The efficient utilization of plantation bamboo for pulp and paper making is tested and discussed in this article. The principle focus of the discussion is the influence of plantation age on the physical and chemical characteristics of fiber and pulp.
The results indicate that plantation bamboo reaches maturity during the first year of growth. In order to get optimal culm recruitment, however, a cutting cycle of 36 months is recommended for plantation bamboo. Guidelines for raising bamboo plantations are suggested.
Bamboo is considered to be a unique source of woody raw material and is noted for quick growth, easy availability, and superior wood quality. It is used for various purposes, including the manufacture of rural houses, ladders, mats, baskets, pipes and handicrafts.
The largest single use of bamboo is in the manufacture of paper. During the last few decades, bamboo has become increasingly important as a source of raw material for the pulp and paper industry in India. As of 1994, the paper industry has an installed capacity of 3.0 million tons, made-up of 316 small, medium and large paper mills and produces about 2.75 million tons of paper and paperboard.
The use of bamboo for pulping has declined over the years from about 73.5% in 1952 to 26.53% in 1990. This proved that, overall use of bamboo has risen but proportional use of bamboo has declined due to non-availability of the bamboo.
The paper industry is presently faced with an inadequate supply of suitable fibrous raw materials. Bamboo plantations can potentially provide the fibre necessary for the pulp and paper and paper industry on a sustainable basis. In order to meet the present and future requirements of the industry, efforts must be made to use existing bamboo resources judiciously and efficiently. This study is designed to investigate the efficient utilization of plantation bamboo in pulp and paper manufacture.
Materials and Methods:
(a) Raising of Bamboo Plantation:
(i) Tissue Cultured Seedling:
Bambusa bambos seedlings were cloned from tissue cultures, and were collected from the Institute of forest genetics and tree breeding, Coimbatore.
(ii) Preparation of Nursery Bed:
The study area is a six year old plantation Bambusa bambos at Kalipatty, Tamil Nadu, India. The areas lies between 11°28′ and 12° east of Latitude and 76°59′ and 77°47′ north longitude. Its altitude is 540 m above mean sea level. Nursery beds of 10 x 5 m were prepared in the field and filled with a mixture of soil and sand (3:1).
About 15-25 seedlings, grown to 7 cm in height, were planted in every square meter of the nursery beds. One weak prior planting, the nursery bed were drenched with commercial mixtures such as 0.01% Aldrex and 0.05% Bavistin to prevent termite and fungal attack respectively.
(iii) Nursery Management:
Nursery beds were covered with a thatch to protect the seedlings from direct sunlight. Watering was done 2-3 times a day. Care was taken to avoid over saturation. The seedlings were kept in the nursery for six months.
(iv) Soil Characteristics:
The soil classification is plinthite, with colour from red to brown and sandy loam texture. The soil pH ranges between 7.4 to 7.8. The mean rain fall is 600 mm concentrations in N, P, K, Ca and Mg were 3800, 360, 3600, 1600 and 1800 kg, ha -1 respectively.
(v) Transplanting:
Upon achieving growth of between 70-80 cm in the nursery, the bamboo seedlings were uprooted carefully and transplanted to plots 45 cm x 45 cm at spaced at 6 m x 6 m. The plots were excavated to a depth of sufficient moisture (15 cm deep).
In order to provide an optimal initial growing environment to the seedlings, the lower 7.5 cm of the pit was refilled with the original soil, while the upper portions of the pits were filled-up with a complex of 25g special fertilizing Vijay complex (NPK) (17:17:17).
The transplanted seedlings were watered for two hours every morning and two hours every evening. At end of one year, the watering schedule was changed to irrigation every 15 days. Protection against damage by rodent, grazing and browsing animals were provided by brushwood fence.
(vi) Growth and Production on Culms:
All the transplanted seedlings produced rhizomes which in turn yield culms or shoots. The culm bud emerge with the onset of early rains and grow rapidly. The total numbers of culms in years 1-6 were 1250, 2250, 3000, 3500, 4000 and 4250 respectively.
The culm heights in years 1 to 6 were 1.4 m, 3.2m, 9.6m, 21.8m, 27.2m and 28.5 m. The corresponding diameters in years 1-6 were 2.3 cm, 3.3 cm, 4.3cm, 4.8cm, 6.3cm, and 8.3 cm respectively. An unusual rain during winter months may induce the emergence of new culms but these do not tend to grow as successfully as those produced in rainy seasons.
The productivity of new culms is most closely related to the degree of congestion, clump age and rainfall of the previous year. It was noted that annual recruitment of culms proportionately with age.
