Human urine consists of large amounts of phosphorus (P) and potassium (K), which are essential chemical elements for living species and plants growth. In this study, we investigate the effects of reflux rate on crystallization promotion to simultaneously recover P and K from urine. The effects of potassium ion presence in the formation of magnesium ammonium phosphate (MAP) in the fluidized bed reactor (FBR) is also studied. The largest removal efficiency of P at 96.57% and K at 68.40% can be achieved under the optimal conditions of: pH 9.5, P:Mg:N molar ratio of 1:1.4:1.2, and reflux rate of 12 L min^–1. The purity of produced MAP and magnesium potassium phosphate (MPP) are both promoted, owing to the improved formation frequency among particles, when reflux rate is increased. During the MAP production process, MgKPO₄ is initially nucleation and growth under turbulence environmental in FBR. Afterwards, with the presence of NH₄⁺ in solution, K ⁺ ion can be replaced by NH₄⁺ and formed the MAP due to more stability of MgNH₄PO₄ compound than MgKPO₄. The cost analysis demonstrates that FBR system can provide a profit of $2.01/m³ on urine treatment. The investigation can shed lights on efficient removal and recovery process of P and K elements from urine through changing various reflux rates for further development.

人尿包含大量的磷（P）和钾（K），它们是生物物种和植物生长所必需的化学元素。在这项研究中，我们调查了回流速率对促进结晶以同时从尿液中回收磷和钾的影响。还研究了流化床反应器（FBR）中钾离子的存在对磷酸镁铵（MAP）形成的影响。在以下最佳条件下可实现最大的P去除率：96.57％和K：68.40％：pH 9.5，P：Mg：N摩尔比为1：1.4：1.2和回流速率为12  L  min ^–1。当提高回流速率时，由于提高了颗粒间的形成频率，因此提高了生成的MAP和磷酸镁钾（MPP）的纯度。在MAP生产过程中，MgKPO ₄最初是在FBR中在湍流环境下成核和生长的。之后，在溶液中存在NH ₄ ⁺的情况下，由于MgNH ₄ PO ₄化合物比MgKPO ₄具有更高的稳定性，因此K ⁺离子可以被NH ₄ ⁺取代并形成MAP 。成本分析表明，FBR系统可以提供$ 2.01 / m ³的利润。在尿液治疗上。通过改变各种回流速率，尿液中磷和钾元素的有效去除和回收过程可为进一步开发提供启示。