Recovery of struvite from stored human urine

In previous work, synthetic urine was used as a readily available proxy for real urine for determining the factors which affect the recovery of struvite from urine. Based on these findings with synthetic urine, we recovered struvite from real urine and, thus, showed that a) the synthetic urine served as an adequate model for determining the processes which affect struvite precipitation, and b) high quality struvite can be recovered from real human urine. For urine solutions diluted up to four times, an average of 23% of phosphorus and 80% of magnesium was precipitated naturally; the remaining supernatant was then dosed with magnesium to recover the phosphorus still in solution. The struvite recovered was approximately 99% pure regardless of storage conditions although full strength urine was best for struvite recovery since it contains the greatest mass of harvestable phosphorus. We conclude that synthetic urine can be used as a proxy for real urine when investigating struvite recovery provided the synthetic mixture is consistent with the expected composition in the specific context.