Recycling of Waste Materials

8/10/2019 Recycling of Waste Materials

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GOVERNMENT COLLEGE OF TECHNOLOGY COIMBATORE-641013

By J. Niveyth !111116"#

$. N %thi%i !1111164#



RECYCLING OF &A'TE MATERIAL'

AB'TRACT

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1. INTRO89CTION

Recycling is a process of collection and reuse of materials that would otherwise be

thrown away. Materials ranging from precious metals to broken glass, from old newspapersto plastic spoons, can be recycled. The recycling process reclaims the original material anduses it in new products.

Fig 1

An average city dweller may produce a ton of refuse in a year, a volume thatrapidly overflows local dumps. ities running out of space for landfill often turn toincinerating their waste or transporting it to other areas, although up to !" percent of thematerial might have been recycled.

#n general, using recycled materials to make new products costs less and re$uiresless energy than using new materials. Recycling can also reduce pollution, either byreducing the demand for high%pollution alternatives or by minimi&ing the amount of

pollution produced during the manufacturing process. Recycling decreases the amount of land needed for trash dumps by reducing the volume of discarded waste.

Recycling can be done internally 'within a company( or e)ternally 'after a productis sold and used(. #n the paper industry, for e)ample, internal recycling occurs whenleftover stock and trimmings are salvaged to help make more new product. *ince therecovered material never left the manufacturing plant, the final product is said to containreconsider waste. +)ternal recycling occurs when materials used by the customer arereturned for processing into new products. Materials ready to be recycled in this manner,such as empty beverage containers, are called post consumer waste.



:. TY;E' OF MATERIAL' RECYCLE8

ust about any material can be recycled. -n an industrial scale, the most commonlyrecycled materials are those that are used in large $uantities metals such as steel and

aluminum, plastics, paper, glass, and certain chemicals.

:.1 'TEEL

There are two methods of making steel using recycled material/ the basic oxygen furnace '0-F( method and the electric arc furnace '+AF( method. The 0-F methodinvolves mi)ing molten scrap steel in a furnace with new steel. About 2 percent of the new

product is recycled steel. *teel made by the 0-F method typically is used to make sheet%steel products like cans, automobiles, and appliances. The +AF method normally uses 1""

percent recycled steel. *crap steel is placed in a furnace and melted by electricity that arcs

between two carbon electrodes. 3imestone and other materials are added to the molten steelto remove impurities. *teel produced by the +AF method usually is formed into beams,reinforcing bars, and thick plate.

Appro)imately 42 percent of all steel is recycled5 making it one of the worlds6smost recycled materials.

:.: AL9MINI9M

Fig

. About kg 'about 7 lb( of ore, a mi)ture of aluminum o)ides called bau)ite, areneeded to make ".8 kg '1 lb( of aluminum. Aluminum cans almost always produce a profitin community recycling programs. A number of states re$uire deposits for beveragecontainers and have established redemption centers at supermarkets. The overall recyclingrate of all forms of aluminum is about 98 percent.

ans brought to collection centers are crushed, baled, and shipped to regional millsor reclamation plants. The cans are then shredded to reduce volume and heated to remove



coatings and moisture. :e)t, they are put into a furnace, melted, and formed into ingots, or bars, weighing 1",""" kg '9",""" lb( or more. The ingots go to another mill to be rolledinto sheets. The sheets are sent to a container plant and cut into disks from which new cansare formed. The cans are printed with the beverage makers6 logos and are shipped 'withtops separate( to the filling plant.

About 1"" billion aluminum beverage cans are used each year in the ;nited *tatesand about 48 percent of these are then recycled. The average aluminum can in the ;nited*tates contains 7" percent post consumer recycled aluminum. About !< percent of all softdrink cans and !! percent of all beer cans are made of aluminum.

:.3 ;LA'TIC'

Fig 9

Many plastic products aremarked tohelpconsumerstell which

plastics can be recycled.

ollecting,sorting, andrecycling

plastics is ane)pensive

process.Although automated plastic sorting machines are being developed, many recyclingoperations sort plastic by hand, as shown here. =lastics are more difficult to recycle thanmetal, paper, or glass. -ne problem is that any of seven categories of plastics can be usedfor containers alone. For effective recycling, the different types cannot be mi)ed. Most

states re$uire that plastic containers have identification codes so they can be more easilyidentified and separated.

The code assigns a particular number to each of the seven plastics used in packaging. The number 1 refers to polyethylene teraphthalate '=+T( and the number refers to high%density polyethylene '>?=+(. =+T can be made into carpet, or fiberfill for ski @ackets and clothing. >?=+ can be recycled into construction fencing, landfill liners,and a variety of other products. =lastics coded with the number 4 are polystyrene '=*(,which can be recycled into cafeteria trays, combs, and other items.

The recycling process for plastic normally involves cleaning it, shredding it intoflakes, and then melting the flakes into pellets. The pellets are melted into a final product.

*ome products work best with only a small percentage of recycled content. -ther products,such as >?=+ plastic milk cases, can be made successfully with 1"" percent recycled



content. The plastic container industry has concentrated on weight reduction and sourcereduction.

:.4 ;A;ER AN8 ;A;ER ;RO89CT'

Fig 7

:ewspapers are shredded and bailed Recyclable ollection enter. The papers will be usedfor making recycled paper products. Mi)ed resource collection necessitates costlyseparation of paper from metal and plastics, while collection of paper alone reduces therecycling costs.

=aper products that can be recycled include cardboard containers, wrapping paper,and office paper. The most commonly recycled paper product is newsprint.

