Drizo Aleksandra, Comeau Yves, Forget Christiane, Chapuis Robert P
Department of Civil, Geological and Mining Engineering, Ecole Polytechnique of Montreal, Quebec, Canada.
Environ Sci Technol. 2002 Nov 1;36(21):4642-8. doi: 10.1021/es011502v.
Phosphorus (P) adsorption capacities of materials derived from batch experiments can vary by several orders of magnitude depending on the method used, leading to potential misinterpretation of the P retention capacity on a long-term basis and unrealistic estimations of constructed wetland systems (CWS) longevity. The objective of this study was to determine if the P saturation of the material in a column could be used for this purpose with an improved accuracy. A 278-d column experiment with a synthetic P solution was conducted to investigate the long-term P retention capacity of electric arc furnace (EAF) steel slag up to its P saturation point. EAF slag showed a high affinity for P, reaching a saturation value of 1.35 g of P kg(-1). Investigations of the regeneration of the P adsorbing capacity by this material showed that, after 4 weeks of water desaturated resting, EAF steel slag was able to increase its initial P adsorptive capacity to 2.35 g of P kg(-1). A sequential P fractionation experiment was performed to quantify the proportion of P bound to mineral compounds in EAF. From the most loosely bound to the most strongly bound P fraction, P was associated with resin extractable (14%), Fe extractable (0.5 M Na2CO3, 47%), Al extractable (0.1 M NaOH, 1%), Ca extractable (1 M HCl, 12%), and Ca in a stable residual pool (concentrated hot HCl, 26.5%). X-ray fluorescence analyses of EAF steel slag chemical composition revealed that the continuous application of a P solution resulted in 75% and 59% increases in K2O and P2O5 respectively; Al2O3 and FeO increased by 8%, while the portion of CaO remained unchanged. The investigated properties (P retention potential, regeneration of P adsorption, P fractionation) provide useful data about the suitability of slag material as a media for long-term P removal and should enable an improved prediction of the longevity of full-scale CWS.
批量实验所得材料的磷（P）吸附能力可能因使用的方法不同而相差几个数量级，这可能导致对磷长期保留能力的潜在误解以及对人工湿地系统（CWS）寿命的不切实际估计。本研究的目的是确定柱中材料的磷饱和度是否可用于此目的并提高准确性。进行了一项为期278天的合成磷溶液柱实验，以研究电弧炉（EAF）钢渣直至其磷饱和点的长期磷保留能力。电弧炉钢渣对磷表现出高亲和力，达到1.35 g P kg⁻¹的饱和值。对该材料磷吸附能力再生的研究表明，经过4周的水不饱和静置后，电弧炉钢渣能够将其初始磷吸附能力提高到2.35 g P kg⁻¹。进行了连续磷分级实验以量化电弧炉中与矿物化合物结合的磷的比例。从结合最松散到结合最强的磷组分来看，磷与树脂可提取部分（14%）、铁可提取部分（0.5 M Na₂CO₃，47%）、铝可提取部分（0.1 M NaOH，1%）、钙可提取部分（1 M HCl，12%）以及稳定残留池中钙（浓热HCl，26.5%）相关。电弧炉钢渣化学成分的X射线荧光分析表明，持续施加磷溶液分别导致K₂O和P₂O₅增加75%和59%；Al₂O₃和FeO增加8%，而CaO的比例保持不变。所研究的特性（磷保留潜力、磷吸附再生、磷分级）提供了有关炉渣材料作为长期除磷介质适用性的有用数据，并且应该能够改进对全尺寸人工湿地系统寿命的预测。
