Contamination from plastic pipes in small systems: migration and leaching

Abstract

In recent years, extensive laboratory-scale research has focused on the biofilm formation, leaching, and migration of organic chemical compounds from plastic pipes into drinking water. This research has been conducted on an existing distribution network in three rural villages near the dead ends to study the small diameter pipes associated with stagnant or low flow conditions. The distribution network was constructed more than ten years ago using unplasticized polyvinyl chloride pipes. Samples of water, soil, and aged pipes have been collected and tested in the laboratory. Results showed a heavy biofilm formed on the inner surfaces of the uPVC pipes. The biofilm has resulted in high concentrations of trihalomethanes, total organic carbon, and PAHs in the drinking water. The predominant PAHs were the acenaphthylene followed by the naphthalene, while no PAHs have detected at the source. The SEM images showed deterioration of pipe walls, swelled parts, and pores. The EDX confirms the migration of some elements including O, Cl, Ca, Ti, Mg, Fe and K due to the biodegradation of the pipe material and the Ca/Zn stabilizers. However, PAHs released from the plastic pipes into the flowing water are caused by metabolic activities. In addition, results showed that the surrounding soil has classified as having low organic content. Hence, uPVC pipes need protection or change in the manufacturing processes to reduce their hazards in distribution networks over time.