In the first and second part of this series, we explored ways on-farm generated and processing operations wastes can be converted into useful products. This article will further expatiate on the utilisation of additional waste materials generated during the processing operation of other agricultural crops.
By Oyewole Okewole
Sustainable agricultural processes integrates these three goals: environmental health, social equity, and economic profitability. It is therefore important that these goals are embedded in the various agricultural practices, to highlight and promote our local unique operational circumstances.
During agricultural processing operations, it is significant to address these sustainable goals with respect to their human and environmental impacts, giving cognisance to how wastes are disposed and how the raw materials are sourced and produced. These operations should also put into consideration, what methods are used in recycling waste, how flexible and need-based these methods are, whether or not they are implemented with fairness and equitability, how profitable these operations are, and the ability of the generated revenue to cater for all the expenses and total input costs
These questions can be addressed using due diligence in waste disposal and adapting sustainable practices for waste management. The global agricultural waste market is valued at USD 16.4 billion as at 2022, and is projected to remarkably increase to about 28.6 billion by 2029, with a robust CAGR of 7.2% according to a newsletter by MMR market analysis.
In the first and second part of this series, we explored ways on-farm generated and processing operations wastes can be converted into useful products. This article will further expatiate on the utilisation of additional waste materials generated during the processing operation of other agricultural crops.
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COCONUT SHELLS
Coconut shells have become an essential product in the handicraft and aesthetic industry. Coconut shell is the protective layer of the coconut meat. The shell stays in between the coconut meat and the coconut husks. They are mostly discarded when processing coconut, but recent utilisation strategies have made coconut shells a high-demand product.
Coconut shells produce coconut shell charcoal, coconut shell activated carbon, coconut shell powder, and many other uses through up cycling in the home and garden.
They are domestically utilised as plant pot due to their organic and biodegradable characteristics, ideal for seedlings, and thus, can beautifully be made into attractive holders for herbs, succulents, microgreens and perhaps indoor air plants. They are also used to make hanging planters and for creating vertical garden. They can also be polished to make small bowls and sometimes as a waterproof bowls, soap dishes, candle holders, or designed and used as jewelry.
However, they are commercially used as both industrial and domestic fuel. Coconut shell charcoal is a main ingredient for producing activated carbon — which is superior in its calorific value to other biomass-like wood. Coconut shell charcoal is derived by combustion under limited air. It is therefore widely used in laundries, by blacksmiths, and by goldsmiths.
Its activated carbon is one of the best natural products used. It can be further utilised for manufacturing medicines, soaps, and toothpaste. It is also used as a food supplement for animals and in humans to promote immunity, in the manufacturing of air and water purifiers, building golf courses, and as odour eliminators.
GROUNDNUT SHELLS
Groundnut shells are approximately 20% of the dried peanut pod by weight. In some cases, an increase in groundnut shell, occasioned by an intense processing of groundnut, results in the wastes being buried or burnt. Groundnut shells are composed of cellulose, hemicellulose, and lignin, and therefore can be utilised in both commercial and industrial forms. Groundnut shells are useful in enzyme and hydrogen production, and in dye and heavy metal degradation. It is further used in food, feed, paper, and bioenergy industries. They can also be used as a component in animal feed. Other uses includes for composting wet materials, for wastewater treatment, in the manufacture of plastic wardrobes, insulation board, metal casing, as a medium in pesticides production, and in the production of activated carbon.
According to research, biodiesel can be produced from the fungus Aspergillus niger from lipase-catalysed groundnut shells. In addition, bioethanol can be produced from groundnut shells using various fermenting microorganisms. The technological and biochemical process entails the extraction of cellulose from biomass and its conversion into sugars by cellulolytic action of microorganisms. Groundnut shell ash is also used as a building material, with its use as a binder in sandcrete blocks as cement replacement. They can be further used in carbon nano-sheet formation and nano-fibre preparation.
