Conference : "Challenges of Sustainable Development"
22-25 August, 1996
By
Megahed M.M.* and H.EI-Mously**
*Dept. of Foreslry and Wood Technology, Faculty of
Agriculture, Alexandria University , and
**Dept. of Production Engineering, Faculty of Engineering,
Ain Shams University , Egypt
A DISCUSSION ON USE OF AGRICULTURAL RESIDUES IN
COMPOSITION PANELS: EGYPTIAN EXPERIENCE
A Paper Presented to Workshop 2.3, part A:
"Industry and Sustainability : Pioneer Industries
on Sustainable Renewable Resource Use"
Conference : "Challenges of Sustainable Development"
22-25 August, 1996
By
Megahed M.M.* and H.EI-Mously**
*Dept, of Forestry and Wood Technology, Faculty of
Agriculture, Alexandria University , and
**Dept. of Production Engineering, Faculty of Engineering Ain- Shams University , Egypt
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ABSTRACT
This paper addresses options for using agricultural residues alone or in combination with wood to produce composition panel products. The discussion is concentrated on the Egyptian experience and brief performance properties of panels that can be obtained using these fibers is provided.
Agricultural residues that seem most appropriate and available in Egypt are bagasse, date palm leaves' midribs, flax shives, rice straw, rice husks and common reed. The paper discusses also the obstacles, promises and priority areas in this subject.
1 .Introduction
Legnocellulosic substances contain both cellulose and lignin. Sources of legnocellulosic
include wood, agriculture residue, water plants, grasses, and other plant substances. In general, iignocellulosic have been included in the term biomass and have also been called photomass because they are a result of photosynthesis.
A lignocellulosic composite is a reconstituted product made from a combination of one or more substances using some kinds of bonding agents to hold the components together. The most known Iignocellulosic composites are plywood, particleboard, fiberboard,and laminated lumber.
Egypt , like many developing countries in arid zones, do not possess adequate forest resources to cover their needs for fuelwood, industrial wood, sawn wood, and wood based composition panel. Limited supply of these materials, coupled with the growing future demands for wood panel, requires the search for additional raw material supply other than wood. However, relatively large quantities of other lignocellulosic materials are available in form of agricultural residues from field crops. Many of these residues (flax shives, bagasse and rice straw) have been used in Egypt since the early 1960's in production ofparticleboard and fiberboard.
Particleboard industry in Egypt depends mainly on agricultural residues and on casuarinas and eucalypt wood as raw material. The boards produced from casuarina and eucalypt are of relatively low quality. The major problem of utilizing casuarina and eucaiypt (the two major wood species growing in Egypt as windbreak and shelterbelts) is its high density which is considered the most important variable that affects the particleboard properties. The use of casuarina and eucalypt wood in a mixture with raw material from agricultural residues having lower density could be a partial solution to reduce board density and improve the properties of particleboard produced from such a mixture. Therefore, it is important to test and use agricultural residues and low-density wood wastes to be mixed with casuarina and eucalypt wood. In addition unused agricultural residues and wastes cause environmental problems and result a high disposal
costs.
Although there is a great opportunity to use agricultural residues in panel production, the resulting material must perform satisfactory. This require evaluation of characteristics that affect the performance of the products. This characteristics include mechanical , physical and dimensional stability properties, insulative and acoustical properties and toxicity hazardous. These products must be also economically feasible and acceptable to consumers.
Using agricultural fibers in composition panels has been discussed extensively by Youngquist (1993). This paper will discussed options for using agricultural residues alone or in combination with wood to produce lignocellulosic panel. The discussion is concentrated on Egypt experience.
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2. Agricultural residues supply information in Egypt :
Success in developing technologies to produce value added products from agricultural residues depends upon many factors. The most important factor is the availability of raw material. The agricultural fibers that seem 10 be the most appropriate and available in Egypt are flax shives, bagasse, cotton stalks, palm leaves, rice straw, rice husks, common reed and water hyacinth.
The cultivated area in Egypt is about 6 million feddan (2.4 million, hectare). Ali the cultivated area covered with agricultural crops and fruit trees. The timber trees are planted only along roads and canals, windbreaks and shelterbelts, for shading and recreation. Table (1) represents the area of agricultural crops and residue estimate in Egypt .
Besides, there are a considerable amount of perennial weed grasses such as common reed (Phragmitis comninnis) and water hyacinth (Eichhornia crassipes). The estimated area of common reed in Egypt is about 150,000 feddan. The expected weight of its stems is about 150,000 tons if harvested annually.
3. Composites from agricultural residues in Egypt
All particleboard and fiberboard manufactured in Egypt in the period from 1960 to 1977 were from agricultural residues (flax shives, and bagasse for particleboard and rice straw for fiberboard). In 1978 and 19SO, two particleboard plants were constructed based on casuarina and eucalypt wood. After few years the production of particleboard in one of these two plants was terminated due to shortage of raw material. Table (2) represents the production of lignocellulosic panels from agricultural residues and wood in Egypt in the last three decades.
