EXPERIENCES OF CLEANER PRODUCTION EWLEMENTATION IN RUBBER INDUSTRY AND POTENTIAL FOR FUTURE IN SRI LANKA Sena Peiris Cleaner Production Professionals Association of Sri Lanka

Summary Rubber Industry is a major thrust industry in Sri Lanka, which has a significant contribution to national economy. Also, Rubber Industry generates many employment opportunities to rural population having lower level of education. The technology used by most of raw rubber manufacturers is very old and this results in low productivity and high environmental damage which people to do not tolerate any longer. A closer look reveals that rubber industry consumes large volumes of water, uses tons of chemicals and other utilities and discharges enormous amounts of wastes and effluents. The few cleaner production assessments and implementation programs carried out in Sri Lanka has shown tremendous benefits. Some of them are lesser usage of chemicals, energy and utilities including water, improvement in productivity and profitability, lesser loads and volumes of effluent discharged to the neighbourhood, better image and relationship with employees internally and with the neighbourhood externally. These benefits should encourage many rubber industrialists to follow a cleaner production program in their own places. Many have realised cleaner production is the only way to survive in today's competitive market where cost of production is on the increase and prices are dwindling. Keywords Cleaner Production, Reduce, Reuse, Recycle, Rubber industry, Sri Lanka INTRODUCTION For several decades rubber has been a main revenue earner for a large population of rural masses in Sri Lanka until industries like tea, textiles and apparel, tourism became prime attractions. Though high cost of production and fluctuating prices have affected the growth, rubber industry is going to remain a major source of income and generator of employment to people in the rubber growing areas, in the millennium too. Sri Lanka has about 180 factories producing raw dry rubber, which is used in production of tyres, tubes, toys, shoes, garden hoses and many others. Also, 15 factories produce concentrated latex, which is the main raw material for surgical and household gloves, condoms and balloons, rubberised coir mattresses etc. [1] One third of the raw rubber production is consumed locally in rubber based manufacturing industries and the balance is exported. The government has accepted the importance of rubber industry in the local economy and its influence to the livelihood of rural poor. Therefore,

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rubber is identified as a major ~t industry along with a few other industries. A five-year plan is drawn to develop the industry and to consume 50% of the raw rubber production locally, in value added industries for export [2]. Cleaner Production Assessments in Rubber Sector In 1996 and 1997 under Industrial Pollution Reduction Program of UNDPI0 Cleaner Production assessments were carried out in two crepe rubber factories and a rubber goods factory. In 1998 and 1999 the author with the assistance of Project SMED (Small and Medium Enterprise Developers) carried out preliminary assessment at two concentrated latex and gloves manufacturing plants. Also, the Rubber Research Institute (RRI) together with Rubber Development Department conducted a preliminary survey to find an alternative to effluent treatment, where the author was fortunate to be involved in introducing Cleaner Production. This paper presents a few key relevant findings of the above CP assessments and at the survey. RUBBER PRODUCTION As shown in Table 1 raw rubber is produced as Smoked Sheets, Sole Crepe, Latex Crepe, Scrap Crepe and Technically Specified Rubber in the dry form and as Concentrated Latex in liquid form [3]. The latex tapped from the rubber tree, which is called the field latex, is the basic raw material, which undergoes many processes during its conversion to dry rubber or concentrated latex. The tapping of latex, cleaning and caring for the tree as well as addition of chemicals are important steps in the field latex production. Latex tapping is a skilled job, which requires many attributes in performing. A tapper has to tap a block of 300 trees a day in 6 to 8 hours. The operation covers collection of latex, cleaning cup lump and the tree lace, do a new cut, fix the cup, and move to the next tree. The whole operation should be completed in less than 2 minutes. The small holders do their own tapping as part time employment or hire tappers. Unfortunately, due to the low social status associated with the rubber tapping on one hand and the low incomes generated compared to other employment on the other hand, only the poor and illiterate of the rural areas, and mostly females, have remained as latex tappers in the plantations.

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Item

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

Total production (million kg)

121.8

122.4

110.1

113.1

103.9

106.1

104.2

105.3

105.7

112.5

Smoked sheets

55.6

62.8

54.3

58.6

51.3

44.4

43.7

40.9

42.2

53.2

Sole crepe

4.7

3.0

2.6

3.7

2.4

3.6

3.8

4.0

2.7

3.7

Scrap crepe

9.1

5.0

3.7

5.0

7.4

5.6

4.1

4.4

2.9

4.1

Latex crepe

35.1

33.6

31.3

29.1

28.7

24.9

25.1

30.1

29.3

33.7

Latex

5.7

3.8

4.8

6.7

7.2

12.2

13.1

14.5

5.6

6.7

T.S.R.

