Utilisation Of Agro-Industrial Wastes
Poku Adaa
In Agriculture and in manufacturing industries, large quantities of surplus debris and apparently useless materials are produced. POKU ADAA, our Tropical Sciences Correspondent discusses the various ways in which the discards of Cocoa, Sugar and other crops can be commercially utilised to stimulate rural and small-scale industries.Cocoa and sugar are two agricultural commodities which sustain the economies of many developing countries through the sale of cane-syrup and cocoa beans on international markets. The irony is that despite various inter national trade associations and agreements, the prices of these commodities are hardly ever stable. They fluctuate randomly from month to month and from year to year, producing catastrophic effects on these poorer countries as projected incomes tend to be less and less steady and predictable.
One solution that has been proposed to offset these uncertainties is that new ways have to be found for the use of the crops. Products that have been pre viously discarded must be reexamined to ensure that new avenues could be found to generate extra revenues to offset price and market short falls. Cocoa pods, banana and plantain stems, coconut husks and sugar-cane chaffs which are usually destined for the waste heaps have enormous riches. stored in them and if these are commercially exploited, they could offer a substantial potential for the development of integrated small-scale industries.
Research and scientific evidence to date indicate that discarded cocoa pods contain about 25-30% of a substance called Pectin which is always in great demand by the food canning and processing industries. Salad dressings contain 2-3% of pectin, fruit juices contain up to 1%, ice creams contain about 0.8%, fruit jellies, jams, marmalades contain from 0.1-0.8% etc.
Ordinarily, pectin is obtained from citrus fruits: lime, lemon, grape, oranges. In Ghana, for instance, a fruit juice factory in the lime growing district of Asebu and the Cape Coast Citrus factory, all do export dried lime peels to markets in the U.K. Cocoa pods, however, are cheap and regularly available all the year round.
Professor D. Adomako, a Ghanaian scientist, has reported a 25-30% yield of pectin from cocoa pods, and today technical information on the nature of the substance and how to produce it in a form suitable for export is widely available. The cost of equipment and chemicals has prevented commercial production in developing countries so far and that is why the citrus juices factories in Ghana only export the raw itself. lime peels.
However, it is believed that small scale batch operations and sun-drying of the pods can reduce initial capital inputs. The fact that the product has whole overseas market and possible generation of foreign capital makes it a viable proposition indeed. There are indications that due to the introduction of new food products requiring high pectin content, there is the likelihood of increase in demand for the substance from developing countries. Even now current supplies barely satisfy demand and world prices are likely to remain steady for sometime to come.
TECHNOLOGY
Normally in Ghana, and perhaps in many other tropical countries, bananas and plantains are harvested by felling down of the whole tree. When the crop bunches are taken away, the stems are left to rot. It has been like that for ages. However, new technologies have made possible the conversion of banana and plantain stems into hard tissue and special grade paper products. bagasse. In 1978, The United Nations Industrial Development Organisation (UNIDO) organised an international forum in New Delhi on 'Appropriate Industrial Technologies for small Pulp mills and Paper Products and subsequently published a Monograph which offers a wealth of guidance, advice, expertise and a store of information of the commercial and technical exploitation of this discarded resource.In this case, however, the logistics would involve the organisation of transport to collect the raw materials, but even there, the current mode of operation of lumbermen and timber producers can be adopted in some way to transport these stems from farms to selected depots for feeding to pulp and paper mills. Farmers in rural communities will have a whole new way of extra income through selling of discarded plantain and banana stems.
