Opportunities, challenges and future prospects of carbon nanotubes-infused nanocomposite membranes in complex industrial wastewater treatment: A systematic review

Harmful effects of wastewater have become more pronounced recently as the population experiences unprecedented growth resulting in generation of high volumes of complex wastewater. The low-level existence of Per-and polyfluoroalkyl substances (PFASs) in the environment has caused alertness as they bioaccumulate, they are persistent and have a potential to cause endocrine disrupting in humans and animals. The other contaminants such as oils, salts and aromatics also have pronounced negative effects on humans and the ecosystems health. These contaminants are main constituents of complex industrial wastewater, which is difficult to treat as such most studies focus on treating specific contaminant or a particular class of contaminants in wastewater rather than focusing on removing all kinds of contaminants from industrial effluents. To deal with this issue of treating complex industrial effluents sophisticated novel treatment alternatives are needed. Membrane technology has proved to be an answer to this issue of complex industrial wastewater. This method is gradually replacing conventional methods in treatment of industrial wastewater as it is efficient, capable of removing both organic and inorganic contaminants, economical and environmentally friendly as compared to conventional methods. There is limited literature on treatment of complex wastewater to remove all contaminants in the wastewater. This is mainly due to the complexity of this kind of wastewater. To treat it fully, one must have complete knowledge about it, its chemistry, characteristics of its constituents and how they interact with each other. This complexity of this kind of wastewater has led to most studies in wastewater treatment focusing on one class of contaminants within wastewater. This has opened gap on information about complex wastewater and treatment methods suitable for treating this kind of wastewater. The main objective of this review is to investigate current literature on the performance of carbon nanotubes (CNTs)-infused nanocomposites membranes in the treatment of complex wastewater. Specific focus is on constituents of complex wastewater in South African freshwater bodies. Moreover, the comparisons and contrasts in performance of different treatment methods that are used to remove PFASs in water are given. The review highlights contaminants removal mechanisms of CNTs-infused nanocomposites membranes. It provides insights on how to optimize performance of nanocomposites. Economic and environmental aspects of nanocomposite membranes are discussed in this paper. This paper aims at furthering on research gaps and area of improvement in nanocomposite membrane-based treatment.