11.6

14.2

14.0

9.9

6.7

15.5

13.9

11.5

14.5

11.1

Local usage

19.3

19.9

21.0

23.6

26.7

28.8

32.8

36.4

36.9

39.9

Exports

106.0

99.3

86.0

86.8

76.4

78.6

69.6

69.1

83.7

72.1

F.O.B. Price (Rs)

27.6

33.7

36.2

35.5

33.5

37.6

44.3

51.8

68.3

79.8

Cost of production (Rs)

14.3

17.2

19.4

21.4

22.9

124.5

30.2

60.8

33.4

36.7

Table 1: Economic data of Rubber [4] WASTE GENERATION IN RUBBER INDUSTRY The waste generation in rubber industry ~ be categorised into three areas.

§ Waste in preparation of field latex § Waste in raw rubber manufacture – dry rubber §

Waste in raw rubber manufacture – concentrated latex

§

Waste in rubber based goods manufacture

Waste in preparation of Field Latex As mentioned earlier, the rubber tapping is a skilled job. Lack of skill in tapping leads to poor yield of latex due to incorrect cuffing angle and depth. The damage to a tree can result in unnecessary consumption of tree bark, which cannot be corrected other than by replanting. Also, the tapper has to ensure that latex does not coagulate prior to reaching the factory by adding chemicals to his yield. Generally, tappers add more chemicals than required which is a main reason for many problems in a manufacturing plant. Waste in Raw Rubber Manufacture- Dry Rubber 50% of total rubber production in Sri Lanka is smoked sheets (RSS). The RSS making is simple and is carried out in many thousands of small rubber factories by tappers, small holders and even untrained labourers. The main waste from RSS is wastewater and serum discharged into nearby water drain. The small volumes at individual factories does not cause much environmental harm but the serum and water carry chemicals and other useful non-rubber 536

particles. RSS when coagulated is rolled to get the sheets using a large volume of water in the mills. The final sheet is then dried in a smoke chamber where smoke and heat is generated using solid fuel (rubber wood). The wastes generated in crepe rubber factories are large in quantities and affect the environment. In crepe rubber factories the field latex is diluted to a predetermined strength in tanks called ‘bulking tanks’ and chemicals are added. The white fractions which, is separated after 2 to 3 hours is used for manufacturing of sole crepe and grade 1 crepe while the yellow fraction is used in lower grade. The yellow fraction contains all non-rubber particles, carotenoid substances, rust, dirt and other impurities gathered while collecting, handling and transporting latex from the field to factory. Many instances were found where the tappers were using galvanised iron buckets and factories were using iron bowsers to handle latex which adds rust and impurities to field latex. Also most of the factories use untreated water from a nearby stream or a well where iron content and other impurities are high. The natural consequence is a larger yellow fraction. The white and yellow fractions are then separately coagulated in coagulation tanks by the addition of chemicals. The coagulum thus formed is then cut into size by an employee who is immersed up to the waist level in the water in the tank. The blocks cut like that are not of a uniform size.

These blocks are then milled in a set of different mills to make thin laces or mats. The widths of these laces vary and the edges have to be cut off later. These mats are then dried in a drying tower for several days. The drying tower is a large room where hot air is circulated into at 340 Celsius. Therefore all the laces in the room gets equal heat irrespective of the degree of their dryness thus wasting heat and prolonging drying time. The dried laces are then processed into blankets or bundles depending on the grade and requirement of the customer. The excess width of the blanket is cut off at this stage resulting in scrap crepe of lower market value. The tree laces and cup lumps are too brought to the factory and washed to remove sand and dirt using large volumes of water and they too undergo a milling process to form them into laces and dried in smoke rooms or drying towers. The scrap crepe has a very good market in industries where quality of rubber is not very important and due to low price. Waste in Raw Rubber Manufacture- Centrifuged Latex In centrifuged latex factories the field latex is transported by bowsers, feed into bulking tanks and add chemicals to preserve the latex until centrifuging. In recent years almost all centrifuged latex factories either coated their bowser insides with epoxies or switched over to stainless steel bowsers to prevent rust contamination of latex. In centrifuging a large volume of scrum water is discharged. This serum water is rich in many products such as proteins, carbohydrates and Nitrogen, Phosphorus, and Potassium (NPK). As a result the load discharged in wastewater also is very high. The addition of lightly polluted wash water from bowsers and tanks add to the volume making it difficult to handle the total effluent volume. Tables 2 and 3 show the average chemical composition and effluent parameters of rubber factory waste discharges [51.

