energy required to make the same amount of aluminum from its virgin source, bauxite."[23]

Economist Steven Landsburg has suggested that the sole benefit of reducing landfill space is trumped by the energy needed and resulting pollution from the recycling process.[24] Others, however, have calculated through life cycle assessment that producing recycled paper uses less energy and water than harvesting, pulping, processing, and transporting virgin trees.[25] By using less recycled paper, additional energy is needed to create and maintain farmed forests until these forests are as self-sustainable as virgin forests.

Public policy analyst James V. DeLong points out that recycling is a manufacturing process and many of the methods use more energy than they save. In addition to energy usage, he notes that recycling requires capital and labor while producing some waste. These processes need to be more efficient than production from original raw material and/or traditional garbage disposal for recycling to be the superior method.[26]

Saves money[සංස්කරණය]

The amount of money actually saved through recycling depends on the efficiency of the recycling program used to do it. The Institute for Local Self-Reliance argues that the cost of recycling depends on various factors around a community that recycles, such as landfill fees and the amount of disposal that the community recycles. It states that communities start to save money when they treat recycling as a replacement for their traditional waste system rather than an add-on to it and by "redesigning their collection schedules and/or trucks."[27]

In many cases, the cost of recyclable materials also exceeds the cost of raw materials. Virgin plastic resin costs 40% less than recycled resin.[28] Additionally, a United States Environmental Protection Agency (EPA) study that tracked the price of clear cullet from July 15 to August 2, 1991, found that the average cost per ton ranged from $40 to $60,[29] while a USGS report shows that the cost per ton of raw silica sand from years 1993 to 1997 fell between $17.33 and $18.10.[30]

In a 1996 article for The New York Times, John Tierney argued that it costs more money to recycle the trash of New York City than it does to dispose of it in a landfill. Tierney argued that the recycling process employs people to do the additional waste disposal, sorting, inspecting, and many fees are often charged because the processing costs used to make the end product are often more than the profit from its sale.[31] Tierney also referenced a study conducted by the Solid Waste Association of North America (SWANA) that found in the six communities involved in the study, "all but one of the curbside recycling programs, and all the composting operations and waste-to-energy incinerators, increased the cost of waste disposal."[32]

Working conditions[සංස්කරණය]

Critics often argue that while recycling may create jobs, they are often jobs with low wages and terrible working conditions.[33] These jobs are sometimes considered to be make-work jobs that don't produce as much as the cost of wages to pay for those jobs. In areas without many environmental regulations and/or worker protections, jobs involved in recycling such as ship breaking can result in deplorable conditions for both workers and the surrounding communities.

Recycling proponents counter that the jobs involved in recovery of an equal amount of virgin material creates worse jobs. Timber harvesting and ore mining are more dangerous than paper recycling and metal recycling.[තහවුරු කරන්න]

Saves trees[සංස්කරණය]

Economist Steven Landsburg has claimed that paper recycling actually reduces tree populations. He argues that because paper companies have incentives to replenish the forests they own, large demands for paper lead to large forests. Conversely, reduced demand for paper leads to fewer "farmed" forests.[34] Similar arguments were expressed in a 1995 article for The Free Market.[35]

When foresting companies cut down trees, more are planted in their place. Most paper comes from pulp forests grown specifically for paper production.[26][32][35][36] Many environmentalists point out, however, that "farmed" forests are inferior to virgin forests in several ways. Farmed forests are not able to fix the soil as quickly as virgin forests, causing widespread soil erosion and often requiring large amounts of fertilizer to maintain while containing little tree and wild-life biodiversity compared to virgin forests.[37] Also, the new trees planted are not as big as the trees that were cut down, and the argument that there will be "more trees" is not compelling to forestry advocates when they are counting saplings.