From the above table, it is clear that agricultural residues were the only source of raw material for fiberboard and particleboard over 15 years. Now, about 70 % of panels produced in Egypt are made from agricultural residues.
4. Research on the production and quality of composition panels from agricultural in Egypt :
The research on the composition panels in Egypt using agricultural residues is concentrated on fiberboard production and quality (Fadi et al. 1978,1984, andl990: Fahmi and Fadl 1974 and Mobarak and Nada 1975) and on particleboard quality (El-Mously 1993, El-Osta et al, 1982, and Megahed et al. 1994) and in mixing wood as raw material for particleboard industry with agricultural residues (El-Osta et al. 1991, and EL-Osta et al, 1995).
The quality of panels produced from agricultural residues in Egypt satisfies the local standards (EL-Mously 1993) as well as American standards (Fadi et-al. 1984 and Youngquist et al. 1993).
Comparing the quality of particleboard produced from agricultural residues (flax board) to particleboard from casuarina wood, EL-Osta et al. 1988 found that the properties of flaxboard were superior to casuarina wood,
On the other hand mixing agricultural residues (flax shives and date palm leaves' midrib) to wood furnishes in particleboard production improved the properties of particleboard (EL-Osta et al, 1991 and 1995).
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5. Agricultural residues as raw material for panels in Egypt : obstacles
Due to scarcity of animal fodder in Egypt coupled with (lie increasing population, a great part of agricultural residues is as a roughage for animal feeding. This, in turn, increases the prices of agricultural residues. Table (3) represents the estimates of prices of traditional agricultural residues in Egypt . These data were collected recently in August 1996 .
3. Relative prices of agricultural residues and small diameter logs and branches ofcasuarina wood (August, 1996)
The other major obstacle facing the utilization of agricultural residues for panel production is its low density. Low bulk density increase transport costs significantly. This explains the wide range of utilization of agricultural residues associated with other industries as bagasse and flax shives. Other obstacles are related to the type of raw material and will discussed below:
a- Bagasse
Bagasse is composed of fiber and pith for the best quality bagasse fiberboard and particleboard, only the fibrous portion is utilized. In Egypt the cane harvest usually lasts about 3 months (from December to the end of February). For the remainder of year the material must be depithed and stored. Locally, the particleboard plant worked only 8 months due to difficulties in bagasse storage.
Now, two big plants (one for MDF and other for pulp production) are under construction
to utilize all the bagasse residues resulted from sugar industry in Egypt .
b- Cereal straw
In Egypt , rice straw can be economically used for panel production. Rice straw was used before for production of hardboard but the production was terminated due to some technological and management problems. Rice straw have a high ash content (15-20 %) and a high silica content (9-14 %) and this increases rapidly. The wear rate on cutting tools and in boilers and digestion tanks.
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c- Cotton stalks
There are opportunilies to use cotton stalks in panel production in Egypt due to its availability in relatively low price Besides, storage of cotton stalk upon the farmer house roofs as it stored in Egypt makes it hazardous waste and causes fires. Also stored cotton stalks serve as a home for boll worms ( Earias insulana and Pectinophora gossypeiella ) and infected the next year's crop. The major obstacles facing the utilization of cotton stalk for panel production is its lower bulk density (voluminous) and difficult handling for feeding in shipping machine. Primary pressing of cotton stalks in ballets, will overcome most of these obstacles.
d- Date palm leaves' midrib (DPLM)
Utilizing date palm in panel industry will be discussed by Dr. H. EL-Mously in the next session.
e- Common reed and other perennial grasses
Common reed and water hyacinth have adapted well to every area into which it has been introduced, creating serious environmental and hygienic problems to the Inhabitants. Due to their vegetative propagation and extremely fast growth rate, reed and water hyacinth spread rapidly, clogging drainage, ditches, shading out other aquatic vegetation and interfering with shipping and recreation.
The chemical composition of reed (Rowell 1992) comparable to composition of bamboo. It can be used for particleboard and fiberboard production. Water hyacinth can be utilized also for paper board making (Gash et al. 1984). The major obstacles of utilizing these materials are the cost of harvesting.
5. Use of agricultural residues in composition panels: Priority areas of research
5.1. Field study of supply and availability of agricultural residues and analyzing the efficiency of processing concepts.
5.2. Developing methods for collecting and converting agricultural residues into form suitable for subsequent processing.
5.3. Combination, or mixing with other resources. It is possible to make different types of
composites by combining different resources. The priority area is mixing the recycled fibers and/or wood residues with agricultural residues. An example for tins is that the reconditioning of machines of particleboard plant near Alexandria to use different types of raw materials as cotton stalks, DPLM, reeds, wastes of veneer and wood industry mills, branches and small logs. The combination also can include other materials such as glass, plastics, and synthetic resins, to produce new classes of materials.
5.4. Evaluation of characteristics of panels that affect the product's performance when it used. The evaluation must include mechanical and physical properties, moisture effects and durability, and toxicity hazards. The establishment of testing, design, and evaluation standards to measure and maintain this performance is also required.
5.5. Studying the effect of using agricultural residues on the environment.
5.6. Chemical modification for property improvement.
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References
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