Oil Palm Tree Wastes 2: Industrial and agricultural uses of oil palm fronds

Published Date: 12th October 2020

Introduction

The oil palm tree is a highly useful tree crop that yields 10 – 35 tons of fresh fruit bunch yearly per hectare depending on the variety, and production methods applied. The yield under plantation conditions using improved varieties is much higher than in the wild and semi-wild conditions found in the West, and Central African rainforest zones. The matured oil palm is a single-stemmed tree of about 20 – 30 meters in height. The frond is pinnate and about 3 - 5 meters long, and made up of the central petiole and the leaflets. There are about 41 leaflets in each frond of the mature oil palm tree. The palm oil petiole is therefore the stalk of the palm oil frond without the leaflets, and the outer layer, and constitutes about 30 percent of palm oil frond by weight. Generally, the economic life of the oil palm tree starts at about 3 years after planting, and lasts for about 25 – 30 years, with the peak yield at about 12 – 14 years after planting. Under standard plantation practice, two fronds are routinely pruned per oil palm every month on average, with each tree yielding about 24 fronds per year. At a planting density of 200 oil palm trees per hectare, 4800 pruned fronds could be harvested per hectare per year. At the end of the economic life of the trees, they are felled, and the fronds can also be harvested. Thus, fronds are readily available year-round biomass material from oil palm plantations and account for more than 50 percent of the total biomass generated in the oil palm industries.

Currently in Nigeria, and other West and Central African oil palm producing countries, oil-palm fronds are left rotting between the rows of palm trees in the plantation, primarily for soil conservation, erosion control, and eventually the long-term benefit of nutrient recycling. They are therefore basically discarded as waste materials which are sometimes burnt to reduce their volume. In Asian countries, however, technologies have been developed for processing the large quantities of fronds produced in palm plantations each year into value added products through conversion to animal feeds, gasification for biofuel production, and extraction of the juice for industrial uses. For example, the frond can be freshly chopped and preserved as frond silage or chopped, dried, and pelleted as a ruminant feedstuff.

Different uses of oil palm frond
Traditional uses: In the tropical rain forest of West Africa, the oil palm is grown for the purposes of satisfying household, and industrial demand for vegetable oil. The production and processing of palm oil is an important cottage industry that generates employment in many rural communities. In these communities, palm frond features prominently as an important raw material in the cottage industries. The intact frond is used for fencing, and making sheds during ceremonies, and as a shed in yam, and cocoyam barns. The tender frond feature prominently in religious, and ritual practices as well as a sign that an area is restricted or dangerous. After removing the leaflets, the remaining petiole can be used as a building material, and for staking yam in the farm, and in the barn. The broad base of the petiole has been used as capping on mud fences to prevent their damage from rain. The strong flat strands peeled out of the petioles are used in weaving baskets, trays, and battle shields. Brooms are also produced from the leaflets, while the leafy potion if fed to ruminants or used as mulch, and manure on the farm. Recently in southeastern Nigeria, rural women have engaged in mass production of baskets, and brooms from oil palm fronds as livelihood activities. These baskets are exported to northern Nigeria for packaging of farm produce like tomatoes, garden egg, pepper, carrots, and cucumber among others. Such rural industries are effectively absorbing the large number of palm fronds generated in the region every year, and converting them into value-added products.

Production of fertilizer and biochar: Oil palm frond-like other oil palm by-products has the potential to improve the soil fertility because of its high content of organic matter, and mineral elements. This is why in some palm plantations, routinely pruned fronds are left between rows to decay by a natural process in order to encourage nutrient recycling. Composted oil palm fronds have been shown to release their nutrients slowly over a long period of time, and are less likely to leach out of the media. Oil palm frond compost has been utilized in soilless culture systems, and in the control of plant diseases. Trichoderma sp., a fungus well known for its special ability to degrade lignin in woody materials by metabolizing wood polysaccharides to produce an array of cellulolytic and hemicellulolytic compounds has also been applied in the composting of oil palm fronds. Several types of Trichoderma sp. fungi proven beneficial in the enhancement of the nutrient value of oil palm biomass, and improvement of the fungal colonization process, increasing the yield of plants, controlling diseases especially in combination with bacterial biocontrol agents or other beneficial microorganisms.

