Making the most of Africa's biowaste
Cassava peel, sugar cane vinasse and overripe bananas - residues such as these may be known as biowaste, but that doesn't mean they're necessarily wasted. An EU-funded project identified sources and current uses of such materials in five African countries and proposed quick, simple ways of processing them into products with higher added value.
The Biowaste4SP project focused on biowaste in Egypt, Ghana, Kenya, Morocco and South Africa, identifying streams that could be put to better use. It produced a catalogue of residues from agriculture and food production, and looked into ways of transforming these materials into bioethanol, biogas, chemicals, biofertiliser, or food and feed ingredients.
In addition to partners from the five participating African countries, the project involved teams from Denmark, Italy, Malaysia, Sweden and Turkey. It provided training opportunities for half a dozen young researchers from Africa and Italy, helping to hone skills that they, in turn, will be able to transmit to others in order to add to the momentum, says project coordinator Anne-Belinda Bjerre of the Danish Technological Institute.
An abundant resource
Most of the biowaste produced in the countries under consideration turned out to be starchy, Bjerre notes. This type of residue is far easier to process than the straw and woody (or lignocellulosic) materials that make up most of the biowaste generated in Europe, she adds. Affordable, well-understood technologies are available to do so sustainably.
To provide an example of particularly abundant residues, Bjerre described the case of cassava, a tuber produced worldwide in vast amounts. Referring more specifically to Ghana, where it is a staple, she noted that about a third of the cassava handled in processing plants tends to end up as biowaste. Ethanol made from this biomass could replace the equivalent of 30 % of the fuel used for transport in Denmark, she adds.
Cassava peel and stalks thus rank prominently among the agricultural residues produced in Ghana. Potential feedstocks generated in Egypt include sugar cane vinasse, a by-product of the fermentation of molasses notably for the production of bioethanol, whereas the unused portion of banana crops offers particular promise in Morocco.
Bananas also feature on the short list of candidate feedstocks identified for South Africa, and the top five for Kenya include waste from coffee processing. The project produced a catalogue of such residues in the five countries, which includes detailed datasheets on every one of these resources.
From residue to revenue
The listed materials are already used for various purposes. However, Biowaste4SP argued, it might be possible to derive even more benefit from them – by using such residues to produce bioethanol, for example, thereby helping to reduce the world’s reliance on fossil fuels. Simple, affordable and sustainable technologies to do so could also open up new revenue streams for the local economy.
Even compost, a time-honoured way of turning waste into an asset, can benefit from a sprinkling of research. Many residues that are harder to process sustainably and cost-effectively are nonetheless suitable for this purpose, Bjerre notes. “Biowaste4SP has looked into ways of enriching compost with bacteria that take nitrogen from the air and release phosphorous from the soil,” Bjerre explains. These bacteria, she adds, can also be cultivated with sugars extracted from residues.
Biowaste4SP was funded for a period of three years, which ended in September 2015. Bjerre is hoping for a follow-on project that could take the most promising applications forward, ideally with the help of private sector partners.
In the meantime, what was it like to coordinate a consortium that combined expertise from several continents? “It was one of the greatest experiences of my entire career,” Bjerre notes, adding that she enjoyed the opportunity to work with so many excellent researchers from so many different backgrounds. “We are very focused on ourselves, here in Europe — and, to some extent, on the United States and parts of Asia,” she notes. But there is a whole world out there, with lots of insight and inspiration to share.