Migration of organic compounds leached from polymeric water supply networks in Madinah Al-Munawarah, Kingdom of Saudi Arabia

Abstract

Contamination of organic compounds from polymeric-based drinking water supply networks is a significant issue in Madinah Al-Munawarah, Kingdom of Saudi Arabia. Drinking water is found contaminated with various volatile organic compounds (VOCs) and phenols leached from polymeric pipes, polyethylene, crosslinked polyethylene and polyvinylchloride (PE, PEX and PVC). Due to their low cost and robustness, polymeric pipes have replaced the metallic piping in water distribution networks. In Saudi Arabia, the polymeric pipes are the main plumbing materials in residential units and domestic water networks. However, many concerns about the potential health damage of these materials have been raised up. Extremely high temperature in summer is anticipated to accelerate the migration of organic contaminants from polymeric pipes into tap water. Thus, the objectives of this study were to screen and investigate the occurrence of volatile organic compounds (VOCs), benzene, toluene, ethylbenzene, xylene, styrene (BTEXS) and phenols originated from home polymeric (PE, PEX and PVC) water supply networks, to determine the release of organic contaminants originated from home PVC polymer water supply network and to evaluate the efficiency of granular activated carbon (GAC) adsorbent in removing selected organic pollutants from tap water in the residential areas in Madinah Al-Munawarah, Kingdom of Saudi Arabia. The presence of organic pollutants was analysed from a total of 10 water samples collected from the storage tanks and 158 water samples that were collected from tap water from old and new residential units. Samples were processed using solid phase extraction as an eco-friendly sample preparation approach and the extracted molecules were analyzed by using gas chromatography equipped with flame ionization detector (GC-FID). The results show that migration of 31volatile organic compounds VOCs from home polymeric water supply networks were ranged from 1μg/L to 141μg/L, with the most significant contribution was observed from 2-butanone, benzene and 1,2,3-trichloropropane. Meanwhile, the levels of the eight organic pollutants such as 2-butanone, benzene, carbon tetrachloride, 1,2 dichloroethane, 1,2,3 trichloroethane, 1,2 dichlorobenzene, cis 1,3-dicholoropropane and trans 1,3-dichloropropane exceeded the World Health Organization (WHO) limits. For phenols, it was found that the concentrations of phenolic compounds were ranged from 2.02μg/L to 24.03μg/L, whereas, the level of pentachlorophenol exceeded the WHO limit. Pollutants removal using granular activated carbon (GAC) were also conducted to test the feasibility of this adsorbent materials to remove the migrated organic pollutants from tap water prior to consumption. The results demonstrate that the use of GAC filter could reduce the level of organic compounds in water significantly (> 90%), thus minimize the risk associated with them. It can be concluded that different types of polymeric pipes produce different levels of organic pollutants. Other important factors such as temperature, time of incubation, solvents and additives used in the manufacturing contribute to the variation in the level of organic contamination in the tap water. Future work needs to be explored to include cause-effect pathway and potential risk of these pollutants on human health damage.