The recycling of paper should not be confused with saving the tropical forest. Many people have the misconception that paper-making is what's causing deforestation of tropical rain forests but rarely any tropical wood is harvested for paper. Deforestation is mainly caused by population pressure such as demand of more land for agriculture or construction use. Therefore, the recycling paper, although reduces demand of trees, doesn't greatly benefit the tropical rain forests [38]

Possible income loss and social costs[සංස්කරණය]

In some prosperous and many less prosperous countries in the world, the traditional job of recycling is performed by the entrepreneurial poor such as the karung guni, the rag and bone man, waste picker, and junk man. With the creation of large recycling organizations that may be profitable, either by law or economies of scale,[39][40] the poor are more likely to be driven out of the recycling and the remanufacturing market. To compensate for this loss of income to the poor, a society may need to create additional forms of societal programs to help support the poor. Like the parable of the broken window, there is a net loss to the poor and possibly the whole of a society to make recycling artificially profitable through law.

Because the social support of a country is likely less than the loss of income to the poor doing recycling, there is a greater chance that the poor will come in conflict with the large recycling organizations.[41][42] This means fewer people can decide if certain waste is more economically reusable in its current form rather than being reprocessed. Contrasted to the recycling poor, the efficiency of their recycling may actually be higher for some materials because individuals have greater control over what is considered “waste.”

One labor-intensive underused waste is electronic and computer waste. Because this waste may still be functional and wanted mostly by the poor, the poor may sell or use it at a greater efficiency than large recyclers.

Many recycling advocates believe that this laissez-faire individual-based recycling does not cover all of society’s recycling needs. Thus, it does not negate the need for an organized recycling program. Local government often consider the activities of the recycling poor as contributing to property blight.

Newsprint[සංස්කරණය]

There are upper limits on the percentage of the world’s newsprint that can be manufactured from recycled fiber. The most obvious upper limit is imposed by the nature of recycling itself. Some of the fiber that enters any recycled pulp mill is lost in pulping, due to inefficiencies inherent in the process. According to the web site of the U.K. chapter of Friends of the Earth[43] wood fiber can normally only be recycled up to five times due to damage experienced to the fiber. Thus, unless the quantity of newsprint used each year worldwide declines to reflect the lost fiber, a certain amount of new (virgin) fiber is required each year globally, even if the individual newsprint mill may continue to use 100% recycled fiber.

Additionally, some old newspapers never make it to a recycling plant, being used for a variety of household and industrial applications or simply ending up in landfill. Recycle rates (the percentage of annual newsprint consumption which is then recycled) vary from country to country and, within countries, from city to rural areas as well as from city to city. The American Forest & Paper Association estimates that more than 72% of newsprint produced in North America in 2006 was recovered for re-use or export, with about 58% of that going back to a paper or paperboard mill for re-use, 16% being used by molded pulp mills (to make products such as egg cartons) and the balance being shipped offshore. Of the percentage that is re-used by a North American paper or paperboard mill, AFPA estimates that about a third goes back into newsprint manufacture. Recycle rates can also vary over time with the price paid by the market for old newspapers, which can be quite volatile. As an example, in recent years, with China growing as a manufacturer of various kinds of paper and packaging – using significant quantities of recycled fiber imported from the U.S. and elsewhere – its demand for old newspapers has at times been strong enough to influence recycled fiber prices worldwide. While high recycled fiber prices are good news for the goal of reducing landfill quantities, they can affect the profitability of newsprint mills using recycled fibers.

An important consideration in fiber selection by newsprint mills aside from cost is the high speeds of both modern newsprint machines and modern newspaper printing presses. There are newsprint machines in the U.S. operating at speeds approaching 1,400 meters per minute, according to industry information group RISI Inc., while the newest machines in the world (including some recently installed in China) can have speeds topping 1,800 meters per minute. Modern newspaper presses can run at speeds of up to 90,000 copies per hour (according to publishing industry association IFRA), with a few approaching 100,000 cph.

