Turning an environmental menace into a success story

In the late 1980s, water hyacinth (Eichhornia crassipes), a South American aquatic weed, was introduced into Lake Victoria. As a result, the world’s largest tropical lake, and a hotspot for biodiversity, has undergone a severe transformation which has affected both the ecology of the lake and the economy of the region.

Water hyacinth has an astonishing growth rate – an individual plant is theoretically capable of producing the equivalent of 28,000 tonnes of fresh weight in one year – and it has clogged up shipping lanes, raised toxicity and created the ideal breeding conditions for malarial mosquitoes and schistosomiasis. One estimate puts the economic damage caused by water hyacinth at US$350 million a year.

A group of scientists, including Henry Neufeldt, who directs climate change research at the World Agroforestry Centre, are proposing a solution for this invasive species. “We believe it may be possible to transform an environmental catastrophe into a success story by turning this aggressive weed into feedstock for biogas,” he says.

Most water hyacinth management programmes have focused on its eradication. According to the scientists, it is time to attempt a new approach, and focus on the sustainable management of the weed. This approach centres on creating an economic incentive to exploit water hyacinth by generating renewable energy and high-value organic fertilizers. There are several compelling arguments in favour of this. For one thing, the countries around the lake – Kenya, Tanzania and Uganda – have significant unmet energy needs. And the surrounding farmlands are seriously depleted of soil nutrients; organic matter from water hyacinth could provide a much-needed boost to fertility.

Neufeldt and his colleagues point out that current extraction and processing technologies need to be tested in pilot plants, as there is too little experience with the management of the weed. Getting the mix right between collection, processing, energy generation and further use of the residues will be a challenge, as will be working with governance and energy policy issues. The authors, however, are confident about the plant’s bioenergy potential. “With innovative uses of new technology, water hyacinth could become a viable tool for energy generation, environmental remediation and food security,” says David Güereña.

Reference

1. Güereña D, Neufeldt H, Berazneva J, Duby S. 2015.Water hyacinth control in Lake Victoria: Transformingan ecological catastrophe into economic, social, and environmental benefits. Sustainable Production and Consumption 3 (2015) 59–69