BACKGROUND: Struvite precipitation has been applied to several types of wastewater for removal and recovery of nutrients. Engineering criteria for these applications, particularly crystallization, have yet to be developed. In the present study, effects of solution composition on the induction period and crystallization rate of struvite were experimentally investigated. Experiments were conducted as batch tests and on synthetically prepared samples. High foreign ion concentrations up to 160 mmol L-1 were used for the evaluation.