Sustainable Fertilisers from Fly Ash

Cooperating countries: Namibia, South Africa and Austria

Coordinating institution: Danube University Krems (DUK), Dr. Nils Haneklaus, nils.haneklaus@donau-uni.ac.at

Partner institution: University of Pretoria (UP), University of Namibia (UNAM)

Project duration: 1 June 2022 - 31 May 2024

Abstract:

Fly ash from burning coal for energy production can contain elevated amounts of phosphorus (P) and nitrogen (N) that are crucial elements for plant growth and thus food security. The chance to substitute P from finite phosphate rock resources by a low-cost fertiliser or soil amendment from fly ash seems particularly promising in Africa where mineral fertiliser use, due to the relatively high costs, is still far lower than in the rest of the world. Besides P and N fly ash can contain toxic heavy metals (Cu, Zn, Cd, Pb, Ni, Cr, etc.) and in some cases even valuable rare earth elements (REEs) that would need to be extracted prior to fertiliser use. Alternatively, biochar can be added to reduce the bioavailability of accompanying toxic elements.

The 2-year project “Ash2Fertiliser” will investigate the possibility of using fly ash from South Africa as an inexpensive unconventional raw material in fertiliser production. The interdisciplinary team is led by Dr. Haneklaus from DUK who is actively working on heavy element extraction during phosphate fertiliser production and global phosphate resource security, Prof. Van der Merwe and Prof. Truter from UP who both extensively worked on various fly ash beneficiation projects including valuable element extraction from South African fly ash (Prof. Van der Merwe) and soil amendment (Prof. Truter) as well as Dr. Mupambwa from UNAM who pioneered work using biochar to reduce the bioavailability of heavy metals in fertilisers. This work will directly support UN-SDG 12: Responsible Consumption and Production and is intended to initiate larger joint projects between the project partners.