(vii) Growth and Development:
Upon emerging, the culms appear very slender and exhibit slow growth. They gradually began to grow faster till the culm reached maximum and stops thereafter. The daily average growth height of culm was approximately 30cm till, 32nd day the internodes were
wrapped with sheaths and thereafter during the 1st month these sheaths were lost. After 50days, branch buds began to develop.
These branch buds .numbered two to three in circular pattern, and were clearly visible after 60 days. Their length began to increase up-to 30 days (i.e. 90 days after the emergence), and subsequently leaf buds began to appear on their nodes alternately. Again, these leaves began to mature within 30 days of their visual appearance.
They varied in their length from 15-20 cm and were simple long leaves. It was at this point that the older culms began to change their hardness and colour. The new culms were produced peripherally from the outer edge of the clump and tended to grow inwards and get entangled among the older culms.
(b) Chemical Testing
(i) Preparation of the Bamboo Sample:
The bamboo was chipped by means of electrical saw. The screened chips of a density of 224.76 kg/m3 were collected from summer chipper was used for the chemical analysis.
(ii) Methods of Chemical Analysis:
The analysis was carried out as per Tappi standard methods:
(c) Fibre Analysis:
Pulping Technique:
For the determination of fibre length, soda pulp prepared under conditions given below was used:
To study the pulp and paper characteristics, screened chips at a density of 224.76 kg/m3 were collected from summer chipper from 1-6 years age group. They were pulped individually in the laboratory series digester heated with indirect steam. The digester was initially heated to a temperature of 80°C, upon which time, oven-dried chips equivalent to 2000g were charged with chemicals.
The cooking was done to get two values of Kappa number. The H-factors was maintained at 1300. The pulping of bamboo can be regulated by the H’ factor which singly represents time and temperature. This concept can be applied to achieve similar pulp variations due to unforeseen reasons in temperatures or duration of cooking. The cooking conditions were maintained at 19-22% to 22% active alkali (as Na20), 25% sulphidity, 1:3 liquor- to- chip ratio and 90 minutes to raise the temperature to 170°C.
After cooking, the chips were discharged, thoroughly washed, disintegrated and then screened. The screened pulps were pressed to remove excess water, shredded, weighed and then sampled for determining moisture content.
The screened chips were also oven dried. The pulp yield and screened pulp Kappa number were determined and physical strength properties were studied in the unbleached pulp. The bleaching experiments were carried out for the pulps using CEH sequence (Successive stages of Chlorination, alkaline extraction, hypochlorination).
The bleached pulp samples were then refined in a valley beater to different freeness values and hand sheets were made to determine the strength properties after conditioning the sheets at 23 ± 1°C and 50 ± 1% relative humidity.
All the sheets were tested according to Scan test methods. The black liquor obtained in each case was analyzed for total solids, inorganic- organic ratio, acid soluble inorganics, the presence of sodium salts (Na2O), free alkali, swelling volume ratio (SVR) calorific value and viscosity at different concentrations.
Results and Discussion:
(a) Fibre Characters:
The fibres sclerencymatous tissues which occur as, caps over vascular bundles as isolated strands. A gradual minimum increase in fibre length could be monitored with increase in age. The fibre a length obtained ranges from 2mm to 2.5mm in 1 and 6 year old Bambusa bambos. The influences of fibre on the physical properties of pulp have been reported by many scientific studies.
There are three principal factors affecting the pulp strength, fibre density, fibre length and fibre strength, Fibre density is associated with cell wall thickness, (or) the ratio of cell wall thickness of fibre diameter, (or) ratio of lumen diameter to fibre diameter and together with runkal ratio, (runkal ratio is one fiber properties measured by 2W/l-w=fiber wall thickness, l=lumen width) they predetermine and dictate the tensile, bursting strength and folding endurance of the paper produced. Fibre strength and fibre strength on the other hand are essential for fibre bending. Tearing strength depends upon fibre length, fibre strength and cell wall thickness.
Fibre length of forest bamboo is well documented. Fibre length is an important criterion in identifying the fitness of the wood in pulping as it has direct correlation with the tearing strength of the paper Bmabusa bambos plantation attains maturity during the first year of growth and fibre length slowly increases with age, which may vary between species.
Fibres obtained from plantation bamboo forests are shorter in length (2 mm to 2.5 mm, present study) in comparison with those from counterparts in natural forests (Bambusa polymorpha, (4.19 mm). Dendrocalamus giganteous (3.69 mm), D. hamiltonii (3.36 mm), and Oclandra travencorica (4.03 mm).
