A review on nanomaterial contaminants and their removal from industrial and municipal wastewater by conventional filtration and ultrafiltration membrane techniques

Naturally existing and manufactured nanomaterials (NMs) are increasingly used for domestic and industrial applications due to their excellent properties. These NMs end up being nanocontaminants in municipal and industrial wastewater through different ways, which include domestic drainage systems, industrial effluent, and surface runoff from soils. Most of the NMs have a negative effect on the environment and impose threats to human life due to their toxicity. Treatment methods have been established, and some are still being developed to remove NMs from wastewater. Generally, this review highlights the origins of NMs, their deposition into municipal and industrial wastewater and their removal from wastewater by conventional filtration and membrane techniques. It further indicates the improvements in water filtration in terms of removal of NMs using conventional filtration and the current membrane filtration techniques. The conventional filtration methods, which include coagulation, flocculation, sedimentation, and granular filtration, exhibit lower removal efficiency of NMs compared with hybrid membranes systems, which are more advanced.