ABSTRACT
68The effectiveness of bank filtration (BF) is highly dependent on the source water quality (e.g., the organic matter composition, pH, temperature, and concentration of heavy metals (HMs)) and hydrogeological conditions at the subsurface. In this study, the impact of dissolved organic matter (DOM) on the removal of selected metals (Cu, Zn, Pb, Se, and Ni) during BF was investigated. Laboratory-scale column studies were conducted at 30 °C with feed water sources of different organic matter composition. The selected HMs were spiked at concentrations similar to their levels in surface waters. Fluorescence excitation–emission matrix coupled with parallel factor analysis (PARAFAC–EEM) was used to characterise the organic composition of the different feed waters. Moreover, another series of column studies was conducted to assess the impact of DOM type (humic, protein) and concentration on the removal of HMs. The experimental results revealed a high Pb(II) removal efficiency (> 90%) during filtration, which depends only slightly on the organic matter content of the feed water. In contrast, Cu(II), Zn(II), and Ni(II) exhibited relatively lower removal efficiencies (65%–95%) for the columns fed with different water sources. These removal efficiencies decreased considerably in the presence of humic compounds, regardless of their origin (terrestrial or microbial). On the other hand, the removal efficiency of Se(IV) increased as the concentration of biodegradable organic matter in the feed water increased, and a positive correlation was found between the Se(IV) removal efficiency and the protein-like fluorescence intensity (ρ = 0.72, p < 0.01). In general, it can be concluded that the organic composition of the source water affects profoundly the removal and sorption of HMs during the BF, and should be considered in the design of bank filtration systems.