Such high speeds place severe demands on the strength of the sheet, both on the paper machine during the manufacturing process and on the press during printing. A number of newsprint mills around the world manufacture commercially acceptable qualities of newsprint using 100% recycled fiber. However, such mill operators must be very selective about the purity of the waste stream, making sure they employ a minimum of contaminants and include as much long-fibered old newsprint as possible. Virgin newsprint is made from long-fibered (softwood) trees such as spruce, fir, balsam and pine, while some paper and paperboard products are manufactured from shorter-fibered hardwood species. Newsprint mills prefer to use old newspapers, or a mix of old newspapers and old magazines, rather than recycling other paper grades. As U.S. municipalities have recently moved toward “single stream” recycling – collecting various waste products in a single compartment of a vehicle – mills have been forced to spend more money to procure a clean, appropriate waste stream for pulping purposes.

Toilet paper[සංස්කරණය]

Toilet paper is sometimes made from recycled paper; however, large amounts of virgin tree pulp is still used.[44] Environmentally friendly toilet paper may also be unbleached.

In Feb. '09, Greenpeace issued a guide distinguishing between (a) "soft" brands, which require more long fiber from virgin tree pulp to manufacture, and (b) those which, while less soft and perhaps unbleached, use more or all recycled content and/or use wood pulp from sustainably managed forests certified by the Forest Stewardship Council. Greenpeace also issued guides covering facial tissue, napkins, and paper towels.[45] In an article noting the release of the report, The New York Times said that sales of the soft brands were up by 40 percent in some markets in 2008, according to Information Resources, Inc., a marketing research firm. However, and possibly aiding the environmental interests, a decline in the past few months in sales of premium toilet paper of 7 percent nationally was reported, citing Ali Dibadj, a senior stock analyst with Sanford Bernstein, a financial management firm.

In the United States[සංස්කරණය]

In a 1996 article in The New York Times, John Tierney claimed that government mandated recycling wastes more resources than it saves.[21] Some highlights from the article:

  • In cases where recycling truly does save resources, such as with large scraps of aluminium, this will be reflected in market prices, and voluntary recycling will take place. Thus, there is no need for the government to mandate it.
  • Tree farmers plant more trees than they cut down.
  • Government mandated recycling is more expensive than putting the garbage into landfills.
  • Some small towns with landfills are happy to import garbage from other cities and states because it provides jobs and tax revenue.
  • Today's modern landfills are much cleaner and safer, and much less likely to leak and pollute than the landfills of the past.
  • Incinerators make more energy than recycling saves. Also, some things, such as glossy paper, can't be recycled, and it is better to burn such materials for energy.
  • Regarding the claim that the U.S. is running out of landfill space, Tierney wrote, "A. Clark Wiseman, an economist at Gonzaga University in Spokane, Washington, has calculated that if Americans keep generating garbage at current rates for 1,000 years, and if all their garbage is put in a landfill සැකිල්ල:Convert/yd deep, by the year 3000 this national garbage heap will fill a square piece of land 35 හැතැප්මs (56 km) on each side. This doesn't seem a huge imposition in a country the size of America. The garbage would occupy only 5 percent of the area needed for the national array of solar panels proposed by environmentalists. The millennial landfill would fit on one-tenth of 1 percent of the range land now available for grazing in the continental United States. And if it still pains you to think of depriving posterity of that 35-හැතැප්ම (35-kilometre (සැකිලි ලූපය අනාවරණය කෙරිණි: සැකිල්ල:Convert/mi)) square, remember that the loss will be only temporary. Eventually, like previous landfills, the mounds of trash will be covered with grass and become a minuscule addition to the nation's 150,000 square miles (390,000 km2) of parkland."

Tierney's article received a referenced critique from the Environmental Defense Fund, which noted that "the article relied heavily on quotes and information supplied by a group of consultants and think tanks that have strong ideological objections to recycling".[46] In 2003, the city of Santa Clarita, California was paying $28 per ton to put garbage into a landfill. The city then adopted a mandatory diaper recycling program that cost $1,800 per ton.[47] In a 2007 article, Michael Munger, the Chair of Political Science at Duke University, wrote, "... if recycling is more expensive than using new materials, it can't possibly be efficient... There is a simple test for determining whether something is a resource... or just garbage... If someone will pay you for the item, it's a resource... But if you have to pay someone to take the item away... then the item is garbage."[48] In a 2002 article for The Heartland Institute, Jerry Taylor, director of natural resource studies at the Cato Institute, wrote, "If it costs X to deliver newly manufactured plastic to the market, for example, but it costs 10X to deliver reused plastic to the market, we can conclude the resources required to recycle plastic are 10 times more scarce than the resources required to make plastic from scratch. And because recycling is supposed to be about the conservation of resources, mandating recycling under those circumstances will do more harm than good."[49] In 2002, WNYC reported that 40% of the garbage that New York City residents separated for recycling actually ended up in landfills.[50]