Available data also indicate that vermicomposting of the fronds is another appropriate method of recycling the oil palm waste to value-added vermicompost. Vermicomposting is a process that involves the oxidation and stabilization of organic wastes through the joint action of earthworms, and microorganisms to turn the waste into a valuable soil amendment product. This technique has been widely used to process different types of residue, including organic, and industrial wastes. Oil palm frond has also been processed into biochar for agricultural uses. Biochar is the biomass-derived black carbon generally produced by burning biomass materials like oil palm frond under low oxygen environment to transform them into char. Due to its high pH and cation exchange capacity, biochar is used as a soil conditioner and is particularly valuable in ameliorating acidic soils.

Production of oil palm frond juice: Oil palm frond petiole is high in moisture made up a natural juice that contains large amounts of sugars. This juice has been reported to be a potential industrial fermentation substrate due to its high sugars content, and availability of oil palm frond. Researchers at the Universiti Putra Malaysia, Serdang, Selangor, Malaysia, extracted oil palm frond juice from the shredded petioles using conventional sugarcane pressing machine. The juice was centrifuged, and the supernatant filtered and sterilized to prevent sugar degradation by bacteria. On analysis, the juice contained a high amount of sugars, (73 percent glucose, 16 percent sucrose, and 11 percent fructose) making it a potential fermentation feedstock for various value-added products such as bioethanol, biobutanol, lactic acid, and succinic acid among others. The potential free sugar content in the petiole was 44.8 g/kg, which is considered high.

Production of pulp and particle boards: Several investigations have been carried out to add value to oil palm biomass like the fronds, and trunks and have led to the production of hybrid plywood, medium-density fiberboard, polymer composites, particle boards, paper, pulp, furniture, biofuels, etc. The fiber from oil palm frond contains the highest composition of hemicellulose compared to coir, pineapple, banana, and even soft, and hardwood fibers. This fiber has been shown to be shorter, and thicker than other oil palm biomass-derived fibers. It also has a high density, indicating that the fiber is strong. In a Malaysian study in which the suitability of oil palm frond petioles was tested for the production of binderless boards, samples made from the trunks, and the fronds were found to possess sufficient internal bond strength to meet industrial standards. The internal bond strength of boards made from the mid-part panels of the trunk also met the standard. However, binderless board prepared from the bark and leaves exhibited poor internal bond strength. Malaysian researchers have also demonstrated that oil palm frond fibers can easily be pulped using chemical processes to produce pulp and paper of better properties than most hardwoods pulps. On analysis, the chemical composition of oil palm frond fibers lies between that of hardwoods, and that of straws and grasses.

The nutritional value of oil palm frond as ruminant feed

The abundance and availability of oil palm frond in most oil palm producing countries have made it a regular evergreen forage for ruminants both in traditional and intensive production systems. It has been shown to be a good source of roughage for ruminants and can be used as a substitute for grasses for fattening beef cattle as well as for intensive dairying, especially in places where forage or fodder is limiting. A considerable amount of research has been carried out to investigate the nutritional value and economic viability of utilizing oil palm frond as a feedstuff for ruminants.

Chemical composition: The chemical composition of oil palm frond has been reported as 48.78 percent dry matter, 5.33 percent, crude protein, 78.05 percent neutral detergent fiber, 56.93 percent acid detergent fiber, 21.12 percent hemicelluloses, 27.94 percent cellulose, 16.94 percent lignin, and 0.6 percent silica. Other proximate constituents have also been reported as moisture content 58.22 percent, crude fiber 38.50 percent, ether extract 2.10 percent, total ash 3.2 percent, and metabolizable energy 5.65 MJ/Kg. The leaflets separate from the petiole have an average crude protein composition of 11.00 percent indicating its potential value for livestock feeding since its crude protein contents are much higher than the critical 6.25 percent required to maintain normal intake by ruminants. The leaflets have much higher crude protein, and ether extract values than the petioles, while cellulose levels are usually lower than hemicellulose in both petioles, and leaflets. The leaflets also contain significant amounts of carotene, and vitamin E, which serve as effective antioxidants when fed to animals.

