Phosphorus recovery through struvite crystallization from real wastewater: Bridging gaps from lab to market
Yixin Yan, Nomiki Kallikazarou, Olympia Nisiforou, Qingyu Shang, Dafang Fu, Maria G. Antoniou, Ioannis A. Fotidis
Abstract
Food security will be jeopardized as reserves of the non-renewable phosphate rock, which is used to manufacture phosphorus fertilizers, are rapidly depleting. Meanwhile, excess nutrient (phosphorus and nitrogen) loads coming from improperly treated nutrient-rich wastewaters are disposed in soil and water resources, and significantly affect the atmosphere, lithosphere, hydrosphere and biosphere. Struvite crystallization (SC) offers a promising solution, recovering nutrients as a slow-release fertilizer. However, SC's application across various wastewater types remains limited, with few full-scale implementations. This review examines SC process, focusing on studies using real wastewaters. Key SC methodologies include chemical, electrochemical, ion-exchange precipitation, membrane crystallization, and microbial mineralization. Wastewater pretreatment methods are classified and critically evaluated, while SC-affecting factors like calcium and salinity are discussed. To enhance SC's economic sustainability, future research should prioritize cost-efficient reactor designs, energy recovery strategies, and regulatory compliance to develop market-ready, waste-derived fertilizers that are safe for agricultural applications.