Department of Natural Resources and Environmental Design, North Carolina A&T State University, Greensboro, NC, USA.
Water Sci Technol. 2010;61(3):599-606. doi: 10.2166/wst.2010.861.
Constructed wetland systems have gained attention as attractive solutions for wastewater treatment. Wetlands are not efficient to treat wastewater with high concentrations of phosphorus (P). In order to remove high soluble P loads by wetland, sorbent beds can be added prior to the discharge of wastewater into wetlands. Sorption by sorbent materials is identified as a method for trapping excess P in wastewaters. In the present investigation, shale has been identified as a sorbent material for removal of phosphate (PO(4)-P) due to the cost effectiveness, stability and possibility of regeneration. The study focuses on the removal of PO(4)-P from wastewater using shale and the feasibility of using the P-sorbed material as slow-release fertilizer. Phosphorus sorption experiments were conducted by using shale (2 mm and 2-4.7 mm). Results indicate that Shale I (particle size = 2 mm) showed the highest sorption of PO(4)-P (500 +/- 44 mg kg(-1)). Breakthrough point was reached within 10 h in columns with flow rates of 2 and 3 ml min(-1). Lower flow rate of 1 ml min(-1) showed an average residence time of about 2 h while columns with a higher flow rate of 3 ml min(-1) showed a residence time of about 40 minutes. Variation in flow rate did not influence the desorption process. Since very low concentrations of PO(4)-P are released, Shale saturated with PO(4)-P may be used as a slow nutrient release source of P or as a soil amendment. The sorbent can also be regenerated by removing the sorbed PO(4)-P by using 0.1 N HCl.
人工湿地系统作为处理废水的有吸引力的解决方案已经引起了人们的关注。湿地对于处理高浓度磷（P）的废水效率不高。为了通过湿地去除高溶解性 P 负荷，可以在将废水排放到湿地之前添加吸附床。吸附剂材料的吸附被认为是一种捕获废水中过量 P 的方法。在本研究中，由于成本效益、稳定性和再生可能性，页岩已被确定为一种用于去除磷酸盐（PO 4 -P）的吸附剂材料。本研究重点研究了利用页岩从废水中去除 PO 4 -P 以及将吸附 P 的材料用作缓释肥料的可行性。通过使用页岩（2 毫米和 2-4.7 毫米）进行了磷吸附实验。结果表明，页岩 I（粒径=2 毫米）对 PO 4 -P 的吸附量最高（500±44mgkg -1 ）。在流速为 2 和 3mlmin -1 的柱中，在 10 小时内达到了突破点。流速较低的 1mlmin -1 的平均停留时间约为 2 小时，而流速较高的 3mlmin -1 的柱的停留时间约为 40 分钟。流速的变化并不影响解吸过程。由于 PO 4 -P 的释放浓度非常低，因此可以将饱和 PO 4 -P 的页岩用作缓慢释放 P 的养分源或作为土壤改良剂。也可以通过使用 0.1N HCl 去除吸附的 PO 4 -P 来再生吸附剂。