Analogues to fibre length, the percent content of +50, +100, and -100 mesh fibres showed gradual minimum increase in unbleached and bleached pulp. The life cycle of the bamboo culm will account for some of the variations. It is conceivable that, external factors, such as soil conditions and climatic changes during fibre development might influence the fibre length.
(b) Chemical Analysis:
Proximate chemical analysis revealed gradual increase in the distribution of chemical components with age, which was also observed in Bambusa polymorpha, B. tulda, Dendrocalamus, hamiltonii, D. longispaths, D. strictus, Melocanna baccifera. The lower ash content is favorable for pulping since it reduces problems in the chemical recovery system of a pulp mill. However, the alcohol-benzene soluble were 2 to 5% higher than Bambusa vulgaris. The cold and hot water, besides 1% alkali soluble were almost similar with that of other bamboos.
Generally, bamboo species with higher holocellulose had lower cold and hot water soluble extractives and lower lignin content. Bamboos possessing higher holocellulose and lower lignin content are better suited for pulp and paper. In the present study, a proportionate increase of lignin with age was observed. The high lignin content indicates the need of more chemical consumption during bleaching. Corresponding increase in holocellulose, lignin and ash contents with age were reported.
(c) Pulp Characters:
The results of the pulping data are presented in Table 4. It was observed that, the bleachable grade pulp yield ranged from 46.36% in the 1st year to 48.80% in the 6th year. The physical strength properties of unbleached pulp are presented in Table 5. The burst factor, tear factor breaking length and double fold strengths showed a gradual minimal increase from 1 to 6 years.
The results of bleach ability testing are given in Table 6. It showed that the pulp requires 8.9-10.5 chloride for getting final 75% brightness in the 1st year; the same chloride load gives a final brightness of 84% in the 6th year. The bleaching loss decreased from 14.04% to 13.63% in the 1st and 6th year respectively.
The physical strength properties of bleached pulp are presented in Table 7. It reveals that burst factors, tear factor, breaking length and double fold strengths showed a gradual minimal increase from 1st year to 6th year. The black liquor analysis is presented in Table 8. The black liquor characteristics such as total solids, inorganic content, acid soluble ash, sodium oxide content and Swelling Volume Ratio (SVR) also increased with age.
The bleachable grade pulp yield ranges between 46.36% to 48.80% which is comparable with 42-48% of the sulphate process and45-539 % of Kraft pulping. While cooking is made separately for each age group, a minimum of 19% alkali is required to get a pulp having a Kappa number of 27 ± 2 based on the percentage yield.
If stationary digester is charged with 22 tons bamboo chips and with 18-19% alkali, keeping other parameters constant, the output would be 8.7 to 9.0 tons of pulp. Good tear, burst tensile and folding endurance values are the requisites of good quality paper.
The pulp requires only 8.19 to 10.40% chlorines for bleaching to develop a brightness of 75% to 84%. The bleaching loss varies from 14.04% to 13.63% with decrease in age. In the bleached pulp all the physical strength properties increased with age.
The increase in breaking length on both unbleached and bleached pulp could be attributed to the increase in fibrillation, which leads to fibre bonding. Tear resistance, on the other hand, depends entirely on the fibre length. The black liquor analysis indicate that the total solids obtained ranges from 200-209, the inorganics 46.90% to 48.33%, the acid insoluble ash from 4.20 gpl to 5.50 gpl. The swelling volume ratio of all ages is more than 25 ml/g. The calorific value ranges from 3795 cal/grm (year 1) to 3968 cal/grm (year 6).
In a plantation bamboo crop, it can be assumed that, no appreciable change in chemical composition of pulp could be monitored with increasing age; probably these bamboo species may attain maturity during the first year of growth. Hence, one to six year old culms can be used as raw material for pulping.
However, in order to get higher annual recruitments of culms in the subsequent years it is recommended that a cutting cycle of 36 months is ideally suitable for pulping purposes. Bose et al, (1988) suggested a cutting cycle of 21 months for muli bamboo (Melocanna baccifera) from the point of yield gain. Biennial felling cycle has also been observed to give maximum yield and superior quality pulp in case of Dendrocalamus strictus. From a management point of view biennial felling cycle does not cause any serious difficulties. Youdi et al., (1995) also concluded for ten bamboo species that the bamboos should not be older than 36 months for chemical utilization if practices of cultivation and rotation are considered.
