Nitrogen removal and recovery from human urine by struvite precipitation

In this study, struvite precipitation of human urine was experimentally studied on both synthetic and actual urine samples. One of the main conclusions of the study was that removal of the ions constituting struvite from the solution was not in proportion with the stoichiometry of the solid and excess magnesium and phosphate removals varied from 2.5% to 4.8% on a molar basis. Redissolution of the solid yielded a similar result. Potassium and calcium affected the struvite precipitation performance. The remaining ammonia concentration was over 100 mg/l. Ionic strength affected the precipitation efficiency. Organic matrix of the urine had no significant effect on the process.