Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
Environ Sci Pollut Res Int. 2013 Jan;20(1):60-5. doi: 10.1007/s11356-012-1052-4. Epub 2012 Jul 6.
This research investigated the feasibility of changing waste into useful materials for water treatment and proposed a coagulation-magnetic separation technique. This technique was rapid and highly effective for clearing up harmful algal blooms in freshwater and mitigating lake eutrophication. A magnetic coagulant was synthesized by compounding acid-modified fly ash with magnetite (Fe(3)O(4)). Its removal effects on algal cells and dissolved organics in water were studied. After mixing, coagulation, and magnetic separation, the flocs obtained from the magnet surface were examined by SEM. Treated samples were withdrawn for the content determination of chlorophyll-a, turbidity, chemical oxygen demand (COD), total nitrogen, and total phosphorus. More than 99 % of algal cells were removed within 5 min after the addition of magnetic coagulant at optimal loadings (200 mg L(-1)). The removal efficiencies of COD, total nitrogen, and phosphorus were 93, 91, and 94 %, respectively. The mechanism of algal removal explored preliminarily showed that the magnetic coagulant played multiple roles in mesoporous adsorption, netting and bridging, as well as high magnetic responsiveness to a magnetic field. The magnetic-coagulation separation method can rapidly and effectively remove algae from water bodies and greatly mitigate eutrophication of freshwater using a new magnetic coagulant. The method has good performance, is low cost, can turn waste into something valuable, and provides reference and directions for future pilot and production scale-ups.
本研究探讨了将废物转化为用于水处理的有用材料的可行性，并提出了一种混凝-磁分离技术。该技术快速高效，可用于清除淡水中的有害藻类水华，并减轻湖泊富营养化。通过将酸改性粉煤灰与磁铁矿（Fe(3)O(4)）复合合成了磁性混凝剂。研究了其对水中藻类细胞和溶解有机物的去除效果。混合、混凝和磁分离后，用 SEM 检查了从磁铁表面获得的絮体。处理后的样品用于测定叶绿素-a、浊度、化学需氧量（COD）、总氮和总磷的含量。在最佳负载（200mg/L）下添加磁性混凝剂后，5 分钟内可去除超过 99%的藻类细胞。COD、总氮和磷的去除效率分别为 93%、91%和 94%。初步探索的藻类去除机制表明，磁性混凝剂在介孔吸附、网捕和桥接以及对磁场的高磁响应方面发挥了多种作用。磁混凝分离方法可以使用新型磁性混凝剂快速有效地从水体中去除藻类，极大地减轻淡水富营养化。该方法具有良好的性能、低成本、变废为宝的特点，为未来的中试和生产规模扩大提供了参考和方向。