Improvement of nutritional value: Oil palm frond tends to become moldy during storage due to its moisture content of 55 – 58 percent. Different drying and pelleting techniques have been used to overcome mold growth although these can add to the processing cost. Again, the high silica content and the slow rate of fermentation of its fiber reduces volatile fatty acids generation and their role in overall energy efficiency. Invariably, it is however the high neutral detergent fiber and lignin contents that are the major constraints to oil palm frond use as livestock feed. To degrade the lingo-cellulosic bonds, and improve the bioavailability of nutrients in the oil palm frond, various physical, and chemical delignification methods have been tested in agricultural co-products such as rice and wheat straw. Microwave-alkaline pretreatment has been used to disrupt and enhance the value of the chemical constituents, such as cellulose, hemicellulose, and lignin in oil palm fronds. Such treatment has been used to increase cellulose release by 64.42 percent, while hemicellulose and lignin reduced by 64.00 and 17.97 percent respectively. Research at the Malaysian Agricultural Research and Development Institute has shown that oil palm frond could be conserved as silage. Urea could be added at the rate of 1 to 2 percent (on a dry matter basis) during the ensilage in order to enhance the protein value, and also prevent aerobic deterioration of the silage. The nutritive value of the silage was found to be as high as that of rice straw-based on voluntary intake, and digestibility, and therefore a suitable substitute for tropical grasses in the feeding of ruminants.

Furthermore, colonization with the white-rot fungi (WRF) has also been shown to hold some promise, because of its preferential degradation of lignin. White rot fungi such as Bjerkandera adusta, Ceriporiopsis subvermispora, Ganoderma lucidum, Lentinula edodes, Phanerochaete chrysosporium, Phlebia brevispora, Schizophyllum commune, Pleurotus eryngii, Pleurotus ostreatus, and Trametes Versicolor are known to be effective basidiomycetes for biological pre-treatment as they degrade lignin extensively, and have been used to biodegrade oil palm trunk and frond. Some of the white-rot fungi like G. lucidum, L. edodes, P. eryngii, and P. ostreatus are edible mushrooms, which can be harvested as food after the biodegradation process. Researchers at the Prince of Songkla University, Songkhla, Thailand, have also ensiled oil palm fronds to improve its nutrient value. They chopped the fronds into 1 - 2 cm length and blended them uniformly, before packing them in a 150-liter plastic drum without any preservative. The drum and its content were then tightly sealed to provide anaerobic conditions and kept at room temperature for 30 days. The silage contained 4.12 percent crude protein, 76.19 percent neutral detergent fiber, and 58.40 percent acid detergent fiber on a dry matter basis, indicating relatively little change in these parameters as a result of the process. Indeed, several studies have shown that good quality oil palm frond silage could be produced without using any additives, provided the ensiling was done under proper anaerobic conditions. Urea addition at the rate of 1 - 2 percent prevented mold growth and delayed the initiation of heat production by 28 hours, while at more than 3 percent inclusion, there was a reduction in the nutritive value of the silage, although no adverse effect on animals was observed.

