The Treating Wastes for Restoring Land Sustainability (TWIRLS) was a project conerned with improving, restoring or remediating degraded land in Europe, using locally sourced waste materials. These materials can be mixed together for the sustainable production of a growing medium, enabling plants to become established and a whole ecosystem to develop.

The project was funded by the European Commission LIFE-Environment programme between October 2004 and September 2007, and managed in the College of Natural Sciences at Bangor University,Wales. Partner organisations and collaborators in the project were: the quarrying companies Alfred McAlpine Slate (in Wales) and Titan Cement (in Greece), the paper manufacturer UPM Kymmene UK (in Wales), the Soil Science Institute of Athens, the Association of Communities and Municipalities of the Attica Region (ACMAR), the waste-management company Envar (in England), and the Welsh Assembly Government.