Rubber Manufacturing

Sustainable Engineering-LO1

Assessment 1 component 1

Abstract

This report uses collected data from various sources to explain the impact on the environment of rubber manufacturing

in Sri Lanka, and about the process of manufacturing each type of rubbers where the latex is collected and then

continued with blending, coagulation, milling and drying are explained in detail (process may slightly vary for

different types of rubber) , the raw materials and a detailed information about the contents of the rubber latex, plus the

chemicals which are released into the environment and the effects to the society due to the release of effluent waste,

mainly by waterways. And finally, ending the report with the measures taken to prevent any future damage to the

environment.

Introduction

Rubber manufacturing is considered to be one of the biggest business in Sri Lanka, giving a turnover

of roughly $1 billion in the year of 2011. Hevea brasiliensis, generally known as Rubber Tree is the

source of latex, which is then processed to produce different types/grades of rubber. Sri Lanka

covers about 301,000 acres of rubber tree cultivation producing about $600 million per year in

exports, although it is a profitable business, it is also categorized as major polluting business, due to

its release of effluent waste into the environment, During 2006, a total of 114,700 Metric tons (MT)

of rubber was produced in Sri Lanka thus the industry discharged effluents totaling 4.5 to 5.7 billion

liters in that year alone.

Grades of Rubbers produced

There are three grades of rubber produced in Sri Lanka, this includes Crepe Rubber, Sheet rubber

and Technical Specified rubber (TSR) or known as block rubber, these are produced in three

different ways, they are explained below including the raw material and the process involved.

Sheet Rubber

The production of Sheet Rubber includes blending, coagulation, milling, drying and finishing.

Latex from rubber tree is collected and blended in a large blending tank, this is to ensure that the

production of rubber is uniform. Coagulation is effected by diluting latex with water. Individual

smallholdings blend and coagulate their latex in 4-5 liters pans. Milling is sending the slabs of

coagulum into rollers to produce uniform thickness of rubber, then it is dried in smoke house in

successive temperature.

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Crepe Rubber

Crepe rubber is produced from either latex or cup lump, the method of making crepe rubber is

similar to making sheet rubber, but one extra step is to remove the yellow carotenoid, and the latex

is treated by fractional coagulation.

Block Rubber /Technical Specified rubber

This is a recent method of making rubber, it is much complex than crepe rubber or Sheet rubber.

The latex is collected from the source and it is fed into the blending tank, and then chemicals are

added to control the viscosity and affect colour. Then the latex containing the chemicals is then

coagulated, and the solid latex coagulum is processed into crumb by either physical or chemical

means, and finally the rubber is dried firing burner or apron driers, and the dry rubber is finally

baled and wrapp ed in polythene to prevent adhesion between bales in the crate.

Environmental Effects

Effluent produced by rubber are directly discharged into water streams in many cases.

Production of rubber releases effluent into the environment which contains chemicals as

carbohydrates, lipid protein enzymes and metal ions, hydrocarbons and lactic acid.

The chemicals added in the production process of rubber are also present in the effluent. These

include sodium sulphite, ammonia or formalin formic, acetic, oxalic acid sodium bisulphite,

metabisulphite and xylyl mercaptan. The Effluent from the rubber production is mainly liquid waste,

an average of 40-50 liters of effluent is discharged to produce one kilogram of rubber. An average of

3 to 4 million tons of effluent is produced mainly due to the production of sheet and crepe rubber.

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Sri Lankan Rubber Production

If effluent is released without treatment, it reduces the amount of oxygen level in water, and the

water will become undrinkable, and will not support life, the water animals will die, and also

provide suitable environment for anaerobic bacteria, which are harmful. Contaminated water cannot

be used in other industries or in the households.

Releasing the effluent to a smaller area, might kill the organisms in that certain area, when these

organism decompose, it will further deplete the oxygen in the surrounding area, this forms a chain

reaction and the whole water body can be effected in matter of days.

The environment is polluted, not only by rubber production itself, but by the products made from

rubber. When rubber products are disposed directly into the environment, it takes several weeks to

decay, for instance, tires, if thrown directly into the environment, will take many years, or even

decades decay.

Treatment

The central Environmental authority was under pressure to face the effluent problems, therefore The

Rubber research industry managed to find a new method in 1995, to treat the effluent released. This

project was funded US$30000 from Sri Lanka Council for agricultural research policy, and was

based on a novel, anaerobic digester.

The method used is anaerobic ponding system, where large number of ponds or tanks are needed to

carry out this treatment. The tank is designed to hold 2 days’ worth of effluent, Water Vascular

plants like Water hyacinth (Eichhornia crassipes), are used in the ponds to reduce the retention ()

time of the rubber from 22 ½ days to 10 days, which means in turn reducing the pond size and the

area required. Water hyacinth covers the whole pond making a suitable environment for anaerobic

bacteria to grow underneath, when rubber effluent is passed through, the anaerobic bacteria converts

the dissolved pollutants into biogas (methane, carbon dioxide and hydrogen sulfide) which are not

harmful when released into environment.

The portion above is oxygenized, therefore aerobic bacteria present in that portion of the tank

biodegrades organic pollutants while ammonia and nitrogenous compounds are oxidized into

nitrates.

Although anaerobic ponding system was widely in use, there were two other methods used in

treating effluents, they are, Oxidation ditch and rotating bio disc. Since these two methods were

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costly and limiting feasibility, land the new method of using vascular plant (anaerobic digester) was

tested for 2 years, this test was carried out in the Rubber Research Institute, Agalawatte.

Life Cycle of Rubber

Rubber Latex is tapped from a rubber tree, then processed into different grades of rubber (as

mentioned above), these are sent to different factories, to make different products such as rubber

bands, tires, wet suits etc... Natural Rubber by itself is biodegradable and, presently most rubbers

made are recyclable, for example car tires are recyclable, and sent to factories to make other

products or tire.

Conclusion

The above given information about rubber manufacturing and the impacts of it clearly pictures that

many rubber manufacturing industries alone are not concerned about the environment, releasing of

effluents without treating them well will only effect the future generation. Water, as a main source

of life should be carefully preserved, since rubber manufacturing mainly releases its waste into

waterways.

Reference

http://r0.unctad.org/infocomm/anglais/rubber/technology.htm http://tcdc2.undp.org/GSSDAcademy/SIE/Docs/Vol1/16%20Sri%20Lanka.pdf [PDF] –

Sharing innovative experiences-Volume one http://en.wikipedia.org/wiki/Hevea_brasiliensis https://www.google.lk/url?

sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCYQFjAA&url=http%3A%2F%2Fwww.sljol.info%2Findex.php%2FJEPSL%2Farticle%2Fdownload%2F5139%2F4105&ei=apIRU4K1A6WSiQf_8ICICQ&usg=AFQjCNFm5lHtBHZ-FpcgklCBvUr9HkjIHg&sig2=8Y2PQb-JyOGFE6zCVtOVPw&bvm=bv.62286460,d.aGc&cad=rja [PDF]

http://www.horanaplantations.com/Ceylon-Rubber.html http://ecoport.org/ep?SearchType=earticleView&earticleId=644&page=4373

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http://www.srilankabusiness.com/find-sri-lankan-suppliers/product-profiles/rubber-and-rubber-products

http://www.srilankabusiness.com/find-sri-lankan-suppliers/product-profiles/rubber-and-rubber-products

http://www.parliament.lk/papers_presented/20112012/annual_report_rubber_research_board_2010.pdf [PDF]