බහුල ප්‍රතිචක්‍රියක (Common recyclables)[සංස්කරණය]

Many different materials can be recycled but each type requires a different technique.

Aggregates and concrete[සංස්කරණය]

Concrete blocks

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.[51]

බැටරි[සංස්කරණය]

Some batteries contain toxic heavy metals, making recycling or proper disposal a high priority

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.[52]

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 United States, the recycling rate is 90%, with new batteries containing up to 80% recycled material.[52]

දිරාපත්වන අපද්‍රව්‍ය (Biodegradable waste)[සංස්කරණය]

Garden waste for composting

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.

Clothing[සංස්කරණය]

Recycling clothes via consignment or swapping has become increasingly popular. In a clothing swap, a group of people gather at a venue to exchange clothes amongst each other. In organizations like Clothing Swap, Inc., unclaimed clothing is donated to a local charity.

Electronics disassembly and reclamation[සංස්කරණය]

An abandoned computer monitor

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.

යකඩ අඩංගු ලෝහ (Ferrous metals)[සංස්කරණය]

Steel crushed and baled for recycling

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).[53] 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.[54]

යකඩ නොවන ලෝහ (Non-ferrous metals)[සංස්කරණය]

Aluminium is one of the most efficient and widely-recycled materials.[55][56] 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.[6] 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. Americans throw away enough aluminium every year to rebuild their entire commercial air fleet. Also, the energy saved by recycling one aluminium can is enough to run a television for three hours.[12]

වීදුරු[සංස්කරණය]

Public glass waste collection point for separating clear, green and amber glass

Glass bottles and jars are gathered by a curbside collection truck 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.

Paint[සංස්කරණය]

Paint is often collected at government-run Household Hazardous Waste facilities. From there, it is taken to paint recyclers, where it is sorted by quality. Uses for paint that cannot be reprocessed and resold varies by recycler.

කඩදාසි[සංස්කරණය]

Paper can be recycled by reducing it to pulp and combining it with pulp from newly harvested wood. As the recycling process causes the paper fibres to break down, 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 fibre fragments.[57]

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 its already poor quality.[57]

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 of. 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 fibre.[57]

ප්‍ලාස්ටික්[සංස්කරණය]

Plastic shipping crates

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.

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.

Textiles[සංස්කරණය]

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 either for charity or sold at a cheaper price.[58] Many international organisations collect used textiles from developed countries as a donation to those third world countries. This recycling practise is encouraged because it helps to reduce unwanted waste while providing clothing to those in need.[59] 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.[60]

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.

දැව (Timber)[සංස්කරණය]

A stack of wooden pallets awaits reuse or recycling.

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.[61]

Other techniques[සංස්කරණය]

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.

Tire recycling is also common. Used tires can be added to asphalt for producing road surfaces or to make rubber mulch used on playgrounds for safety. They are also often used as the insulation and heat absorbing/releasing material in specially constructed homes known as earthships.

