Ganvié, Sô-Ava, Porto-Novo, Dangbo (Benin), report. © Sébastien Roux

The water hyacinth has been spreading for decades in Benin, threatening the lifestyle of the residents of Lake Nokoué. However, some have stumbled onto the virtuous properties of this invasive plant, which can be used for depollution, the production of biogas or to make a “magic compost”.

For the fishermen living in Ganvié, known as the “Venice of Africa”, the day begins before well sunrise. Perched on their long, thin wooden canoe, they criss-cross Lake Nokoué, north of Cotonou, the economic capital and the largest city in Benin, in search of tilapias, shad or white catfish. The women will then sell the catch in Tokpa, West Africa's largest open-air market, for a few CFA francs, enough to survive on their home on stilts. However, season after season, fishing and navigating are become more and more complicated, threatening their way of life. This is due to the invasion of the water hyacinth, an aquatic plant native to South America that accidentally spread during the colonial period in many tropical areas. In the Fon language, the Beninese use the term tôgblé (“the country is spoiled”) to refer to the consequences of the water hyacinth, which is also responsible for the development of certain diseases such as malaria, with the influx of mosquitoes.

However, in recent years, entrepreneurs such as Fohla Mouftaou, co-founder of Green Keeper Africa in 2014, have been using the amazing properties of this plant to “turn this scourge into an opportunity” and change mentalities: the term tôgblé is replaced by that of tognon, the country is no longer spoiled, it is “good”. Water hyacinth is used by the organization as a clean-up solution to recover industrial oil spills on cushions, rolls or mats. In fact, the residues of this plant can absorb up to 17 times their weight in hydrocarbon, thus halting the dispersion of a polluting liquid in case of leakage or following an oil spill.

Located in the municipality of Sô-Ava, Green Keeper Africa’s warehouse is still rustic in appearance with its wood and sheet metal construction in which the dust is constantly stirred up by the wind. Inside, ten people are busy transforming water hyacinth stems, after the plant has been left to dry in the sun. Florent Liaigre, technical manager of the operating area, is responsible for maintenance: “Our approach is ecological in that we take inspiration from ‘maker’ and ‘do it yourself’ culture to test other ways of doing things and to create new production techniques. And even if it doesn’t work, we still make progress,” explains this young Frenchman as he presents the different machines on the site. One of them will grind the stems to make powder, while another retains the fibres, a more effective material against heavy liquids, such as oil.

The other strength of Green Keeper Africa comes from its relationship with lake dwellers who harvest water hyacinth: while there were only a dozen or so collectors in 2014, the number had grown to between 1.000 and 1.200 in number in early 2019, with women accounting for 85% of collectors. Between December and March, this seasonal activity gives them greater financial autonomy and allows the company to build up a stock, allowing it to produce all year long. Then, adopting a circular economy approach, Green Keeper Africa proposes to recycle its products after use to turn the final fuel into a source of energy.

Producing energy by recycling water hyacinth is at the heart of the integrated system developed by Songhaï, an organic farming laboratory set up by Godfrey Nzamujo in 1985 in northern Porto-Novo, Benin’s administrative capital. This green area of 22 hectares brings together 326 employees as well as students intent on learning how to “produce more and better with less” and “on pushing poverty out of Africa”. Organic waste from livestock, fish farming, crops and water hyacinth is recovered to produce biogas, a 100% natural energy. The waste is placed once or twice a week in tanks that will heat to produce gas for the entire site, which includes a restaurant and a hotel run on ecotourism principles. The nutrient-rich effluents released as a result of the treatment are returned to the crops to fertilize the soil. The Songhaï centre also uses water hyacinth to dispel odours around public toilets.

“It all comes from the earth, where the energy is most concentrated. That is our most valuable bank. We must observe it and be inspired by it: This approach, known as biomimicry, is a source of authentic innovations,” says Godfrey Nzamujo, a Dominican priest of Nigerian descent who studied microbiology and developmental sciences in California before settling in Benin and expanding the Songhaï network in other cities and countries in Sub-Saharan African. “Training is essential to creating a movement of young Africans ready to take up the ecological challenges of this century. The Songhaï centre has trained nearly 6.000 farmers who are now self- employed,” tells us Godfrey Nzamujo after his daily morning visit of the different areas of the site.

A few kilometres north of the Songhaï centre, in the commune of Dangbo, the NGO Jevev has been training locals in a green and sustainable economy since 2010. At the end of January 2019, it organized the “water hyacinth route” training course for two weeks with a theoretical approach the first three days followed by field work to learn how to make “magic compost”. After collecting several kilos of water hyacinth on the banks of the Ouémé River, the various members of the NGO brought them to one of their experimental sites.

Castello Zodo, a trainer specialising in crop and seed production with the NGO explains it is necessary to “put the hardest vegetable waste on the bottom to facilitate decomposition and obtain a better quality of compost”. In a one-metre round pit, the ten students superimpose neem branches, still waterlogged hyacinth stems and neem flowers (neem) before covering them with palm branches and placing a piece of wood in the centre of the hole to let the compost breathe and better observe its evolution. After turning it twice in other tanks to homogenize it, the “magic compost” becomes a multi-active product contributing to sustainable development of the land. Chancelle Loumedjinon, a 21 year old Beninese woman training in public health environmental engineering, sees it as a way of “preserving nature by stopping the use of chemical fertilisers while helping fishermen cope with the spread of water hyacinth”. For Henri Totin, executive director of the NGO Jevev and young consultant for the World Bank, these courses make it possible "to take concrete actions while leaving a positive legacy for the whole community. Water hyacinth is a green gold with many virtues”.