# An Overview of Nanofiltration and Nanoadsorption Technologies to Emerging Pollutants Treatment
###### Abstract  
The presence of emerging contaminants in water resources has been a global concern due to their environmental impact and effects on human and animal health. These compounds include pharmaceuticals and personal care products, pesticides, fire retardants, hormones, and plasticizers, among others. These contaminants are not completely removed during water and wastewater conventional treatment. Thus, alternative processes are necessary to face this issue. In this context, nanotechnology represents a promising strategy for the remediation of emerging contaminants. Nanostructured materials have highlighted properties, such as adsorption capacity and porosity, chemical stability, reactivity, mobility, and antimicrobial activity. The diversity of nanomaterials and the possibility of combining them contribute to their application in contaminant mitigation. Furthermore, they can be used in different removal techniques such as adsorption, and membrane filtration. Thus, this review article provides an overview and advances in the production and application of nanofiltration membranes and adsorbent nanomaterials for the treatment of effluents containing emerging pollutants. carbon-based nanomaterials; metal-based nanoadsorbents; nanofiltration membranes; surface area; surface modification +
Footnote †: journal: Medical Engineering  
1 Laboratory of Microbiology and Biochemistry, College of Chemistry and Food Engineering, Federal University of Rio Grande, Rio Grande 96203-900, RS, Brazil 1  
T.D., Z., M., and A. A., and J. A., and J.  
addition to the discharge of effluents by industries, many compounds from fire retardants can be released into the environment by industrial emissions and undergo atmospheric deposition, reaching water resources [9]. Recent studies have assessed the contamination and ecological risks of contaminants present in water resources in different countries [7; 8; 10; 11]. Even at low concentrations, these pollutants can resist biological and chemical degradation. This feature makes it difficult to treat water and effluents using conventional processes and natural attenuation systems [4; 6]. Limitations in treatments are mainly due to the complexity of contaminants, selectivity of treatment technologies, and possible formation of unwanted by-products [2; 12]. Physical, chemical, biological, and hybrid technologies can be used to treat emerging pollutants [5]. The use of activated sludge, commonly used to reduce the organic load, is not recommended for removing emerging contaminants, especially those in low concentrations. Concerning activated sludge systems, biological membrane reactors have higher efficiency, from 15 to 42%. However, hybrid systems must be used to remove these pollutants. In this sense, the main techniques used for treating these pollutants are conventional/advanced oxidation processes, adsorption, or their combination with biological processes [13]. Adsorption systems offer good recovery of drugs, pesticides, and personal care products, even when present in low concentrations. Biological treatments such as the construction of wetlands showed good efficiency in removing drugs such as ibuprofen (74-99%), ketoprofen (47-91%), naproxen (76-97%), diclofenac (24-93%), tramadol (54-85%), paracetamol (95-100%), atenol (58-99%), metoprolol (60-93%), furosemide (80-96%), triclosan (62-91%), gabapentin (53-88%), and caffeine (93-99%) [14]. Although many of these methods present satisfactory performance in emerging contaminants treatment, problems such as high costs, equipment maintenance, treatment time, and energy demand are restrictions that must be addressed. These problems can influence the cost-effectiveness, large-scale application, and the total elimination of these substances from the environment [5; 12; 15]. In this context, nanotechnology can be considered a quick and efficient option to overcome the challenges of conventional and unconventional water treatment methods [16; 17].