#n newspaper recycling, old newspapers are collected and searched for contaminantssuch as plastic bags and aluminum foil. The paper goes to a processing plant where it ismi)ed with hot water and turned into pulp in a machine that works much like a big kitchen

blender. The pulp is screened and filtered to remove smaller contaminants. The pulp thengoes to a large vat where the ink separates from the paper fibers and floats to the surface.The ink is skimmed off, dried and reused as ink or burned as boiler fuel. The cleaned pulp

is mi)ed with new wood fibers to be made into paper again.+)perts estimate the average office worker generates about < kg 'about 18 lb( of

wastepaper 'about 1,8"" sheets( per month. +very ton of paper that is recycled saves about1.7 cu m 'about 8" cu ft( of landfill space. -ne ton of recycled paper saves 1< pulpwoodtrees 'trees used to produce paper(.

:.< GLA''=

*crap glass taken from the glass manufacturing process, called cullet, has beeninternally recycled for years. The scrap glass is economical to use as a raw material because



it melts at lower temperatures than other raw materials, thus saving fuel and operatingcosts.

lass that is to be recycled must be relatively free from impurities and sorted bycolor. lass containers are the most commonly recycled form of glass, and their colors areflint 'clear(, amber 'brown(, and green. -ther glass, such as window glass, pottery, andcooking utensils, are considered contaminants because they have different compositionsthan glass used in containers. The recycled glass is melted in a furnace and formed into new

products.

lass containers make up !" percent of the total glass used. -ther uses for recycledglass include glass art and decorative tiles. ullet mi)ed with asphalt forms a pavingmaterial called glassphalt.

3. REA'ON' FOR RECYCLING

Rare materials, such as gold and silver, are recycled because ac$uiring new suppliesis e)pensive. -ther materials may not be as e)pensive to replace, but they are recycled toconserve energy, reduce pollution, conserve land, and to save money.

3.1 Re( +* e C %(e*v ti % Re y /i%5

This conserves natural resources by reducing the need for new material. *omenatural resources are renewable, meaning they can be replaced, and some are not. =aper,corrugated board, and other paper products come from renewable timber sources. Treesharvested to make those products can be replaced by growing more trees. #ron andaluminum come from nonrenewable ore deposits. -nce a deposit is mined, it cannot bereplaced.

3.: E%e*5y C %(e*v ti % Re y /i%5

This saves energy by reducing the need to process new material, which usuallyre$uires more energy than the recycling process. The amount of energy saved in recyclingone aluminum can is e$uivalent to the energy in the gasoline that would fill half of thatsame can. To make an aluminum can from recycled metal takes only 8 percent of the totalenergy needed to produce the same aluminum can from unrecycled materials, a !8 percentenergy savings. Recycled paper and paperboard re$uire <8 percent less energy to producethan new products. *ignificant energy savings result in the recycling of steel and glass, aswell.

3.3 ; //+ti % Re2+ ti % Re y /i%5This reduces pollution because recycling a product creates less pollution than

producing a new one. For every ton of newspaper recycled, < fewer kg '14 lb( of air pollutants are pumped into the atmosphere. Recycling can also reduce pollution byrecycling safer products to replace those that pollute. *ome countries still usechlorofluorocarbons ' F s( to manufacture foam products such as cups and plates. Manyscientists suspect that F s harm the atmosphere6s protective layer of o&one. ;singrecycled plastic instead for those products eliminates the creation of harmful F s.

3.4 L %2 C %(e*v ti % Re y /i%5

This saves valuable landfill space, land that must be set aside for dumping trash,construction debris, and yard waste ' see *olid Baste ?isposal/ Landfill (. #n the ;nited



*tates, each person on average discards almost a ton of municipal solid waste 'M*B( per year. M*B is raw, untreated garbage of the kind discarded by homes and small businesses.Baste from industry and agriculture normally is not part of M*B, but construction anddemolition wastes are. The ;nited *tates has the highest M*B discard level of any countryin the world.

3andfills fill up $uickly and acceptable sites for new ones are difficult to find because of ob@ections by neighbors to noise and smells, and the ha&ard of leaks intounderground water supplies. The two ma@or ways to reduce the need for new landfills are togenerate less initial waste and to recycle products that would normally be considered waste.

#n 1!!7 about 4.2 million metric tons '<.8 million ;.*. tons( of food and yard debriswere composted in the ;nited *tates, accounting for about one%si)th of the overall 9.4

percent recycling rate. The combined effort of reducing waste and recycling resulted in 71million fewer metric tons '78 million ;.*. tons( of material going to landfills.

*olid waste can also be burned instead of buried in the ground. Typically, waste%to%

energy 'BT+( facilities burn trash to heat water for steam%turbine electrical generators.This BT+ recycling keeps another 14 percent of municipal solid waste out of the landfills.

3.< E % ,i ' vi%5( Re y /i%5

This in the short term is not always economically profitable or a break%evenfinancial operation. Most e)perts contend, however, that the economic conse$uences of recycling are positive in the long term. Recycling will save money if potential landfill sitesare used for more productive purposes and by reducing the number of pollution%relatedillnesses.

4. CONCL9'ION

The above%discussed kinds of wastes are the common types that are available as tonesof stocks occupying a considerable land space for dumping them. >ence we suggest the waysthat can work effectively and economically to reuse those waste materials and the advantageswhich in turn will be caused by following them. Reusing the materials will bring about achange in economy of the same. Thus the management of solid wastes can be done all over the world with the effective tool called CRecyclingD on a large scale or by part that suits theefficiency of the nation in order to control the accumulation of wastes, preserve the e)istingenvironment, improve the surroundings and to secure a better atmosphere of life for thefuture inhabitants on this watery planet.

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Recycling of Waste Materials