Phosphate recovery from wastewater using selectrodialysis and crystallization process

Abstract

Stimulated by the depletion of phosphate resources and the need to avoid eutrophication, phosphate removal/ recovery has been studied in recent years. The aim of this study is to investigate the feasibility of phosphate recovery from wastewater by the hybrid system consisting of pellet reactor and selectrodialysis. The phosphates will be pre-concentrated in the selectrodialysis and then be recovered by a crystallization process where it will precipitate on to sand grains as calcium phosphate in a pellet reactor. The results of selectrodialysis show that the co-existing ions in the wastewater affect the fractionating phosphate from wastewater; however, the efficiency is still good enough to obtain the high phosphate concentration in the product. The phosphate concentration in the product can reach 4 mM after 10h. After that, the pellet reactor was run to precipitate calcium phosphate, the efficiencies fluctuated between 70 and 80% during the period of the experiments. That proved that it is possible to recover phosphate as calcium phosphate from wastewater with high efficiency.