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MAIZE/CORN COBS
Maize cobs are by-products of maize processing. In particular, maize cobs without the grains are usually discarded and can cause environmental pollution. The intensity of maize processing has increased which has resulted in the production of this by-product. An approximate 18% composition by weight of corn cobs are generated from a tonne of shelled maize. This translates to about 180kg of corn cobs. They are a major by-product in many maize-producing countries around the globe.
Their utilisation prospects cuts across many industrial and agricultural applications. They are rich in fibre, though low in nutrients; they can be used as fodders for ruminants, as mulch, and as soil conditioner. They are used for generating sustainable heat energy input/fuel due to their high calorific value. They are also dried and utilised as fuel for various heat-required processes. They are used as litter for livestock animals including poultry (in using as litter for poultry, they are dried and finely ground).
They are also utilised to clean up industrial or environmental spills due to their high absorbent property, absorbing finishing fluids, oil, and water in industrial processes. According to feedipedia, they are used to produce chemicals like furfural, or the sugar replacement xylitol, and used to blast and polish many materials including jewellery, nuts and bolts and golf heads. Further research has shown that maize cobs can be used in replacement of pinewood for the production of particleboard panels.
OKARA
Okara is a byproduct from soymilk production. It is a whitish-yellow fibrous residue – and sometimes pulp – consisting of the insoluble fraction of the soybean seeds remaining after extraction and filtration of the aqueous fraction during the production of soymilk and tofu. It contains about 50% dietary fibre, 25% protein, 10% lipid, and other nutrients.
Studies have indicated that it is a good and nutritive ingredient for the development of Soy-based snack foods. This is to maximise its health benefits while also utilising its organoleptic qualities, and reducing environmental wastes. It is utilised primarily for animal feed and for producing industrial fertiliser.
In addition, other research indicates that there are quite a number of health benefits of okara. Its high fibre and low production cost has also made it a rich source of fibre and as a dietary supplement to prevent diabetes, obesity, and hyperlipidemia. It has the potential to be used as a partial replacement for wheat or soyflour to increase fibre and protein content of foods.
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BREWERY WASTES
Beer brewing produces substantial quantities of by-products. The major brewery organic wastes generated from the production of beer are brewer’s spent grain, spent hops/hot trub, and residual brewer’s yeast. Brewing entails several processing steps that ultimately involve fermentation of sugars contained in malt and their conversion into alcohol and carbon dioxide by yeasts. Proper management of the wastes and their utilisation enhances sustainability. They are utilised as low-cost and highly nutritional source of feed and food additives. They are also utilised in the extraction of valuable substances in the food industry, and in the production of enzymes.
These wastes have high nutritional value. They are rich in carbohydrate, fibre, protein, vitamins, minerals, phenolic compounds, and very high in moisture content. They are therefore extensively utilised as animal feeds. Brewer’s spent grain is especially useful in this regard for livestock and poultry feed. Spent hops on the other hand have high fibre content with an unpleasant flavour.
Other applications include the use of anaerobic sludge digestion technology to produce energy and bio gas. They can also be utilised as food supplements, in mushroom cultivation, as a substrate for composting, and also incorporated into paper materials.
In summary, most organic wastes from agricultural processing operations are being utilised in one form or the other. This is the current reality, and it explains the effectiveness of the circular economy. It is crucial to know that today, the sustainability in processing of agricultural materials entails the optimised use of the raw materials and the waste subsequently generated.
On the other hand, new products are being discovered everyday, as a result of the increased utilisation of by-products as indicated in this article. Perhaps these replacement products will prove more environmentally friendly, and have increased nutritional values when utilised in animal production.
Progressively, more products are being sourced organically and from agricultural sources. This indicates a form of change, and a shift from the conventional, inorganic process of creating industrial products. Therefore, it becomes important to engage research to expand the opportunities domiciled in these future prospects.
Oyewole Okewole. Agricultural Project Development Specialist
Cover photo by Sri Lanka on Unsplash
