Engineered nanoparticles (ENPs) present in natural water systems and wastewater treatment plants, due to their wide use in industrial products and consumer goods, represent a hazard to human health, especially if occur in surface waters used for human consumption. Different nanoparticles may co-exist in the natural waters and until now no works have been developed on the impact of the co-existing nanoparticles on water treatment processes. Thus, this work evaluates the removal of different co-existing metal-based ENPs (TiO₂, Ag and CuO) from natural surface waters applying the most used water treatment process, coagulation/flocculation/sedimentation (C/F/S). Results showed that C/F/S is effective in the removal of the co-existing ENPs from the studied hydrophilic natural waters (low/medium turbidity and moderate/moderate-high natural organic matter content) with efficiencies above 93% for TiO₂, Ag and CuO nanoparticles. The formation of destabilised nanoparticle-organic matter aggregates in C/F promoted their precipitation. For the lowest turbidity and organic content water, Ti presented the lowest concentration, followed by Ag and Cu, because of titanium properties. For the highest turbidity and organic content water, the residual Cu concentration was the lowest and Ag the highest, due to the natural water characteristics. Water characteristics played an important role on the coagulant demand and removal of ENPs mixture by C/F/S. Results also demonstrated that ENPs mixture did not hampered the treated water quality for turbidity and natural organic matter. For the lowest turbidity and natural organic matter water, ENPs appear to contribute to a higher removal of these parameters.

天然水系统和废水处理厂中存在的工程化纳米颗粒（ENP），由于它们广泛用于工业产品和消费品中，对人体健康构成了危害，尤其是在人类食用地表水中存在的情况下。天然水中可能会共存不同的纳米粒子，到目前为止，尚无关于共存纳米粒子对水处理过程影响的研究。因此，这项工作评估了不同的共存金属基ENP（TiO ₂（Ag和CuO），天然地表水，采用最常用的水处理工艺（混凝/絮凝/沉淀（C / F / S））。结果表明，C / F / S可有效去除亲水性天然水中共存的ENP（低/中浊度和中/中等-高天然有机物含量），对于TiO ₂效率高于93％，Ag和CuO纳米粒子。C / F中不稳定的纳米有机物聚集体的形成促进了它们的沉淀。对于最低的浊度和有机物含量，由于钛的特性，Ti的浓度最低，其次是Ag和Cu。对于最高浊度和有机含量的水，由于天然水的特性，残留的铜浓度最低，而银最高。水分特性对混凝剂的需求和C / F / S去除ENP混合物起着重要作用。结果还表明，ENPs混合物不会因浊度和天然有机物而影响处理后的水质。对于最低的浊度和天然有机物水，ENP似乎有助于这些参数的更高去除。