Nucleation in the formation of struvite: state of art

ABSTRACT Recent estimation for the duration of global phosphate reserves does not exceed 400 years and the production of nitrogen fertilizers is energetically unsustainable. Nowadays, wastewater treatment plants have been seen as resource recovery facilities (water, energy and nutrients) instead of “end-of-pipe” utilities. Thus, nutrient-recovery technologies should be prioritized over the removal ones. Struvite (phosphate of ammonium and magnesium) is a crystal, produced from sewage, with a higher agricultural efficiency when compared to conventional fertilizers. Despite the crystallization is a topic extensively studied worldwide and highly technologically developed, its use in sanitary engineering is still not common, especially in Brazil. As the aspects related to struvite nucleation have been insufficiently studied, this paper presents a critical and updated literature review, and shows the gaps in the current knowledge about this topic.