Assessment of selected heavy metals in some water treatment plants and household tap water in Greater Cairo, Egypt

Purpose - The purpose of this paper is to assess and monitor a sample of heavy metals, namely lead, cadmium and copper, in water treatment plants at Greater Cairo, Egypt, to assess the efficiency of water treatment plants for metals removal and to monitor lead concentrations in the distribution system.Design methodology approach - Water samples were collected from two water treatment plants. In addition, randomly flushed tap water samples from different districts at Greater Cairo were analyzed for lead concentration. Other water quality parameters also were monitored in water samples.Findings - The study indicated that for water treatment plant intake, the mean concentrations were 4.44, 0.38 and 5.54μg l for lead, cadmium and copper respectively. However, the final effluent shows that the mean concentrations of lead, cadmium and copper were 2.0, 0.15 and 2.78μg l respectively. The drinking water mean metals concentrations were below World Health Organization drinking water guidelines and the Egyptian drinking water standards. The results revealed that water-treatment plants have a high efficiency for metals removal where lead, cadmium and copper concentrations were reduced by 54.9, 60.5 and 49.8 per cent respectively. On the other hand, as expected, the water treatment plant sludge showed high accumulation with metals in concentrations decreased in the following order Fe > Mn > Zn > Cu > Cr > Ni > Pb > Cd. The mean lead concentration was 9.5μg l in tap water samples.Originality value - Water treatment plants have a high efficiency for metals removal; water treatment plant sludge contains high concentrations of metals and should be treated before discharge; lead contamination from the distribution system is well established and lead concentration in homes in studied areas were higher than concentrations in plant effluent.