Nanotechnology in Wastewater Management: A New Paradigm Towards Wastewater Treatment

Abstract

Clean and safe water is a fundamental human need for multi-faceted development of society and a thriving economy. Brisk rises in populations, expanding industrialization, urbanization and extensive agriculture practices have resulted in the generation of wastewater which have not only made the water dirty or polluted, but also deadly. Millions of people die every year due to diseases communicated through consumption of water contaminated by deleterious pathogens. Although various methods for wastewater treatment have been explored in the last few decades but their use is restrained by many limitations including use of chemicals, formation of disinfection by-products (DBPs), time consumption and expensiveness. Nanotechnology, manipulation of matter at a molecular or an atomic level to craft new structures, devices and systems having superior electronic, optical, magnetic, conductive and mechanical properties, is emerging as a promising technology, which has demonstrated remarkable feats in various fields including wastewater treatment. Nanomaterials encompass a high surface to volume ratio, a high sensitivity and reactivity, a high adsorption capacity, and ease of functionalization which makes them suitable for application in wastewater treatment. In this article we have reviewed the techniques being developed for wastewater treatment using nanotechnology based on adsorption and biosorption, nanofiltration, photocatalysis, disinfection and sensing technology. Furthermore, this review also highlights the fate of the nanomaterials in wastewater treatment as well as risks associated with their use.

Keywords: adsorption and biosorption; carbon; disinfection; metals; nanofilters; nanotechnology; photocatalysis; sensors; wastewater treatment; zeolites.

Figure 1

Various sources of wastewater.

Figure 2

Typical composition of sewage water.

Figure 3

Graphical representation of structure and absorption sites of graphene sheets (Reproduced with permission from [65]).

Figure 4

Graphical representation of (A) excitation of a nanophotocatalyst during the photocatalytic process; (B) photocatalytic treatment of polluted water and recovery of nanophotocatalyst (Reproduced with permission from [130]).

Figure 5

Schematic presentation of the different mechanisms of antimicrobial action of nanomaterials (Reproduced with permission from [161]).

Figure 6

Mechanisms of cell damage by NPs. (1) Physical damage of membranes. (2) Structural changes in cytoskeleton components. (3) Disturbance of transcription and oxidative damage of DNA. (4) Damage of mitochondria. (5) Disturbance of lysosome functioning. (6) Generation of reactive oxygen species. (7) Disturbance of membrane protein functions. (8) Synthesis of inflammatory factors and mediators (Reproduced with permission from [189]).