Lei Jie, Peng Bing, Min Xiaobo, Liang Yanjie, You Yang, Chai Liyuan
a Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University , Changsha , China.
b Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution , Changsha , China.
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2017 Apr 16;52(5):449-458. doi: 10.1080/10934529.2016.1271668. Epub 2017 Jan 17.
This study focuses on the modeling and optimization of lime-based stabilization in high alkaline arsenic-bearing sludges (HAABS) and describes the relationship between the arsenic leachate concentration (ALC) and stabilization parameters to develop a prediction model for obtaining the optimal process parameters and conditions. A central composite design (CCD) along with response surface methodology (RSM) was conducted to model and investigate the stabilization process with three independent variables: the Ca/As mole ratio, reaction time and liquid/solid ratio, along with their interactions. The obvious characteristic changes of the HAABS before and after stabilization were verified by X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size distribution (PSD) and the community bureau of reference (BCR) sequential extraction procedure. A prediction model Y with a statistically significant P-value <0.01 and high correlation coefficient R = 93.22% was obtained. The optimal parameters were successfully predicted by the model for the minimum ALC of 0.312 mg/L, which was validated with the experimental result (0.306 mg/L). The XRD, SEM and PSD results indicated that crystal calcium arsenate Ca(AsO)OH and Ca(OH)(AsO)·4HO formation played an important role in minimizing the ALC. The BCR sequential extraction results demonstrated that the treated HAABS were stable in a weak acidic environment for a short time but posed a potential environmental risk after a long time. The results clearly confirm that the proposed three-factor CCD is an effective approach for modeling the stabilization of HAABS. However, further solidification technology is suggested for use after lime-based stabilization treatment of arsenic-bearing sludges.
本研究聚焦于高碱性含砷污泥（HAABS）中基于石灰的稳定化处理的建模与优化，并描述了砷渗滤液浓度（ALC）与稳定化参数之间的关系，以建立一个预测模型，从而获得最佳工艺参数和条件。采用中心复合设计（CCD）和响应面方法（RSM）对稳定化过程进行建模和研究，其中有三个自变量：钙/砷摩尔比、反应时间和液/固比，以及它们之间的相互作用。通过X射线衍射（XRD）、扫描电子显微镜（SEM）、粒度分布（PSD）和标准物质组（BCR）连续萃取程序验证了HAABS稳定化前后明显的特征变化。获得了一个预测模型Y，其P值具有统计学显著性（P<0.01）且相关系数R = 93.22%较高。该模型成功预测了使ALC最低达到0.312 mg/L的最佳参数，实验结果（0.306 mg/L）对其进行了验证。XRD、SEM和PSD结果表明，砷酸钙Ca(AsO)OH和Ca(OH)(AsO)·4HO晶体的形成在降低ALC方面发挥了重要作用。BCR连续萃取结果表明，处理后的HAABS在短时间内于弱酸性环境中是稳定的，但长时间后会带来潜在的环境风险。结果清楚地证实，所提出的三因素CCD是一种对HAABS稳定化进行建模的有效方法。然而，建议在对含砷污泥进行石灰基稳定化处理后采用进一步的固化技术。
