Evaluation of The Factors Affecting Microplastics and Nanoparticles in Plastic Water Supply Pipes

Abstract

Water distribution system (WDS) supplies good quality water to individual households. It can affect the water quality, human health, and hence the role of WDS on the water quality must be investigated. Various pipe materials have been used in WDS. However, plastic materials have been commonly used recently in pipe networks because of their low cost, durability, and other advantages. Even though plastic pipes are preferred, the supplied water can be contaminated. Disintegration of plastic particles in the form of microplastics can be a cause of concern. Although their effects on human health are still unclear, it is perceived to have a negative effect on both organisms and ecosystems. The overall aim of this thesis is to identify the presence and source of microplastics and nanoparticles in the drinking water distribution system and to investigate the effect of several parameters (pipe material, pH, chlorine and time) on the leaching of microplastics and nanoparticles. Three standard pipe loop systems were used as the experimental setup, each having a different pipe material (polyvinylchloride (PVC), polyethylene (PE), and polypropylene (PPR)). A total of twenty-seven experiments were conducted at three phases. The pH was fixed for each phase, while varying the chlorine doses, in order to study their effects on leaching microplastics and nanoparticles. Standard analytical methods were used to evaluate relevant water quality parameter. Both the visual and spectroscopic detection methods were used to identify microplastics and nanoparticles. Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Analysis (EDX) tests were conducted to evaluate whether the microplastics and nanoparticles are formed from the plastic pipe materials of the WDS. Results show that microplastics and nanoparticles were significantly present in the samples in different shapes and sizes. It was found that basic pH values resulted in high number of particles. As for free chlorine, no specific conclusion could be drawn. Overall, PE had the highest number of particles, followed by PPR and PVC. It was also noticed that the number of particles decreased with time. FTIR and SEM-EDX analysis was not conclusive.