මෙම ලිපිත් බලන්න[සංස්කරණය]

සැකිල්ල:EnergyPortal

Types of recycling
General topics
Trade associations

Further reading[සංස්කරණය]

References[සංස්කරණය]

  1. PM Advisor hails recycling as climate change action "Lets recycle". http://www.letsrecycle.com/legislation/news.jsp?story=6231 PM Advisor hails recycling as climate change action. සම්ප්‍රවේශය කෙරුණු දිනය 2006-11-08. [dead link]
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 The League of Women Voters (1993). The Garbage Primer. New York: Lyons & Burford. pp. 35–72. ISBN 1558218507. 
  3. 3.0 3.1 Black Dog Publishing (2006). Recycle : a source book. London, UK: Black Dog Publishing. ISBN 1904772366. 
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 "The truth about recycling". The Economist. June 7, 2007. http://www.economist.com/opinion/displaystory.cfm?story_id=9249262. 
  5. Out of the Garbage-Pail into the Fire: fuel bricks now added to the list of things salvaged by science from the nation's waste, Popular Science monthly, February 1919, page 50-51, Scanned by Google Books: http://books.google.com/books?id=7igDAAAAMBAJ&pg=PA50
  6. 6.0 6.1 6.2 6.3 6.4 6.5 "The price of virtue". The Economist. June 7, 2007. http://www.economist.com/opinion/displaystory.cfm?story_id=9302727. 
  7. Rowan & Associates Go Green: July 18, 2007 Press Release - NJBiz.com. Retrieved July 22, 2007.
  8. Currently the president of the promotional products boutique Rowan & Associates.
  9. "Regulatory Policy Center - PROPERTY MATTERS - James V. DeLong". http://jamesvdelong.com/articles/environmental/wasting-away.html. සම්ප්‍රවේශය කෙරුණු දිනය 2008-02-28. 
  10. ScienceDaily. (2007). Recycling Without Sorting Engineers Create Recycling Plant That Removes The Need To Sort.
  11. Unless otherwise indicated, this data is taken from The League of Women Voters (1993). The Garbage Primer. New York: Lyons & Burford. pp. 35–72. ISBN 1558218507. , which attributes, "Garbage Solutions: A Public Officials Guide to Recycling and Alternative Solid Waste Management Technologies, as cited in Energy Savings from Recycling, January/February 1989; and Worldwatch 76 Mining Urban Wastes: The Potential for Recycling, April 1987."
  12. 12.0 12.1 "Recycling metals - aluminium and steel". http://www.wasteonline.org.uk/resources/InformationSheets/metals.htm. සම්ප්‍රවේශය කෙරුණු දිනය 2007-11-01. 
  13. Lavee D. (2007). Is Municipal Solid Waste Recycling Economically Efficient? Environmental Management.
  14. Vigso, Dorte (2004). "Deposits on single use containers - a social cost-benefit analysis of the Danish deposit system for single use drink containers". Waste Management & Research 22 (6): 477. doi:10.1177/0734242X04049252. PMID 15666450. http://wmr.sagepub.com/cgi/content/abstract/22/6/477. 
  15. Gunter, Matthew. "Do Economists Reach a Conclusion on Household and Municipal Recycling?" (Jan 2007). [1]
  16. Much toxic computer waste lands in Third World
  17. Environmental and health damage in China
  18. Illegal dumping and damage to health and environment
  19. Hogg M. Waste outshines gold as prices surge. Financial Times.ASDAQ:INTC) increased 1.9% on news the business may form a foundry relationship with Apple Inc. (NASDAQ:AAPL).Sprint Nextel Corp (NYSE:S) fell 2.1% when Stifel Nicolaus Co.In nearby Arachova and Livadi there's plenty of nightlife with numerous lively bars and restaurants.The UNESCO World Heritage site of Delphi is probably 30 minutes drive from Elatos. It ranks being among the most significant archaeological sites belonging to the ancient world. That it was home to the oracle a vey important oracle in the classical Greek world a
  20. Bonnie DeSimone. (2006). Rewarding Recyclers, and Finding Gold in the Garbage. New York Times.
  21. 21.0 21.1 Tierney, John (June 30, 1996). "Recycling Is Garbage". New York: New York Times. p. 3. http://query.nytimes.com/gst/fullpage.html?res=990CE1DF1339F933A05755C0A960958260&sec=&spon=&pagewanted=1. Retrieved 2008-02-28. 