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Substance

Percent content (5)

Proteins

1

Free amino acids

0.018

Other organic acids

0.04

Nitrogenous bases

0.08

Inorganic anions

Trace amounts

Metallic ions

Trace amounts

Formic acid

0.012

Un-coagulated rubber

1

Carbohydrates

2.3

Table 2: Average chemical composition of rubber processing effluent [6] Parameter

RSS

Crepe TSR

Latex Dipped concentrate products

Toleranc e limits

PH

4.9

5.0

5.7

3.7

7.2

6.5-8.5

Settable solids (mg/l)

50

45

155

100

200

Suspended solids (mg/l)

140

130

237

190

241

100

Total solids (mg/l)

3745

3500

1915

7576

2457

1500 / 1000

COD (mg/l)

3300

3500

2740

6201

2011

400

BOD (mg/l)

2630

2500

1747

3192

1336

50 / 60

Ammonical nitrogen (mg/l)

75

80

66

401

126

300 / 40

Total nitrogen (mg/l)

500

550

147

616

180

300 / 60

1610

72

1000

Sulphates (mg/l)

Table 3: Effluent quality parameters and tolerance limits [7]

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Waste in Rubber based Goods Manufacture The waste streams in value added rubber goods industries vary from factory to factory depending on the final product and the process used. The gloves factories showed a very high consumption of energy and compressed air, heavy usage of water in leaching and washing and high reject rates. A rubber band manufacturing factory showed high use of steam and compressed air, fillers and chemicals and also high percentage of off-cuts. WASTE REDUMON IN RUBBER INDUSTRY Below we have looked at a selected few opportunities relevant to all raw rubber factories, which can be applied without incurring high costs. However, the involvement of the government in certain areas such as rubber tapper training, were highlighted at a recent seminar held in Colombo. Rubber Tapping and Transportation A program for the training of tappers and elevating their social status has to be launched immediately as most of the processing problems are rooted in tapping. A proposal to train a batch of rubber tappers is being studied by the Vocational Training Authority. Usage of traditional coconut shell as the cup for latex collection gives a large cup lump increasing the scrap crepe. This is now being replaced by a plastic bowl and the traditional galvanised iron bucket is replaced by plastic buckets. The overall national savings add up to millions of Rupees (1$US = 70 Rupees approximately) by this simple conversion. The addition of chemicals to the field latex is still a problem and training of tappers and other personnel seems to be the main option available. The transportation of the field latex by mild steel bowsers adds rust to latex. A coating of epoxy has proved to be very effective and many factories have already carded out the above to eliminate rust contamination of latex. A significant improvement is noticed in the output of grade 1 crepe by the above solutions. Bulking The addition of water and chemicals in the bulking stage is inevitable but no rubber factory in Sri Lanka has considered reuse or recycling of water as the water is freely available still. The streams are fast drying up and recycling appears to be the most economic and viable option to the water shortage. Coagulation A simple partitioning of the coagulation tank using wooden planks proved to be very effective instead of cutting the coagulum to size by a knife. This saved labour involved and the blocks were of uniform size, which produced uniform edged laces at milling. Skim Coagulation In centrifuging plants the scram water contains about 1% rubber [6] which is usually coagulated using sulphuric acid. The addition of ammonia in the field as well as in the factory prior to centrifuging results in high usage of acid for skimming and causes many problems in final treatment of effluent. To get the most effective latex formulation and chemical dosing at 539

