**Abstract**

The EU has the ambitious goal to transition from linear to circular economy. In circular economy, the old saying of "one's waste is the other's treasure" is being implemented. In this chapter, valorisation of industrial side streams, traditionally branded as waste, is discussed with respect to their applications as raw materials for new adsorptive products – geopolymers (GP) and alkali-activated materials (AAM) – as adsorbents in wastewater treatment. The chemical nature and structure of materials generally have great influence on GP/AAM adsorption capability. The approaches used for the raw materials preparation (chemical or physical) prior geopolymerization to increase the adsorption capacity of the final products will be discussed. Adsorption properties and performance of GPs/AAMs towards various contaminants are described, and the latest research on testing those materials as water remediation are reviewed. Special attention is paid to regeneration of exhausted materials and available resource recovery options that the regeneration approach opens. New forms of geopolymer adsorbent such as foams or core-shell structures are described and in the last part of the chapter, a short economic evaluation of resource recovery models is provided.

**Keywords:** adsorption, metal removal, nutrient recovery, geopolymer composite, wastewater treatment
