Removal of microplastics by membrane filtration and organic pollutants by UV-B and UV-C LED based technologies for water purification

Abstract

In the big challenge of water contamination, the presence of contaminants of emerging concern (CECs) in treated water poses a risk to the safety of the environment and the health of the human being. Existing treatment plants have been proven inadequate in removing these CECs, which are being introduced into the environment, nonetheless. Their detection in wastewater, aquatic environments, and drinking water requires implementing adequate measures and elimination processes to avoid their impact on humans and ecosystems. Additionally, the increase in human pollution and natural disasters due to climate change is negatively affecting the water available. The peculiarity of these contaminants is also that they are not subjected to specific regulations in drinking water and are not controlled by standard legislation; thus, more effort is needed to prevent and reduce their occurrence. As a result, it is crucial to increase water resilience, and it is important to act at drinking water treatment plants, if not directly at tap water, considering the several routes of these contaminants into the environment. It is also essential to develop specific and optimised strategies to remove CECs, including, among others, microplastics (MPs) and organic compounds such as pharmaceuticals and personal care products. MPs are defined as plastic particles smaller than 5 mm and gained great concern due to their ubiquitous and abundant presence in the water. There is also evidence that MPs act as vectors of various contaminants due to their additives and ability to sorb and accumulate toxic organic and inorganic pollutants on their surface. Moreover, because of their plastic nature, they take a very long time to biodegrade, and their small size makes them easily ingested. Among the engineered technologies explored for removing MPs, membranes have received considerable attention thanks to their simple implementation and stable effluent quality. The technology can be cost-effective and easily implemented depending on the membrane characteristics and the configuration. In this work, microfiltration was selected due to its simple implementation and the lowest operational energy costs compared to the other membrane processes. However, membrane fouling is a representative problem, and its mechanism and kinetic should be evaluated to help develop appropriate filtration and cleaning procedures and increase the efficiency of MPs removal. Filling the gap would encourage and allow the safe implementation of the system in our daily water treatments, including in household systems.