A design of experiments to assess phosphorous removal and crystal properties in struvite precipitation of source separated urine using different Mg sources

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2016-08, Vol.298, p.146-153
• Main Authors: Barbosa, Sónia G., Peixoto, Luciana, Meulman, Brendo, Alves, Maria Madalena, Pereira, Maria Alcina
• Format: Article
• Language: English
• Subjects: Crystals; Design of experiments; Human; Human Urine; Magnesium oxide; Magnesium sources; Phosphorus; Phosphorus recovery; Recovering; Science & Technology; Stirring; Stirring speed; Struvite crystal size; Urine
• ISSN: 1385-8947; 1873-3212; 1385-8947
• DOI: 10.1016/j.cej.2016.03.148

[Display omitted] •Only the variable Mg:P molar ratio had a significant influence on P recovery.•99% of P was recovered with MgO as Mg2+ source, 2:1 molar ratio and 30rpm.•Struvite crystals with 50–100μm size were obtained.•XRD patterns were coherent with the standard model for struvite crystals.•Only the variable stirring speed had a significant effect on crystal size. Phosphorus recycling and recovery has received special attention due to its non-replaceable and non-renewability. Phosphorus recovery from human urine in the form of struvite crystals is a potential alternative source. In this work, the efficiency of struvite precipitation from source separated human urine and struvite crystals size were analyzed using three different Mg2+ sources (MgCl2, Mg(OH)2 and MgO), individually evaluated using a statistical design of experiments to assess the combined effect of Mg2+:P molar ratio (1:1, 1.5:1 and 2:1) and stirring speed (30, 45 and 60rpm). Formation of struvite crystals was confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with an energy dispersive spectrometer (EDS). Using the optimal conditions determined, MgO as Mg2+ source at 2:1 molar ratio and a stirring speed of 30rpm, 99% of P was recovered as struvite crystals with a size of 50–100μm.