DOI: 10.14457/tu.the.2020.94
title: Micro-plastics contamination in drinking water: case study of Phnom Penh

description: Global plastic consumption is increasing tremendously each year and is expected to continue growing, making it a critical problem. It is known that large plastic debris can eventually break down to form micro-plastics (MPs) under certain environmental conditions. These micro-plastics (MPs) contaminate drinking water. This contamination has become a global concern, and many researchers have shown the negative impacts of this contamination on human health. This study illustrates the presence of MPs in Cambodia in different sources of drinking water, including drinking water treatment plants (WTPs), tap water, and bottled drinking water.Bottled water samples (plastic and glass bottles) were purchased from supermarkets and grocery stores in Phnom Penh, while tap water samples were collected from households. Two main drinking water treatment plants, Chroy Chongva (WTP1) and Phum Prek (WTP2), were selected for this study. Samples were collected from the inlet, sedimentation, sand filtration and distribution tanks of the two treatment plants. The MPs were analysed for the sizes of the particles present: 6.5-20, 20-53, 53-500, and &gt;500 micrometer (μm). The quantification of particles was carried out using an optical microscope and a fluorescence microscope (Nile Red tagging). The polymers were identified using Fourier transform infrared spectroscopy (FT-IR) for particles with size fractions of 53-500 and &gt;500 μm. Additionally, μ-FT-IR was also used to identify polymers within the size fraction of 6.5-20 and 20-53 μm.For the treatment plant samples, the MPs counted were 1180.5±158 p/L in the inlet, and 521±61 p/L in the distribution tank of WTP1. MPs in WTP2 were 1463±126 p/L in the inlet, and 617±147 p/L in the distribution tank. This result comprised average removal of 55.9% and 57.8% in WTP1 and WTP2, respectively. Sedimentation and filtration tanks of both treatment plants contributed to the highest removal efficiency. MPs counted in water samples from taps for all size fractions were 598±35 p/L, which is similar to MPs concentration in the effluence of WTP2, which is the origin of this water source. For bottled water, MPs were found in every sample and type of packaging. Moreover, plastic bottled water samples contained a higher proportion of MPs than samples obtained from glass bottles. The average concentration of particles found in plastic and glass bottled water was 230±63 p/L and 135.5±23 p/L, respectively. One 20-liter plastic bottle showed a much higher particle concentration of 374±42 p/L. The smallest particle size fraction always predominated in every sample, while fiber and fragment were abundantly found in bottled water samples and treatment plant samples, respectively. Polymers like PE and PET were commonly present, followed by some other types such as PP, PES, PA and others in much lower distribution.The findings of this study provide proof that different types of drinking water in Cambodia are contaminated with MPs which are being easily ingested through daily use. As per our findings, distribution seems predominantly toward the least size fraction. Further studies are required to observe particle size fractions smaller than the range we looked at and to propose methods to reduce contamination in all the sources of drinking water.