Farmers in Freetown, Sierra Leone, are growing food on land contaminated with industrial wastewater and sewage. This project will test whether native plants can clean that water and stabilise the soil, turning polluted urban plots into safer, more productive farmland. Urban and peri-urban agriculture supplies up to 30 percent of global food, but in sub-Saharan Africa it often takes place on toxic ground. Current solutions—importing clean water or relocating farms—are expensive or impractical. The GRASS project fills a gap by asking which indigenous plants can absorb heavy metals and pathogens, and how local farmers can integrate them into existing planting schemes. If the approach works, it could give Freetown’s growers a low-cost, nature-based tool to improve water quality and food security without relying on external infrastructure. The same method could be adapted for other rapidly urbanising African cities facing similar contamination. The research is applied—it directly tests a practical intervention—but it also builds fundamental understanding of how native plant species behave as phytoremediators in real-world, highly contaminated settings.
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Project Background: Cities, and their rapidly expanding urban ecological footprints, are growing faster in sub-Saharan Africa than in any other region in the world. Estimates suggest that Africa's population will double between now and 2050, with two-thirds of this growth absorbed by urban areas; this will have concomitant effects on already existing issues with water quality, food supplies, and diminished green space, amongst others. In many African countries, one spontaneous, community-driven response to this urban crisis has been the proliferation of urban and peri-urban agriculture (UPA). It is estimated that UPA contributes to up to 30 percent of global food production. UPA activities often take place in locations that are highly contaminated by industrial wastewater and sewage.This project investigates the use of sustainable, plant-driven infrastructure (i.e., phytoremediation) as a means of directly improving water quality for crop production and food security at UPA sites. Focusing on the burgeoning city of Freetown in Sierra Leone, where the applicants have a long track record of carrying out field-based research on urban food production, the GRASS research project aims to provide interdisciplinary understanding of how the use of indigenous phytoremediator plants can be used in coordination with UPA to enhance food and water security, as well as the literal and figurative 'roots' within urban agriculture communities. Specifically, the project will investigate: 1) the potential of indigenous plants to act as phytoremediators and soil stabilizers; and 2) how these plants might be integrated into local food production systems with the help of local farmers, to establish engineered planting schemes as a nature-based solution at UPA sites.
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