Tshikovhi, NAMudzanani, KPhadi, TMasindi, VhahangweleFoteinis, S2026-01-142026-01-142025-101944-39941944-3986https://doi.org/10.1016/j.dwt.2025.101527http://hdl.handle.net/10204/14586Among many plights caused by eutrophication, the overabundance of algae and aquatic plants constitutes external pressures and stresses mounted on aquatic ecosystems. Of the aquatic plants known to infest rivers and dams, water hyacinth is considered the most problematic due to its invasiveness that disrupts waterways and pose detrimental environmental and health risks. This non-native (alien or exotic) species is already impairing aquatic ecosystems in South Africa, while vast harvested quantities, currently considered a waste, further exacerbate the problem. However, when viewed under the circular economy and waste valorization lenses, water hyacinth can be an important resource. Here, this was used for biochar production, by examining different temperatures, with 500 °C providing high carbon content. HR-SEM-EDS, HR-TEM-EDS, and XRF revealed varying biochar compositions, all enriched with notable phosphorus levels. This reflects the highly degraded state of freshwater bodies in South Africa since water hyacinth is a known phosphorus hyperaccumulator. Thermal analysis revealed that the raw water hyacinth mainly (96 %) comprises water, while weight losses for biochar at 167–990 °C correspond to moisture and volatile matter removal. Finally, biochar yield decreased from 32.5 % at 300 °C to 24.7 % at 700 °C, confirming progressive devolatilization and carbon enrichment at higher temperatures. Overall, results suggest that water hyacinth, an invasive species that wreaks havoc in aquatic ecosystems, can be sustainably managed to improve freshwater quality through nutrients removal and then used for biochar production. The produced biochar could be a good candidate for (waste)water treatment (adsorption) and particularly soil amelioration, given its high phosphorus content, and carbon dioxide removal (CDR) capabilities.FulltextenInvasive water hyacinthPyrolysis processBiochar synthesisCircular economyValorisation for agricultureNutrients removal and attenuationArticleN/A