In the manufacture of sugar, the first process involves the squeezing out of the sugar juice leaving the fibrous chaff of crushed cane. This material is called Bagasse, which make up a quarter of all sugar-cane crushed or milled. Primarily, when this residue is dry it is burnt to provide fuel for the generation of steam for the factory
However due to technological improvements in the design of boilers and efficient generation and use of steam, more surpluses of bagasse are unused and disposing of them sometimes becomes a problem. In certain sugar factories in the Caribbean countries, up to 20,000 tonnes of bagasse are produced per year. Bagasse has, in recent years, become the centrepiece of the armoury of appropriate technology proponents. And not without reason. It is a most sought after multi-purpose product indeed and one which can provide sufficient raw material base for small-scale industries in the production of certain building materials, paper products and livestock feeds. Bagasse has been described as the developing world's most promising source of fibre for paper making. It has a chemical composition that is similar to wood and contains about 75% of Celluloses, an ingredient for paper making. Over the essential thirty developing countries as at present in Central America, Middle East, Far East now produce newsprint, writing paper and printing paper from bagasse
Papermaking from bagasse dates back from 1932 when a Peruvian Company first started the method and by 1945, over 200,000 tonnes per year were readily produced, production which continues today, wrapping paper, grocery paper bags, cartons, which are in daily use, are obtained from bagasse. In fact, paper making from non-wood sources is gaining worldwide acceptability and application since in theory, fibre crops and agricultural wastes such as rice straw, wheat straw, reeds, bamboo, flax, cotton stalk, jute, kenaf can all be converted into paper grades.
The examples given here of cocoa and sugar illustrate how with proper planning, basic industries can generate spin-off incomes to increase their economic viability. There are several examples of other agro-based industries where diversification in product output is a real challenging alternative, especially in the production of fertiliser components, from say, palm oil mills and coconut oil extraction plants.
The case for integrated industries is that small-scale industries which may be dependent on one another for raw materials should all be fitted into a definite planning programme, such that a sugar factory has from the onset, distilleries and pulp mills to absorb surplus bagasse and molasses. What- ever the case, private entrepreneurs should be encouraged to invest in such industries. It offers one way to achieve, in the long run, total and profitable industrialisation.
The problem is the availability of such raw materials continuously for an all-the-year round operation of a paper mill. In that respect, bagasse and kenaf offer the greatest viable prospects as far as, say, Ghana is concerned. Kenaf will be the subject of another feature report later on in the year. Suffice it to say here that it is a crop that looks like a young bamboo shoot suitable for plantation farming and superbly ideal for making all kinds of paper.
Hardboards manufactured from bagasse are suitable for furniture components, door and window frames, window louvres and panels for the building trades. Also specially blended concrete products can be obtained from bagasse by mixing finely milled bagasse fibre with ordinary concrete or line. This combination of bagasse and concrete is used in the making of blocks for low cost housing projects in some tropical countries.
In its use as a component of animal feed, scientific experimentation and new developments have been relatively fast. The bagasse is partially dried and ground to a fine powder, the coarse ones are sieved off and the remainder are mixed with molasses which is also a by-product of the sugar-making process containing 60% carbohydrates and 4% crude protein. This mixture has been found to be as good for cattle as hay or green grass.
Banana, cocoa and groundnut wastes can turn to money if the proper technology is applied.
In recent times, nitrogen compounds such as urea are being added to the bagasse-molasses mixtures to improve further the nutritional quality and taste for the animals. It has been proved that a cow fed on about 5½ pounds of the feed mixture per day could gain up to 3½ pounds in weight as a result.
Another by-product of the sugar-making process is the 'cake' or residue drawn off from the filter presses. Apart from their use as good fertiliser material, they also contain highly marketable waxes which are used for making carbon paper and for all kinds of polishes and similar products. Cuba has the most well developed plant know-how for production of these waxes, turning out over 5 million tonnes annually. If the manufacture of sugar-cane wax could be exploited more widely, it could assist in diversifying the market potential and economy of the sugar industry.
Molasses has been mentioned already as a useful component of animal feed. This is apart from its demand as an industrial alcohol. Caribbean rum-making depends on molasses from sugar-cane processing. Molasses is also a raw material for many chemical substances, for example, fermentation of molasses can produce citric acid which finds extensive uses in food and chemical industries.
