It is difficult to achieve resource separation and recovery from hazardous vanadium-extracted effluent containing high ammonia nitrogen and hexavalent chromium. Multi-objective optimization by response surface methodology (RSM) based on the Box-Behnken design (BBD) was applied to maximize ammonia nitrogen recovery percent (R(N), %) and minimize the Cr loadings (L(Cr), %) during struvite precipitation to realize Cr(VI) separation and resources recovery from vanadium-extracted effluent. The response variables were correctly predicted by two second-order polynomial models, and R(N) of 98.87% and L(Cr) of 0.118% were achieved under optimal conditions (pH of 9.16, Mg/N of 1.3, and P/N of 1.165). Besides, the morphology of the precipitation sample under the optimal condition was confirmed as struvite crystals by XRD and SEM, and the Cr content of the recovered struvite meets the requirements of fertilizer. This paper demonstrated the reliability and validity of direct recover ammonia nitrogen by struvite precipitation from the vanadium-extracted effluent. Moreover, it provided practical support for an effective way on Cr(VI) separation and resources recovery from high hexavalent chromium and ammonia nitrogen complicated effluent like hazardous vanadium-extracted effluent.

高氨氮、高六价铬的危险提钒废水难以实现资源分离和回收。应用基于 Box-Behnken 设计 (BBD) 的响应面法 (RSM) 进行多目标优化，以最大化氨氮回收率 ( R (N), %) 并最小化 Cr 负载量 ( L (Cr), %)在鸟粪石沉淀过程中实现从提钒废水中分离Cr(VI)和资源回收。响应变量被两个二阶多项式模型正确预测，R (N)为98.87%，L在最佳条件下（pH 值为 9.16，Mg/N 为 1.3，P/N 为 1.165），(Cr) 达到 0.118%。此外，优化条件下沉淀样品的形貌经XRD和SEM证实为鸟粪石晶体，回收的鸟粪石Cr含量满足肥料要求。本文论证了从提钒流出物中鸟粪石沉淀直接回收氨氮的可靠性和有效性。为从高六价铬和氨氮复杂的出水如危险的提钒出水中分离和回收六价铬的有效途径提供了实际支持。