3. Results and discussions
3.1. Lead
Table 3 summarizes the concentrations of Pb in the wastewater samples collected from in-let, out-let and different cells of CW. In the wastewater samples, Pb concentrations ranged from 0.78 to
1.56 mg/L and exceeded the permissible limit (0.5 mg/L) set for industrial and sewage wastewater (Pak-EPA, 2000). The ANOVA analyses showed that the concentration of Pb in the out-let wastewater samples was significantly lower (P < 0.001) than in-let of the CW, indicating that the wetland has efficiently removed Pb
from the wastewater. Pb concentrations ranged from 1.0 to 2.9 mg/ kg in the sediment samples (Table 4). In the sediment samples, Pb concentrations were decreased as the distance increased from the in-let and the interaction between concentrations and distance was significant (P < 0.01) only for in-let and out-let samples. A strong
decrease in Pb concentrations in the sediments was also reported
by Lesage et al. (2007). The removal performance of the CW was different for all selected HMs. The Pb removal efficiency of the CW was 50%, higher than those (33%) reported in the literature (Ter- zakis et al., 2008). In the study conducted by Lesage et al. (2007), Pb removal efficiency of a CW was 81%. This can be attributed to the