  22. Energy Information Administration Recycling Paper & Glass. Retrieved 18 October 2006.
  23. Environmental Protection Agency Frequently Asked Questions about Recycling and Waste Management. Retrieved 18 October 2006.
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  25. Selke 116
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  27. Waste to Wealth The Five Most Dangerous Myths About Recycling. Retrieved October 18, 2006.
  28. United States Department of EnergyConserving Energy - Recycling Plastics. Retrieved 10 November 2006.
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  30. United States Geological SurveyMineral Commodity Summaries. Retrieved 10 November 2006.
  31. Recycling Suddenly Gets Expensive : NPR
  32. 32.0 32.1 New York Times Recycling... Is Garbage (nytimes.com Published 30 June 1996) Recycling... Is Garbage (article reproduced) Recycling... Is Garbage (article reproduced). Retrieved 18 October 2006.
  33. Heartland Institute Recycling: It's a bad idea in New York. Retrieved 18 October 2006.
  34. Landsburg, Steven A. The Armchair Economist. p. 81.
  35. 35.0 35.1 The Free Market Don't Recycle: Throw It Away!. Retrieved 4 November 2006.
  36. Jewish World Review The waste of recycling. Retrieved 4 November 2006.
  37. Baird, Colin (2004) Environmental Chemistry (3rd ed.) W. H. Freeman ISBN 0-7167-4877-0
  38. "All About Paper". Paper University. http://www.tappi.org/paperu/all_about_paper/faq.htm. සම්ප්‍රවේශය කෙරුණු දිනය 2009-02-12. 
  39. NRDC: Too Good To Throw Away - Appendix A
  40. Mission Police Station
  41. The News-Herald - Scrap metal a steal
  42. Raids On Recycling Bins Costly To Bay Area : NPR
  43. Friends of the Earth
  44. "Kimberly-Clark 2005 Sustainability Report page 28"
  45. "Greenpeace Shopper's Guide to Ancient Forest Friendly Tissue" Greenpeace Web site. Retrieved 2-26-09.
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  47. Diaper Recycling in California The Free Liberal, September 8, 2003
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  49. Recycling: It's a bad idea in New York The Heartland Institute, May 1, 2002
  50. City Council Holds Hearings on Saving Recycling, WNYC, April 18, 2002
  51. "Concrete Recycling". Associated Construction Publications. http://acppubs.com/article/CA484296.html. සම්ප්‍රවේශය කෙරුණු දිනය 2008-02-21. [dead link]
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  53. "Sustainable Development and Steel, Canadian Institute of Steel Construction". http://www.cisc.ca/content/sustainable/default.aspx. සම්ප්‍රවේශය කෙරුණු දිනය 2006-11-16. 
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  56. Environmental Protection Agency Frequently Asked Questions about Recycling and Waste Management
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  58. UK in 'frightening' reliance on foreign textile sorting "www.letsrecycle.com". http://www.letsrecycle.com/materials/textiles/news.jsp?story=6232 UK in 'frightening' reliance on foreign textile sorting. සම්ප්‍රවේශය කෙරුණු දිනය 2006-11-08. [dead link]
  59. Salvation Army "Salvation Army". http://www.salvationarmy.org/ihq/www_sa.nsf/vw-dynamic-index/2F2892552ED40F1585256E3D006A9BC7?openDocument Salvation Army. සම්ප්‍රවේශය කෙරුණු දිනය 2008-02-29. 
  60. Councils "need to understand" importance of textile quality "www.letsrecycle.com". http://www.letsrecycle.com/materials/textiles/news.jsp?story=6294 Councils "need to understand" importance of textile quality. සම්ප්‍රවේශය කෙරුණු දිනය 2006-11-24. [dead link]
  61. , www.citywood.co.uk. Retrieved November 24, 2006.

External links[සංස්කරණය]

සැකිල්ල:RecyclingByRegion සැකිල්ල:Waste management සැකිල්ල:Sustainable technology සැකිල්ල:ධරණීයතාව

"http://si.wikipedia.org/w/index.php?title=ප්‍රතිචක්‍රණය&oldid=269126" වෙතින් සම්ප්‍රවේශනය කෙරිණි