The feeding value of oil palm frond for ruminants: Whole oil-palm fronds (the petiole and leaflets), can be chopped into pieces of 2 cm length and utilized as ruminant feed either green or conserved as silage in combination with other ingredients as total mixed rations. Oil palm fronds are most suitable for feeding beef and dairy cattle, sheep, goats, and even ostrich, and deer. Palm leaf pellet is a valuable feedstuff, which furnishes quality fiber for equine feed. It also contains a significant amount of vitamin E, which serves as an antioxidant for enhanced male fertility, and reproductive performance of equine animals. There may be the need to add extra protein sources in order to properly balance the formulation of a complete ration using palm fronds, especially for high-performance beef, and dairy cattle.
Researchers at the Malaysian Agricultural Research and Development Institute, Kuala Lumpur, Malaysia, investigated the feeding value of processed oil palm frond for cattle. Different treatment methods such as oven-drying, pelleting, ensilage, and treatment of silage with sodium hydroxide were used to enhance the feeding value of the frond. These were added to palm kernel cake-based rations and fed to determine their palatability, digestibility, and voluntary intake by cattle. The cattle fed the pelleted oil palm fronds recorded higher dry matter intake and palatability, but the lower digestibility than the others. The digestibility, and dry matter intake of the ensiled, and oven-dried oil palm fronds were however similar, while palatability of the silage was higher. Sodium hydroxide treated silage recorded the highest digestible dry matter intake although it had low palatability. The study shows that alkaline treatment of ensiled oil palm frond improves the nutrient value of the frond and should be promoted. Researchers at the Prince of Songkla University, Songkhla, Thailand, have also reported that the application of fibrinolytic enzyme (xylanase, β-glucanase, cellulase, mannanase, and amylase) produced by Aspergillus spp at a low level (2 g/kgDM) in goat diets containing 60 percent oil palm frond silage could increase ruminal availability of slowly digestible carbohydrate and improve goat performance.

Conclusion

The oil palm frond is an abundant, and readily available biomass waste from oil palm plantations, which can be converted into several value-added products. It is currently discarded as waste by most West and Central African oil palm producers, although several Asian studies have shown that it can be converted into organic fertilizer, vermicomposts, biochar, pulp for papermaking, and particle boards. Oil palm frond juice can be extracted and used as a fermentation feedstock for various value-added products. The leaflets. and petioles have also been processed into quality feedstuffs for ruminant feeding. Utilizing oil palm fronds in these various ways will not only reduce the pressure on forest resources but also help to mitigate the environmental problems arising from oil palm production.

Bibliographic References

Che Maail, C.M.H., Ariffin, H., Hassan, M.A., Md Shah, U.K., and Shirai, Y. (2014). Oil palm frond juice as future fermentation substrate: a feasibility study. BioMed Research International, Volume 2014, Article ID 465270, 8 pages. http://dx.doi.org/10.1155/2014/465270

Dahlan, I. (2000). Oil Palm Frond, a Feed for Herbivores. Asian-Aus. J. Anim. Sci., 13 Supplement, C: 300-303.

Ishida, M., and Abu Hassan, O. (1997). Utilization of oil palm frond as cattle feed. JARQ 31, 41-47.

Kawamoto, H., Mohamed, W.Z., Mohd Shukur, N.I., Mohd Ali, M.S., Ismail, Y. and Oshio, S. (2001). Palatability, digestibility, and voluntary intake of a processed oil palm frond in cattle.  JARQ, 35(3): 195 – 200.

Lai, L., and Idris, A. (2013). Disruption of oil palm trunk and frond by microwave-alkaline treatment. BioResource, 8(2): 2792 – 2804.

Mohammad I. B.  (2008). Oil palm frond (OPF) as an alternative source of pulp & paper production material.  Bachelor of Chemical Engineering Project Report, Universiti Malaysia Pahang, Malaysia.

Rahmana, M.M., Lourenc¸ M., Hassimb, H.A., Baarsc, J.J.P., Sonnenbergc, A.S.M., Coned, J.W., De Boevere, J., and Fievez, V.  (2011). Improving ruminal degradability of oil palm fronds using white rot Fungi. Animal Feed Science and Technology, 169: 157– 166.

Shafawati, S.N., and Siddiquee, S. (2013).  Composting of oil palm fibers and Trichoderma spp. as the biological control agent: A review. International Biodeterioration & Biodegradation, 85: 243e253

Vakili, M., Rafatullah, M., Ibrahim, M.H., Salamatinia, B., Gholami, Z., and Zwain, H.M. (2014). A review on composting of oil palm biomass. Environ. Dev. Sustain., DOI 10.1007/s10668-014-9581-2

Wahyuni, R.D., Ngampongsai, W., Wattanachant, C., Visessanguan, W., and Boonpayung, S. (2012). Effects of enzyme levels in total mixed ration containing oil palm frond silage on intake, rumen fermentation, and growth performance of male goat. Songklanakarin J. Sci. Technol., 34(4), 353-360.