Metals in Occluded Water: A New Perspective for Pollution in Drinking Water Distribution Systems

Abstract

Occluded water is water that remains inside corrosion scales within deteriorating distribution pipes. The accumulation of iron and manganese in the occluded water is a potential risk for water quality. Thus, this study investigated the change in metal (iron, manganese, copper and chromium) concentration in occluded water, the effect of these metals on the flowing water, and the source of iron and manganese in the occluded water using a simulation device. The results showed that total iron and total manganese were enriched in the occluded water, while the concentrations of total copper and total chromium in the occluded water gradually decreased over time. The iron and manganese in the occluded water migrate to the flowing water causing pollution in the flowing water. Also, copper and chromium adsorb on the corrosion scales within the pipes. The iron and manganese in the occluded water mainly came from the corrosion of the metal pipes, and the corrosion scales had a certain obstructive effect on the outward migration of iron in the occluded water but had less hindrance to the migration of manganese. Occluded water plays a critical role in the pollution of drinking water, and additional work is needed to control metal accumulation and release.

Characterization of Metallic Off-Flavors in Drinking Water: Health, Consumption, and Sensory Perception

“…Reported population thresholds for metallic flavor of ferrous iron range from 0.03 to 0.5 mg/L among individuals with varying sensitivities and ages [ 6 , 56 ], while for cupric copper, reported population thresholds range from 0.4 to 2.5 mg/L [ 57 , 58 ]. Recognizing the findings from previous studies that indicate metallic flavor sensations from foods and beverages are associated with the detection of odorous by-products of LO [ 4 , 8 , 21 ] upon interaction with salivary fluid, metallic flavor detection thresholds for Fe(II) and Cu(II) are consistent with their respective LO profiles as demonstrated by this study. For Fe(II), LO became measurable by the TBARS method at a concentration of 0.5 mg/L (9 µM), while for Cu(II), LO was measurable at a concentration of 5.7 mg/L (90 µM), approximately 10 times greater than that of Fe(II).…”

“…They are associated with many taste complaints among drinking water consumers as indicated in a survey of North American utilities [ 3 ]. They can be caused by corrosion of iron or copper [ 4 , 5 ] pipes in water distribution systems or occurrence of ferrous iron in groundwater [ 6 , 7 ]. In human sensory studies, perceived flavors of iron and copper have been characterized as metallic, salty, bitter, and astringent [ 8 , 9 , 10 , 11 ].…”

Level of Heavy Metals and Pathogenic Bacteria in Tap Water of Rusafa side Hospitals in Baghdad

“…The four hospitals are either inside or on the outskirts of Al-Sadr City, which has a very high population density and a low economic level. Figure (1) depicts the location of the hospitals included in the study in relation to Al-Sadr City and Baghdad in general.…”

“…Table (1) shows the average values of chemical and physical specifications of tap water collected from different hospitals in Rusafa, Baghdad, Iraq. Table 1 demonstrates that all values were within the normal levels determined by WHO published reports, confirming that the water supplied through the pipe network within the study area was within acceptable levels that did not negatively affect the public health of its consumers.…”

“…Water quality has a significant impact on the occurrence of many diseases and epidemics. As a result, maintaining good drinking water quality specifications will have a positive impact on the health of those who consume water [1]. The World Health Organization (WHO) emphasizes the importance of water education, as it is an important factor in transmitting many diseases, and it has published a number of periodicals in which it has set appropriate standards for drinking water [2].…”