Calcium Silicate Hydrate Triggered Phosphorus Recovery – An Efficient Way to Tap the Potential of Waste- and Process Waters as Key Resource

The global economic situation requires the development of sustainable concepts, in order to provide potential recyclables from waste and to recirculate them to the cycles of matter. Considering furthermore the increasing limitation of global phosphate rock resources, the recovery of phosphate from various waste- and process waters is vitally important. Therefore, research has recently been focused on the development of technologies for an efficient recovery of phosphorus within the waste- and process water treatment. Approaches are based on the generation of phosphate minerals as substitutes to be processed in the phosphate industry or to be straightly applied as fertilisers in agriculture. One approach to achieve this goal is the use of calcium silicate hydrates (CSH), which are by-products of the building material industry, in order to recover phosphorus as a potential recyclable by crystallisation. This was realized with the P-RoC process, the P-recovery from the aqueous phase by crystallisation. Investigations show that, apart from hydrochemical parameters, the physical and chemical properties of the applied CSH compounds play a decisive role as trigger materials for the P-elimination efficiency. Thus, the nature and quality of the generated products could be specifically optimized.