field and in the factory through controlled trials is the most appropriate solution to the problem which is complicated and time consuming. The long-term benefits of this solution are very attractive. Before skim coagulation, the de-ammoniation of effluent helps to reduce usage of sulphuric acid. In all centrifuged latex factories the scrum water from latex, centrifuge wash water and bowser wash water is discharged as one stream. The segregation of these streams can help to reduce final treatment cost and possibility of recycling of the wash water with a little treatment for selected uses. Energy Consumption In the factories where CP studies were carried out the electrical consumption was monitored and the milling programs were planned to reduce the operating time. The uniform edged laces reduced the milling needs and blankets and bundles formed took lesser time. In the dryer tower the internal partitioning and systematic passing of hot air from chamber to chamber improved the drying efficiency. The total reduction of electrical and thermal power for the same output was approximately 10%. In a glove factory the reduction of waste heat from the drying chamber and reduction of electrical energy through power factor correction and other measures also amounted to 11 %. Scrum Water The serum water has many nutrients and other substances, which can be of high commercial value. Trials are being conducted to use serum water as a liquid fertiliser. The results of initial trials are very encouraging. Another proposal to make an animal food out of serum water is under consideration. Quality Improvement of Finished Goods The author wishes to highlight one instance where the quality of the final product- household and surgical gloves- was affected by quality of field latex. It was observed that the reject rate in a glove factory to be high around 8.5% where as standard was only about 1.5%. The major reason for the rejects was pin poles. The investigation revealed that the latex used for dipping had foam and froth which when transferred to the mould result in pin holes. The laboratory analysis of the centrifuged latex showed high dose of soaps and also the inferior quality of chemicals used in the field. By testing the latex from individual suppliers the problem could be traced to two specific estates and currently field trials are in progress to develop a revised chemical formulation for the latex. A trial production run using revised formulation resulted in only 2.5% rejects whereas the control trial using the factory latex under %me conditions resulted in 7.8% rejects. Specific Techniques Used in Waste Reduction in Rubber Factories The well known 3R's, Reduce, Reuse and Recycle is unheard of in rubber factories. In all factories assessed, the consumption of water could be reduced by 20% and chemical usage by 10% without any interference to general operations and without incurring any expenditure. Through segregation the water can be reused in selected non-critical operations. The mildly contaminated water can be recycled at a very low cost for reuse.

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A crepe rubber factory in a outstation village 90 kilometres away from Colombo was in a very awful situation a year ago. The cost of production was high, the quality was poor, employee motivation low and the factory could be rated amongst the dirtiest with absolutely no house keeping and it was impossible to cross the area without closing one's nose due to smell generated by factory discharges. In 1998 March, the divisional superintendent (D8), being in a desperate situation realised some thing has to be done to prevent total disaster. He devised a plan to implement a 5S program at the start. The employees were trained, teams formed and leading by example the DS motivated the factory employees to develop. Now, after one year the factory has transformed into a model factory with excellent house keeping. The employees have reduced the obvious waste streams without any knowledge of Cleaner Production, improved the quality of the final product, gained customer satisfaction through faster service and now they are prepared to introduce a proper Cleaner Production Implementation program in order improve the productivity and environment. Final Treatment of Effluent The techniques of cleaner production can reduce the total volume and the load of effluent from the factory but a quantity of effluent remains to be treated at the end. Usually, the most distasteful job of the rubber factory owner or manager is the final effluent treatment. Cleaner production can be successfully applied at this stage too in a rubber factory. The treatment plants installed at many factories spending millions of Rupees has failed to give satisfactory results due to incorrect operation or ignoring salient parameters or due to operation of the system intermittently. A treatment plant at the dipped glove factory mentioned earlier was not discharging water at the permissible standard due to overloading of the plant as the influent to the plant was having excessive loads. The Cleaner Production practices in the factory reduced the total load at the effluent plant by 30-40% and the plant is now functioning according to the expectations. CONCLUSION The limited experience of Cleaner Production practice in the rubber industry in Sri LMM shows potential for tremendous savings in waste cost and the elimination of long drawn battle between the factory owners and the neighbourhood of environmental degradation. The impact of the results of cleaner production can be felt nationally through the rubber sector which can be an alternative to overcome the down trodden industrial sector of Sri Lanka. REFERENCES: [1]

Central Environmental Authority (1994). Industrial Pollution Control Guidelines- Booklet 1, p.1-8.

[2]

Department of Census and Statistics. Sri Lanka (1997). Survey of rubber Base Industries, p.3.

[3]

Central Bank of Sri Lanka (1997). Economic and social statistics of Sri Lanka p.35.

[4]

Central Bank of Sri Lanka (1997), Economic and social statistics of Sri Lanka, p35.

[5]

Department of Census and Statistics, Sri Lanka (1 997). Survey of rubber Base Industries

[6]

Dr W.M.G. Seneviratne (1 999).Wastewater treatment and allied industrial effluents, p.1

[7]

Dr W.M.G. Seneviratne (1 999). Wastewater treatment and allied industrial effluents, p.1

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