Pulp and Paper Characteristics of Plantation Bamboo:
Bambusa Bambos:
During the extraction of bamboo from the forest, no cutting age is maintained. Rather, bamboos of different age groups were extracted indiscriminately. As a result, pulping of a mixture of bamboos of different age groups may result in heterogeneous cooking, producing inferior quality pulp. With a view of overcoming these problems, an attempt has been made to observe the influence of age on pulp and paper making characteristics.
The pulp and paper-making characteristics of one to six year old plantation grown Bambusa bambos were studied. The salient points of fibre and pulp qualitative characters were almost equal among all the ages of bamboos. The principal difference was in the total biomass production, which is related to the age of the plantation, indicating that age was not a criteria for qualitative fibre harvest.
1. Fibre and pulp qualitative characteristics were almost equal among all the ages of bamboos. Their quantity difference was dependent on the total biomass production, which is related to the age of the plantation, indicating that age not a criteria for qualitative fibre harvest.
2. With increase in age, cellulose, lignin, pentosans, 1% NaOH soluble, Alcohol-benzene soluble, cold and hot water soluble, ash contents also increase.
3. It was observed that with increasing age, active alkali requirements to get a fixed Kappa number increases. Total pulp yield also increase with increase in age of culm.
4. The physical and strength properties of both unbleached and bleached pulp increase with increase in age of bamboo.
5. Based on the percentage pulp yield, if stationery digester is charged with 20 tons of bamboo chips with 19-24% alkali the output would be 8.7 to 9.0 tons of pulp.
Further, the study revealed that in plantation bamboo though no appreciable change in chemical composition of pulps could be monitored with increasing age, these bamboo species attain their maturity during the first year of growth. Hence, one to six year old culms can be used as raw material for pulping. However, in order to get higher annual recruitment of culms in the subsequent years it is recommended that 36 months cutting cycle is ideally suitable for pulping purposes.
Research Work on Selecting Bamboo Species for Paper Making:
The research work on pulp and paper making with different kinds of bamboo are to be carried out through division of Research and Development (R&D) in the paper industries. Based on the data derived from these experiments, the industries can identify those species ideal for pulp yield. Papers made from these were better than those produced from other species of bamboo in strength and Physical properties.
Species, which have attained a crop status in agriculture, have decades of directed endeavor behind them – Bamboos have not attained the same status due to lack of sustained investigations. A few problems of fundamental and applied nature are listed below which need to be tackled immediately.
1. It is necessary to evolve appropriate technology for raising plantations of selected bamboo species particularly in:
(a) Degraded areas,
(b) Logged over forest,
(c) Marginal farmland in Agro forestry initiatives.
2. Research should be directed to address the role for bamboo in community agro-forestry settings, to produce models of the most efficient methods of growing it in waste areas, elevated ground, along field bunds and on river and canal banks.
3. For raising large-scale plantation, seedlings from seeds come handy than rhizome propagules. Hence, propagation through various vegetative techniques including use of growth regulators should be initiated.
4. Experiments were to be carried out in the bamboo plantations to determine the optimum level of fertilizer needed for increasing production.
Suggestions for Raising Bamboo Plantations:
The Development Council for pulp and paper in the Ministry of Industry appointed a Raw material Committee for pulp and paper. This committee worked-out scale of investment needed for pulp-wood planting, their economics, suggestions for the management etc.
The report recommended that the user industries should be encouraged to produce 50 per cent of their wood requirement by 1990 and 10 per cent of their wood needs by the year 2000. This could be achieved by the afforestation of 10th portion of the 82.8 million ha. of wastelands available in India. The estimated area needed to be afforested in 10 years either by the mills themselves (or) by the joint sector to make up the projected wood short-fall was projected to be 0.71 million ha.
This was based on an anticipated yield of 50 t/ha-1 with 10 year period of rotation. The deficit of 0.5 ton of bamboo could be made up by cultural operations in natural bamboo forests. This effort was suggested to be supplemented by encouraging the taking-up of pulpwood in agro forestry in marginal farmlands and extension forestry schemes.
The report also recommended strategies for the flow of credit, changes in existing land laws and provision of incentives of encourage investments by mills on such long gestation crops. The committee devised models for pulpwood planting, identified species, worked-out economics and suggested financial arrangements.
Conclusion:
The following conclusions can be drawn from this study:
1. Gradual minimal increase in the fibre length and chemical composition of this irrigated plantation bamboo, with increase in age.
2. 1 to 6 year old bamboo culms can be used as a raw material for pulping.
3. However, to increase the production of culms in the subsequent years, 36 months culm harvesting can be suggested.