State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, Jiangsu, PR China.
J Hazard Mater. 2010 Apr 15;176(1-3):444-50. doi: 10.1016/j.jhazmat.2009.11.049. Epub 2009 Nov 13.
Phosphorus removal and recovery by ferric phosphate (FePO(4) x 2 H(2)O) precipitation has been considered as an effective technology. In the present study, we examined chemical precipitation thermodynamic modeling of the PHREEQC program for phosphorus removal and recovery from wastewater. The objective of this research was to employ thermodynamic modeling to evaluate the effect of solution factors on FePO(4) x 2 H(2)O precipitation. In order to provide comparison, with the evaluation of thermodynamic modeling, the case study of phosphate removal from anaerobic supernatant was studied. The results indicated that the saturation-index (SI) of FePO(4) x 2 H(2)O followed a polynomial function of pH, and the solution pH influenced the ion activities of ferric iron salts and phosphate. The SI of FePO(4) x 2 H(2)O increased with a logarithmic function of Fe(3+):PO(4)(3-) molar ratio (Fe/P) and initial PO(4)(3-) concentration, respectively. Furthermore, the SI of FePO(4) x 2 H(2)O decreased with a logarithmic function of alkalinity and ionic strength, respectively. With an increase in temperature, the SI at pH 6.0 and 9.0 decreased with a linear function, and the SI at pH 4.0 followed a polynomial function. For the case study of phosphate removal from anaerobic supernatant, the phosphate removal trend at different pH and Fe/P was closer to the predictions of thermodynamic modeling. The results indicated that the thermodynamic modeling of FePO(4) x 2 H(2)O precipitation could be utilized to predict the technology parameters for phosphorus removal and recovery.
通过磷酸铁（FePO4·2H2O）沉淀去除和回收磷已被认为是一种有效的技术。本研究采用 PHREEQC 程序的化学沉淀热力学模型，考察了从废水中去除和回收磷的方法。本研究的目的是利用热力学模型来评估溶液因素对 FePO4·2H2O 沉淀的影响。为了提供比较，我们在评价热力学模型的基础上，研究了从厌氧上清液中去除磷酸盐的实例。结果表明，FePO4·2H2O 的饱和度指数（SI）随 pH 的多项式函数变化，溶液 pH 影响铁盐和磷酸盐的离子活度。FePO4·2H2O 的 SI 随 Fe3+：PO43-摩尔比（Fe/P）和初始 PO43-浓度的对数函数增加。此外，FePO4·2H2O 的 SI 随碱度和离子强度的对数函数降低。随着温度的升高，在 pH 6.0 和 9.0 时 SI 随线性函数降低，在 pH 4.0 时 SI 遵循多项式函数。对于从厌氧上清液中去除磷酸盐的实例研究，不同 pH 和 Fe/P 条件下的磷酸盐去除趋势更接近热力学模型的预测。结果表明，FePO4·2H2O 沉淀的热力学模型可用于预测去除和回收磷的技术参数。
